Foamable dairy products

Abstract

The invention provides a dairy composition with improved aeration properties, where the dairy composition comprises a protein deamidase and optionally a second polypeptide derived from the propeptide of a protein deamidase proform. The invention further provides an improved method for producing aerated dairy products from dairy compositions, where a protein deamidase and optionally a second polypeptide derived from the propeptide of a protein deamidase proform- has been added to the dairy composition.

Description

[0001] FOAMABLE DAIRY PRODUCTS

[0002] Reference to sequence listing

[0003] This application contains a Sequence Listing in computer readable form. The computer readable form is incorporated herein by reference.

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to dairy products that are treated to enhance the foamability of the dairy product. The present invention also provides a method of treating the dairy product to enhance foamability.

[0006] BACKGROUND OF THE INVENTION

[0007] Cappuccino-style beverages, which typically feature a mix of coffee and milk and a head of milk foam on top, frequently with a design, or “latte art”, in the top layer of the foam, are very popular today. Milk provides both a creamy texture to the beverage and a smoothness to the foam. Typically, whole milk is used, and frequently preferred, for the beverage. However, many health-conscious consumers prefer a lower fat milk, particularly milks that contain less than 2% milkfat, or even skim milk, which contains a very minimal amount of milkfat. Unfortunately, it is difficult to produce a foam of the same quality using low fat milk or skim milk compared to a foam produced using whole milk. Additionally, sometimes even whole milk can be difficult to foam to a desirable consistency and texture.

[0008] SUMMARY OF THE INVENTION

[0009] The invention provides a dairy composition with improved aeration properties, where the dairy composition comprises a first polypeptide which is a mature protein deamidase and optionally a second polypeptide which is a propeptide derived from a protein deamidase proform. The invention further provides an improved method for producing aerated dairy products from dairy compositions, where a protein deamidase and optionally a second polypeptide derived from the propeptide of the protein deamidase proform has been added to the dairy composition. Unexpectedly, the presence of the propeptide in the dairy composition improves the foamability of the dairy composition, producing an improved aerated dairy product compared to a method where only the mature protein deamidase is added.

[0010] The invention also provides a method for improved foaming of a dairy composition, where the dairy composition comprises a first polypeptide which is a mature protein deamidase and optionally a second polypeptide which is a propeptide derived from a protein deamidase proform. The invention further provides a method for improving latte art produced from a dairy composition, where the dairy composition comprises a first polypeptide which is a mature protein deamidase and optionally a second polypeptide which is a propeptide derived from a protein deamidase proform.

[0011] SEQUENCES

[0012] SEQ ID NO: 1 : Amino acid sequence of proform polypeptide of deamidase from Chryseobacterium viscerum comprising the propeptide variant of F99G.

[0013] SEQ ID NO: 2: Amino acid sequence of mature deamidase derived from SEQ ID NO: 1.

[0014] SEQ ID NO: 3: Amino acid sequence of propeptide from Chryseobacterium viscerum comprising F99 (wild-type).

[0015] SEQ ID NO: 4: Amino acid sequence of proform polypeptide of deamidase from Chryseobacterium gambrini.

[0016] SEQ ID NO: 5: Amino acid sequence of mature deamidase derived from SEQ ID NO: 4.

[0017] SEQ ID NO: 6: Amino acid sequence of propeptide derived from SEQ ID NO: 4.

[0018] SEQ ID NO: 7: Amino acid sequence of proform polypeptide of deamidase from Chryseobacterium culicis.

[0019] SEQ ID NO: 8: Amino acid sequence of mature deamidase derived from SEQ ID NO: 7.

[0020] SEQ ID NO: 9: Amino acid sequence of propeptide derived from SEQ ID NO: 7.

[0021] SEQ ID NO: 10: Amino acid sequence of proform polypeptide of deamidase from Chryseobacterium defluvii.

[0022] SEQ ID NO: 11 : Amino acid sequence of mature deamidase derived from SEQ ID NO: 10.

[0023] SEQ ID NO: 12: Amino acid sequence of propeptide derived from SEQ ID NO: 10.

[0024] SEQ ID NO: 13: Amino acid sequence of proform polypeptide of deamidase from Chryseobacterium proteolyticum.

[0025] SEQ ID NO: 14: Amino acid sequence of mature deamidase derived from SEQ ID NO: 13.

[0026] SEQ ID NO: 15: Amino acid sequence of propeptide derived from SEQ ID NO: 13.

[0027] SEQ ID NO: 16: Propeptide variant F99G of SEQ ID NO: 3.

[0028] SEQ ID NO: 17: Propeptide variant F99A of SEQ ID NO: 6.

[0029] SEQ ID NO: 18: Propeptide variant F99G of SEQ ID NO: 9.

[0030] SEQ ID NO: 19: Propeptide variant L101G of SEQ ID NO: 12.

[0031] SEQ ID NO: 20: Propeptide variant L100G of SEQ ID NO: 15.

[0032] SEQ ID NO 21 : Variant of SEQ ID NO: 4 comprising the propeptide variant of SEQ ID NO: 17.

[0033] SEQ ID NO 22: Variant of SEQ ID NO: 7 comprising the propeptide variant of SEQ ID NO: 18.

[0034] SEQ ID NO 23: Variant of SEQ ID NO: 10 comprising the propeptide variant of SEQ ID NO: 19.

[0035] SEQ ID NO 24: Variant of SEQ ID NO: 13 comprising the propeptide variant of SEQ ID NO: 20.

[0036] DEFINITIONS Deamidase: The term “deamidase” means a protein-glutamine glutaminase (also known as glu- taminylpeptide glutaminase) activity, as described in EC 3.5.1.44, which catalyzes the hydrolysis of the gamma-amide of glutamine substituted at the carboxyl position or both the alpha-amino and carboxyl positions, e.g., L-glutaminylglycine and L-phenylalanyl-L- glutaminylglycine. Thus, deamidases can deamidate glutamine residues in proteins to glutamate residues and are also referred to as protein glutamine deamidases. Deamidases comprise a Cys-His-Asp catalytic triad (e.g., Cys-156, His- 197, and Asp-217, as shown in Hashizume et al. “Crystal structures of protein glutaminase and its pro forms converted into enzyme-substrate complex”, Journal of Biological Chemistry, vol. 286, no. 44, pp. 38691-38702) and belong to the InterPro entry IPR041325.

[0037] Deamidase activity: Deamidase (protein glutaminase) activity was measured using the assay described in the Examples. The activity assay consists of two separate de-coupled parts: (1) an enzymatic step wherein ammonia is formed by the catalytic action of the protein deamidase; and (2) a non-enzymatic detection step, wherein the ammonia formed in step (1) is derivatized to a blue indophenol compound with an absorption maximum at 630 nm. The amount of enzyme producing 1 pmol ammonia per minute at 37°C is defined as 1 unit (given in Indophenol Assay Unit: IPA(U)). The activity may be determined relative to a standard of declared strength.

[0038] Deamidase Inhibitory Domain: The term “deamidase inhibitory domain” means a sequence of amino acids that interacts with the amino acid residues of the deamidase active site and inhibits or reduces the deamidase activity. For example, the deamidase activity can be reduced to less than 50%, preferably less than 40%, in the presence of the deamidase inhibitory domain (as compared to the deamidase activity without the presence of the deamidase inhibitory activity). cDNA: The term “cDNA” means a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic or prokaryotic cell. cDNA lacks intron sequences that may be present in the corresponding genomic DNA. The initial, primary RNA transcript is a precursor to mRNA that is processed through a series of steps, including splicing, before appearing as mature spliced mRNA.

[0039] Coding sequence: The term “coding sequence” means a polynucleotide, which directly specifies the amino acid sequence of a polypeptide. The boundaries of the coding sequence are generally determined by an open reading frame, which begins with a start codon, such as ATG, GTG, or TTG, and ends with a stop codon, such as TAA, TAG, or TGA. The coding sequence may be a genomic DNA, cDNA, synthetic DNA, or a combination thereof.

[0040] Control sequences: The term “control sequences” means nucleic acid sequences involved in regulation of expression of a polynucleotide in a specific organism or in vitro. Each control sequence may be native (i.e., from the same gene) or heterologous (i.e., from a different gene) to the polynucleotide encoding the polypeptide, and native or heterologous to each other. Such control sequences include, but are not limited to leader, polyadenylation, prepropeptide, propeptide, signal peptide, promoter, terminator, enhancer, and transcription or translation initiator and terminator sequences. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the polynucleotide encoding a polypeptide.

[0041] Expression: The term “expression” means any step involved in the production of a polypeptide including, but not limited to, transcription, post-transcriptional modification, translation, post- translational modification, and secretion.

[0042] Expression vector: An “expression vector” refers to a linear or circular DNA construct comprising a DNA sequence encoding a polypeptide, which coding sequence is operably linked to a suitable control sequence capable of effecting expression of the DNA in a suitable host. Such control sequences may include a promoter to effect transcription, an optional operator sequence to control transcription, a sequence encoding suitable ribosome binding sites on the mRNA, enhancers and sequences which control termination of transcription and translation.

[0043] Extension: The term “extension” means an addition of one or more amino acids to the amino and / or carboxyl terminus of a polypeptide, wherein the “extended” polypeptide has deamidase activity.

[0044] Fragment: The term “fragment” means a polypeptide having one or more amino acids absent from the amino and / or carboxyl terminus of the mature polypeptide, wherein the fragment has deamidase activity.

[0045] Fusion polypeptide: The term “fusion polypeptide” is a polypeptide in which one polypeptide of the invention is fused at the N-terminus and / or the C-terminus of another polypeptide of the invention. A fusion polypeptide is produced by fusing two or more polynucleotides encoding the polypeptides of the invention together. Techniques for producing fusion polypeptides are known in the art and include ligating the coding sequences encoding the polypeptides so that they are in frame and that expression of the fusion polypeptide is under control of the same promoter(s) and terminator. Fusion polypeptides may also be constructed using intein technology in which fusion polypeptides are created post-translationally (Cooper et al., 1993, EMBO J. 12: 2575-2583; Dawson et al., 1994, Science 266: 776-779). A fusion polypeptide can further comprise a cleavage site between the two polypeptides. Thus, the fusion polypeptides may comprise a cleavage site for a site-specific endopeptidase, for example within 20 amino acids, preferably within 10 amino acids, of the C-terminal end of the first polypeptide. Examples of well-known sitespecific endopeptidases include glutamyl endopeptidase (e.g., EC 3.4.21.19 or EC 3.4.21.82), trypsin- and chymotrypsin-like endopeptidases (incl. enteropeptidase). Many other examples of cleavage sites and the corresponding endopeptidases include, but are not limited to, the sites disclosed in Martin et al., 2003, J. Ind. Microbiol. Biotechnol. 3: 568-576; Svetina et al., 2000, J. Biotechnol. 76: 245-251 ; Rasmussen-Wilson et al., 1997, Appl. Environ. Microbiol. 63: 3488- 3493; Ward et al., 1995, Biotechnology 13: 498-503; and Contreras et al., 1991 , Biotechnology 9: 378-381 ; Eaton et al., 1986, Biochemistry 25: 505-512; Collins-Racie et al., 1995, Biotechnology 13: 982-987; Carter et al., 1989, Proteins: Structure, Function, and Genetics 6: 240-248; and Stevens, 2003, Drug Discovery World 4: 35-48.

[0046] Heterologous: The term “heterologous” means, with respect to a host cell, that a polypeptide or nucleic acid does not naturally occur in the host cell. The term “heterologous” means, with respect to a polypeptide or nucleic acid, that a control sequence, e.g., promoter, of a polypeptide or nucleic acid is not naturally associated with the polypeptide or nucleic acid, i.e., the control sequence is from a gene other than the gene encoding the mature polypeptide.

[0047] Host Strain or Host Cell: A “host strain” or “host cell” is an organism into which an expression vector, phage, virus, or other DNA construct, including a polynucleotide encoding a polypeptide of interest (e.g., an amylase) has been introduced. Exemplary host strains are microorganism cells (e.g., bacteria, filamentous fungi, and yeast) capable of expressing the polypeptide of interest and / or fermenting saccharides. The term “host cell” includes protoplasts created from cells.

[0048] Introduced: The term “introduced” in the context of inserting a nucleic acid sequence into a cell, means “transfection”, “transformation” or “transduction,” as known in the art.

[0049] Isolated: The term “isolated” means a polypeptide, nucleic acid, cell, or other specified material or component that is separated from at least one other material or component with which it is naturally associated as found in nature, including but not limited to, for example, other proteins, nucleic acids, cells, etc. An isolated polypeptide includes, but is not limited to, a culture broth containing the secreted polypeptide.

[0050] Mature polypeptide: The term “mature polypeptide” or “mature protein” means a polypeptide in its mature form following N terminal processing (e.g., removal of signal peptide and / or propeptide).

[0051] Signal Peptide: A “signal peptide” is a sequence of amino acids attached to the N-terminal portion of a protein, which facilitates the secretion of the protein outside the cell. The mature form of an extracellular protein lacks the signal peptide, which is cleaved off during the secretion process.

[0052] Native: The term “native” means a nucleic acid or polypeptide naturally occurring in a host cell.

[0053] Nucleic acid: The term “nucleic acid” encompasses DNA, RNA, heteroduplexes, and synthetic molecules capable of encoding a polypeptide. Nucleic acids may be single stranded or double stranded, and may be chemical modifications. The terms “nucleic acid” and “polynucleotide” are used interchangeably. Because the genetic code is degenerate, more than one codon may be used to encode a particular amino acid, and the present compositions and methods encompass nucleotide sequences that encode a particular amino acid sequence. Unless otherwise indicated, nucleic acid sequences are presented in 5’-to-3’ orientation.

[0054] Nucleic acid construct: The term “nucleic acid construct” means a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or is modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic, and which comprises one or more control sequences operably linked to the nucleic acid sequence.

[0055] Operably linked: The term “operably linked” means that specified components are in a relationship (including but not limited to juxtaposition) permitting them to function in an intended manner. For example, a regulatory sequence is operably linked to a coding sequence such that expression of the coding sequence is under control of the regulatory sequence.

[0056] Purified: The term “purified” means a nucleic acid or polypeptide that is substantially free from other components as determined by analytical techniques well known in the art (e.g., a purified polypeptide or nucleic acid may form a discrete band in an electrophoretic gel, chromatographic eluate, and / or a media subjected to density gradient centrifugation). A purified nucleic acid or polypeptide is at least about 50% pure, usually at least about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.5%, about 99.6%, about 99.7%, about 99.8% or more pure (e.g., percent by weight on a molar basis). In a related sense, a composition is enriched for a molecule when there is a substantial increase in the concentration of the molecule after application of a purification or enrichment technique. The term “enriched” refers to a compound, polypeptide, cell, nucleic acid, amino acid, or other specified material or component that is present in a composition at a relative or absolute concentration that is higher than a starting composition.

[0057] In one aspect, the term “purified” as used herein refers to the polypeptide or cell being essentially free from components (especially insoluble components) from the production organism. In other aspects, the term “purified” refers to the polypeptide being essentially free of insoluble components (especially insoluble components) from the native organism from which it is obtained. In one aspect, the polypeptide is separated from some of the soluble components of the organism and culture medium from which it is recovered. The polypeptide may be purified (i.e. , separated) by one or more of the unit operations filtration, precipitation, or chromatography.

[0058] Accordingly, the polypeptide may be purified such that only minor amounts of other proteins, in particular, other polypeptides, are present. The term “purified” as used herein may refer to removal of other components, particularly other proteins and most particularly other enzymes present in the cell of origin of the polypeptide. The polypeptide may be “substantially pure”, i.e., free from other components from the organism in which it is produced, e.g., a host organism for recombinantly produced polypeptide. In one aspect, the polypeptide is at least 40% pure by weight of the total polypeptide material present in the preparation. In one aspect, the polypeptide is at least 50%, 60%, 70%, 80% or 90% pure by weight of the total polypeptide material present in the preparation. As used herein, a "substantially pure polypeptide" may denote a polypeptide preparation that contains at most 10%, preferably at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, most preferably at most 1 %, and even most preferably at most 0.5% by weight of other polypeptide material with which the polypeptide is natively or recombinantly associated.

[0059] It is, therefore, preferred that the substantially pure polypeptide is at least 92% pure, preferably at least 94% pure, more preferably at least 95% pure, more preferably at least 96% pure, more preferably at least 97% pure, more preferably at least 98% pure, even more preferably at least 99% pure, most preferably at least 99.5% pure by weight of the total polypeptide material present in the preparation. The polypeptide of the present invention is preferably in a substantially pure form (i.e. , the preparation is essentially free of other polypeptide material with which it is natively or recombinantly associated). This can be accomplished, for example by preparing the polypeptide by well-known recombinant methods or by classical purification methods.

[0060] Recombinant: The term “recombinant” is used in its conventional meaning to refer to the manipulation, e.g., cutting and rejoining, of nucleic acid sequences to form constellations different from those found in nature. The term recombinant refers to a cell, nucleic acid, polypeptide or vector that has been modified from its native state. Thus, for example, recombinant cells express genes that are not found within the native (non-recombinant) form of the cell, or express native genes at different levels or under different conditions than found in nature. The term “recombinant” is synonymous with “genetically modified” and “transgenic”.

[0061] Recover: The terms “recover” or “recovery” means the removal of a polypeptide from at least one fermentation broth component selected from the list of a cell, a nucleic acid, or other specified material, e.g., recovery of the polypeptide from the whole fermentation broth, or from the cell-free fermentation broth, by polypeptide crystal harvest, by filtration, e.g. depth filtration (by use of filter aids or packed filter medias, cloth filtration in chamber filters, rotary-drum filtration, drum filtration, rotary vacuum-drum filters, candle filters, horizontal leaf filters or similar, using sheed or pad filtration in framed or modular setups) or membrane filtration (using sheet filtration, module filtration, candle filtration, microfiltration, ultrafiltration in either cross flow, dynamic cross flow or dead end operation), or by centrifugation (using decanter centrifuges, disc stack centrifuges, hyrdo cyclones or similar), or by precipitating the polypeptide and using relevant solid-liquid separation methods to harvest the polypeptide from the broth media by use of classification separation by particle sizes. Recovery encompasses isolation and / or purification of the polypeptide.

[0062] Sequence identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “sequence identity”. For purposes of the present invention, the sequence identity between two amino acid sequences is determined as the output of “longest identity” using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, Trends Genet. 16: 276-277), preferably version 6.6.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. In order for the Needle program to report the longest identity, the nobrief option must be specified in the command line. The output of Needle labelled “longest identity” is calculated as follows:

[0063] (Identical Residues x 100) / (Length of Alignment - Total Number of Gaps in Alignment)

[0064] Variant: The term “variant” means a polypeptide having deamidase activity comprising a manmade mutation, i.e., a substitution, insertion (including extension), and / or deletion (e.g., truncation), at one or more positions. A substitution means replacement of the amino acid occupying a position with a different amino acid; a deletion means removal of the amino acid occupying a position; and an insertion means adding 1-5 amino acids (e.g., 1-3 amino acids, in particular, 1 amino acid) adjacent to and immediately following the amino acid occupying a position.

[0065] Wild-type: The term “wild-type” in reference to an amino acid sequence or nucleic acid sequence means that the amino acid sequence or nucleic acid sequence is a native or naturally-occurring sequence. As used herein, the term “naturally-occurring” refers to anything (e.g., proteins, amino acids, or nucleic acid sequences) that is found in nature. Conversely, the term “non-naturally occurring” refers to anything that is not found in nature (e.g., recombinant nucleic acids and protein sequences produced in the laboratory or modification of the wild- type sequence).

[0066] Milk: The term “milk”, also referred to as “dairy milk”, generally refers to the milk from a cow, however it may also refer to milk from a goat, sheep, buffalo, or camel. Milk is typically available in three versions which differ by their fat content. Whole milk has on average 3.8% milk fat, with a minimum of 3.2% milk fat. Low-fat milk, also referred to as lite milk or reduced-fat milk, generally contains 2% milk fat or less. In some embodiments, low-fat milk contains about 2% milk fat. In some embodiments, low-fat milk contains about 1 % milk fat. Skim milk, also referred to as skimmed milk, nonfat milk or fat-free milk, generally has 0.5% milk fat or less. In some embodiments, skim milk has 0.1 % milk fat or less. In some embodiments, skim milk might have extra milk solids, such as lactose and / or protein, to optimize the taste and texture due to its very low fat content.

[0067] Barista milk: The term “barista milk” is milk which may comprise additional ingredients to create a milk which produces a better foam, with high coherency for consistent pouring and the creation of latte art. Barista milk may have more fat and / or more protein compared to standard whole milk.

[0068] Dairy composition: The term “dairy composition” refers to compositions derived from milk, including cream, milk, butter, concentrated milk, evaporated milk, condensed milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0069] Dairy dessert: The term “dairy dessert” refers to ice cream, frozen custard, frozen yogurt, gelato, and ice milk.

[0070] Aeration: The term “aeration” refers to the introduction of air into a material, such as a dairy composition. For the present invention, aeration is typically achieved through whipping or beating the dairy composition, sometimes with the aid of steam. The product of aeration is a lighter, fluffier dairy composition. The aerated dairy composition may be referred to as a foam. Examples of aerated dairy products include ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, whipped butter, and whipped butter spread.

[0071] Milk foam: The term “milk foam”, also referred to as “foamed milk” or “foam”, is milk or cream into which air has been introduced, typically also with heat. Foam can be created with steam, such as by using the steam wand of an espresso machine. It may also be produced by whisking, shaking, or whipping. Electric milk frothers can also be used to produce milk foam. Milk foam may be further characterized as “microfoam”. Microfoam has microscopic, uniform bubbles, can be shiny, and is slightly thickened. Microfoam has a consistency which ressembles wet paint. Microfoam is preferred for latte art, as the microfoam provides definition and stability to the patterns and / or etchings.

[0072] An important quality of milk foam is its “coherency”. Foam coherence is determined by the interaction of the foam-liquid interphase, where the foam adheres to the surface of the liquid milk. No or poor foam coherency results in the foam lagging behind the liquid milk when the foamed milk is poured, so that blobs of foam will linger in the foamer and then plop out. Such foam blobs are considered undesirable when preparing beverages comprising the foamed milk, and may prevent the creation of or ruin or destroy latte art. Foam with very good coherency pours smoothly from the foamer, so that the foam and the liquid pour simultaneously or nearly simultaneously and there is no or little residual foam lagging toward the end of the pour.

[0073] Latte art: The term “latte art,” also referred to as coffee art, barista art, or coffee designs, refers to particular patterns or designs that are intentionally created on the top layer of milk or cream foam, typically the top layer of milk foam of a hot beverage such as a latte, cappuccino, or hot chocolate. Latte art may also be created for other hot liquids which comprise milk or cream, for example cream-based soups such as a squash soup or a tomato soup. Latte art is created by pouring microfoam into a shot of, for example, espresso, in a particular manner to create the pattern or design. Common latte art include tulip, rosetta, and heart patterns. Latte art may also use etching, where images are drawn on the top layer of milk foam of a hot beverage using a thin rod, such as a toothpick. Using etching, latte art can be any drawn image, including faces and animals. A stencil may be used to aid in etching. Latte art is particularly difficult to create consistently, due in part to the conditions required of the foamed milk. Variability in the milk can make it difficult to predict if the milk foam produced will have the high density of microfoam and high coherency required to create latte art.

[0074] Conventions for Designation of Variants:

[0075] For purposes of the present invention, the polypeptide disclosed in SEQ ID NO: 5 is used to determine the corresponding amino acid positions in another propeptide and / or deamidase. The amino acid sequence of another propeptide and / or deamidase is aligned with the polypeptide disclosed in SEQ ID NO: 5, and based on the alignment, the amino acid position number corresponding to any amino acid residue in the polypeptide disclosed in SEQ ID NO: 5 is determined using the Needleman- Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443- 453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice etal., 2000, Trends Genet. 16: 276-277), preferably version 5.0.0 or later. The parameters used are gap open penalty of 10, gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix.

[0076] In describing variants, the nomenclature described below is adapted for ease of reference. The accepted IUPAC single letter or three letter amino acid abbreviation is employed.

[0077] Substitutions. For an amino acid substitution, the following nomenclature is used: Original amino acid, position, substituted amino acid. Accordingly, the substitution of threonine at position 226 with alanine is designated as “Thr226Ala” or “T226A”. Multiple mutations are separated by addition marks (“+”), e.g., “Gly205Arg + Ser411 Phe” or “G205R + S411 F”, representing substitutions at positions 205 and 411 of glycine (G) with arginine I and serine (S) with phenylalanine (F), respectively.

[0078] Deletions. For an amino acid deletion, the following nomenclature is used: Original amino acid, position, *. Accordingly, the deletion of glycine at position 195 is designated as “Gly195*” or “G195*”. Multiple deletions are separated by addition marks (“+”), e.g., “Gly195* + Ser411*” or “G195* + S411*”.

[0079] Insertions. For an amino acid insertion, the following nomenclature is used: Original amino acid, position, original amino acid, inserted amino acid. Accordingly, the insertion of lysine after glycine at position 195 is designated “Gly195GlyLys” or “G195GK”. An insertion of multiple amino acids is designated [Original amino acid, position, original amino acid, inserted amino acid #1 , inserted amino acid #2; etc.]. For example, the insertion of lysine and alanine after glycine at position 195 is indicated as “Gly195GlyLysAla” or “G195GKA”.

[0080] In such cases, the inserted amino acid residue(s) are numbered by the addition of lower case letters to the position number of the amino acid residue preceding the inserted amino acid residue^). In the above example, the sequence would thus be:

[0081] Multiple alterations. Variants comprising multiple alterations are separated by addition marks (“+”), e.g., “Arg170Tyr+Gly195Glu” or“R170Y+G195E” representing a substitution of arginine and glycine at positions 170 and 195 with tyrosine and glutamic acid, respectively.

[0082] Different alterations. Where different alterations can be introduced at a position, the different alterations are separated by a comma, e.g., “Arg170Tyr,Glu” or“R170Y,E” represents a substitution of arginine at position 170 with tyrosine or glutamic acid. Thus, “Tyr167Gly,Ala + Arg170Gly,Ala” or “Y167G.A + R170G.A” designates the following variants:

[0083] “Tyr167Gly+Arg170Gly”, “Tyr167Gly+Arg170Ala”, “Tyr167Ala+Arg170Gly”, and “Tyr167Ala+Arg170Ala”.

[0084] In the context of the present invention, the term “variant” means a polypeptide comprising an alteration, i.e., a substitution, insertion, and / or deletion, at one or more (e.g., several) positions. A substitution means replacement of the amino acid occupying a position with a different amino acid; a deletion means removal of the amino acid occupying a position; and an insertion means adding one or more (e.g., several) amino acids, e.g., 1-5 amino acids, adjacent to and immediately following the amino acid occupying a position.

[0085] The amino acid changes may be of a minor nature, that Is conservative amino acid substitutions or insertions that do not significantly affect the folding and / or activity of the protein; small deletions, typically of 1-30 amino acids; small amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue; a small linker peptide of up to 20-25 residues; or a small extension that facilitates purification by changing net charge or another function, such as a polyhistidine tract, an antigenic epitope or a binding domain. Examples of conservative substitutions are within the groups of basic amino acids (arginine, lysine and histidine), acidic amino acids (glutamic acid and aspartic acid), polar amino acids (glutamine and asparagine), hydrophobic amino acids (leucine, isoleucine and valine), aromatic amino acids (phenylalanine, tryptophan and tyrosine), and small amino acids (glycine, alanine, serine, threonine and methionine). Amino acid substitutions that do not generally alter specific activity are known in the art and are described, for example, by H. Neurath and R. L. Hill, 1979, In, The Proteins, Academic Press, New York. Common substitutions are Ala / Ser, Val / lle, Asp / Glu, Thr / Ser, Ala / Gly, Ala / Thr, Ser / Asn, Ala / Val, Ser / Gly, Tyr / Phe, Ala / Pro, Lys / Arg, Asp / Asn, Leu / lle, Leu / Val, Ala / Glu, and Asp / Gly.

[0086] Alternatively, the amino acid changes are of such a nature that the physico-chemical properties of the polypeptides are altered. For example, amino acid changes may affect the thermal stability of the polypeptide, alter the substrate specificity, change the pH optimum, and the like.

[0087] Essential amino acids in a polypeptide can be identified according to procedures known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, 1989, Science 244: 1081-1085). In the latter technique, single alanine mutations are introduced at every residue in the molecule, and the resultant mutant molecules are tested for endopeptidase activity to identify amino acid residues that are critical to the activity of the molecule. See also, Hilton et al., 1996, J. Biol. Chem. 271 : 4699-4708. The active site of the enzyme or other biological interaction can also be determined by physical analysis of structure, as determined by such techniques as nuclear magnetic resonance, crystallography, electron diffraction, or photoaffinity labeling, in conjunction with mutation of putative contact site amino acids. See, for example, de Vos et al., 1992, Science 255: 306-312; Smith et al., 1992, J. Mol. Biol. 224: 899- 904; Wlodaver et al., 1992, FEBS Lett. 309: 59-64. The identity of essential amino acids can also be inferred from an alignment with a related polypeptide.

[0088] Single or multiple amino acid substitutions, deletions, and / or insertions can be made and tested using known methods of mutagenesis, recombination, and / or shuffling, followed by a relevant screening procedure, such as those disclosed by Reidhaar-Olson and Sauer, 1988, Science 241 : 53-57; Bowie and Sauer, 1989, Proc. Natl. Acad. Sci. USA 86: 2152-2156; WO 95 / 17413; or WO 95 / 22625. Other methods that can be used include error-prone PCR, phage display (e.g., Lowman et al., 1991, Biochemistry 30: 10832-10837; U.S. Patent No. 5,223,409; WO 92 / 06204), and region-directed mutagenesis (Derbyshire et al., 1986, Gene 46: 145; Ner et al., 1988, DNA 7: 127).

[0089] Mutagenesis / shuffling methods can be combined with high-throughput, automated screening methods to detect activity of cloned, mutagenized polypeptides expressed by host cells (Ness et al., 1999, Nature Biotechnology 17: 893-896). Mutagenized DNA molecules that encode active polypeptides can be recovered from the host cells and rapidly sequenced using standard methods in the art. These methods allow the rapid determination of the importance of individual amino acid residues in a polypeptide.

[0090] DETAILED DESCRIPTION OF THE INVENTION

[0091] The present invention is directed toward an improved dairy composition for aeration, wherein a protein deamidase and optionally a second polypeptide derived from the propeptide of a protein deamidase proform is added to the dairy composition prior to aeration. The invention also comprises a method for producing improved aerated dairy products. In some embodiments, the resulting aerated dairy product has improved foam density, comprising smaller, more uniform bubbles. This improvement in foam density creates an aerated dairy product with a lighter, fluffier, and / or smoother texture and with improved foam stability compared to a dairy composition that was not treated with a protein deamidase prior to aeration. In some embodiments, the aerated dairy product is foamed milk, where the foam has better stability, smoother texture, and / or higher quality microfoam compared to a foam produced from milk that was not treated with a protein deaminase. This higher quality foam improves the creation of latte art in the final product comprising the foamed milk, such as latte art on the surface of a hot beverage or soup.

[0092] Deamidase

[0093] In the present invention, a “protein deamidase”, “deamidase”, “mature protein deamidase”, or “mature deamidase” refers to an enzyme having an effect of directly acting on an amide group of a side chain of an amino acid that constitutes a protein to cause deamidation and release of ammonia without cleaving a peptide bond of the protein and / or crosslinking proteins. Specific examples of a protein deamidase include a protein glutaminase (EC 3.5.1.44) that directly acts on an amide group of the side chain of a glutamine residue contained in a protein, releasing ammonia and thus converting the glutamine residue into a glutamate residue. Another example of a protein deamidase is a protein asparaginase that directly acts on an amide group of the side chain of an asparagine residue contained in a protein, releasing ammonia and thus converting the asparagine residue into an aspartate residue. In the present invention, as a protein deamidase, any one of the protein glutaminase and the protein asparaginase can be used, or both can be used in combination. In some embodiments, the protein deamidase used in the present invention is a protein glutaminase.

[0094] A protein deamidase to be used in a method of the present invention may be obtained from microorganisms of any genus. For purposes of the present invention, the term “obtained from” as used herein in connection with a given source shall mean that the polypeptide encoded by a polynucleotide is produced by the source or by a strain in which the polynucleotide from the source has been inserted. In one aspect, the polypeptide obtained from a given source is secreted extracellularly.

[0095] A protein deamidase may be obtained from Chryseobacterium genus, Flavobacterium genus, Empedobacter genus, Sphingobacterium genus, Aureo bacterium genus, or Myroides genus. Protein deamidases can be obtained from a culture broth of the above-described microorganisms and used in the present invention.

[0096] In some embodiments, the protein deamidase may be derived from Chryseobacterium genus, such as Chryseobacterium viscerum, C. gambrini, C. culicis, C. defluvii, or C. proteolyti- cum. In some embodiments, the deamidase in the methods of the invention is derived from or obtained from Chryseobacterium viscerum (the strain has formerly been referred to as Chryseobacterium sp-62563).

[0097] EP1839491 discloses cloning of a protein glutaminase from Chryseobacterium proteolyt- icum expressed in Corynebacterium glutamicum.. A protein glutaminase derived from Chryseobacterium proteolyticum is commercially available as, for example, Amano PG500 (manufactured by Amano Enzyme Inc.)

[0098] The protein deamidases in the methods of the invention act on milk proteins, such casein and whey proteins. Casein proteins include alpha-s1-casein, alpha-s2-casein, beta-casein, and kappa-casein. Whey proteins include alpha-lactalbumin and beta-lactoglobulin. In some embodiments, the deamidase mainly acts on casein proteins.

[0099] Protein deamidases such as those derived from Chryseobacterium species are typically produced as an inactive proform (also referred to herein as the “proform” or “proform protein deamidase”), which is expressed as a fusion protein and comprises an N-terminal propeptide domain, also referred to as a “propeptide” or “propeptide derived from the proform protein deamidase”, which is both upstream of and tightly bound to its C-terminal deamidase domain. Because of the binding of the propeptide to the deamidase domain, the proform has reduced deamidase activity, which protects the viability of the cell. In nature, the fusion protein is postprocessed to remove the propeptide and release the active, mature deamidase outside of the microbial cell. In recombinant expression systems, the fusion protein is secreted outside of the host cell as an inactive proform comprising the propeptide which then may be cleaved off to separate it from the mature deamidase. The cleavage may be performed by a site-specific endopeptidase, such as a glutamyl endopeptidase, trypsin or a trypsin-like endopeptidase, or chymotrypsin or a chymotrapsin-like endopeptidase.

[0100] For many deamidase proforms, even after cleavage of the proform the propeptide is difficult to separate from the mature deamidase because of the high binding affinity of the propeptide for the deamidase domain. Because of its inhibitory effect, a mature protein deamidase still bound to its propeptide has reduced activity. Therefore, there is a strong desire in the art to remove the cleaved propeptide from the mature deamidase, and significant resources are spent to purify the propeptide from the mature deamidase. However, it has been found that new proforms of deamidase enzymes can be produced, where the binding affinity of the propeptide to the mature deamidase can be reduced (WO 2023 / 170177, incorporated by reference herein). Unexpectedly, it has been found in the present invention that the presence of these modified propeptides may provide a beneficial effect to the activity of the deamidase.

[0101] The protein deamidases of the methods and compositions of the present invention are mature deamidases where the propeptide has been cleaved from the proform protein deamidase. In some embodiments, the propeptide derived from the same proform as the mature protein deamidase may still be present in the composition comprising the mature deamidase. In some embodiments, a purified propeptide is separately added to a composition comprising a mature protein deamidase.

[0102] The propeptides of the invention comprise a deamidase inhibitory domain which may interact with the deamidase domain of the proform. The deamidase inhibitory domain of the propeptide comprises the amino acid sequence motif [l / M][L / l / V][S / T]AQ, which corresponds to amino acids 39-43 of SEQ ID NOs: 3, 6, and 9, amino acids 41-45 of SEQ ID NO: 12, and amino acids 40-44 of SEQ ID NO: 15. The propeptides also comprise the amino acid sequence motif [K / R][V / I / L][S / A / N]X[I / M][L / I / V][S / T]AQ, which corresponds to amino acids 35-43 of SEQ ID NOs: 3, 6, and 9, amino acids 37-45 of SEQ ID NO: 12, and amino acids 36-44 of SEQ ID NO: 15. After expression of the proform polypeptide in a recombinant expression system, a site-specific endopeptidase is used to cleave off the propeptide, leaving an active, mature deamidase. In some embodiments, the cleaved propeptide is not purified away from the mature deamidase. Therefore, the propeptide is present in the composition with the mature deamidase.

[0103] In some embodiments, the propeptides are mutated variants which have a lower binding affinity to the deamidase domain of their corresponding deamidase, so that they are more easily enzymatically cleaved off after recombinant expression and secretion from of the host cell. Propeptide mutations which affect the binding affinity of the propeptide for the mature deamidase are described in WO 2023 / 170177, herein incorporated by reference in its entirety.

[0104] In some embodiments, the propeptide comprises an amino acid change in a position corresponding to a position of SEQ ID NO: 3 selected from the group consisting of 23, 38, 39, 43, 45, 67, 69, 88, 91 , 92, 94, 95, 96, 98, 99, 100, and 101. In further embodiments, the propeptide comprises an amino acid change in a position corresponding to a position of SEQ ID NO: 3 selected from the group consisting of V23, F38, M39, Q43, Y45, E67, P69, T88, D91 , I92, Y94, F95, K96, F98, F99, T100, and K101. In further embodiments, the propeptide comprises an amino acid change in a position corresponding to a position of SEQ ID NO: 3 selected from V23G,D,Y,S; F38A,C,D,G,N,T,V; M39D,E,F,G,H,K,N,P,Q,R,S,W,Y; Q43D,E,F,G,I,K,M,R,Y; Y45A,C,G,I,K,M,N,Q,R,S,T,V; E67D,K,N,P,W; P69D,F,G,H,K,L,M,Q,R,S,T,W,Y;

[0105] T88F,I,K,L,P,R,V,W,Y; D91 F,G,H,K,L,M,N,P,Q,R,S,Y; I92G,N,P,Q,S,T; Y94A,E,I,K,P,Q,R,T; F95A,D,E,G,H,I,K,L,M,N,R,S,T,V; K96C,F,I,P,V,Y; F98A,C,D,E,G,H,K,N,P,Q,R,S,T,W,Y; F99A,C,D,G,H,K,P,Q,R,V,W,Y; T100E,P,W; and / or K101 E.P. It is recognized that the propeptide of the invention may comprise the amino acid sequence of SEQ ID NO: 3, 6, 9, 12, or 15-20 and further comprise any of the mutations described here in the positions corresponding to the position in SEQ ID NO: 3.

[0106] In some embodiments, the propeptide comprises an amino acid change in a position corresponding to a position of SEQ ID NO: 3 selected from V23G,D,Y,S; F38A,C,D,G,N,T,V; M39D,E,F,G,H,K,N,P,Q,R,S,Y; Q43D,E,I,K,R; Y45A,C,G,I,K,M,N,Q,R,S,T,V; E67D,N,P;

[0107] P69D,F,G,H,K,M,Q,R,S,T,W,Y; T88I,P,W; D91G,H,K,N,P,Q,R,S; I92G,P,S; Y94A,E,I,P,Q,R,T; F95A,D,E,G,H,K,N,R,S,T,V; K96P; F98D,E,G,N,P,Q,S; F99A,C,D,G,H,K,P,Q,R; and / or T100P,W. In further embodiments, the propeptide comprises an amino acid change in a position corresponding to a position of SEQ ID NO: 3 selected from the group consisting of V23S, F38C, Y45G, Y45T, Y45I, Y45M, Y45R, P69D, P69G, P69L, P69M, P69Q, P69S, P69T, Y94P, F99A, F99G, and / or F99K.

[0108] In some embodiments, the propeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 16-20. In further embodiments, the propeptide comprises the amino acid sequence of SEQ ID NO: 16-20.

[0109] In some embodiments, the proform may comprise the amino acid sequence of SEQ ID NO: 1 , 21 , 22, 23, or 24, which may be cleaved to produce a propeptide comprising the amino acid sequence of SEQ ID NO: 16-20, respectively, and a mature protein deamidase comprising the amino acid sequence of SEQ ID NO: 2, 5, 8, 11 , and 14, respectively.

[0110] In some embodiments, the methods and compositions of the present invention comprise: a) a proform protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 1 , where the proform may be cleaved to release a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2 and a propeptide comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 16; b) a proform protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 21 , where the proform may be cleaved to release a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5 and a propeptide comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 17; c) a proform protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 22, where the proform may be cleaved to release a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8 and a propeptide comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 18; d) a proform protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 23, where the proform may be cleaved to release a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 and a propeptide comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 19; or e) a proform protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 24, where the proform may be cleaved to release a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 14 and a propeptide comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 20;

[0111] In the methods of the present invention, a protein deamidase is added to whole milk, low fat milk, or skim milk to improve the foamability of the milk. The resulting foamed milk has better stability, a higher density of microfoam, higher volume, higher coherency, and / or a smoother texture compared to a foam produced from a dairy composition that was not treated with a deamidase. The ability for milk to foam and the quality of this foam is dependent upon the protein and the fat present in the milk. Higher-quality foam is typically made with whole milk, while foam that is made with low-fat milk or skim milk is less desirable. Surprisingly, the methods and compositions of the present invention are able to produce high quality foam with low fat milk and even skim milk, which has no or essentially no milk fat at all. The high quality of the foam and the resulting beverage is similar to or better than that of a beverage prepared with whole milk to which a protein deamidase has not been added. Further, in methods of the present invention, a protein deamidase and the propeptide of a protein deamidase are added to skim milk (also referred to as “skimmed milk”) to improve the foamability of the milk. Unexpectedly, the methods and compositions of the present invention are able to produce a higher quality foam with skim milk where both a protein deamidase and the propeptide of a protein deamidase are added compared to a method where only the protein deamidase was added.

[0112] It is well-known in the art that latte art can be difficult to produce, and depends on extremely high quality milk foam, with a high density of microfoam and high coherency. It is generally accepted that milk foam produced with low-fat or skim milk does not have the stability, volume, quantity of microfoam, and / or high enough coherency to create latte art. Further, even whole milk can be inconsistent in the quality of milk foam produced. Therefore, it is extremely desirable to have a dairy composition which is highly reliable for the production of latte art.

[0113] Compositions of the invention, which comprise milk and a protein deamidase, and optionally a propeptide of a protein deamidase, satisfy this need. Methods and compositions of the invention produce a milk foam with a high density of microfoam and high coherency suitable for the production of latte art. Further, methods and compositions of the invention which comprise low-fat or skim milk also produce a milk foam with a high density of microfoam and high coherency suitable for the production of latte art.

[0114] In some embodiments, the texture of the beverage itself is also improved, so that it is creamier and smoother compared to a similar beverage prepared with low fat or skim milk to which protein deamidase has not been added.

[0115] As stated above, in some embodiments, a first polypeptide, namely a mature protein deamidase, and a second polypeptide is added to the milk, where the second polypeptide is a propeptide of a deamidase. In some embodiments, the second polypeptide is a propeptide that resulted from cleavage of the proform to produce the first polypeptide. In some embodiments, the second polypeptide is a mutated propeptide variant. In further embodiments, the second polypeptide is a mutated propeptide variant which binds less tightly to the mature deamidase compared to the native propeptide. In some embodiments, the second polypeptide is a mutated variant of the propeptide derived from the same species as the deamidase added to the dairy composition. In other embodiments, the second polypeptide is a mutated variant of a propeptide that is derived from a different species as the deamidase added to the dairy composition, where the dairy composition may comprise milk. In some embodiments, the second polypeptide is synthetic and not related to the deamidase added to the dairy composition. In some embodiments, the second polypeptide comprises the amino acid sequence motif [l / M][L / l / V][S / T]AQ and / or [K / R][V / I / L][S / A / N]X[I / M][L / I / V][S / T]AQ. In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NOs: 3, 6, 9, 12, or 15.

[0116] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3. In further embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3.

[0117] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 16.

[0118] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 17.

[0119] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 18.

[0120] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 19.

[0121] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 100 of SEQ ID NO: 15. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 20.

[0122] A person of skill in the art would recognize that the amount of protein deamidase provided to a dairy composition would be sufficient to get the desired improved aerated dairy product, and the sufficient amount is determined in part by the temperature of incubation with the enzyme and the length of time of the incubation. In some embodiments, the protein deamidase is provided to a dairy composition of the invention in an amount between 0.01-20 IPA(U) / gram protein substrate, or per gram milk protein, also referred to as per g protein. In further embodiments, the protein deamidase is provided in an amount between 0.1-15 IPA(U) / g protein; 0.5-11 IPA(U) / g protein; 1.0-10 IPA(U) / g protein; 1.0-8.0 IPA(U) / g protein; 2.0-10.0 IPA(U) / g protein; 2.0-8.0 IPA(U) / g protein; 2.0-7.0 IPA(U) / g protein; or 2.5-7.0 IPA(U) / g protein. In some embodiments, at least 1.0, at least 2.0, at least 2.5, at least 3.5, at least 4.0, at least 4.5, at least 5.0, at least 5.5, at least 6.0, at least 6.5, or at least 7.0 IPA(U) / g substrate protein is added to the dairy composition in the methods of the invention. In some embodiments, the protein deamidase is provided to a dairy composition of the invention at 0.01 , 0.05, 0.1 , 0.25, 0.5, 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 , 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15 IPA(U) / g protein.

[0123] The amount of protein deamidase used in the methods of the invention, either as a proform, a propeptide, and / or a mature protein deamidase, does not significantly contribute to the total amount of soluble protein in the dairy compositions of the invention and are not likely to be the reason for the observed increase in foamability of the dairy composition. The weight of milk protein in each reaction is at least 1000-fold higher than the combined weight of added enzyme protein and propeptide.

[0124] A person of skill in the art would recognize that the improved foam demonstrated here similarly applies to methods of aeration of dairy compositions to produce other aerated or whipped dairy products. Similar to the foamed milk, the presence of fat in a dairy composition has a positive effect on the aeration of the dairy composition and on the quality of the aerated dairy product. The introduction of air throughout the dairy product produces a smooth, melt-in-the-mouth texture. As described above for the milk foam, fat is a critical component for successful introduction of air into a dairy composition. Therefore, a desirable, smooth texture in low-fat or no-fat aerated dairy products such as dairy desserts, whipped cream cheese, whipped yogurt, whipped butter, or whipped butter spread (where the butter spread comprises both butter and additional vegetable oils, such as canola, olive, or vegetable oil) are difficult to produce.

[0125] Methods of the invention include a method for producing improved aerated dairy products, comprising adding a protein deamidase to a dairy composition and aerating the dairy composition to produce an aerated dairy product, wherein the aerated dairy product is improved compared to a similar method where a protein deamidase is not added to the dairy composition. Methods of the invention also include a method for producing improved aerated dairy products, comprising adding a protein deamidase and a propeptide of a deamidase to a dairy composition and aerating the dairy composition to produce an aerated dairy product, wherein the aerated dairy product is improved compared to a similar method where a protein deamidase is added but a propeptide of a deamidase is not present in dairy composition.

[0126] In some embodiments, the dairy composition of the invention comprises cream, milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof. In some embodiments, the milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, and / or whey protein concentrate is or is prepared from low- fat or skim milk.

[0127] In some embodiments, the methods and compositions of the present invention include dairy compositions which have a lower amount of milk fat, such as dairy compositions derived from low-fat or skim milk. In some embodiments, the milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, and / or whey protein concentrate comprises 3.8% or less, 3.25% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1 % or less, 0.5% or less, 0.25% or less, or 0.15% or less fat.

[0128] In some embodiments, the protein deamidase and optionally a propeptide of a deamidase are added to the dairy composition immediately before aeration. In some embodiments, the dairy composition may be further processed before aeration. In some embodiments, additional ingredients are added to the dairy composition before or after the addition of the protein deamidase and optionally a propeptide of a deamidase.

[0129] The dairy composition may be heat treated. Heat treatments may be a Low Temperature Long Time (LTLT), High Temperature Short Time (HTST), Higher Heat Shorter Time (HHST), Ultra-High Temperature (UHT), Ultra Pasteurized (UP) treatment, or any other form of heat treatment known in the art. In some embodiments, the protein deamidase is added to the dairy composition prior to heat treatment. In other embodiments, the protein deamidase is added to the dairy composition after heat treatment. In some embodiments, the dairy composition may be heat treated both before the deamidase is added and after, as part of the process of producing the resulting dairy product.

[0130] In some embodiments, the dairy composition comprises butter and optionally vegetable oil, and the aerated dairy product is whipped butter or whipped butter spread. In some embodiments, the dairy composition comprises fermented milk, and the aerated dairy product is whipped yogurt or the dairy dessert frozen yogurt. In some embodiments, the aerated dairy product is a dairy dessert, such as ice cream, frozen custard, frozen yogurt, gelato, or ice milk. In some embodiments, the aerated dairy product comprises 3.8% or less, 3.25% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1 % or less, 0.5% or less, 0.25% or less, or 0.15% or less fat.

[0131] Similar to the methods of foaming milk described above, in some embodiments, a deamidase and a second polypeptide are added to the dairy composition. This second polypeptide may be a propeptide of a deamidase. In some embodiments, the second polypeptide is a mutated propeptide variant. In further embodiments, the second polypeptide is a mutated propeptide variant which binds less tightly to the mature deamidase compared to the native propeptide. In some embodiments, the second polypeptide is a mutated variant of the propeptide derived from the same species as the deamidase added to the dairy composition. In other embodiments, the second polypeptide is a mutated variant of a propeptide that is derived from a different species as the deamidase added to the dairy composition. In some embodiments, the second polypeptide is synthetic and not related to the deamidase added to the dairy composition. In some embodiments, the second polypeptide comprises the amino acid sequence motif [l / M][L / l / V][S / T]AQ and / or [K / R][V / I / L][S / A / N]X[I / M][L / I / V][S / T]AQ. In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NOs: 3, 6, 9, 12, or 15.

[0132] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 16.

[0133] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 17.

[0134] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 18.

[0135] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 19.

[0136] In some embodiments, the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 15. In further embodiments, the second polypeptide comprises the amino acid sequence of SEQ ID NO: 20.

[0137] It is possible to adjust the amount of aeration of the dairy composition by controlling the amount of deamidase, reaction time, reaction temperature, and other factors known to a person of skill in the art. It is similarly possible to adjust the degree of foamability of the milk or the texture of the foam by controlling the amount of deamidase, reaction time, reaction temperature, and other factors known to a person of skill in the art. Additionally, it is possible to adjust the aeration of the dairy composition or the foamability of the milk by the speed, time, and / or intensity of the mechanical aeration or foaming.

[0138] PREFERRED EMBODIMENTS

[0139] 1. A method for producing improved aerated dairy products, comprising: a) obtaining a dairy composition; b) adding a first polypeptide to the dairy composition, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase; c) optionally adding a second polypeptide to the dairy composition, wherein the second polypeptide is a propeptide derived from a proform protein deamidase; and d) aerating the dairy composition to produce an aerated dairy product; wherein the aerated dairy product is improved compared to a similar method where the first polypeptide and optionally the second polypeptide is not added to the dairy composition.

[0140] 2. The method of embodiment 1 , wherein the dairy composition comprises cream, milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0141] 3. The method of any one of the proceeding embodiments, wherein the dairy composition comprises 3.8% or less, 3.25% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or less, 0.25% or less, or 0.15% or less fat.

[0142] 4. The method of any one of the proceeding embodiments, wherein the aerated dairy product has improved foam density, a lighter, fluffier, and / or smoother texture, and / or improved foam stability compared to an aerated dairy product that was produced without the addition of a protein deamidase.

[0143] 5. The method of any one of the proceeding embodiments, wherein the aerated dairy product is ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, whipped butter, or whipped butter spread.

[0144] 6. The method of any one of the proceeding embodiments, wherein the aerated dairy product comprises 3.8% or less, 3.25% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or less, 0.25% or less, or 0.15% or less fat.

[0145] 7. A method for producing an improved foam of a dairy composition, comprising: a) obtaining a dairy composition; b) adding a first polypeptide to the dairy composition, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase; c) optionally adding a second polypeptide to the dairy composition, wherein the second polypeptide is a propeptide derived from a proform protein deamidase; and d) aerating the dairy composition to produce a foam; wherein the foam of the dairy composition is improved compared to a similar method where the first polypeptide and optionally the second polypeptide is not added to the dairy composition.

[0146] 8. A method for improving latte art produced from a dairy composition, comprising: a) obtaining a dairy composition; b) adding a first polypeptide to the dairy composition, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase; c) optionally adding a second polypeptide to the dairy composition, wherein the second polypeptide is a propeptide derived from a proform protein deamidase; and d) aerating the dairy composition to produce a foam; and e) producing latte art with the foamed dairy composition; wherein the latte art is improved compared to a similar method where the first polypeptide and optionally the second polypeptide is not added to the dairy composition.

[0147] 9. The method of embodiments 7 or 8, wherein the foam has better stability, a higher density of microfoam, higher volume, higher coherency, and / or a smoother texture compared to a foam produced from a dairy composition that was not treated with a deamidase. 10. The method of any of embodiments 7 to 9, wherein the dairy composition is cream, milk, concentrated milk, condensed milk, reconstituted milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0148] 11. The method of any of embodiments 7 to 9, wherein the dairy composition is whole milk, low fat milk, or skim milk.

[0149] 12. The method of embodiment 11 , wherein the milk comprises 3.8% or less, 3.25% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or less, 0.25% or less, or 0.15% or less milk fat.

[0150] 13. The method of any one of the proceeding embodiments, wherein the first polypeptide is a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NOs: 2, 5, 8, 11 or 14.

[0151] 14. The method of any one of the proceeding embodiments, wherein the first polypeptide is a mature protein deamidase comprising the amino acid sequence of SEQ ID NOs: 2, 5, 8, 11 or

[0152] 14.

[0153] 15. The method of any one of the proceeding embodiments, wherein the deamidase is added in an amount ranging from 0.01-15.0 IPA(U) / g protein; 0.1-11.0 IPA(U) / g protein; 0.5-7.0 IPA(U) / g protein; or 2.5-7.0 IPA(U) / g protein.

[0154] 16. The method of any one of the proceeding embodiments, wherein the dairy composition is heat treated prior to treatment with the deamidase.

[0155] 17. The method of embodiment 16, wherein the heat treatment is performed at 60-140 °C.

[0156] 18. The method of embodiments 16 or 17, wherein the heat treatment is a Low Temperature Long Time (LTLT), High Temperature Short Time (HTST), Higher Heat Shorter Time (HHST), Ultra-High Temperature (UHT), or Ultra Pasteurized (UP) treatment.

[0157] 19. The method of any of embodiments 1 to 15, wherein the dairy composition is not heat treated prior to treatment with the deamidase.

[0158] 20. The method of any one of the proceeding embodiments, wherein the second polypeptide is a propeptide derived from a proform protein deamidase and comprises the amino acid sequence motif [l / M][L / l / V][S / T]AQ and / or the amino acid sequence motif [K / R][V / I / L][S / A / N]X[I / M][L / I / V][S / T]AQ.

[0159] 21. The method of any one of the proceeding claims, wherein the second polypeptide is a propeptide which comprises: a) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; d) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12; or e) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 100 of SEQ ID NO: 15.

[0160] 22. The method of any one of the proceeding embodiments, wherein the second polypeptide comprises the amino acid sequence of SEQ ID NOs: 16, 17, 18, 19, 20.

[0161] 23. The method of any one of the proceeding embodiments, wherein the first polypeptide and the second polypeptide are derived from the same proform protein deamidase.

[0162] 24. The method of any one of the proceeding embodiments, wherein the proform protein deamidase comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NOs: 1 , 21 , 22, 23, or 24. 25. The method of any one of the proceeding embodiments, wherein the first and second polypeptide are derived from a proform comprising an amino acid with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NOs: 1 , 21 , 22, 23, or 24, such that the first polypeptide is a mature protein deamidase comprising an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NOs: 2, 5, 8, 11 , or 14, respectively, and the second polypeptide is a propeptide comprising an amino acid with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NOs: 16, 17, 18, 19, or 20, respectively.

[0163] 26. The method of one of the proceeding embodiments, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12; or e) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 14, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 100 of SEQ ID NO: 15.

[0164] 27. The method of any one of embodiments 1-22 and 26, wherein the first polypeptide and the second polypeptide are not derived from the same proform protein deamidase.

[0165] 28. The method of embodiment 27, wherein the second polypeptide is a propeptide that was expressed and purified without a proform intermediate.

[0166] 29. The method of any one of the proceeding embodiments, wherein the addition of the second polypeptide increases the performance of the deamidase.

[0167] 30. A dairy composition comprising a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from a proform protein deamidase.

[0168] 31. The dairy composition of embodiment 30, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12; or e) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 14, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 100 of SEQ ID NO: 15.

[0169] 32. The dairy composition of embodiments 30 or 31 , wherein the dairy composition has an improved aeration or foamability compared to a dairy composition that does not comprise the first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from a proform protein deamidase.

[0170] 33. The dairy composition of any one of embodiments 30 to 32, wherein the dairy composition comprises cream, milk, butter, concentrated milk, evaporated milk, condensed milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0171] 34. The dairy composition of any of embodiments 30 to 33, wherein the dairy composition is processed to produce aerated dairy products, such as ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, or whipped butter.

[0172] 35. The dairy composition of any of embodiments 30 to 33, wherein the dairy composition is whole milk, low fat milk, or skim milk.

[0173] 36. The dairy composition of embodiment 35, wherein the dairy composition is processed to produce barista milk.

[0174] 37. The dairy composition of any one of embodiments 30-36, wherein the first polypeptide and the second polypeptide are not derived from the same proform protein deamidase. 38. The dairy composition of embodiment 37, wherein the second polypeptide is a propeptide that was expressed and purified without a proform intermediate.

[0175] 39. An aerated dairy product produced by the method of any one of embodiments 1-7 and 13- 29.

[0176] 40. The aerated dairy product of embodiment 39, wherein the aerated dairy product is ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, whipped butter, or whipped butter spread.

[0177] 41. The aerated dairy product of embodiment 39 or 40, wherein the aerated dairy product has improved foam density, a lighter, fluffier, and / or smoother texture, and / or improved foam stability compared to an aerated dairy product that was produced without the addition of a protein deamidase and optionally a second polypeptide, wherein the second polypeptide is derived from a deamidase propeptide.

[0178] 42. A foam produced by the method of any of embodiments 8-29.

[0179] 43. The foam of embodiment 42 wherein the foam has better stability, a higher density of microfoam, and / or a smoother texture compared to a foam produced from milk that was not treated with a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from a proform protein deamidase.

[0180] 44. Use of a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from a proform protein deamidase, to produce a dairy composition with improved aeration or foamability.

[0181] 45. The use of embodiment 44, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12; or e) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 14, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 15 and has a glycine at the position corresponding to position 100 of SEQ ID NO: 15.

[0182] 46. The use of embodiment 44 or 45, wherein the protein deamidase comprises the amino acid sequence of SEQ ID NO: 2, 5, 8, 11 , or 14.

[0183] 47. The use of any of embodiments 44-46, wherein the dairy composition comprises cream, milk, butter, concentrated milk, condensed milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0184] 48. A method for producing improved aerated dairy products, comprising: a) obtaining a dairy composition; b) adding a first polypeptide to the dairy composition, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase; c) optionally adding a second polypeptide to the dairy composition, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase; and d) aerating the dairy composition to produce an aerated dairy product; wherein the aerated dairy product is improved compared to a similar method where the first polypeptide and optionally the second polypeptide is not added to the dairy composition.

[0185] 49. The method of embodiment 48, wherein the aerated dairy composition produced by adding the first polypeptide and the second polypeptide is improved compared to a similar method where the first polypeptide and not the second polypeptide is added to the dairy composition.

[0186] 50. The method of embodiment 48 or 49, wherein the dairy composition comprises cream, milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0187] 51. The method of any one of embodiments 48-50, wherein the mature protein deamidase comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NOs: 2, 5, 8, or 11.

[0188] 52. The method of any one of embodiments 48-51 , wherein the second polypeptide is a propeptide which comprises a mutation which decreases its binding affinity for the deamidase domain compared to the parent propeptide.

[0189] 53. The method of any one of embodiments 48-52, wherein the second polypeptide is a propeptide which comprises: a) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

[0190] 54. The method of any any one of embodiments 48-53, wherein the second polypeptide comprises the amino acid sequence of SEQ ID NOs: 16, 17, 18, or 19.

[0191] 55. The method of any one of embodiments 48-54, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

[0192] 56. A dairy composition comprising a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase. 57. A dairy composition comprising a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase.

[0193] 58. The dairy composition of embodiment 56 or 57, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

[0194] 59. The dairy composition of any one of embodiments 56-58, wherein the dairy composition comprises cream, milk, butter, concentrated milk, evaporated milk, condensed milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

[0195] 60. The dairy composition of any one of embodiments 56-59, wherein the dairy composition is processed to produce aerated dairy products, such as ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, or whipped butter. 61. An aerated dairy product produced by the method of any of embodiments 48 to 55.

[0196] 62. The aerated dairy product of embodiment 61 , wherein the aerated dairy product is ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, whipped butter, or whipped butter spread.

[0197] 63. Use of a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase, to produce a dairy composition with improved aeration or foamability.

[0198] 64. Use of a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and of a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase, to produce a dairy composition with improved aeration or foamability.

[0199] 65. The use of embodiment 62 or 63, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

[0200] The invention described and claimed herein is not to be limited in scope by the specific embodi-ments herein disclosed, since these embodiments are intended as illustrations of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this inven-tion as well as combinations of one or more of the embodiments.

[0201] Various references are cited herein, the disclosures of which are incorporated by reference in their entireties. The present invention is further described by the following examples which should not be construed as limiting the scope of the invention.

[0202] EXAMPLES

[0203] Materials and Methods

[0204] Example 1 : Protein deamidase activation and purification

[0205] Purification of the proform: Proforms of protein deamidases were expressed in a heterologous expression system and the cell mass removed by centrifugation followed by germ filtration. The proforms were purified by standard protein purification techniques known to a person skilled in the art. Purity of the final samples was checked by SDS-PAGE. These samples were used for activation.

[0206] Activation and Purification of Mature Form: A specific glutamyl endopeptidase was added to the purified proforms and incubated with gentle shaking at room temperature. Standard SDS-PAGE was used to check the progress of the activation process (shift from approx. 30 kDa to approx. 20 kDa). When the activation process was completed, to separate the mature enzyme from the propeptide and to inactivate / remove the glutamyl endopeptidease, the samples were buffer-ex- changed following standard protocols using a column packed with a Sephadex G-25 resin. Eluted fractions were checked by SDS-PAGE and the fractions containing the mature, activated molecule were pooled. The resulting sample was loaded on a cation-exchanger, Source 15S, calibrated using the same buffer and eluted using a linear gradient (0-100% in 20 CV’s). Peak fractions were analyzed by SDS-PAGE and relevant fractions (mature deamidase) were pooled. Concentration was determined using an A280 measurement on a NanoDrop equipment in combination with a theoretical extinction coefficient. The samples were frozen at -18°C until further use. Purification of the propeptide: The propeptide of a protein deamidase was cloned and expressed in a heterologous expression system. At the end of the fermentation, cell mass was removed by centrifugation followed by germ filtration. The resulting sample was buffer-exchanged following standard protocols using a column packed with a Sephadex G-25 resin. The peak fractions were pooled and loaded on an anion-exchange column (Source 15Q) equilibrated using the same buffer. The run-through and wash fractions were pooled and loaded onto a Source 15Q column. The run-through and wash fractions were pooled and concentrated using a pressurized UF cell equipped with a 5 MWCO membrane. Concentration of the resulting retentate was determined using an A280 measurement on a NanoDrop equipment in combination with a theoretical extinction coefficient.

[0207] Example 2: Skimmed milk treated with deamidase and foamed

[0208] Enzyme treatment: 4 x 250 g pasteurized skimmed milk (Egelykke, Aria Foods, Viby, Denmark; 3.5 g protein / 100 g; 0.1 g Fat / 100 g; 4.7 g carbohydrate / 100 g) were weighed out in bluecap bottles and heated to 55°C in a water bath. Mature protein deamidase comprising the amino acid sequence of SEQ ID NO: 2 (derived from C. viscerunr, 350 IPA(U) / g) was added at a concentration of 0, 1.4, 3.4, or 6.8 IPA(U) / g milk protein and incubated for 30 min. After enzymatic treatment, the bottles were transferred to a 75°C water bath and held for 15 seconds upon reaching 72°C. The bottles were then cooled on ice and stored at 5°C for at least 90 minutes.

[0209] Foaming in Milk Frother: 120 g (+ / - 1 g) of cold (5°C) enzyme treated milk was weighed out. 2x4 samples of 120 g covering the dosage response of 0, 1.4, 3.4, and 6.8 IPA(U) / g milk protein were each heated to 50° or 60°C. The heated samples were added to a Milk Frother (Severin SM3587 Spuma 700 plus; Severin Elektrogerate GmbH, Sundern, Germany) and stirred for 60 seconds without further heating. The foamed milk was transferred to a 500 ml measuring glass and the total volume, the volume of the foam, and the volume of the liquid were each measured. The total volume, volume of the foam, and volume of the liquid were measured again after 10 minutes at room temperature to assess the stability of the foam. The samples performed with 0 IPA(U) / g protein are the control samples.

[0210] Table 1 : Results from foaming of skimmed milk treated with the protein deamidase of SEQ ID

[0211] NO: 2

[0212] The addition of the protein deamidase of SEQ ID NO: 2 significantly increased foam volume at both 50°C and 60°C.

[0213] In addition to volume, the quality of the foam was evaluated. The foam was analyzed for airiness, which can range from larger bubbles which are clearly and individually visible, to a homogeneous microfoam with a silky appearance, and also for coherence. Foam coherence was evaluated while the foamed milk was transferred from the Milk Frother to the measuring glass. The coherence of the foam was rated in the quality assessment as the following: None (foam and liquid milk were separated and there was no airiness in the liquid phase resulting in no possibility for creating latte art); poor (foam and liquid milk were separated and there was some airiness in the liquid phase resulting in some possibility for creating latte art although foam blobs could occur); good (foam and liquid milk were partly integrated and there were good airiness in the liquid phase resulting in a good possibility for creating latte art); and very good (foam and liquid milk were fully integrated and there were high airiness in the liquid phase resulting in a very good possibility for creating latte art).

[0214] Table 2: Quality assessment of skimmed milk after foaming

[0215] The addition of the protein deamidase of SEQ I D NO: 2 improved foam volume and quality at both 50 and 60°C. A positive correlation between enzyme dose and foam volume and development of microfoam with a silky appearance and good foam coherency was observed. Example 3: Semi-skimmed and whole milk treated with deamidase and foamed

[0216] Enzyme treatment: 4 x 500 g pasteurized semi-skimmed milk (Aria Foods, Viby, Denmark; 3.5 g protein / 100 g; 1.5 g fat / 100 g; 4.6 g carbohydrate / 100 g) and 4 x 500 g pasteurized whole milk (Aria Foods; 3.4 g protein / 100 g; 3.5 g fat / 100 g; 4.6 g carbohydrate / 100 g) were weighed out in bluecap bottles and heated to 55°C in a water bath. Mature protein deamidase comprising the amino acid sequence of SEQ ID NO: 2 was added at a concentration of 0, 1.4, 3.4, and 6.8 IPA(U) / g milk protein and incubated for 30 minutes. After enzymatic treatment, the bottles were transferred to a water bath at 75°C and held for 15 seconds upon reaching 72°C. The bottles were then cooled on ice and stored at 5°C for at least 90 minutes.

[0217] Foaming in Milk Frother: 120 g (+ / - 1 g) of cold (5°C) enzyme treated semi-skimmed or whole milk was weighed out. 3x4 samples of 120 g covering a dosage response of 0, 1.4, 3.4, and 6.8 IPA(U) / g milk protein were heated to 40°, 50°, or 60°C. The heated samples were added to a Milk Frother (Severin SM3587 Spuma 700 plus) and stirred for 60 seconds without further heating. The foamed milk was transferred to a 500 ml measuring glass and the total volume, the volume of the foam, and the volume of the liquid were each measured. The total volume, volume of the foam, and volume of the liquid were measured again after 10 minutes at room temperature to assess the stability of the foam.

[0218] Volume results from foaming the semi-skimmed milk and the whole milk are shown below in Tables 3 and 5, respectively. The quality of the produced foams, in terms of airiness and coherency, for the semi-skimmed and whole milk are described in Tables 4 and 6, respectively. The samples performed with 0 IPA(U) / g protein are the control samples.

[0219] Table 3: Results from foaming of semi-skimmed milk treated with the protein deamidase of SEQ ID NO: 2

[0220] Table 4: Quality assessment of semi-skimmed milk after foaming

[0221] Table 5: Results from foaming of whole milk treated with the protein deamidase of SEQ ID NO: 2

[0222] T able 6: Quality assessment of whole milk after foaming

[0223] The addition of the protein deamidase of SEQ ID NO: 2 surprisingly improved foaming ability for both semi-skimmed milk and whole milk. The quality of milk was improved airiness, such that more microfoam was generated with a silky appearance, and very good coherency.

[0224] Example 4: Skimmed milk treated with deamidase, purified deamidase and commercial deamidase and foamed

[0225] The protein deamidases of the invention are produced from a proform, inactivated polypeptide. The proform is cleaved to release the propeptide from the mature protein deamidase. In this Example, samples are assayed which contain a mature protein deamidase with or without a propeptide. The molarity of the added propeptide is within a factor of two of the molarity of the mature protein deamidase.

[0226] Enzyme treatment: 8x120 g (+ / - 1 g) skimmed milk (Egelykke, Aria Foods; 3.5 g protein / 100 g; 0.1 g Fat / 100 g; 4.7 g carbohydrate / 100 g) were weighed out in bluecap bottles and heated to 55°C in a water bath. Control samples did not have a protein deamidase or propeptide added to the milk. Mature protein deamidase comprising the amino acid sequence of SEQ ID NO: 2, with or without a propeptide comprising SEQ ID NO: 16, or PG500 (Amano Enzyme Europe Ltd., Oxfordshire, UK; 300.5 IPA(U) / g)) was added at a concentration of 0, 1.3, or 3.4 IPA(U) / g milk protein and incubated for 30 minutes. After enzymatic treatment, the bottles were transferred to a water bath at 75°C and held for 15 seconds upon reaching 72°C. A subsample of 200 pl of the inactivated samples were kept for ammonium analysis. The bottles were then cooled on ice and stored at 5°C for at least 90 minutes.

[0227] Foaming in Milk Frother: 8 samples of cold (5°C) enzyme treated skimmed milk were heated in a Milk Frother (Severin SM3587 Spuma 700 plus) while stirring for 80 sec. The foamed milk was transferred to a 250 ml measuring glass and the total volume, the volume of the foam, and the volume of the liquid were each measured. The total volume, volume of the foam, and volume of the liquid were measured again after 10 minutes at room temperature to assess the stability of the foam.

[0228] Ammonium assay: The activity assay consists of two separate de-coupled parts; 1) An enzymatic step wherein ammonia is formed by the catalytic action of the protein deamidase; and 2) A non- enzymatic detection step wherein the ammonia formed in step (1) is derivatized to a blue indophenol compound with an absorption maximum at 630 nm.

[0229] In step (1), the ammonia is developed by the deamidating action of the protein deamidase. In step (2), the generated ammonia reacts with phenol to form dioxyphenylamine under alkaline conditions. The reaction is catalyzed by sodium pentacyanonitrosylferrate(lll) (sodium nitroprusside). “Color Reagent solution A” contains phenol and sodium nitroprusside. “Color Reagent Solution B” provides alkaline reaction conditions. The intermediate is then oxidized by addition of sodium hypochlorite (“Color Reagent Solution C”) to form indophenol blue. This compound absorbs visible light at 630 nm. The enzyme activity is then calculated using a standard curve.

[0230] Assay Procedure:

[0231] Step (1) Enzymatic Step with ammonia formation

[0232] Reagents:

[0233] Assay dilution solution: 0.2 M Na-phosphate buffer, 0.01% Triton X-100, pH 6.5

[0234] Assay buffer: Same as above. Used to prepare stock solution and diluted sample of protein deamidase (referred to in the following as “enzyme”).

[0235] Substrate solution: 30 mM Z-GIn-Gly (Merck C6154-1G) in assay dilution solution (check pH after dissolution).

[0236] Stop solution: 0.4M TCA

[0237] Standard: NH4CI (Ammonium Standard for IC, Merck 59755-100ML, 1000 mg / L NH4+in water) diluted in assay dilution solution (see also “Standard curve” section). Dissolve / dilute enzyme product in assay buffer and prepare suitable dilution resulting in a linear assay response.

[0238] Incubation:

[0239] 1. Add 10 pL of diluted enzyme samples in triplicates to the wells of a 96-well microtiter plate (MTP).

[0240] 2. Add 100 pL of substrate solution to each well.

[0241] 3. For blank samples add 100 pL 0.4M TCA solution.

[0242] 4. Seal the plate using transparent plate sealer.

[0243] 5. Incubate the plate for 10 minutes at 37°C, 500 rpm, on a thermomixer equipped with a lid heating function.

[0244] 6. To stop the reaction, carefully add 100 pL 0.4M TCA solution (except for the blank samples, which already contain TCA).

[0245] Total reaction volume: 210 pL

[0246] Step (2) Ammonia Detection Step

[0247] Reagents:

[0248] Color reagent A: 4% (w / v) Phenol, 0.015% (w / v) sodium pentacyanonitrosylferrate(lll) dihydrate (sodium nitroprusside) (Na2[Fe(CN)sNO]-2H2O).

[0249] Color reagent B: 5% (w / v) Potassium hydroxide.

[0250] Color reagent C: 28% (w / v) Potassium carbonate, 6% (v / v) sodium hypo-chlorite (Sigma-Aldrich 239305-25ml, < 5% available Cl2).

[0251] Incubation:

[0252] 1. Transfer 15 pL from each well from step (1) into a new 96-well MTP.

[0253] 2. Transfer 45 pL Milli-Q water to each well.

[0254] 3. To each well, add 30pL of color reagent B (on lab table, shake gently by hand to mix).

[0255] 4. To each well, add 60pL of color reagent A (on lab table, shake gently by hand to mix).

[0256] 5. To each well, add 60pL of color reagent C (on lab table, shake gently by hand to mix).

[0257] 6. Color development: Carefully seal the plate and leave it on lab table for 30 minutes.

[0258] 7. Carefully transfer the MTP to a plate reader and measure absorbance at 630 nm.

[0259] Total reaction volume: 210 pL

[0260] Standard curve:

[0261] Standard stock solution: 1000 mg NH4+ / L.

[0262] The standard curve is prepared by adding dilutions of the ammonium standard in the assay dilution buffer in the ammonia detection step. That is, mixing 15 pL diluted ammonia standard with 45 pL water and then add the color reagents in the order given above; B, A, and C. The amount of enzyme producing 1 pmol ammonia per minute at 37°C is defined as 1 unit (Indophenol Assay Unit; IPA(U)): detsrtiOTi (pp)n r. - - - ur generated (j^ ) where mlNH4+180.04 ml * min. where

[0263] • CNH4+ is the ammonia concentration in reaction solution derived from the ammonium standard curve (i.e., taking into account the dilution of the prediluted ammonium standard solution in the ammonia derivatization step).

[0264] • 18.04 is the molecular mass of ammonium used for the standard solution.

[0265] • Vreaaion is the reaction volume in the well when ammonia is generated (210 pL).

[0266] • Venzyme is the volume of enzyme solution added to the well when ammonia is generated (10 pL).

[0267] • VNH3 detection is the reaction volume in the well when ammonia is detected (210 pL).

[0268] Volume results and the results of the ammonium assay for all tested protein deaminases are shown in Table 7. The propeptide added to the samples comprises the amino acid sequence of SEQ ID NO: 16. The quality of the produced foams, in terms of airiness and coherency, are described in Table 8. The control samples did not have a protein deamidase added to the milk.

[0269] Table 7: Results from foaming of skimmed milk treated with protein deamidases

[0270] The quality of foam in terms of airiness (size of air bubbles spanning from clearly visible to homogeneous micro foam with a silky appearance) and coherence (ability to make latte art and avoid foam blobs) was evaluated while transferred from the Frother to the measuring glass.

[0271] Table 8: Quality assessment of skimmed milk treated with protein deamidases

[0272] The preparation comprising both mature protein deamidase and propeptide surprisingly performed better than the purified mature form and the commercial product Amano PG500 in terms of higher foam, higher release of ammonium and improved foam quality.

[0273] Example 5: Skimmed milk treated with deamidase, purified deamidase and foamed using FoamScan.

[0274] Protein deamidase purification’. Protein deamidase proforms comprising the amino acid sequence of SEQ ID NOs: 1 , 21 , 23, or 24 were purified according to Example 1. The proform polypeptides were enzymatically cleaved to produce the mature protein deamidase, as described in Example 1 . In samples where the propeptide is present, there were no further purification steps to remove the propeptide. In samples where no propeptide is present, the propeptide was removed as described in Example 1. Enzyme treatment: 80 g skimmed milk (Egelykke, Aria Foods Group, Denmark; 3.5 g protein / 100 g; 0.1 g Fat / 100 g; 4.7 g carbohydrate / 100 g) were weighed out in bluecap bottles and heated to 55°C in a water bath. Protein deamidase comprising the proform amino acid sequence of SEQ ID NOs: 1 , 21 , 23, or 24 was added at a concentration of 0 (blank control) or 3.4 IPA(U) / g milk protein and incubated for 30 minutes. After enzymatic treatment, the bottles were transferred to a water bath at 75°C and held for 15 seconds upon reaching 72°C. The bottles were then cooled on ice and stored at 5°C.

[0275] Foaming in FOAMSCAN™: 60 ml of enzyme treated milk and control milk without enzyme were applied to the tube in the FOAMSCAN™ (Teclis Scientific, Lyon, France) according to the instruction protocol by the manufacturer, with the following settings: Initial liquid volume = 60 ml, Nitrogen gas flow rate = 100 mL / min, Final time of foaming = 90 s and Total gas volume = 150 ml (i.e. , final time of foaming). The foam was recorded for at least 300 sec to measure the half-life (t 14) of the foam volume after nitrogen gas flow were stopped. The final volume of the foam (in mL) and 1 14 of the foam volume (in seconds) was recorded, and the results are shown in Table 9.

[0276] Ammonium assay: Performed as described in Example 4.

[0277] Volume results and the results of the ammonium assay for all tested protein deaminases are shown in Table 9. The control samples did not have a protein deamidase added to the milk. The ammonium generated is shown with the blank subtracted.

[0278] Table 9: Results from foaming of skimmed milk treated with protein deamidases

[0279] As shown in Table 9, protein deamidases derived from various Chryseobacterium species improve the foaming of skimmed milk compared to a sample where no enzyme was added. Surprisingly, final foam volume is higher in samples with propeptide present compared to enzyme treatments where the propeptide was removed. The half-life of the foam volume is also prolonged in the enzyme treatments with propeptide present. Additionally, the measured ammonia generated correlates with the final foam volume. In conclusion, the presence of the propeptide has a pronounced effect on the milk foam generated, increasing the efficiency of the enzymes when the propeptide is present.

Claims

CLAIMS1. A method for producing improved aerated dairy products, comprising: a) obtaining a dairy composition; b) adding a first polypeptide to the dairy composition, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase; c) optionally adding a second polypeptide to the dairy composition, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase; and d) aerating the dairy composition to produce an aerated dairy product; wherein the aerated dairy product is improved compared to a similar method where the first polypeptide and optionally the second polypeptide is not added to the dairy composition.

2. The method of claim 1 , wherein the dairy composition comprises cream, milk, butter, concentrated milk, condensed milk, evaporated milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

3. The method of claim 1 or 2, wherein the mature protein deamidase comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NOs: 2, 5, 8, or 11.

4. The method any one of the proceeding claims, wherein the second polypeptide is a propeptide which comprises a mutation which decreases its binding affinity for the deamidase domain compared to the parent propeptide.

5. The method of any one of the proceeding claims, wherein the second polypeptide is a propeptide which comprises: a) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

6. The method of any one of the proceeding claims, wherein the second polypeptide comprises the amino acid sequence of SEQ ID NOs: 16, 17, 18, or 19.

7. The method of any one of the proceeding claims, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO:

8. A dairy composition comprising a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase.

9. The dairy composition of claim 8, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

10. The dairy composition of claim 8 or 9, wherein the dairy composition comprises cream, milk, butter, concentrated milk, evaporated milk, condensed milk, reconstituted milk, fermented milk, milk protein concentrate, whey protein concentrate, or a combination thereof.

11. The dairy composition of claims 8 to 10, wherein the dairy composition is processed to produce aerated dairy products, such as ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, or whipped butter.

12. An aerated dairy product produced by the method of any of claims 1 to 7.

13. The aerated dairy product of claim 12, wherein the aerated dairy product is ice cream, whipped cream, whipped yoghurt, whipped cream cheese, foamed milk, whipped butter, or whipped butter spread.

14. Use of a first polypeptide, wherein the first polypeptide is a mature protein deamidase derived from a proform protein deamidase, and optionally a second polypeptide, wherein the second polypeptide is a propeptide derived from the same proform protein deamidase, to produce a dairy composition with improved aeration or foamability.

15. The use of claim 14, wherein: a) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 2, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 3 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 3; b) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 5, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 6 and has an alanine at the position corresponding to position 99 of SEQ ID NO: 6; c) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 8, and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 9 and has a glycine at the position corresponding to position 99 of SEQ ID NO: 9; or d) the first polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 11 , and the optional second polypeptide comprises an amino acid sequence with at least 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%,89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or at least 99% sequence identity to SEQ ID NO: 12 and has a glycine at the position corresponding to position 101 of SEQ ID NO: 12.

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