WHEY protein composition with high heat stability

Abstract

Heat stable whey protein composition comprising a protein content, based on dry matter, of 60-95 wt%, a total concentration of β-lactoglobulin, based on total protein, of at least 30 wt%, at least 90% thereof being denatured β-lactoglobulin, and a total concentration of α-lactalbumin, based on total protein, of at least 20 wt%, 60-84% thereof being denatured α-lactalbumin.

Description

[0001] WHEY PROTEIN COMPOSITION WITH HIGH HEAT STABILITY

[0002] The present invention relates to a partially denatured whey protein and its use in high protein nutritional compositions.

[0003] There are many instances where individuals may be in need of special, high protein diets; when they suffer from malnutrition, e.g. as a result of age, diseases, or surgery, or in order to support drug therapy.

[0004] For example, patients who have had bariatric surgery and are on a post-operative fluid diet after surgery may rely on high protein drinks when they are unable to gain enough protein from food alone. Formulations for bariatric patients may be high in protein content but lower in fat and carbohydrate content in order to control the overall intake of calories.

[0005] Other individuals, however, have to rely on liquid nutritional compositions as their sole source of nutrition; e.g. surgical patients, patients who suffered a trauma or receive cancer therapy, or individuals whose general health status makes them too weak, or unwilling, to eat or drink at all or in insufficient amounts. Often, such individuals have to rely on sip feeding or tube feeding. In order to be suitable as sole source of nutrition, the liquid composition needs to comprise a complete diet, meaning that it should contain, in addition to a relatively high concentration of protein, also sources of fat and carbohydrates, vitamins, minerals, and optionally fibers (complete nutritional products). In order to make such compositions suitable for individuals with a fluid restriction, the nutrient concentration and energy density should be as high as possible, e.g. 1 .5 - 2.5 kcal / ml.

[0006] In addition to medical applications of high protein drinks, also athletes use such compositions in order to build and support muscle mass.

[0007] A known problem with concentrated compositions is that the high concentration of protein may lead to a high viscosity of the composition and / or instability issues during processing, especially after heat-treatment of the compositions (e.g. to sterilize them). This is particularly problematic in compositions intended for use as a sip feed or a tube feed in medical nutrition, which may also contain fat, carbohydrates, and vitamins, and minerals. Also for patients who have problems swallowing, viscosity of the composition is important. In compositions intended for sip or tube feeding, particularly in compositions intended for sip feeding, it is important that a relatively small serving of the composition comprises a high amount of protein, and preferably also carbohydrate and / or fat. In these compositions it is further preferred that the energy density is relatively high, e.g. in the range of 1 .5-2.5 kcal / ml.

[0008] The protein source on which high protein nutritional compositions are based may vary. In nutritional compositions containing high concentrations of proteins, usually dairy protein ingredients such as milk protein isolate or milk protein concentrate, micellar casein, caseinate(s) such as sodium caseinate, potassium caseinate or calcium caseinate, or whey protein concentrates or isolates are used.

[0009] Of the two main classes of dairy proteins - casein and whey protein - whey protein is characterized by a considerably higher leucine content compared to casein. Because leucine has been identified as the amino acid that directly stimulates postprandial muscle protein accretion. Furthermore, whey protein is digested faster than casein protein. It is therefore desired for high protein compositions to contain a significant amount of whey protein.

[0010] Unfortunately, whey proteins have a strong tendency to gel and / or aggregate upon heat treatment, resulting in significant viscosity increase. This seriously hinders the use of whey protein in highly concentrated liquid formulations, especially those that need a heat sterilization treatment, such as those intended as sip feed or tube feed.

[0011] Many solutions have been proposed for achieving an acceptable balance between high nutrient (incl. protein) content on the one hand, and heat stability and viscosity on the other. For instance, WO 2010 / 140891 and WO 2010 / 140877 propose to reduce the monovalent metal ion content to below 25 mg per g protein in order to keep sufficiently low viscosity. Other documents require the use of micellar casein in combination with caseinate (WO 2009 / 072885), the use of intact protein with low specific volume (WO 2009 / 072884), the combination of micellar casein and hydrolysed whey protein (WO 2016 / 174651 ), or the application of a specific preparation method using a dry blend of micellar casein and carbohydrates (WO 2014 / 104872).

[0012] The object of the present invention is the provision of a heat stable whey protein that is particularly suitable for use in high protein nutritional compositions. Whey results from the separation of (skimmed) milk into a casein-rich and a whey protein-rich fraction - either by renneting to form cheese and so-called cheese whey, by acidification to form caseinate and so-called acid whey, or by microfiltration to form a micellar casein fraction and a so-called ideal whey or serum fraction.

[0013] The proteins in whey can be concentrated - resulting in whey protein concentrates (WPC) and whey protein isolates (WPI) - by subjecting whey to membrane filtration, precipitation, and / or ion exchange techniques in order to remove a large part of the water, lactose, and ash from the whey protein-rich fraction.

[0014] WPCs conventionally have a protein content (based on dry solids) of 60 wt% up to about 85 wt%, whereas WPIs are manufactured by removing more of the non-protein components, thereby concentrating the whey protein content to about 90-95 wt%.

[0015] Processes for the production of WPC or WPI may involve concentrating the entire protein fraction in the raw material, but may also include a selective enrichment in particular protein. Examples thereof as WPCs and WPIs selectively enriched in either a-lactalbumin or [3-lactoglobulin.

[0016] The proteins present in WPC and WPI are essentially in native, i.e. non-denatured, state. A native protein is defined as a protein in its properly folded and / or assembled form, which is operative and functional. It possesses all four levels of its biomolecular structure, with the secondary through quaternary structure being formed from weak interactions along the covalently bonded backbone. In a denatured protein, at least part of the weak interactions of the secondary through quaternary structure is disrupted, whereas the primary structure - i.e. the covalently bonded backbone - is still intact. A denatured protein therefore differs from a hydrolysed protein, as in the latter also the primary structure has been disrupted.

[0017] As indicated above, aqueous compositions of WPC or WPI can gel and / or aggregate upon heating, thereby affecting the viscosity of the composition. Denatured whey proteins, on the other hand, are less inclined to gel and aggregate upon heating.

[0018] The combination of heat treatment and mechanical forces, in particular high shear, allows for the formation of small whey protein particles / aggregates with a high degree of denaturation. The so-produced whey protein material is known to be suitable for increasing the protein content of food products and is generally termed microparticulated whey protein. Other names for these types of particles are heat- denatured whey protein particles, whey protein aggregates or microparticles, and whey protein micelles.

[0019] Microparticulated whey protein was first described in US 4,734,287, which formed the basis for the commercial fat replacer Simplesse®. This fat replacer was offered for use in frozen desserts, cheese, dressings, and mayonnaise, and allowed a creamy texture despite the reduced fat content.

[0020] Equipment used for microparticulation includes pressurized tubular reactors or heat exchangers (WO 2006 / 057968, WO 2010 / 120199) and / or homogenizers (W02008 / 063115).

[0021] An overview of various applications of microparticulated whey protein is provided by R. Ipsen, Int. Dairy J. 67 (2017) 73-79 and by B. Kew, Trends in Food Science & Technology 106 (2020) 457-468.

[0022] WO 2007 / 108709 discloses a process for the microparticulation of whey proteins by changing the pH of a WPC or WPI containing 3 g / kg dry solids of a divalent metal ion content, preferably calcium hydroxide, to 6.0-8.5, most preferably 6.9-7.5, followed by heat-treating the obtained solution at more than 70°C, preferably above 85°C. At temperatures of about 120°C only a few minutes were sufficient; at 70°C, 40-60 minutes were required.

[0023] WO 2007 / 108709 theorizes that a high divalent metal ion content affects the proteinprotein interactions, thereby promoting the formation of non-covalently associated aggregates instead of disulphide associated aggregates. The first are more readily broken by mechanical shear than the latter. The median particle size of the resulting whey protein particles was more than 10 microns and less than 70 microns.

[0024] WO 2010 / 120199 discloses a process in which whey protein concentrate or isolate is denatured at a temperature of at least 50°C under turbulent flow conditions and without mechanical shear, after which it is transferred directly to a drier, without any intermediate processing.

[0025] Although the heat stability of denatured whey protein particles is high compared to native whey protein, its application in heat treated products (e.g. sterilized high protein drinks) still encounters limitations in terms of gelation, sedimentation, heat stability, viscosity, and / or sandy / gritty mouth feel. It has now been found that optimal heat stability and, hence, viscosity, can be obtained if the denaturation degrees of beta-lactoglobulin and alpha-lactalbumin are carefully controlled within specific boundaries.

[0026] More specifically, at least 90% of the [3-lactoglobulin should be denatured and 60-84% of the a-lactalbumin should be denatured.

[0027] The invention therefore relates to a heat stable whey protein composition comprising:

[0028] - a protein content, based on dry matter, of 60-95 wt%,

[0029] - a total concentration of [3-lactoglobulin, based on total protein, of at least 30 wt%, at least 90% thereof being denatured [3-lactoglobulin,

[0030] - a total concentration of a-lactalbumin, based on total protein, of at least 20 wt%, 60- 84% thereof being denatured a-lactalbumin.

[0031] It is noted that WO 2023 / 209603 discloses a whey protein composition with a high degree of denaturation. The present finding, however, is that for preparing high protein sterilized liquid formulations, the optimum degree of denaturation differs per type of protein. As shown in the experimental section, the combination of highly denatured [3- lactoglobulin with a-lactalbumin having a denaturation degree in the claimed range leads to lower viscosity than combinations comprising a-lactalbumin with higher or lower denaturation degrees.

[0032] The heat stable whey protein composition of the present invention has a protein content, based on dry matter, of 60-95 wt%, preferably 75-95 wt%, most preferably 80

[0033] - 85 wt%.

[0034] The total concentration of a-lactalbumin and [3-lactoglobulin, based on total protein, is preferably at least 50 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, and most preferably at least 80 wt%. This total concentration includes both native and denatured alpha-lactalbumin and beta-lactoglobulin.

[0035] The total concentration of [3-lactoglobulin, based on total protein, is at least 30 wt%, preferably at least 40 wt%, more preferably at least 50 wt%, most preferably at least 60 wt%. The total concentration of [3-lactoglobulin, based on total protein, is generally at most 75 wt%. The total concentration of a-lactalbumin, based on total protein, is at least 20 wt%, preferably at least 30 wt%, most preferably at least 40 wt%. The total concentration of a-lactalbumin, based on total protein, is generally at most 50 wt%.

[0036] At least 90 wt%, preferably at least 92%, more preferably at least 94%, and most preferably at least 95% of the [3-lactoglobu lin is denatured (3-lactoglobul in.

[0037] 60-84%, preferably 65-80%, most preferably 70-75% of the a-lactalbumin is denatured a-lactalbumin.

[0038] The native a-lactalbumin and [3-lactoglobulin content can be determined by means of high pressure gel permeation liquid chromatography, as described by C. Holt et al., Int. J. Food Sci. Techn. 34 (1999) 543-556, method 1 of BDI laboratory 1 . To this end, the protein sample is dissolved in distilled water at approximately 2 g / l and the pH of the solution is adjusted to pH 4.6 with acetic acid and sodium acetate. After 0.5 hour standing at ambient temperature, the sample is filtered using a 0.45 pm membrane and subsequently separated using a size exclusion (TSK G2000 SEXL) column, a pH 6.0 phosphate buffer, and detection at 280 nm. The concentration of native [3- lactoglobulin and a-lactalbumin is determined by integration of the peak area. By comparing these concentrations with those of the starting whey protein material, the degree of denaturation can be calculated.

[0039] In one embodiment, the heat stable whey protein composition has the form of an aqueous dispersion with a dry matter of 15-50 wt%, more preferably 18-45 wt%, and most preferably 25-35 wt%. In a preferred embodiment, the heat stable whey protein composition is in spray-dried form.

[0040] The denaturation degrees of beta-lactoglobulin and alpha-lactalbumin can be controlled by carefully controlling the solids content, pH, temperature, and residence time within small boundaries.

[0041] The process according to the present invention involves the following steps: a) providing a whey protein composition with a protein content of 60-95 wt%, based on dry matter, a total concentration of native a-lactalbumin and native [3- lactoglobulin, based on total protein, of at least 50 wt%, b) providing an aqueous whey protein solution comprising the whey protein composition of step a) with a protein concentration of 20-25 wt%, said solution having a pH in the range 6.0-7.5, c) optionally pre-heating said aqueous whey protein solution to a temperature up to 70°C using a heat exchanger, d) transporting the optionally pre-heated aqueous whey protein solution through a heat exchanger with a shear rate of at least 1500 s-1, thereby heating the aqueous whey protein solution to a temperature in the range 76-82°C, e) holding the aqueous whey protein product resulting from step d) at 76-82°C in a holding tube, and f) transporting the whey protein product to the top of a spray-drying tower via a tower feeding line, g) spray-drying the whey protein product to obtain the heat stable whey protein composition, wherein the total residence time of the aqueous whey protein from entering the tubular heat exchanger till arrival at the top of the spray-drying tower is in the range 50-300 seconds.

[0042] The starting material is a whey protein composition with a protein content, based on dry matter, in the range 60-95 wt%, and a total concentration of native a-lactalbumin and [3-lactoglobulin, based on total protein, of at least 50 wt%, preferably at least 60 wt%, more preferably at least 70 wt%, more preferably at least 80 wt%, even more preferably at least 85 wt%, more preferably at least 90 wt%, more preferably at least 95 wt%, most preferably at least 99 wt%.

[0043] The proteins in the starting material are mostly native, i.e. non-denatured. The denaturation degree of the a-lactalbumin and [3-lactoglobulin in said starting material is less than 20%, preferably less than 15%, more preferably less than 10%, and most preferably less than 5%.

[0044] The protein content can be determined using the well-known Kjeldahl nitrogen analysis method and the application of a Kjeldahl conversion factor of 6.38. Examples of suitable whey protein compositions are whey protein concentrate, whey protein isolate, a-lactalbumin enriched WPC or WPI, and [3-lactoglobulin enriched WPC or WPI.

[0045] The starting material may be a dried / powdered whey protein composition or a liquid whey protein composition. An example of such a liquid whey protein composition is a whey product obtained when removing part of the water, lactose and minerals from acid whey (i.e. whey resulting from caseinate production), cheese whey, or ideal whey. More in particular, the liquid whey protein composition is the ultrafiltration retentate of whey, which may have been subjected to further concentration, filtration and / or purification steps.

[0046] The whey protein composition preferably has a calcium content preferably below 1900 mg / 100 g protein, more preferably below 1250 mg / 100 g protein, even more preferably below 950 mg / 100 g protein, and most preferably below 750 mg / 100g protein. Lower calcium contents improve the heat stability.

[0047] In one embodiment, the whey protein composition has been obtained by concentrating whey, preferably cheese whey. In contrast to acid whey or ideal whey, cheese whey contains caseinomacropeptide (CMP). CMP helps to prevent the formation of strong continuous gel structures and might assist in preventing the aggregation of microparticles during heating.

[0048] In another embodiment, the whey protein concentrate or isolate has been obtained by concentrating acid whey.

[0049] Concentration of the whey proteins may have been performed by standard methods, such as ultrafiltration.

[0050] The whey protein composition is either dissolved in water (in case the whey protein concentrate or isolate is in dried or powdered form), or used as is or be diluted with water (in case a liquid whey protein composition is used as the whey protein composition) in amounts that result in a solution with a protein concentration of 20-25 wt%. Using a protein concentration below 20 wt% has turned out to result in a product with insufficient heat stability. Using a protein concentration content above 25 wt% results in processing problems. The pH of the resulting solution should be in the range 6.0-7.5. Outside these ranges, aggregation occurs too quickly upon heating.

[0051] If the pH of the whey protein solution is not already in this range, it may be adjusted to this range by the addition of an acid or base. Suitable acids and bases are KOH, NaOH, Ca(OH)2, Mg(OH)2, NH4OH, carbonates and bicarbonates, trisodium citrate, tripotassium citrate, phosphates, HCI, phosphoric acid, citric acid, lactic acid, tartaric acid, acetic acid, sulphuric acid, hydrochloric acid, malic acid, maleic acid, fumaric acid, and succinic acid.

[0052] In order to denature the whey protein and form particles, the aqueous whey protein solution is first heated under shear in a heat exchanger, preferably a tubular heat exchanger, to a temperature in the range 76-82°C. Below 76°C, there will be insufficient protein denaturation; above 82°C, the proteins denaturation will exceed the required values.

[0053] The shear rate during this heating step is at least 1500 s-1, preferably at least 2000 s’1, and most preferably at least 2300 s’1.

[0054] The shear rate is controlled by the internal diameter of the tubular heat exchanger and by the flow rate of the aqueous solution.

[0055] In one embodiment, the tubular heat exchanger can be used to heat the whey protein solution starting from room temperature or below.

[0056] In another embodiment, the whey protein solution is first pre-heated before entering the tubular heat exchanger. It may be pre-heated up to any temperature, provided the temperature stays below the denaturation temperature of a-lactalbumin and [3- lactoglobulin. In practice, this means a temperature not higher than 70°C, preferably not higher than 65°C. Said pre-heating can be performed with any suitable equipment, including plate heat exchangers, tubular heat exchangers, and scraped surface heat exchangers. In a preferred embodiment, a tubular heat exchanger is used.

[0057] The aqueous whey protein product leaving the tubular heat exchanger is subsequently held in a holding tube at a temperature in this same range 76-82°C. In a preferred embodiment, it is held in this holding tube at a shear rate of at least 1000 s-1, preferably at least 1300 s’1, most preferably at least 1500 s’1. From the holding tube, the whey protein product is transported to the top of a spraydrying tower, via a tower feeding line. The top of a spray-drying tower is defined as a location in the vicinity of the atomizer (e.g. spraying nozzles or a rotating disc), such that the liquid composition can move from the heater to the atomizer within a short time frame, preferably less than about 40 seconds. The tower feeding line can be a high- pressure line or can work under regular process pressure, depending on the type of spray-dryer. If the atomizer of the spray-dryer contains spraying nozzles, the pressure in said line is preferably set in the range 50-350 MPa. A rotating disc atomizer requires pressures in the range 1 -5 MPa.

[0058] The whey protein product within the tower feeding line will still have a above the a- lactalbumin protein and [3-lactoglobulin denaturation temperature, as a result of the previous holding step.

[0059] Transportation from the holding tube to the tower feeding line may optionally involve recirculation of at least part - preferably 5-60 wt%, more preferably 5-40 wt%, even more preferably 5-25 wt%, and most preferably 10-25 wt% - of whey protein product to the tubular heat exchanger of step d). This can be performed with a high pressure pump.

[0060] In order to achieve the required denaturation degree of a-lactalbumin and [3- lactoglobulin, it is important that the total residence time of the aqueous whey protein from entering the tubular heat exchanger till arrival at the top of the spray-drying tower (so, including the heat exchanger, holding tube, tower feeding line, and optional recirculation) is in the range 50-300 seconds, preferably 180-250 seconds, most preferably 200-225 seconds.

[0061] If the total residence time exceeds the 300 seconds, the a-lactalbumin denaturation exceeds the required value; if the residence time is less than 50 seconds, the [3- lactoglobulin denatures to insufficient extent.

[0062] The higher the temperature, the shorter the holding time period required.

[0063] Spray-drying is subsequently performed using hot air with a temperature in the range 140-300°C, preferably 150-260°C, and most preferably 170-210°C.

[0064] Any type of spray-dryer can be used, such as Single Stage, 2-Stage, Multi Stage and Filtermat® type spray dryers. The process of the present invention results in a heat stable whey protein composition comprising (ii) a-lactalbumin with a degree of denaturation of 60-84%, preferably 65- 80%, more preferably 70-75% and (ii) [3-lactoglobulin with a degree of denaturation of at least 90%, preferably at least 92%, more preferably at least 94%, most preferably at least 95%.

[0065] The whey protein particles in the heat stable whey protein composition according to the present invention preferably have a D50 volume average particle diameter in the range 0.05 -20 microns, more preferably 0.05 -10 microns, most preferably 0.05 - 1 .0 microns. Preferably, 90 vol% of the particles (D90) has a diameter of less than 60 microns, more preferably less than 10 microns, most preferably less than 5.0 microns. The span (=(D90-D10) / D50) is preferably in the range 5.0-40, more preferably 5.0-30, most preferably 5.0-20.

[0066] This particle diameter and size distribution are determined using laser diffraction (Malvern Matersizer 2000), with a refractive index of 1 .47, and assuming non-spherical particles with an adsorption of 0.

[0067] The heat stable whey protein composition of the present invention has a wide range of utilities, in particular for raising the protein content of food products without significant change in the texture. Examples of such food products are processed cheese, yoghurt, ice cream, fermented milk products, whey crisps, bakery applications, (high protein) beverages, high protein medical nutrition, and convenience food.

[0068] In one embodiment, the heat stable whey protein composition is used for preparing high protein medical nutrition, such as enteral compositions.

[0069] The use of the heat stable whey protein composition according to the present invention as the or at least one of the protein sources of such high protein liquid medical nutritional composition allows to keep the viscosity of such compositions relatively low. Such liquid compositions may contain 10-25 wt%, preferably 10-20 wt% protein, 25- 100 wt%, preferably 40-60 wt% thereof being the heat stable whey protein composition according to the present invention. Examples of additional protein sources are micellar casein isolate, milk protein isolate, milk protein concentrate, caseinate, and combinations thereof. The pH of such nutritional compositions is preferably about neutral, e.g. 6.0-7.5. The nutritional composition may furthermore contain carbohydrates, fats, vitamins, and minerals.

[0070] Carbohydrates preferably provide 20 to 60% of the total energy content of such nutritional compositions. Examples of suitable carbohydrates include maltodextrin, hydrolyzed, intact, naturally and / or chemically modified starch or cornstarch, malt, maltose, isomaltose, isomaltulose, glucose polymers, corn syrup, corn syrup solids, rice or potato derived carbohydrate, glucose, fructose, sucrose, lactose, trehalose, palatinose, high fructose com syrup, and combinations thereof.

[0071] Fats preferably provide 20 to 50% of the total energy content of the composition. Nonlimiting examples of sources of fat that are suitable for use in the nutritional composition include milk fat or milk fat fractions, food grade coconut oil, fractionated coconut oil, soy oil, corn oil, olive oil, rapeseed oil, safflower oil, high oleic safflower oil, MCT oil (medium chain triglycerides), sunflower oil, high oleic sunflower oil, palm and palm kernel oils, palm olein, canola oil, marine oils (e.g. fish oil), cottonseed oils, long-chain polyunsaturated fatty acids such as arachidonic acid (ARA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and combinations thereof. The nutritional composition may also comprise one or more structured lipids. Structured lipids are predominantly triacylglycerols containing mixtures of medium and long chain fatty acids on the same glycerol backbone.

[0072] In another embodiment, the invention relates to liquid high protein compositions, e.g. protein shots or yoghurt drinks, suitable for athletes, elderly, patients, and anybody else desiring to improve protein intake, recovery and / or muscle synthesis.

[0073] Such compositions may contain 10-25 wt%, preferably 10-20 wt%, more preferably 15- 20 wt% protein, 30-60 wt%, preferably 30-50 wt%, most preferably 35-45 wt% thereof being the heat stable whey protein composition according to the present invention. Examples of additional protein sources are micellar casein isolate, milk protein isolate, milk protein concentrate, caseinate, and combinations thereof, wherein micellar casein isolate is the most preferred additional protein source.

[0074] Such compositions preferably do not contain significant amounts fats and carbohydrates. EXAMPLE

[0075] Example 1

[0076] An aqueous whey protein concentrate (WPC) with 23 wt% protein, pH 6.6, and a whey protein content of 80 wt% on dry matter (20 wt% a-lactalbumin, 77 wt% [3-lactoglobulin based on total protein; 10% denatured a-lactalbumin + [3-lactoglobulin, based on total on total protein) was preheated to 65°C in a tubular heater (internal diameter 7 mm) at 270 L / h. Subsequently, the preheated solution was displaced into the main tubular heater (internal diameter 7 mm, shear rate: 2400 s-1) by means of a positive displacement pump, in which the solution was heated to 80°C. The concentrate subsequently entered a tubular holder (internal diameter 7 mm) without any heating and with a shear rate of 2400 s-1.

[0077] The liquid leaving the holder tube was subsequently transported to the top of a spraydrying tower via a tower feeding line and then spray-dried. The total residence time in the heat exchanger, the holding tube, and the tower feeding line was 226 seconds.

[0078] The resulting product had a beta-lactoglobulin denaturation degree of 92% and an alpha-lactalbumin denaturation degree of 78%.

[0079] Example 2

[0080] The performance of the product of Example 1 in high protein formulations was compared with the performance of two commercially available denatured (microparticulated) whey protein ingredients: A and B.

[0081] Commercial product A had a beta-lactoglobulin denaturation degree of 97% and an alpha-lactalbumin denaturation degree of 97%.

[0082] Commercial product B had a beta-lactoglobulin denaturation degree of 85% and an alpha-lactalbumin denaturation degree of 60%.

[0083] Sterilized high protein formulations with a neutral pH and a total protein content of 15 g / 100ml were prepared, The protein content consisted of 40 wt% micellar casein, 20 wt% sodium caseinate, and 40 wt% denatured whey protein product.

[0084] The viscosities of these formulations after storage for six days at room temperature ranged from about 75 mPa.s’1for the formulation according to the invention to about 150 mPa.s’1for the formulations containing the commercial denatured whey ingredients, thereby illustrating the importance of the denaturation degrees of both beta-lactoglobulin and alpha-lactalbumin.

Claims

CLAIMS1 . Heat stable whey protein composition comprising:- a protein content, based on dry matter, of 60-95 wt%,- a total concentration of [3-lactog lobul in , based on total protein, of at least 30 wt%, at least 90% thereof being denatured [3-lactoglobulin,- a total concentration of a-lactalbumin, based on total protein, of at least 20 wt%, 60-84% thereof being denatured a-lactalbumin.

2. Heat stable whey protein composition according to claim 1 having a protein content of 70-95 wt%, preferably 80-85 wt%,3. Heat stable whey protein composition according to claim 1 or 2 wherein the total concentration of [3-lactoglobulin, based on total protein, is at least 40 wt%, more preferably at least 50 wt%, most preferably at least 60 wt%.

4. Heat stable whey protein composition according to any one of the preceding claims wherein at least 92%, more preferably at least 94%, and most preferably at least 95% of the [3-lactoglobulin is denatured [3-lactoglobulin.

5. Heat stable whey protein composition according to any one of the preceding claims wherein the total concentration of a-lactalbumin, based on total protein, is at least 30 wt%, most preferably at least 40 wt%.

6. Heat stable whey protein composition according to any one of the preceding claims wherein 60-80%, most preferably 70-75% of the a-lactalbumin is denatured a-lactalbumin.

7. Process for producing a heat stable whey protein composition, the process comprising the steps of: a) providing a whey protein composition with a protein content of 60-95 wt%, based on dry matter, a total concentration of native a-lactalbumin and native [3-lactoglobulin, based on total protein, of at least 50 wt%,b) providing an aqueous whey protein solution comprising the whey protein composition of step a) with a protein concentration of 20-25 wt%, said solution having a pH in the range 6.0-7.5, c) optionally pre-heating said aqueous whey protein solution to a temperature up to 70°C using a heat exchanger, d) transporting the optionally pre-heated aqueous whey protein solution through a heat exchanger with a shear rate of at least 1500 s-1, thereby heating the aqueous whey protein solution to a temperature in the range 76- 82°C, e) holding the aqueous whey protein product resulting from step d) at 76-82°C in a holding tube, and f) transporting the whey protein product to the top of a spray-drying tower via a tower feeding line, g) spray-drying the whey protein product to obtain the heat stable whey protein composition, wherein the total residence time of the aqueous whey protein from entering the tubular heat exchanger till arrival at the top of the spray-drying tower is in the range 50-300 seconds.

8. Process according to claim 7 wherein the optionally pre-heated aqueous whey protein solution is transported through the heat exchanger at a shear rate of at least 2000 s-1, preferably at least 2300 s-1.

9. Process according to claim 7 or 8 wherein the aqueous whey protein product resulting from step d) is held in the holding tube at a shear rate of at least 1000 s’1, preferably 1300 s’1, most preferably at least 1500 s’1.

10. Process according to any one of claims 7-9 wherein the total residence time is in the range of 180-250 seconds, preferably 200-225 seconds.

11. Process according to any one of claims 7-10 wherein the whey protein composition of step a) has a calcium content below 1900 mg / 100g protein, preferably below 1250 mg / 100g protein, more preferably below 950 mg / 100g protein, and most preferably below 750 mg / 100g protein.

12. Food product comprising the heat stable whey protein composition of any one of claims 1 -6 or the heat stable whey protein composition obtainable by the process of any one of claims 7-11 , said food product being preferably selected from the group consisting of cheese, yoghurt, ice cream, fermented milk products, whey crisps, bakery applications, food bars, protein beverages, high protein medical nutrition, and convenience food.

13. Liquid nutritional composition having a protein content of 10-25 wt%, preferably 10-20 wt%, more preferably 15-20 wt%, wherein 30-60 wt%, preferably 30-50 wt%, most preferably 35-45 wt% of the protein content is the heat stable whey protein composition of any of claims 1-6 or a heat stable whey protein composition obtainable by the process of any of claim 7-12.

14. Liquid nutritional composition according to claim 13 having an energy density of1.5-2.5 kcal / ml.