Modified citrus fibre

Abstract

The present invention relates to a method for preparing a fibre comprising pectin having a degree of esterification of less than 50%. The method comprises (a) providing citrus fibres comprising pectin having a degree of esterification of at least 50%; (b) subjecting the citrus fibres to homogenization; (c) extracting the homogenised citrus fibres with an organic solvent, yielding a wet cake; (d) drying the wet cake to obtain a fibre powder, wherein in the organic solvent extraction step the citrus fibres are contacted with a composition comprising an enzyme with pectin methyl esterase activity, to de-esterify the pectin in the fibre in order to obtain a fibre comprising pectin having a degree of esterification of less than 50%.

Description

[0001] MODIFIED CITRUS FIBRE

[0002] Field of the Invention

[0003] The present invention relates to a method for the preparation of a citrus fibre comprising low- methoxyl pectin.

[0004] Background of the invention

[0005] Pectins are plant polysaccharides consisting of an alpha 1-4 linked polygalacturonic acid backbone present in soft plant tissues, such as fruits and vegetables. The galacturonic acid residues in pectin are partly esterified with methyl ester groups attached to their carboxyl groups. The degree of esterification is defined as the proportion of total galacturonic acid carboxyl groups which are esterified. Pectin with a degree of esterification of 50% or more is referred to as high methyl ester (or high methoxyl) pectin. Pectin with a degree of esterification lower than 50% is referred to as low methyl ester pectin (or low methoxyl) pectin. Most pectin found in fruits and vegetables is high methyl ester pectin. High methyl ester pectin is extracted and added to food applications for increasing viscosity and for gelling of food products. Sugar and a low pH is required to induce gelling of high methyl ester pectin. Low methyl ester pectin is rare in fruit and vegetables. However, low-methoxyl pectin can be prepared by extracting the high methyl ester pectin and chemical or enzymatical deesterification of the high methyl ester pectin after extraction from fruit or vegetables. This low- methoxyl pectin may be added to food ingredients which need gellification or thickening. Low- methoxyl pectin has the advantage that no sugar is required to induce gelling, the presence of divalent cations like calcium or magnesium is sufficient.

[0006] Dietary fibres are used in food products because of they are considered to contribute to health. To form gellified fibre products, large amounts of sugar have to be added to the fibres which typically comprise high methyl ester pectin. Alternatively, low methyl ester pectin is added for gellification.

[0007] A more recent development is that the high methyl ester pectin in the fibre is converted to low methyl ester pectin. The conversion is done while the pectin remains in the fibre (in situ). In situ conversion of pectin obviates the need to add sugar and / or extra Low methyl ester pectin to the fibre product for gelling, and thus allows for cleaner labelling.

[0008] WO2022 / 029131 discloses a method for preparing a fibre comprising in situ low methyl ester pectin, which method comprises acidic disintegration at pH 0.5-2.5 of the raw material fibre with application of heat before enzymatic or chemical de-esterification of the pectin. EP2188315 discloses a method for preparing a a fibre comprising in situ low methyl ester pectin, which method comprises swelling of the fibre in an acidic aqueous solution before alkali treatment of the fibre at pH 10 to de-esterify the pectin in the fibre. These methods have the disadvantage that they require acidification followed by neutralization, which subjects the fibres to harsh conditions, introduces extra ions, extra volumes and extra steps in the process, which makes the process overall very laborious.

[0009] There is a need for an improved process which produces a fibre comprising low methyl ester pectin of good quality and while the improvements have minimal impact on the production process.

[0010] Detailed description of the invention

[0011] The present invention relates to a method for preparing a fibre comprising pectin having a degree of esterification of less than 50%, the method comprising:

[0012] (a) providing citrus fibre feedstock comprising citrus fibres, which citrus fibres comprise pectin having a degree of esterification of at least 50%;

[0013] (b) subjecting the citrus fibre feedstock to homogenization to obtain homogenised citrus fibre feedstock; (c) extracting the homogenised citrus fibre feedstock with an organic solvent, yielding a wet cake;

[0014] (d) drying the wet cake to obtain a fibre powder, wherein in the organic solvent extraction step the citrus fibres are contacted with a composition comprising an enzyme with pectin methyl esterase activity, resulting in a fibre comprising pectin having a degree of esterification of less than 50%.

[0015] The method has several advantages. A first advantage is that the method is simple and flexible. Since the enzyme with pectin methyl esterase activity is added during the solvent extraction step, the enzyme is already in a liquid environment and no extra liquid has to be added to provide good conditions for the working of the enzyme or for dilution of the enzyme. Not adding large volumes of extra liquid, means not having to remove large volumes of extra liquid, which makes the process more flexible and more manageable. A second advantage is that the method does not require the use of strong alkali or strong acid conditions, which means that the fibres are not exposed to harsh conditions and that there is no acid required to lower the pH, which then has to be followed by alkaline to neutralize back to the pH required for enzymatical or chemical de-esterification. The extra ions from the acid and alkaline steps are not introduced and therefore do not have to be removed. Less steps, means a simpler process, which is important in industrial settings.

[0016] The product of the method, the low-methoxyl ester pectin fibre, allows for stabilising, thickening or gelling of food or feed products without the addition of extra pectin or large amounts of sugar. This allows for preparing low-sugar or low-calorie food or feed, for preparing vegetarian or vegan food, and allows for clean labelling.

[0017] The citrus may be any citrus fruit, such as grapefruits, lemons, limes, mandarins or oranges, Preferably the fruit is lemons or oranges. Most pectin in fruit is high-methoxyl pectin, in combination with cellulose and hemi-cellulose.

[0018] The citrus fibre feedstock which is the raw material of the method, contains pectin having a degree of esterification of at least 50%, at least 60%, at least 70% or at least 80%, such as between 50% and 90%, between 50% and 80%, between 50% and 70% or between 50% and 60%.

[0019] The pectin content of the citrus fibre feedstock may vary depending on the type of citrus fruit, but is commonly between 10% and 40%, such as between 15% and 25%, based on the dry weight.

[0020] In citrus fruits, the pectin is primarily present in the albedo layer (mesocarp) of the peel, which is the white layer of the peel. Therefore, the citrus fibre feedstock is preferably a citrus peel fraction.

[0021] Citrus fruit peel fractions comprising albedo may conveniently be prepared from rejected citrus fruit or from fruit halves, for example from fruit halves which are left-over after fruit juice has been pressed or extracted from citrus fruits, typically left-overs from home, retail or industrial fruit juice processing. In one embodiment, the feedstock comprises or consists of retail peels. Retail peels are left over peels from mechanical juicing or hand juicing carried out in retail environments such as bars, restaurants or super markets. More preferably, the citrus fibre feedstock is a citrus fruit peel fraction enriched in albedo. A peel fraction is enriched in albedo when the albedo proportion in the peel fraction is higher than before enrichment.

[0022] A peel fraction enriched in albedo may be prepared in several ways, in particular by partially or completely separating the albedo layer from other parts of the citrus fruit, i.e. from the flavedo (exocarp, typically the coloured part of the citrus peel) or from the juicy vesicles. In one embodiment, the flavedo layer of the citrus fruit is removed from citrus halves to obtain an albedo enriched citrus peel fraction. The flavedo may be removed partly or completely, such as for at least 50%, for at least 60%, for at least 70%, for at least 80%, or for at least 90% of the flavedo weight such as between 55% and 95%, between 65% and 90% or between 65% and 85% of the flavedo weight.

[0023] The flavedo layer may conveniently be removed by mechanical shaving-off the flavedo. In one embodiment, the flavedo layer of the peel is partially or completely removed by a citrus halves cutting device as described in WO2023 / 104926, which mechanically cuts citrus halves in a lower part enriched in albedo and an upper part enriched in flavedo, starting from the citrus halves. Preferably, between 50 and 80 wt% or between 60 and 70 wt% of the citrus halves is the cut lower part, enriched in albedo. The albedo fraction may still contains some flavedo and juice vesicles. Compared to the flavedo layer, most of the juicy vesicles will be in the albedo layer.

[0024] The citrus fibre feedstock is preferably a clean fraction which consists essentially of the citrus fibres feedstock, devoid of any dirt, grit, plastic, metal, paper or cloth. The fibre stock may still have some juicy membranes left attached to the albedo and some flavedo.

[0025] In one embodiment, the citrus fibre feedstock is subjected to oil extraction, de-watering or size reduction, or a combination of one or more of these processing methods, before it is subjected to homogenization.

[0026] Oil is primarily present in the flavedo layer of citrus peel. Oil from the flavedo-containing citrus peels may be extracted by any suitable method, such as by pressing or extraction. In one embodiment, a sfumatrice is used for extracting oil from the citrus peels.

[0027] De-watering of the citrus fibre feedstock may be performed by squeezing or pressing the citrus fibre feedstock. In one embodiment, a Vincent screw press is used for de-watering the feedstock before it is homogenised.

[0028] Size reduction may be performed by any suitable means, including cutting, slicing, chopping. In one embodiment, an Urschel cutting machine or a colloid mill is used for size reduction of the feedstock. The colloid mill may be used for further size reduction after cutting. The citrus feedstock is preferably reduced to a size of 5 mm or smaller, 3 mm or smaller or 2 mm or smaller, and more preferably to a size smaller than 1 mm or smaller than 0.5 mm, resulting in a slurry, preferably a smooth slurry.

[0029] The citrus fibre feedstock is subjected to homogenization to obtain a homogenised citrus fibres fraction which opens the fibre. Suitable homogenization methods include colloidal milling, pressure homogenization, high shear treatment, extrusion, and combinations of these methods. Preferably, the citrus fibres are subjected to pressure homogenization treatment, typically comprising a reciprocating plunger or piston-type pump together with a homogenizing valve assembly affixed to the discharge end of the homogeniser. More preferably, the citrus fibres are subjected to high pressure homogenization, using high pressure homogenisers known in the art. Suitable high pressure homogenisers include high pressure homogenisers manufactured by GEA Niro Soavi, Parma, Italy, such as the NS Series. High pressure homogenisation is preferably performed at a pressure of at least 250 bar, such as at a pressure in the range of 250-800 bar, 250-600 bar or 250-500 bar.

[0030] During solvent extraction, the homogenised citrus fibres are contacted with an organic solvent, which allows for the removal of water and organic compounds, such as colours, flavours and odours. Solvent extraction is preferably performed using a polar and water-miscible solvent, such as a solvent based on a lower alcohol. Suitable lower alcohols include butanol, ethanol, propanol and isopropanol (IPA, propan-2-ol). In one embodiment, isopropanol is used.

[0031] Extraction of the homogenised citrus fibres with the organic solvent may be performed in a single stage solvent extraction process, but is preferably performed by a multistage extraction process, such as a two-, three-, or four-staged extraction process, preferably with in each next extraction stage a higher concentration of the organic solvent ranging up to 100% solvent.

[0032] The organic solvent is comprised in an extraction liquid. The extraction liquid may consist of the organic solvent or may comprise the organic solvent in aqueous solution. The aqueous solution may comprise at least 30 wt% of the organic solvent, such as between 30 wt% and 95 wt%, between 50 wt% and 80 wt%, between 55 wt% and 80 wt% or between 60 wt% and 85 wt% organic solvent in aqueous solution.

[0033] The extraction is preferably a countercurrent process, more preferably a multi-stage countercurrent solvent extraction is applied. In one embodiment, the citrus fibre feedstock is subjected to a three-stage countercurrent solvent extraction wherein the extraction liquid comprises 60 wt% IPA in the first stage, 80 wt% IPA in the second stage and 100% IPA in the third stage.

[0034] Preferably, the homogenised citrus fibres are contacted with the organic solvent at a solvent- to-solid weight ratio in the range of 0.5:1 to 2:1 In one embodiment, a solvent-to-solid weight ratio 1:1 is used.

[0035] The extraction process results in a wet cake of homogenised solvent washed citrus fibres. The wet cake comprises between 1 wt% and 40 wt% dry matter, such as between 1 wt% and 30 wt%, between 1 wt% and 25% or between 1 wt% and 20% wt %.

[0036] Dry matter may be determined by methods known in the art. Dry matter determination typically comprises removing all or at least 98%, at least 99%, of the moisture in a sample of the cake by evaporation of water, for example by drying a representative sample in an oven or in a dehydrator. In one embodiment, the dry matter content is determined by measuring the weight of a representative sample before and after drying in an oven. Drying may take from several minutes to several hours, for example from 10 minutes to six hours, depending on the drying temperature and the nature, moisture content and size of the sample.

[0037] The wet cake is dried to obtain a citrus fibre powder. In the drying process, citrus fibres and extraction solvent, typically water and organic solvent, are separated. Suitable drying methods which may be used to obtain the dry powder include heating, contacting with hot air, freeze drying and vacuum drying. In one embodiment, the dry powder is obtained by including a heating step with a temperature in the range of 100-130 DEG C for 30 minutes. This also inactivates the pectin methyl esterase used in the process.

[0038] Of course, the skilled person will understand that the citrus fibres and the extraction liquid may also be separated by means of filtration or centrifugation. The organic solvent is preferably reclaimed from the extraction liquid and the gaseous mixture obtained in the drying step. For example, isopropanol is suitably purified to a water content of below 5% w / w. Water may suitably be removed from the spent organic solvent by distillation or pervaporation or a combination of both.

[0039] The citrus fibre powder obtained has a dry matter content of more than 90 wt% and preferably more than 95 wt%, more than 98 w% or more than 99 wt%. The high-methoxyl pectin in the fibre is enzymatically converted to low-methoxyl pectin by contacting the fibre with a composition comprising or consisting of an enzyme with pectin de-esterifying activity.

[0040] Preferably, the composition comprises or consists of an enzyme with pectin methyl esterase activity. An enzyme with pectin methyl esterase activity (EC 3.1.1.11) is capable of catalysing the reaction whereby pectin and water are converted to pectate and methanol due to hydrolysis of methyl ester groups of the pectins. The enzyme used in the method according to the present invention may be a pectin methyl esterase (PME) from any source, such as from a microbial source or from a plant. Preferably, the pectin methyl esterase is a fungal pectin methyl esterase, for example from the genus Aspergillus. The composition comprising the pectin methyl esterase, preferably does not contain pectin depolymerizing activities such as pectin lyase or endopolygalacturonase (PG) activity. Preferably, the enzyme composition is a pure pectin methyl esterase. Apart from the enzyme, the enzyme composition may comprise stabilisers, such as for example glycerol. A suitable pectin methyl esterase composition of fungal origin which may be used in the method according to the invention is Rapidase® PEP, DSM, The Netherlands, from Aspergillus niger.

[0041] The composition preferably comprises at least 5 PE units / mg protein, whereby 1 PE unit will liberate 1.0 micromole of galacturonic acid from polygalacturonic acid per minute at pH 4.0 at 25 deg C.

[0042] The enzyme is dosed in an amount in the range of 0.01 - 2.0 wt%, such as 0.5 to 1.5 wt%, based on the weight of the feedstock.

[0043] The pectin methyl esterase and the fibres are contacted for between 15 minutes and 4 hours, preferably for between 30 minutes and 2 hours, for between 30 minutes and 1.5 hours or for between 15 minutes and 55 minutes.

[0044] The citrus fibres are contacted with esterase enzyme during extraction with the organic solvent. This has the advantage that the contacting with enzyme fits seamless in the original fibre preparation process.

[0045] The fibre obtained by the method according to the invention comprises low-methoxyl pectin, which means that the pectin in the fibre has a degree of esterification of less than 50%. Preferably, the degree of esterification of the pectin in the fibre is less than 40%, less than 30%, less than 25%, less than 20% or less than 10%, such as between 5% and 45%, between 10% and 35%, between 10% and 30%, between 10% and 20%, between 8% and 18% or between 3% and 8%. The low-methoxyl pectin fibre will form a gel in the presence of divalent cations like calcium or magnesium. In one embodiment, calcium chloride is used for gell if ication, adding 10% to 200% calcium chloride based on the dry weight of the fibre. Sugar and acid are not required for gellification of the fibre.

[0046] The fibre also has good water holding capacity (WHC). Water holding capacity may be determined by any suitable method but is preferably determined by mixing 1.0 gram of citrus fibres with a specific amount of water. Spinning the mixture for 10 minutes at 3000 rpm and pouring off the water. Weight before and after the experiment, corrected for the weight of the tube and the weight of the fibre, were used to calculate the water holding capacity of 1 gram of fibre powder. Water holding capacity is preferably at least 10 g / g, at least 15 g / g , at least 20 g / g or at least 22 g / g fibre powder based on dry weight, such as between 12 g / g and 30 g / g, between 18 g / g and 28 g / g or between 22 g / g and 30 g / g.

[0047] The fibre also has good oil holding capacity (OHC). Oil holding capacity may be determined by any suitable method, but is preferably determined by AACC 56-20 (Cereals & Grains Association AACC Approved Methods of Analysis). The oil holding capacity of the fibre is preferably at least 2.5 g / g.

[0048] The fibre must have a good density. Density may be determined by filling up a graduated cylinder and removing any air pockets, for example by gently tapping the cylinder on a bench. The density is then calculated by weighing the cylinder and correcting for cylinder weight. The density of the fibre is preferably between 0.25 and 0.35 kg / l.

[0049] The degree of esterification of the pectin refers to the proportion of the total number of carboxyl groups in the pectin which are esterified, typically with methanol, and can be determined by any suitable method, preferably by the method published by JECFA (Joint FAO / WHO Expert Committee on Food Additives) in Compendium of Food Additive Specifications. Joint FAO / WHO Expert Committee on Food Additives (JECFA), 82nd meeting 2016. FAO JECFA Monographs 19.

[0050] In another aspect, the present invention relates to a citrus fibre containing low-methoxyl pectin obtained by the method according to the invention. In one embodiment, the citrus fibre contains 15-60 wt%, such as 30-50 wt% or 35-45 wt%, low-methoxyl pectin.

[0051] In a further aspect, the present invention relates to the use of a low-methoxyl pectin containing citrus fibre according to the invention in a food or feed product. The food product may be any food product which needs thickening or gelling, such as custards, dressings, jams, juices, mousses, purees, sauces, smoothies or spreads. Therefore, the fibre may be used in food products in bakery applications, dairy applications, meat and meat-alternative applications, or in dietary food for specific groups of people, such as sportspeople, senior people or specific patient groups, for example with reflux or dysphagia. It may be used in or as a coating of desserts, like custards, mousses, puddings, yogurt, dairy based drinks; potato or sweet potato products, formed potato products, such as hash brown and croquettes; spinach pucks; confectionery, such as and fruit drops, pectin based candy, chewings gums, coated candy, drum coated candy, drum coated nuts or chocolate coated products; crips and snacks, including in extruded form; meat, sausages, meat casings, formed meat, poultry, fish products, vegan caviar. The fibre powder may be used as stabiliser or thickening agent for keeping particles in suspension or for stabilising suspensions.

[0052] The feed product may be for any animal, such as for farm animals, sport animals and pets. The low-methoxyl pectin fibre will form a gel in the presence of divalent cations like calcium or magnesium, which cations may be naturally present in the other ingredients of the food, or which may be added for gellifying purposes.

[0053] The fibre powder may be used in any food or feed application in which gelling or thickening agents such as Arabic gum, gelatin, locust bean gum, pectin or xanthan, are typically used to get a gelling or thickening effect. The fibre powder may conveniently completely or partially replace gelling or thickening agents. In this way, low-sugar or low-calorie vegetarian or vegan food products may be obtained.

[0054] EXAMPLES

[0055] Example 1 Enzyme treatment during organic solvent extraction

[0056] To 4 kg of retail orange peel 4 kg of water was added and cut into sub-centimeter size using a Maxima Cutter Delux 12 L from Spangenberg International BV. This slurry was further cut in 500 ml batches using a Vita-Mix Corp Light Industrial Food Preparing Machine at high pulse levels. Any leftover millimeter sized chunks were removed using a metal sieve, resulting in a smooth slurry.

[0057] The slurry was homogenised using a GEA Lab Homogenizer Twin Panda 600 operated at 400 bar. This resulted in a homogenised citrus fibre slurry with a dry weight content of approximately 7 wt% which was divided into two batches of equal composition for a three- stage solvent extraction with isopropanol (IPA) in the presence of pectin methyl esterase (batch 1) or without enzyme (batch 2). Extractions were conducted at 22-23°C.

[0058] First extraction. Batch 1 was extracted for 15 minutes under stirring, using an extraction liquid of 60 wt% IPA, 39 wt% water and 1 wt% pectin methyl esterase (Rapidase®PEP, DSM. Netherlands) solution using equal amounts of homogenised citrus fibre slurry and extraction liquid. Afterwards the batch was dewatered by manual squeezing using 100 micron filter bags, resulting in a wet cake with a dry weight of approximately 20 wt%. For batch 2, water was used instead of enzyme.

[0059] Second extraction. The resulting wet cake was extracted for 15 minutes under stirring, using an extraction liquid of 80 wt% IPA and 19% water and 1% PEP solution, using equal amounts of wet cake and extraction liquid. Afterwards the batch was dewatered by manual squeezing using 100 micron filter bags, resulting in a wet cake with a dry weight of approximately 20 wt%. For batch 2, water was used instead of enzyme.

[0060] Third extraction. For both batches, the resulting wet cake was extracted for 15 minutes under stirring, using an extraction liquid of 100 wt% IPA, using a 50% excess of extraction liquid over the amount of wet cake. Afterwards the batch was dewatered by manual squeezing using 100 micron filter bags, resulting in a wet cake with a dry weight of approximately 20 wt%.

[0061] The final wet cake was dried for 2 hours at 70°C, resulting in a fluffy powder between 95-99 wt%. Table 1 pH of extraction liquid after each extraction step

[0062] This Example shows that in each solvent extraction stage, the pH of batch 1 was lower than the pH of the control (batch 2) indicating hydrolysis of pectin and formation of methanol.

[0063] Gellifying properties

[0064] 2.5 gram of fibre was added to 50 ml of demineralized water under low shear stirring conditions. To this suspension 300 mg of CaCL was added under continuous stirring. The solution containing the enzymatically modified fibre (batch 1) immediately turned into a gel whereas the solution containing the non-treated fibre (batch 2) remained a liquid.

[0065] The fibre (batch 1) was analysed on the following properties: Water Holding Capacity, Density and Oil Binding Capacity. Water holding capacity was determined according to AACC 56-20 method. This implies mixing 1.0 gram of citrus fibres with 50 ml water. Spinning the mixture for 10 minutes at 3000 rpm and pouring off the water. After correcting for dry matter of the powder, the water holding capacity (WHC) of the fibre powder was calculated. WHC of the fibre was 19.1 g / g, which is a good value. Oil holding capacity (OHC) was determined according to AACC 56-20. After correcting for dry matter of the powder, the oil binding capacity was calculated and found to be 2.74 / g, which is a good value. Density was determined by filling up a graduated cylinder, removing any remaining air pockets by gently tapping the cylinder on a bench and weighing the filled cylinder. After correcting for cylinder weight, density was calculated to be 0.35, which is a good value. Results are presented in Table 2 and show that the produced fibre is within the desired specifications (WHC> 15; OHC >2.5 and density 0.25- 0.35).

[0066] Table 2 Gel analysis

[0067] The gel strength of the gel formed by from batch 1 was assessed by measuring compressibility in a texture analyzer (Instron 3344). The gels were placed into a beaker, a plunger coming down on the gel, compressing it to 50% of the original size and the force required to do this was measured (Newton). Rate of compression was 50 mm / min and the tests started after the analyzer measured at least a resistance force of 0,1 N. A force of at least 20 N indicates a good gelling effect. When no gel was formed, the texture analyzer reported very little force (<2 N) required to compress the mixture. The force required to compress the gel was slightly above 100 N.

[0068] This surprisingly shows that low-methoxyl pectine fibres can be prepared in the presence of alcohol and with minimal impact on the existing process, avoiding harsh acid or alkaline conditions, and avoiding the introduction of extra ions and extra volumes. This was not expected since it is known that enzyme activity may be reduced significantly in the presence of alcohol.

[0069] Comparative Example 2 Early enzymatic treatment

[0070] To 4 kg of retail orange peel 4 kg of water was added and the peels were cut into subcentimeter size using a Maxima Cutter Delux 12 L from Spangenberg International BV, resulting in a slurry. This slurry was further cut in 500 ml batches using a Vita-Mix Corp Light Industrial Food Preparing Machine at high pulse levels. Any leftover millimeter sized chunks were removed using a metal sieve, resulting in a smooth slurry.

[0071] To half of this slurry 20 ml of Rapidase® PEP enzyme (DSM) was added (batch 3). No enzyme was added to the other half (batch 4). Incubations were conducted at room temperature (22°- 23C). The pH of the first batch dropped from 5.2 to 3.9 within 15 minutes and then remained stable showing the activity of the enzyme, the pH of the second batch remained constant at pH 5.1-5.2.

[0072] Both batches of slurry were next homogenised using a GEA Lab Homogenizer Twin Panda 600 operated at 400 bar. This resulted in two homogenised citrus fibre slurries with a dry weight content of approximately 7 wt%, which were each subjected to a three-stage solvent extraction with isopropanol (IPA).

[0073] First extraction. Both batches were extracted for 15 minutes under stirring, using an extraction liquid of 60 wt% IPA and 40 wt% water, using equal amounts of homogenised citrus fibre slurry and extraction liquid. Afterwards both batches were dewatered by manual squeezing using 100 micron filter bags, resulting in wet cakes with a dry weight of approximately 20 wt%. The pH of the liquid remaining from batch 1 was 4.4, the pH of the liquid remaining from batch 4 was 5.4

[0074] Second extraction. The resulting wet cakes were both extracted for 15 minutes under stirring, using an extraction liquid of 80 wt% IPA and 20 wt% water, using equal amounts of wet cake and extraction liquid. Afterwards both batches were dewatered by manual squeezing using 100 micron filter bags, resulting in wet cakes with a dry weight of approximately 20 wt%.

[0075] Third extraction. The resulting wet cakes were both extracted for 15 minutes under stirring, using an extraction liquid of 100 wt% IPA, using a 50% excess of extraction liquid over the amount of wet cake. Afterwards both batches were dewatered by manual squeezing using 100 micron filter bags, resulting in wet cakes with a dry weight of approximately 20 wt%.

[0076] Both final wet cakes were dried for 2 hours at 70°C, resulting in fluffy white powders with a dry weight of between 95-99 wt%.

[0077] This Example shows that addition of enzyme to the slurry leads to a decrease in pH, indicating hydrolysis of pectin and formation of methanol, even before the homogenization step.

[0078] Table 3 pH of slurry Gellifying properties

[0079] 2.5 gram of fibre was added to 50 ml of demineralized water under low shear stirring conditions. 300 mg of CaCL was added to this suspension under continuous stirring. Neither the solution of batch 3, nor the solution of batch 4 turned into a gel, indicating that in neither of the batches low-methoxyl pectin inside the fibre was formed. This was confirmed by tests on the texture analyzer.

[0080] The Examples in this patent application show that the pectin which was hydrolysed, indicated by the decrease in pH, can be inside or outside the fibre. Adding the enzyme earlier in the process, leads to a pH decrease, which indicates pectin hydrolysis, but this is not the hydrolysis of pectin within the fibre and therefore does not lead to a gelling fibre. Only when the enzymatic treatment is performed during the solvent extraction step, a fibre with good gellifying properties is obtained. This is in contrast to what would be expected, because it is known to the skilled person that enzyme activity typically decreases in the presence of alcohol.

Claims

CLAIMS1. The present invention relates to a method for preparing a fibre powder composition comprising pectin having a degree of esterification of less than 50%, the method comprising:(a) providing a citrus fibre feedstock comprising citrus fibres, which fibres comprise pectin having a degree of esterification of at least 50%;(b) subjecting the citrus fibre feedstock to homogenization to obtain homogenised citrus fibres;(c) extracting the homogenised citrus fibres with an organic solvent, yielding a wet cake;(d) drying the wet cake to obtain a fibre powder, wherein in the organic solvent extraction step the citrus fibres are contacted with a composition comprising an enzyme with pectin methyl esterase activity resulting in a fibre comprising pectin having a degree of esterification of less than 50%.

2. Method according to claim 1, wherein the citrus fibre feedstock provided in step (a) has been de-watered and reduced in size before they are subjected to homogenization.

3. Method according to claim 1 or 2, wherein the citrus fibre feedstock comprises rejected fruit or left-over peels from retail or industrial fruit juice processing.

4. Method according to any of claims 1 to 3, wherein the citrus is lemon, limes or oranges.

5. Method according to any of claims 1 to 4, wherein the citrus fibre feedstock comprises a citrus peel fraction enriched in albedo.

6. Method according to any of claim 5, wherein the citrus peel fraction enriched in albedo was prepared by mechanically shaving-off the flavedo from citrus halves.

7. Method according to any of claims 1 to 6, wherein the homogenization is pressure homogenization performed at a pressure of between 250 bar and 800 bar.

8. Method according to any of claims 1 to 7, wherein the citrus fibres are contacted with the pectin methyl esterase enzyme for a period of 15 to 55 minutes.

9. Method according to any of claims 1 to 8, wherein the citrus fibre feedstock is solvent extracted in a countercurrent solvent extraction process.

10. Method according to any of claims 1 to 9, wherein the citrus fibre feedstock is solvent extracted in a multistage solvent extraction process.

11. Method according to claim 10, wherein performed in the multistage extraction process, wherein in each next extraction stage a higher concentration of the organic solvent ranging up to 100% is used.

12. Method according to any one of claims 1-11, wherein the pectin methyl esterase is a fungal pectin methyl esterase of the genus Aspergillus.

13. Method according to claim 12, wherein the pectin methyl esterase is a Aspergillus niger.

14. Method according to any one of claims 1-13, wherein the composition comprising the pectin methyl esterase, does not contain pectin lyase or has endopolygalacturonase (PG) activity.

15. Citrus fibre containing low-methoxyl pectin obtained by the method according to claims 1 to 14.

16. Citrus fibre according to claim 15, wherein the fibre has a water holding capacity of at least 15 g / g.

17. Citrus fibre according to any one of claims 15-16, wherein the density of the fibre is between 0.25 and 0.35 kg / l.

18. Use of a low-methoxyl pectin containing citrus fibre according to any one of claims 15- 17 in a food product or feed product.

19. Use according to claim 18, wherein the food product is selected from custards, dressings, jams, juices, mouses, purees, sauces, smoothies and spreads.

20. Bakery, dairy, confectionery, meat or meat-alternative food product which comprises low-methoxyl citrus fibre according to any one of claims 15-17.

Images