Whey protein composition with high heat stability

Abstract

The present invention relates to a method for producing a heat-stable whey protein composition. By using specific temperatures, shear rates and holding times, and applying recirculation of at least a portion of the formed particles, whey protein compositions with surprisingly high heat stability and particles with a lower tendency to settle can be obtained, which can be advantageous in downstream processing and material applications.

Description

[Background technology]

[0001] Whey protein is used as a protein source in a variety of nutritional products, such as sports nutrition, medical nutrition, and in infant formula, including follow-up formula and growing-up formula.

[0002] Suitable whey protein sources for such nutritional products are whey protein concentrates (WPC) and whey protein isolates (WPI), which are obtained by separating skim milk into a casein-rich fraction and a whey protein-rich fraction (either by rennet coagulation to form cheese and so-called cheese whey, by acidification to form caseinates and so-called acid whey, or by microfiltration to form a micellar casein fraction and so-called ideal whey or whey fraction), followed by removal of most of the water, lactose, and ash from the whey protein-rich fraction by membrane filtration, precipitation, and / or ion exchange techniques.

[0003] WPC typically has a protein content of 60% to about 85% by weight (on a dry solids basis), while WPI is produced by removing more of the non-protein components, thereby concentrating the whey protein content to about 90-95% by weight.

[0004] The process for producing a WPC or WPI may involve enriching the total protein fraction in the raw material, but may also involve selective enrichment of specific proteins, examples of which are WPCs and WPIs selectively enriched for either α-lactalbumin or β-lactoglobulin.

[0005] The proteins present in WPC and WPI are substantially in their native, i.e., undenatured, state. A native protein is defined as a protein in its properly folded and / or assembled form, acting and functional. It possesses all four levels of its biomolecular structure, with secondary to quaternary structure formed from weak interactions along the covalently bonded backbone. In a denatured protein, at least some of the weak interactions from the secondary to quaternary structure are disrupted, but the primary structure (i.e., the covalently bonded backbone) remains intact. Thus, a denatured protein differs from a hydrolyzed protein because the primary structure is also disrupted.

[0006] Aqueous compositions at concentrations greater than about 2% by weight of WPC or WPI may gel and / or aggregate when heated, which may affect the rheology and texture of the food product, which may be desirable in some applications but undesirable in others.

[0007] Denatured whey proteins, on the other hand, are less prone to gelation and aggregation when heated. Denaturation can be achieved, inter alia, by exposure to temperatures above the denaturation temperature. However, denaturation also makes the protein more sensitive to changes in pH.

[0008] The combination of heat treatment and mechanical forces, particularly high shear, allows for the formation of small, micron-sized (typically 1-10 microns) whey protein particles / aggregates that are highly denatured. The whey protein material so produced is particularly suitable for increasing the protein content of foods and is commonly referred to as microparticulated whey protein. Other names for this type of particle are thermally denatured whey protein particles, whey protein aggregates or microparticles, and whey protein micelles.

[0009] Microparticulated whey protein was first described in U.S. Patent No. 4,734,287 and formed the basis of the commercial fat substitute, Simplesse®, which was offered for use in frozen desserts, cheeses, dressings, and mayonnaise, allowing for a creamy texture despite the reduced fat content.

[0010] Equipment used for atomization includes pressurized tubular reactors or heat exchangers (WO 2006 / 057968, WO 2010 / 120199) and / or homogenizers (WO 2008 / 063115).

[0011] An overview of the various applications of microparticulated whey protein is provided by R. Ipsen, Int. Dairy J. 67 (2017) 73-79 and B. Kew, Trends in Food Science & Technology 106 (2020) 457-468.

[0012] WO 2007 / 108709 discloses a method for microparticulating whey proteins by changing the pH of a WPC or WPI containing a divalent metal ion, preferably calcium hydroxide, at a content of 3 g / kg dry solids to between 6.0 and 8.5, most preferably between 6.9 and 7.5, and then heat treating the resulting solution at above 70°C, preferably above 85°C. At temperatures of about 120°C, only a few minutes was sufficient; at 70°C, 40 to 60 minutes was required.

[0013] WO 2007 / 108709 theorizes that high levels of divalent metal ions affect protein-protein interactions, thereby promoting the formation of non-covalently associated aggregates rather than disulfide-bonded aggregates, which are more easily disrupted by mechanical shear than disulfide-bonded aggregates.

[0014] The resulting whey protein particles had a median particle size greater than 10 microns and less than 70 microns.

[0015] WO 2010 / 120199 discloses a process in which a whey protein concentrate or isolate is denatured under turbulent flow conditions and without mechanical shear at a temperature of at least 50°C, after which it is transferred directly to a dryer without any intermediate treatment. Summary of the Invention [Problem to be solved by the invention]

[0016] Although the heat stability of whey protein particle compositions is high compared to undenatured whey proteins, their application in heat-treated products (e.g., sterilized high-protein beverages) still faces limitations in terms of gelation, sedimentation, heat stability, viscosity, and / or gritty / gritty mouthfeel. [Means for solving the problem]

[0017] It has now been discovered that the thermal stability of such whey protein compositions can be further improved by the method defined below. This method requires the application of a specific temperature, shear rate, and retention time, and the recycling of at least a portion of the formed particles. It is theorized that the recycling provides a high-temperature stream of aggregates, which allows for a rapid temperature increase of the unagglomerated whey protein stream. This increases reactivity and reduces the time required in the heater. Furthermore, the deposition of unfolded proteins on the outer surface of the already formed aggregates stabilizes the aggregates during high-temperature transport and application of the final formulation.

[0018] Additionally, recirculation allows the atomization process to be decoupled from any downstream processing steps, thereby allowing for adjustment of production capacity without affecting or changing the dimensions of the tubing that controls the shear rate in the heater and holding compartment.

[0019] This method results in whey protein compositions with surprisingly high thermal stability as defined by thermal coagulation time (HCT). In addition, the particles are observed to have a low tendency to settle, which may be advantageous in downstream processing and material applications.

[0020] Accordingly, the present invention relates to heat-stable whey protein compositions having a thermal coagulation time, defined as the time required for a 10% by weight aqueous protein solution at pH 6.6 to form the first visible settling at 121°C, of ​​at least 200 seconds, preferably at least 400 seconds, even more preferably at least 600 seconds, and most preferably at least 800 seconds. DETAILED DESCRIPTION OF THE INVENTION

[0021] HCT can be measured using the oil bath method described by J.B. Magan et al. in Encyclopedia of Dairy Sciences (3rd ed.), Elsevier, 2022, pp. 391-399. An 8 mm inner diameter glass tube is filled with 2 mL of a 10 wt% protein solution at pH 6.6. The tube is placed in a 121 °C oil bath under continuous motion of a vibrating rack at a rate of 7.5 oscillations per minute.

[0022] The change in visible appearance is monitored by a camera. The time that elapses until the liquid stagnates in the tube and stops flowing freely is the thermal coagulation time.

[0023] The heat-stable whey protein composition of the present invention has a protein content of 60 to 95% by weight, preferably 75 to 95% by weight, and most preferably 80 to 85% by weight on a dry matter basis.

[0024] The total concentration of α-lactalbumin and β-lactoglobulin is at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, and most preferably at least 80% by weight based on total protein, this total concentration including both native and denatured α-lactalbumin and β-lactoglobulin.

[0025] The total concentration of native α-lactalbumin and native β-lactoglobulin in the heat-stable whey protein composition of the present invention is 40% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less, even more preferably 15% by weight or less, even more preferably 10% by weight or less, and most preferably 5% by weight or less, based on total protein. The remainder of the total α-lactalbumin and β-lactoglobulin content is in denatured form.

[0026] The degree of denaturation of α-lactalbumin is preferably at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and most preferably at least 70%. The degree of denaturation of β-lactoglobulin is preferably at least 60%, preferably at least 70%, more preferably at least 75%, even more preferably at least 80%, and most preferably at least 85%.

[0027] The content of native α-lactoglobulin and native β-lactoglobulin can be determined by high-pressure gel permeation liquid chromatography, as described in Method 1 of C. Holt et al., Int. J. Food Sci. Techn. 34 (1999) 543-556, BDI Laboratory 1. For this purpose, 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 0.5 M HCl. After standing at ambient temperature for 0.5 hours, the sample is filtered using a 0.45 μm membrane and then separated using a size exclusion (TSK G2000SEXL) column in phosphate buffer, pH 6.0, with detection at 280 nm. The concentrations of native β-lactoglobulin and native α-lactoglobulin are determined by integrating the peak areas. By comparing these concentrations with those of the whey protein starting material, the degree of denaturation can be calculated.

[0028] In one embodiment, the heat-stable whey protein composition is in the form of an aqueous dispersion with a dry matter content of 15-50% by weight, more preferably 18-45% by weight, most preferably 25-35% by weight.

[0029] In another embodiment, the heat stable whey protein composition is in a dried form, such as a spray-dried form.

[0030] The method according to the invention comprises: a) providing a whey protein composition having a protein content of 60-95% by weight on a dry matter basis and a total concentration of native alpha-lactalbumin and native beta-lactoglobulin of at least 50% by weight on a total protein basis; b) providing an aqueous whey protein solution containing the whey protein composition at a dry matter concentration of 15 to 50% by weight and having a pH in the range of 6.0 to 7.5; c) optionally preheating the aqueous whey protein solution to a temperature of up to 70°C using a heat exchanger; d) passing the optionally preheated aqueous whey protein solution through a tubular heat exchanger and for at least 1500 s -1 thereby heating the aqueous whey protein solution to a temperature in the range of 70 to 140°C, preferably 75 to 95°C; e) subjecting the aqueous whey protein product from step d) to a residence time of 1 second to 10 minutes and a temperature of at least 1000 seconds in the holding tube to denature at least 50% of the initial concentration of α-lactalbumin and β-lactoglobulin based on total protein. -1 and maintaining the temperature at 70 to 140°C, preferably 75 to 95°C, at a shear rate of f) recycling at least a portion of the aqueous dispersion of whey protein particles to the heat exchanger of step d) and transporting another portion to a cooling device or dryer; Includes.

[0031] The starting material is a whey protein composition having a protein content in the range of 60-95% by weight based on dry matter and a total concentration of native α-lactalbumin and native β-lactoglobulin of at least 50% by weight based on total protein, preferably at least 60% by weight, more preferably at least 70% by weight, more preferably at least 80% by weight, even more preferably at least 85% by weight, more preferably at least 90% by weight, more preferably at least 95% by weight, and most preferably at least 99% by weight.

[0032] The proteins in the starting material are mostly native, i.e. not denatured, and the degree of denaturation of α-lactalbumin and β-lactoglobulin in said starting material is less than 20%, preferably less than 15%, more preferably less than 10%, most preferably less than 5%.

[0033] Protein content can be determined using the well-known Kjeldahl nitrogen analysis method, applying the Kjeldahl factor of 6.38.

[0034] Examples of suitable whey protein compositions are whey protein concentrate, whey protein isolate, alpha-lactalbumin enriched WPC or WPI and beta-lactoglobulin enriched WPC or WPI.

[0035] The starting material can be a dry / powdered whey protein composition or a liquid whey protein composition. Examples of such liquid whey protein compositions are whey products obtained upon removing a portion of the water, lactose, and minerals from acid whey (i.e., whey obtained from caseinate production), cheese whey, or idealized whey. More specifically, the liquid whey protein composition is an ultrafiltration concentrate of whey, which may have been subjected to further concentration, filtration, and / or purification steps.

[0036] The whey protein composition preferably has a calcium content of less than 1900 mg / 100 g protein, more preferably less than 1250 mg / 100 g protein, even more preferably less than 950 mg / 100 g protein, and most preferably less than 750 mg / 100 g protein. Lower calcium contents result in improved heat stability.

[0037] In one embodiment, the whey protein composition is obtained by concentrating whey, preferably cheese whey. Unlike acid whey or ideal whey, cheese whey contains caseinomacropeptide (CMP). CMP helps prevent the formation of a strong, continuous gel structure and may help prevent aggregation of particulates during heating.

[0038] In another embodiment, the whey protein concentrate or isolate is obtained by concentrating acid whey.

[0039] Concentration of whey proteins may be carried out by standard methods such as ultrafiltration.

[0040] The whey protein composition is either dissolved in water in an amount to result in a solution having a dry matter content of 15-50% by weight, preferably 15-45% by weight, and most preferably 25-35% by weight (if the whey protein concentrate or isolate is in dry or powder form), or used as is or diluted with water (if a liquid whey protein composition is used as the whey protein composition). A lower dry matter content adversely affects heat stability, while a higher dry matter content can result in too high a viscosity, requiring very high shear rates.

[0041] The pH of the resulting solution should be in the range of 6.0 to 7.5. Outside this range, aggregation occurs too rapidly when heated.

[0042] If the pH of the whey protein solution is not already in this range, it can be adjusted to this range by the addition of an acid or base. Suitable acids and bases are KOH, NaOH, Ca(OH), Mg(OH), NH, OH, carbonates and bicarbonates, trisodium citrate, tripotassium citrate, phosphates, HCl, phosphoric acid, citric acid, lactic acid, tartaric acid, acetic acid, sulfuric acid, hydrochloric acid, malic acid, maleic acid, fumaric acid, and succinic acid.

[0043] To at least partially denature the whey proteins and form particles, the aqueous whey protein solution is first heated under shear in a tubular heat exchanger to a temperature in the range of 70-140°C, preferably 70-110°C, more preferably 75-95°C, even more preferably 75-90°C, and most preferably 75-85°C. The shear rate during this heating step is at least 1500 s -1 , preferably at least 2000 s -1 , most preferably at least 2300 s -1 is.

[0044] The shear rate is controlled by the inner diameter of the tubular heat exchanger and the flow rate of the aqueous solution.

[0045] The residence time of the solution in the tubular heat exchanger depends on the temperature used, and when a temperature range of 70 to 140°C is used, it is preferably in the range of 1 to 600 seconds, more preferably 1 to 180 seconds, and most preferably 1 to 60 seconds.

[0046] In one embodiment, a tubular heat exchanger can be used to heat the whey protein solution starting from below room temperature.

[0047] In another embodiment, the whey protein solution is first preheated before entering the tubular heat exchanger. It can be preheated to any temperature, provided that the temperature remains below the denaturation temperature of α-lactalbumin and β-lactoglobulin. In practice, this means a temperature of 70°C or less, preferably 65°C or less. The preheating can be carried out using 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.

[0048] The aqueous whey protein product leaving the tubular heat exchanger is then heated in a holding tube to this same temperature range of 70-140°C, preferably 70-110°C, more preferably 75-95°C, even more preferably 75-90°C, and most preferably 75-85°C for at least 1000 seconds to denature the α-lactalbumin and β-lactoglobulin to a sufficient extent. -1 , preferably at least 1300s -1 , most preferably at least 1500 s -1 and a residence time of 1 to 600 seconds.

[0049] The higher the temperature, the shorter the hold time required.

[0050] An example of a suitable combination of temperature and residence time is 70°C for 120 seconds, 80°C for 30 seconds and 90°C for 10 seconds.

[0051] After leaving the holding tube, a portion of the resulting aqueous dispersion (preferably 5 to 60 wt. %, more preferably 5 to 40 wt. %, even more preferably 5 to 25 wt. %, and most preferably 10 to 25 wt. %) is recycled to the tubular heat exchanger of step d), which can be carried out using a high-pressure pump.

[0052] The remaining portion of the aqueous dispersion is recovered as a liquid (optionally after a cooling step), cooled, and stored until further processing (e.g., drying) or use, and / or sent directly to a drying device or other further processing equipment. Drying can be carried out in a variety of ways, including evaporation, spray drying, and freeze drying. Spray drying is a preferred form of drying.

[0053] The method of the present invention preferably results in (i) denaturation of at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and most preferably at least 70% of the native α-lactalbumin present in the whey protein composition of step a), and (ii) denaturation of at least 60%, preferably at least 70%, more preferably at least 75%, even more preferably at least 80%, and most preferably at least 85% of the native β-lactoglobulin present in the whey protein composition of step a).

[0054] Since these proteins in the starting whey protein composition are predominantly in their native state, this means that the heat-stable whey protein composition resulting from the process of the present invention preferably contains (ii) α-lactalbumin having a degree of denaturation of at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and most preferably at least 70%, and (ii) β-lactoglobulin having a degree of denaturation of at least 60%, preferably at least 70%, more preferably at least 75%, even more preferably at least 80%, and most preferably at least 85%.

[0055] 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 of 0.05 to 20 microns, more preferably 0.05 to 10 microns, and most preferably 0.05 to 1.0 microns. Preferably, 90 vol% of the particles (D90) have a diameter less than 60 microns, more preferably less than 10 microns, and most preferably less than 5.0 microns. The span (=(D90-D10) / D50) is preferably in the range of 5.0 to 40, more preferably 5.0 to 30, and most preferably 5.0 to 20.

[0056] The particle diameter and size distribution are determined using laser diffraction (Malvern Matersizer 2000) assuming non-spherical particles with a refractive index of 1.47 and zero adsorption.

[0057] The heat-stable whey protein compositions of the present invention have broad utility, particularly for increasing the protein content of foods without significantly altering their texture. Examples of such foods are processed cheese, yogurt, ice cream, cultured dairy products, whey crisps, bakery applications, (high-protein) beverages, high-protein medical nutrition, and convenience foods.

[0058] In one embodiment, the heat-stable whey protein composition is used to prepare high protein medical nutritional products, such as enteral compositions.

[0059] Individuals may have to rely on liquid nutritional compositions as their sole source of nutrition, such as surgical patients, patients with trauma, or patients undergoing cancer treatment, or individuals who are too weak or unwilling to eat or drink at all or in sufficient amounts due to general health conditions. Such individuals often must rely on small, frequent feedings or tube feeding. Medical compositions for enteral use, particularly when the compositions are concentrated compositions for fluid-restricted patients, may contain, in addition to a relatively high concentration of protein, fat sources and carbohydrate sources that together provide a total energy density of, for example, a value in the range of 1.5 to 2.5 kcal / ml. Compositions intended to be complete meals, such as enteral compositions intended for small, frequent feedings and / or tube feeding, may also contain necessary amounts of vitamins, minerals, and / or fiber (complete nutritional products).

[0060] A known problem with concentrated compositions is that high protein concentrations can result in highly viscous compositions, especially after heat treatment of the composition (e.g., to sterilize it). This is particularly problematic for compositions intended for use as medical nutritional aliquots or tube feeding, which may also contain fat, carbohydrates, and vitamins and minerals. The viscosity of the composition is also important for patients with swallowing problems. For compositions intended for aliquots or tube feeding, especially for aliquots, it is important that a relatively small amount of the composition also contains a high amount of protein, preferably carbohydrates and / or fat. It is further preferred that these compositions have a relatively high energy density, e.g., in the range of 1.5 to 2.5 kcal / ml.

[0061] The use of a heat-stable whey protein composition according to the present invention as the protein source or at least one protein source in such high-protein liquid medical nutritional compositions allows the viscosity of such compositions to be kept relatively low.

[0062] Such liquid compositions may contain 10-25% by weight, preferably 10-20% by weight, of protein, of which 25-100% by weight, preferably 40-60% by weight, is 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.

[0063] The pH of such nutritional compositions is preferably approximately neutral, for example, between 6.0 and 7.5. The nutritional compositions may further contain carbohydrates, fats, vitamins and minerals.

[0064] Carbohydrates preferably provide 20-60% of the total energy content of such nutritional compositions. Examples of suitable carbohydrates include maltodextrin, hydrolyzed, intact, naturally and / or chemically modified starch or corn starch, sugar, maltose, isomaltose, isomaltulose, glucose polymers, corn syrup, corn syrup solids, carbohydrates derived from rice or potato, glucose, fructose, sucrose, lactose, trehalose, palatinose, high fructose corn syrup, and combinations thereof.

[0065] The fat preferably provides 20-50% of the total energy content of the composition. Non-limiting examples of fat sources suitable for use in the nutritional compositions include milk fat or milk fat fractions, food-grade coconut oil, fractionated coconut oil, soybean 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 oil and palm kernel oil, palm olein, canola oil, marine oils (e.g., fish oil), cottonseed oil, long-chain polyunsaturated fatty acids such as arachidonic acid (ARA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), and combinations thereof. The nutritional compositions may also contain one or more structured lipids. Structured lipids are primarily triacylglycerols containing a mixture of medium- and long-chain fatty acids on the same glycerol backbone.

[0066] In another embodiment, the present invention relates to a liquid high protein composition, such as a protein shot or yogurt drink, suitable for athletes, seniors, patients and anyone wishing to improve protein intake, protein recovery and / or muscle synthesis.

[0067] Such compositions may contain 10-25% by weight of protein, preferably 10-20% by weight, more preferably 15-20% by weight of which 30-60% by weight, preferably 30-50% by weight, most preferably 35-45% by weight is 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, with micellar casein isolate being the most preferred additional protein source.

[0068] Such compositions preferably do not contain significant amounts of fat and carbohydrates. [Example]

[0069] Measurement of HCT HCT was measured as follows: 2 mL of a 10 wt% protein solution was filled into a glass tube with an internal diameter of 8 mm. The pH of the solution was 6.6. Using a dedicated Hettich Benelux testing apparatus, the glass tube was placed in an oil bath at 121°C while the vibrating rack was continuously operated at a rate of 7.5 oscillations per minute.

[0070] The change in visible appearance was monitored by camera. The time that elapsed until the liquid stagnated in the tube and stopped flowing freely was the thermal coagulation time.

[0071] Example 1 An aqueous whey protein concentrate (WPC) with 23% protein by weight, pH 6.6, and a whey protein content of 80% by weight on a dry matter basis (20% α-lactalbumin, 77% β-lactoglobulin by weight based on total protein; 10% denatured α-lactalbumin + β-lactoglobulin by weight based on total protein) was placed in a tubular heater (inner diameter 7 mm) and preheated to 65 °C at 270 L / h. The preheated solution was then pumped using a positive displacement pump into the main tubular heater (inner diameter 7 mm, shear rate: 2400 s -1 The concentrate was then transferred to a centrifuge at a shear rate of 2400 s without heating, in which the solution was heated to 80 °C. -1 The tube was placed in a tubular holder (inner diameter 7 mm) and the liquid was held therein for 30 seconds.

[0072] Of the liquid leaving the holder, 10 vol% was recycled to the suction side of the positive displacement pump (30 L / h), while the remaining 90 vol% was directed to a spiral cooler where it reached a temperature of 5 °C.

[0073] All flows in this setup were monitored and controlled by flow meters.

[0074] As shown in Table 1, the HCT of the resulting product was greater than 989 seconds. 50 is 0.13 μm, and D 90 The mean diameter was 2.00 μm and the span was 15.8. Of the whey proteins, 75% were denatured α-lactalbumin and denatured β-lactoglobulin.

[0075] Example 2 Example 1 was repeated, except that a drain valve was placed between the main tubular heater and the tubular holder. Opening this valve drained the heated concentrate at 100 L / h, effectively reducing the velocity and shear rate in the holder. The results are summarized in Table 1.

[0076] Example 3 Example 1 was repeated except that the inner diameter of the main tubular heater and tubular holder was 12 mm. This increase in inner diameter had a direct effect on the speed and shear rate. The properties of the resulting product are shown in Table 1.

[0077] [Table 1]

[0078] Example 4 The HCT of several commercially available particulate whey protein products was measured and compared to the HCT of the product of Example 1. The results are shown in Table 2.

[0079] [Table 2]

[0080] Example 5 Liquid enteral high protein formulations (A-H) were prepared using the whey protein product of Example 1 and stored at room temperature for 6 days. The viscosities of these formulations were measured using a rotational viscometer in cup and bob geometry (Anton Paar MCR302 rheometer with CC-27) at 20°C at a shear rate of 100 s -1 was measured.

[0081] The composition of the nutritional composition was as shown in Table 3.

[0082] [Table 3]

Claims

1. 1. A method for producing a heat-stable whey protein composition, comprising: a) providing a whey protein composition having a protein content of 60-95% by weight on a dry matter basis, and a total concentration of native α-lactalbumin and native β-lactoglobulin of at least 50% by weight on a total protein basis; b) providing an aqueous whey protein solution comprising the whey protein composition of step a) at a dry matter concentration of 15-50% by weight and having a pH in the range of 6.0-7.5; c) optionally preheating the aqueous whey protein solution to a temperature of up to 70°C using a heat exchanger; d) passing said optionally preheated aqueous whey protein solution through a tubular heat exchanger and for at least 1500 s －１ thereby heating said aqueous whey protein solution to a temperature in the range of 70-140°C; e) denaturing the aqueous whey protein product resulting from step d) in a holding tube for a residence time of between 1 second and 10 minutes and for at least 1000 seconds to denature at least 50% of said initial concentration of α-lactalbumin and β-lactoglobulin based on total protein; －１ and maintaining the temperature at 70-140°C at a shear rate of f) recycling at least a portion of the aqueous dispersion of whey protein particles to the heat exchanger of step d) and transporting another portion to a cooling device or dryer; A method comprising:

2. 2. The method of claim 1, wherein the optionally preheated aqueous whey protein solution is transported through the tubular heat exchanger at a temperature in the range of 70 to 110°C, preferably 75 to 95°C, even more preferably 75 to 90°C, and most preferably 75 to 85°C.

3. The optionally preheated aqueous whey protein solution is passed through the tubular heat exchanger for at least 2000 s －１ , preferably at least 2300 s －１ 3. The method according to claim 1 or 2, wherein the mixture is transported at a shear rate of 0.1 to 1.0 MPa.

4. 4. The method according to any one of claims 1 to 3, wherein the aqueous whey protein product obtained from step d) is held in the holding tube at a temperature of 70 to 110°C, preferably 75 to 95°C, more preferably 75 to 90°C, and most preferably 75 to 85°C.

5. The aqueous whey protein product resulting from step d) is stirred in the holding tube for at least 1300 s －１ , most preferably at least 1500 s －１ The method according to any one of claims 1 to 4, wherein the shear rate is maintained at a shear rate of

6. 6. The method according to any one of claims 1 to 5, wherein the aqueous whey protein product obtained from step d) is held in the holding tube for a residence time of 1 to 600 seconds, preferably 1 to 400 seconds, most preferably 1 to 120 seconds.

7. 7. The method of any one of claims 1 to 6, resulting in (i) denaturation of at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, and most preferably at least 70% of the native alpha-lactalbumin present in the whey protein composition of step a), and (i) denaturation of at least 60%, preferably at least 70%, more preferably at least 75%, even more preferably at least 80%, and most preferably at least 85% of the native beta-lactoglobulin present in the whey protein composition of step a).

8. 8. The method according to any one of claims 1 to 7, wherein the whey protein composition of step a) has a calcium content of less than 1900 mg / 100 g protein, preferably less than 1250 mg / 100 g protein, more preferably less than 950 mg / 100 g protein, and most preferably less than 750 mg / 100 g protein.

9. a protein content of 60-95% by weight, preferably 70-95% by weight, most preferably 80-85% by weight, based on dry matter; a total concentration of native and denatured α-lactalbumin and β-lactoglobulin of at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, most at least 80% by weight, based on total protein; a total concentration of native alpha-lactalbumin and native beta-lactoglobulin of not more than 40% by weight, preferably not more than 30% by weight, more preferably not more than 20% by weight, even more preferably not more than 15% by weight, most preferably not more than 10% by weight; 6. A heat-stable whey protein composition comprising: a 10 wt. % aqueous protein solution of 6.6 having a thermal setting time, defined as the time required for a 10 wt. % aqueous protein solution of 6.6 to form a first visible settling at 121°C, of ​​at least 200 seconds.

10. 10. The thermostable whey protein composition of claim 9, wherein the heat setting time is at least 400 seconds, even more preferably at least 600 seconds, and most preferably at least 800 seconds.

11. 11. A thermostable whey protein composition according to claim 9 or 10, wherein the degree of denaturation of α-lactalbumin is at least 30%, preferably at least 40%, more preferably at least 50%, even more preferably at least 60%, most preferably at least 70% and the degree of denaturation of β-lactoglobulin is preferably at least 60%, preferably at least 70%, more preferably at least 75%, even more preferably at least 80%, most preferably at least 85%.

12. 12. The heat-stable whey protein composition according to any one of claims 9 to 11, in the form of an aqueous dispersion, preferably having a dry matter content of 15 to 50 wt.-%, more preferably 18 to 45 wt.-%, most preferably 25 to 35 wt.-%.

13. 13. A food product comprising the thermostable whey protein composition according to any one of claims 9 to 12 or obtainable by the method according to any one of claims 1 to 8, preferably selected from the group consisting of cheese, yogurt, ice cream, fermented dairy products, whey crisps, bakery applications, food bars, protein drinks, high protein medical nutrition and convenience foods.

14. 13. A liquid nutritional composition having an energy density of 1.5 to 2.5 kcal / ml and a protein content of 10 to 25 wt.-%, preferably 10 to 20 wt.-%, wherein 25 to 100 wt.-%, preferably 40 to 60 wt.-% of the protein content is a thermostable whey protein composition according to any one of claims 9 to 12 or a thermostable whey protein composition obtainable by a method according to any one of claims 1 to 8.

15. 13. A liquid nutritional composition having a protein content of 10-25% by weight, preferably 10-20% by weight, more preferably 15-20% by weight, wherein 30-60% by weight, preferably 30-50% by weight, most preferably 35-45% by weight of said protein content is a thermostable whey protein composition according to any one of claims 9 to 12 or a thermostable whey protein composition obtainable by a method according to any one of claims 1 to 8.

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