FI89449B - Process for preparing a heat-resistant, non-bitter, water- soluble peptide product - Google Patents

Description

! 89449

This invention relates to a process for preparing a heat-resistant, non-bitter, readily water-soluble peptide product from casein-containing whey protein materials.

The peptide products prepared by the method of the invention can be used as supplements and substitutes for proteins in nutrients and refreshments and as an ingredient in diets.

In recent years, there has been an increased interest in making peptide products for such purposes, and these products must have a neutral taste, be hairless, be readily soluble in water, and be heat-resistant. The content of essential amino acids in whey proteins is very advantageous, they are inexpensive and readily available in large quantities, and methods of making peptide products for the above-mentioned purposes from whey proteins are of particular commercial interest.

Various such methods have been proposed.

U.S. Patent No. 4,107,334 discloses a process for preparing a soluble peptide product in which whey protein is heated until 50 Ϊ of the protein has precipitated. The precipitated whey protein, termed 1-actalbumin, is subjected to mild proteolytic, enzymatic hydrolysis, resulting in a hydrolyzate in which the majority of the proteins are cleaved into soluble peptides. The hydrolyzate is then heat treated to inactivate the proteinase used. However, the use of said heat treatment, 2 89449 for both the preparation of 1-albumin and the inactivation of proteinase, results in the loss of important sulfur-containing amino acids, the formation of unpleasant aromas, and the formation of Maillard reaction products in the presence of lactose, often. and Tokitz, F. 1982, Japan J. Zootechn. Sci. Vol. 53, page 344, and Matsuda, T et al. 1985, J. Food Sci. Vol. 50, page 618).

U.S. Pat. No. 4,293,571 also discloses a process for preparing a peptide product from, for example, whey protein by enzymatic hydrolysis followed by heat treatment. The peptide product 1a obtained after ultrafiltration has the same disadvantages as mentioned in connection with the above-mentioned heat treatment product.

EP patent applications 0065663 and 0022019 relate to processes for the preparation of peptide products by enzymatic hydrolysis of whey protein, consisting mainly of small peptides, comprising peptides up to 5 amino acid residues, for use in various diets for patients with impaired or deficient conditions. food containing. Thus, EP patent application 0065663 relates to a peptide product containing at least 50% by weight of a combination of amino acids, dipeptides and tripeptides, and not more than 25% by weight of polypeptides containing 10 or more amino acids, while patent application 0022019 relates to a peptide product with at least 50% by weight. of the number of peptides contains 2 to 5 amino acid residues, and the proportion of free amino acids is less than 15%.

Most proteins tend to produce peptides with a bitter taste when hydrolyzed, and the bitterness is strongest in the case of short-chain peptides that contain less than 10 amino acids, especially 4-8 amino acids. Peptide products rich in peptides of less than 10 amino acids can therefore be very bitter in flavor. Given the fact that hydrophobic amino acids are bitter, while many polar amino acids taste salty, a large amount of free amino acids also causes problems with flavor. In addition, a large amount of free amino acids provides a product with a high osmolarity, which prevents the absorption of liquid from such a product.

a result of the above, European Patent Applications 0065663 and 0022019 across the imported products have a very limited field of use, namely, the special diet preparations, or for patients who suffer from stomach and bowel dysfunction.

Various methods for eliminating bitter taste have been proposed. Hairy peptides are generally hydrophobic, and this can be utilized to selectively remove hairy peptides, by extraction with organic solvents, or by adsorption to activated carbon, glass fibers, or other hydrophobic material.

U.S. Pat. No. 4,075,195 discloses a process comprising adsorption on a phenol-substituted resin.

However, these methods are hampered by the fact that they lose certain essential hydrophobic amino acids and that the adsorbents used must be regenerated with large amounts of organic solvents.

GB 1338936 discloses a method for cleaving bitter peptides using exo-peptidases. However, said cleavage results in the formation of peptide-4 39449 products rich in free amino acids, which is not desirable as mentioned above.

As can be seen from the above, previous peptide products obtained by enzymatic hydrolysis of whey protein contain disadvantages in terms of taste and / or amino acid composition.

It is therefore an object of the invention to provide a process for the preparation of a heat-resistant, non-hairy, easily water-soluble peptide product by enzymatic hydrolysis of whey protein, which does not involve the above disadvantages.

Surprisingly, it has now been shown that hydrolysis of a whey proteinaceous material from which casein has been eliminated by one or more proteinases results in the formation of a peptide product that does not contain a bitter aroma.

Said object is thus achieved by a method characterized according to the invention by the following steps: a) elimination of casein from the whey protein material, b) hydrolysis of the whey casein-free protein material obtained according to a) by at least one proteinase 11a, c) (b) ultrafiltration of the resulting hydrolyzate through a membrane with a cut-off value (exclusive slave value) not exceeding 20000 Daltons, followed by recovery of the filtrate and, if desired, concentration and / or drying of the filtrate.

The casein-containing whey protein used as starting material may be any whey material containing whey protein (defined as whey protein in this patent application, separate from cassava), (liquid phase after precipitation of casein, either in cheese making or in industrial casein production). production), such as sweet whey or sour whey, whey concentrates and whey protein concentrates, obtained by ultrafiltration or its thermal denaturation (1-actalbumin).

The residual casein content of the whey typically constitutes about 30% (of the dry matter) of the total size of the material in the canopy container.

According to an embodiment of the method according to the invention, casein present in the aqueous phase as suspended coats can be eliminated from the whey protein by filtering off casein particles with a membrane with a pore size such that the casein particles are retained while the whey proteins pass through the filter.

It has further been shown that casein can be eliminated from unheated whey according to a more preferred embodiment of the process according to the invention by adjusting its pH to approximately the isoelectric point of casein, i. 4.5-5.0 by adding acid and simultaneously adding

CaCl, after which the mixture was left for at least one hour at 30 ° C to 50 ° C, preferably at 40 ° C. The casein thus doped can be easily separated by filtration or centrifugation. Centrifugation, e.g. with a Westphalian separator, is preferred when the batches are large. As the acid, for example, HCl is used.

The amount of C a Cl added is preferably in the range of 1-25 g / 100 1 2. In this embodiment, it is important that the whey proteins are not heat treated, which results in denaturation and thus precipitation of whey proteins that co-precipitate with casein.

Surprisingly, it has also been found that Bacillus subtili k its neutral metalloproteinase (Neutrase, Novo Industri A / S, Denmark) 6 39449 is very active against caseins, but not at all or only weakly active against native as well as heat-denatured whey proteins. Thus, it has been shown that casein can be eliminated from whey protein material by hydrolyzing casein with a neutral metalloproteinase from Bacillus subtius. The hydrolysis can be carried out at pH 4-9, preferably at pH 7.5, and at a temperature in the range from 30 ° C to 60 ° C, preferably at 50 ° C. The hydrolysis is preferably allowed to complete, i.e. until a degree of hydrolysis of about 4 ϊ: η is reached, depending on the total amount of proteins. The relative proportion between the amounts of neutrase used and whey proteins is not critical, as the amount of enzymes alone determines how quickly the desired degree of hydrolysis is achieved.

Casein cleavage products can be eliminated by ultrafiltration or centrifugation. If the whey proteins have precipitated as a result of the heat treatment, the cleavage products of casein can be eliminated by filtration through a membrane whose pore size allows their passage, or centrifugation with the supernatant. If the whey proteins have been treated only slightly or not at all with heat and are mainly present as native proteins, casein can be eliminated by ultrafiltration using a membrane with a cut-off value not exceeding 20,000.

After the casein has been eliminated from the whey protein, this can be concentrated, preferably by filtration through a leaching membrane 11a with a cut-off value not exceeding 20,000, for example until a protein content of 5 [mu] m is reached. As a result, the lactose is separated, preferably until a lactose content of not more than 0.1% and any salts present are reached, which may be advantageous in order to obtain peptide products which are lactose-free and have a low osmolarity.

7 39449

The hydrolysis of the casein-free whey proteins obtained according to step b) of the method can be carried out with any proteinase. For example, the hydrolysis can be performed with several different proteinases sequentially or simultaneously and optionally in several steps with ultrafiltration between them. It is preferred to use the following proteases:

Corolase PP (pork pancreatic proteinases - Rhom - Federal Republic of Germany),

Rhozyme P41 (Aspergillus oryzae proteinase - G ^ nencore -USA),

Pronase (Streptomyces griseus proteinase - Sigma),

Alcalase 2.4 L (Bacillus 1icheniformis proteinase, Novo

Industri A / S - Denmark), or trypsin (Novo Industri A / S - Denmark).

The relative proportions between the amounts of enzymes and whey proteins used are not critical, as it does not substantially affect the composition or yield of the peptide product, but only matters as to the time taken to achieve the desired degree of hydrolysis.

The hydrolysis is preferably carried out at a pH of about 7.5 and at a temperature of about 50 ° C. The hydrolysis is continued until a degree of hydrolysis ranging between 8 and 18% is reached, depending on the desired size distribution and yield of the peptides contained in the resulting peptide product. For example, the degree of hydrolysis can be measured according to the pH-static method (see Adler-Nissen, J.J. Chem. Tech. Bio-technol. Vol. 32, pages 138-156).

Ultrafiltration is carried out according to step c) of the method, as mentioned, through a membrane with a cut-off value not exceeding 20,000 Daltons, thus separating peptides formed by hydrolysis of casein-free whey products from non-hydrolysed or insufficiently hydrolysed whey proteins which e. The proteinases used in the hydrolysis of the casein-free whey protein material are also retained in said ultrafiltration.

According to the method of the invention, freely available membranes can be used as ultrafiltration membranes, provided that they have a certain cut-off value (exclusive o-limit value). It is preferred to utilize membranes that are commonly available on the market and are made of highly durable, synthetic polymers that can be purified in situ, e.g., with an acid or base. Such ultrafiltration membranes are marketed by, among others, DDS-RO-Division, Denmark, Rhone-Poulenc, France, Romicon, France and Alfa-Laval, Sweden. For example, D61-RO-Division GR61PP membranes can be used as membranes with a cut-off value of 20,000.

It is particularly preferred to utilize a leach filtration membrane having a cut-off value of about 6000.

The filtrate obtained by ultrafiltration can be subsequently, if desired, concentrated and / or dried to obtain the peptide product of the invention.

The peptide product prepared by the process of the invention is not bitter in a 3% by weight aqueous solution, contains a neutral aroma and is completely soluble at pH 4-5 after heating to 100 ° C for 10 minutes. Peptide products prepared according to the invention contain a maximum of 15% peptides containing less than 6 amino acids. In addition, due to the low content of free amino acids and small peptides, their osmolarity is low.

9 89449

Due to their properties, peptide products are suitable for use in vi k diets and are generally suitable as amino acid sources and protein substitutes in nutrients and refreshments, such as readily metabolizable protein supplementation areas for athletes, sausages, pies, ice cream, chocolate, and carbonated beverages, e.g.

Of particular interest are peptide products prepared by the method of the invention by ultrafiltration through a membrane having a cut-off value of 6000 in step c). Said peptide products can be used as protein substitutes in nutrients and refreshments for persons allergic to cow's milk. Said peptide products do not bind antibodies by immunoelectrophoresis or ELISA (enzyme-linked immunosorbent assay) using commercially available antibodies against bovine whey proteins or bovine caseins (Pharmacia, Sweden, and Dako patts, Denmark). Similarly, they do not cause a passive skin sensitization reaction in mice sensitized with murine antibodies against bovine whey proteins or caseins. They also do not cause allergic reactions in irritant stimulation experiments in children with a clinical, clearly demonstrated allergy to cow's milk.

The method according to the invention is illustrated in detail by the following examples.

Example 1

Preparation of peptide products from fresh whey by hydrolysis of Bacillus 1icheniformis proteinase 11a (Alcalase 2.4 L, Novo Industri A / S, Denmark).

20 q CaCl 2 · 2H 0 was added to 200 l of fresh whey, a 2 2 and the pH of the whey was adjusted to 4.6 with 2N HCl. The cheese was then left stirring for 60 minutes at 40 ° C and for a further 60 minutes at 40 ° C without stirring. In this treatment, casein precipitated, and clear whey, which was gently run off, was further clarified by filtration through a sterile cloth. The whey thus obtained was practically casein-free, and contained 0.52% protein, while the cheese whey, before the isoelectric blending of casein, contained 0.79% by weight of protein as measured by the Kjeldahl method. Casein-free whey was subsequently concentrated and lactose removed by ultrafiltration and diafiltration of GR61PP membranes using a LAB 20 ultrafiltration module from DDS-R0-Division, Denmark. The resulting whey protein concentrate free of casein and lactose (15 liters with a protein content of 5% by weight) was heated to 50 ° C and adjusted to pH 7.5 with 4.0 N NaOH. Hydrolysis was then initiated by the addition of 2.4 L (5.0 mL) of Alcalase; and the hydrolysis was continued until a degree of hydrolysis of 12%, measured by the pH-static method, was reached, keeping the pH constant at 7.5 by continuous titration with 4.0 N NaOH. The resulting peptides were separated from non-hydrolyzed whey proteins and proteinases by ultrafiltration onto GR61PP membranes, allowing the peptides to pass through. The peptide-containing permeate thus obtained from ultrafiltration was concentrated by freeze-drying and resuspended in deionized water. The yield of peptides in the peptide product was 72% of the protein pool of whey protein concentrate. A 10% solution of the peptide product was found to be completely soluble at pH o 4.0-5.0 even when heated to 100 ° C for 10 minutes. A 3% solution of the peptide product had a neutral taste. Column chromatographic studies of the molecular weight distribution of the peptides contained in the peptide product by gel filtration on Bio-gel P-6 (Biorad Labs, France) revealed that about 17% by weight of the peptides comprised a molecular weight in excess of 6000. 15% by weight of the peptides ranged in molecular weight from 11,39,449 to 4,000-6,000, 59% by weight of the peptides comprised molecular weights ranging from 1,000 to 4,000, and 9% by weight of the peptides comprised molecular weights below 1,000,

Example 2

Preparation of peptide products from fresh cheese whey by hydrolysis of pancreatic proteinase 11 (Corolase PP, Rhom Chemie, Federal Republic of Germany).

Casein-free and lactose-free whey protein concentrate (15 L with a protein content of 5% by weight) was prepared from fresh cheese whey as described in Example 1.

Whey protein concentrate free of casein and lactose was hydrolyzed at 50 ° C and pH 8.0 by the addition of 3.0 g of Corolase PP, and hydrolysis was continued until a degree of hydrolysis of about 10% was reached. The peptide-containing permeate was prepared by ultrafiltration on GR61PP membranes, and a lyophilized peptide product was obtained as disclosed in Example 1.

The yield of peptides in the peptide product was 49% of the protein content of the whey protein concentrate. The peptide product was stable at pH 4.5 and 100 ° C for 10 minutes and contained a neutral aroma in 3% solution.

Example 3

Preparation of peptide products from fresh whey by hydrolysis of pork with trypsin (Novo Industri A / S, Denmark).

Casein-free and lactose-free whey protein concentrate was prepared as described in Example 1, and hydrolyzed as described in Example 2. The yield of peptides in the peptide product obtained by ultrafiltration with GR61PP mem-39399 brains was 42% of the whey protein concentrate. A 10% solution of the peptide product was stable at pH 4.5, even after heating to 100 ° C for 10 minutes. The aroma of the peptide product was neutral in 3% deionized water solution.

Example 4

Preparation of peptide products from fresh cheese whey by hydrolysis of Aspergillus oryzae proteinase 11a (Rhozyme P41, Gönencore, USA).

Casein-free and lactose-free whey protein concentrate (15 L with a protein content of 5% by weight) was prepared as described in Example 1 and hydrolyzed at 50 ° C and pH 7.5 by adding 15 g of Rhozyme P41. The hydrolysis was continued until a degree of hydrolysis of about 8% was reached. The peptide product was obtained as a permeate filtration permeate on GR61PP membranes, and the peptide yield in the peptide product was 39% of the protein content of the whey protein concentrate. The peptide product was stable in an acidic medium like the products prepared according to Examples 1-3 and contained an acceptable neutral taste.

Chromatographic studies of the molecular weight distribution of the peptides on Biogel P-6 revealed that the majority of the peptides (60%) ranged in molecular weight from 1500 to 2500, while less than 10% had molecular weights greater than 6000 and less than 1000, respectively.

Example 5

Preparation of the peptide product, 100 kg, from fresh cheese whey by hydrolysis of Alcalase 2.4 L and swimming by filtration on GR61PP membranes.

Alcalase 2.4 L was used because this proteinase showed the maximum yield according to Examples 1-4.

13 39449 4500 g of CaCl · 2H 0 were added to 45000 IU of fresh cheese-2 2 whey, and the pH of the cheese whey was adjusted to 4.6 with concentrated o HCl. After standing for 5 hours, casein precipitated at 40 ° C,. after which it was eliminated by centrifugation1a Westphalia se parator 11a (6500 rpm). 35,000 L of clear whey (protein content 0.56 wt%) was collected, concentrated, and lactose removed by ultrafiltration and diafiltration on GR61PP membranes. Whey protein concentrate lacking casein and lactose was recovered and the protein content was adjusted to 5% by weight. 3000 L of whey protein concentrate (pH 7.5) was then hydrolyzed at 50 ° C with 1 L of Alcalase 2.4 L until a degree of hydrolysis of 12% was reached.

In this example, the pH was kept constant at 7.5 by titration continuously with a mixture of Ca (OH), Mg (OH), 2 2 KOH and NaOH, corresponding to 4.0 N NaOH at the base strength. I will come. Said base mixture was used to limit the addition of sodium and at the same time to add the amounts of calcium, magnesium and potassium to the peptide product. After completion of the hydrolysis, the hydrolyzate was ultrafiltered onto GR61PP membranes, and the permeate containing the peptide was evaporated under reduced pressure and lyophilized. The peptide product thus obtained closely corresponded to the product obtained according to Example 1. Due to the very large dead volume of the production equipment in this example, the peptide yield in the peptide product was only 57% of the protein amount of the whey protein concentrate.

Example 6

Preparation of peptide products from fresh whey for use as a nutrient in people allergic to cow's milk.

14 3 9449

Casein-free and lactose-free whey protein concentrate were prepared from cheese whey according to Example 1 and hydrolyzed with Alcalase 2.4 L according to Example 1, Coro-lase PP according to Example 2, or Rhozyme P41 according to Example 4. In contrast to Examples 1-4, the peptides obtained in this example were separated from unhydrolyzed whey protein and proteinases by ultrafiltration on membranes with a cut-off value of 6000 (GR81PP membranes, DDS-RO-Division, Denmark). None of the peptide products obtained bound antibodies by immunoelectrophoresis or ELISA, and none of the peptide products were able to elicit passive skin sensitization reactions in sensitized mice. Table I shows the peptide yield, weight ϊ of the amount of proteins in whey and the relative proportions of the molecular weights of the peptides of the three peptide products.

Table I

Peptide Yield Used Peptides Molecular Weight Proteinase 3000-6000 1000-3000 <1000

Alcalase 2.4 1 44% 20% 64% 16%

Corolase PP 38 Ϊ 33% 47 «20%

Rhozyme P41 39% 18% 76% 6%

As shown in Table 1, the peptide yield of the three peptide products was low compared to the yield in Examples 1-4. The low yield was due to the fact that GR81PP membranes are not permeable to peptides with a molecular weight greater than 6000 and are slightly permeable to peptides with a molecular weight greater than about 4000.

Example 7

Preparation of peptide products from fresh cheese whey for use in nutrients for individuals allergic to cow's milk, utilizing a compound of various proteinases! mi ä.

is 89449

Casein-free and lactose-free whey protein concentrate was prepared according to Example 1. Whey concentrate was hydrolyzed to Alcalase 2.4 L, Corolase PP and Rhozyme P41. combinations, so that each individual hydrolysis was performed on two of said proteinases simultaneously. Each hydrolysis was continued until the process was virtually complete, corresponding to a degree of hydrolysis ranging from 12% to 17% depending on the combination of proteinases used. Peptide products were obtained by ultrafiltration on GR81PP membranes 11a according to Example 6. The combination of Alcalase 2.4 L (6.5 ml / kg whey protein) and Rhozyme P41 (20 g / kg whey protein) was shown to give a particularly suitable peptide product, as well as the high peptide yield obtained in the peptide product (74% by weight). that the peptide or peptide contained a preferred molecular weight distribution of the peptides in which the majority of the peptides (about 70%) ranged in molecular weight from 1500 to 3000 and less than 15% had a molecular weight below 1000.

Example 8

Preparation of a peptide product, 135 kg, from fresh cheese whey hydrolyzed with a mixture of Alcalase 2.4 L and Rhozyme P41, for use in nutrients for persons allergic to cow's milk.

Alcalase 2.4 L and Rhozyme P41 were preferred because this combination resulted in the most suitable peptide product according to Example 7.

4000 liters of casein-free and lactose-free whey protein concentrate with a protein content of 5% by weight were prepared according to Example 5. The whey protein concentrate was heated to 50 ° C and the pH was adjusted to 7.5 with a base mixture of Mg (0H), Ca (0H), Κ0Η and NaOH. Hydrolysis was initiated by the addition of 1300 ml of Alcalase 2.4 L and 16 39449 of 4.0 kg of Rhozyme P41 slurried in 20 L of water. The pH was kept constant by the base mixture as shown in Example 5, and the hydrolysis was continued until a hydrolysis of 16-17% was reached. The peptides were subsequently separated from unhydrolyzed whey protein and proteinases by ultrafiltration into GR81PP membranes (membrane area 35 m). The yield of peptides in the peptide increased to about 60% of the protein content of the whey protein concentrate, and the peptide product was on par with the corresponding product prepared according to Example 7. The resulting peptide product was administered as a daily peptide supplement (10 g per day) over a two-month trial period to 10 children aged 0-7 years who were clinically shown to be clearly allergic to cow's milk, and the children involved showed no signs of allergic reactions.

Example 9

Preparation of peptide products from commercial whey protein concentrate.

Whey protein concentrates produced from cheese whey according to a method involving ultrafiltration and diafiltration, vigorous heat treatment, vacuum evaporation and spray drying are commercially available from various companies. The whey protein concentrate used in this case (Lacprodan-80 from Denmark Protein A / S, Denmark) had a protein content of about 80%, of which about 30-40% by weight was casein, and a lactose content of 10-12%. Whey proteins denature and are therefore insoluble when the powder is mixed with water. In contrast, a permanent slurry is obtained. Hydrolysis of Lacprodan-80 with Alcalase 2.4 L (degree of hydrolysis = 12%) in a control experiment gave a peptide product with an extremely bitter aroma.

17 89449

The casein in Lacprodan-80 was eliminated by hydrolysis of Bacillus subtilis proteinase 11a (Neutrase, Novo Industri A / S, Denmark): a 10 liter suspension of Lacprodan-80 with a protein content of 5% was heated to 50 ° C and the pH was adjusted to 7.5 with 4.0 N NaOH. The hydrolysis of casein was started by adding 10 ml of Neutrase. The pH was kept constant by continuous titration with 4.0 N NaOH, and hydrolysis was continued until the process was complete, corresponding to a degree of hydrolysis of about 4 ϊ of all peptide bonds in the protein contained in Lacprodan-80. Casein binding products and lactose were then eliminated by ultrafiltration and diafiltration into GR81PP membranes. The peptide yield of the permeate was 28%, which was in good agreement with the casein content of Lacprodan-80. The proteins retained in the retentate now formed a casein-free and lactose-free whey protein concentrate in which the denatured whey proteins were still in aqueous slurry. The retentates formed according to this method were subsequently hydrolyzed either with Alcalase 2.4 L alone according to Example 1, or together with Alcalase 2.4 L and Rhozyme P41 as specified in Example 7. The hydrolysates were then ultrafiltered on GR61PP membranes ( as in Example 1) or GR81PP membranes (as in Example 7). The peptide products thus produced were essentially similar to the peptide products produced from fresh whey according to Examples 1 and 7 in terms of lack of bitterness, peptide yield and molecular weight distribution. However, the peptide products of Example 9 contained a faint burnt taste, possibly due to the heat treatment of Lacpro-dan-80 during the preparation of said product.

Example 10

Preparation of peptide products from 1-actalbumin.

89449 BC

Lactalbumin, containing caseins and 1 heat-denatured eastern whey proteins, was prepared from 100 liters of fresh cheese whey according to the following method, which corresponds in principle to the industrial production of 1-actalbumin:

The pH of the whey was adjusted to 4.6 with 2 N HCl and heated to 90 ° C for 30 minutes. A slurry of casein and heat-denatured whey protein, which together form 1-actalbumin, was recovered by centrifugation and resuspended in water to a protein content of 5%. In a control experiment, a sample of 1-actalbumin was hydrolyzed with 2.4 L of Alcalase, thus producing a peptide product with an extremely bitter taste. The caseins contained in the actalbumin thus prepared were hydrolyzed with Neutras as mentioned in Example 9. Ultrafiltration after Neutrase hydrolysis afforded a permeate with a peptide yield of about 32% of the total β-albumin.

The casein-free and lactose-free lactalbumin thus prepared were hydrolyzed either alone with Alcalase 2.4 L or in combination with Alcalase 2.4 L and Rhozyme P41 to give peptide products as shown in Example 9. The obtained peptide products without bitter taste closely corresponded to the peptide products obtained according to Example 9.

Claims (11)

19 89449 A process for preparing a heat-resistant, non-hairy, readily water-soluble peptide product from a casein-containing whey protein material, characterized in that the preparation comprises the steps of: a) eliminating casein from the whey protein material, b) at least hydrolyzing the casein-free whey protein material obtained according to a) proteinase 11a, c) ultrafiltration of the hydrolyzate obtained in b) through a membrane with a cut-off value (exclusion limit) not exceeding 20,000 Daltons, followed by filtration, and thereafter, if desired, concentration and / or drying of the filtrate. Process according to Claim 1, characterized in that the casein is eliminated from the unheated whey in step a) by separating the casein particles with a filter having a pore size such that the casein particles are retained while the whey proteins pass through the filter, preferably about 0.2 μ η pore size . Process according to Claim 1, characterized in that the casein is eliminated from the unheated whey in step a), by adjusting the pH to 4.5 to 5.0 by adding acid, and at the same time adding CaCl in an amount ranging from 1 to 25. g / liter, leaving the mixture at 30-50 ° C for at least one hour, and separating the caseins thus precipitated. Process according to Claim 1, characterized in that the casein is eliminated from the whey protein material in step a) by hydrolysing the casein with a neutral metalloproteinase from Bacillus subtilis until preferably a degree of hydrolysis of about 4%, based on the total amount of protein, and separating the casein cleavage products. 20 39449 Process according to Claim 4, characterized in that the hydrolysis of casein is carried out at a pH ranging from 4 to 9 and at a temperature between 30 ° C and 10 ° C. Process according to Claim 4, characterized in that 1 actin is used as the active ingredient and that, before the hydrolysis in step h), the decomposition of casein yields I. difference spji I ei fh cjo i ma Ma. Process according to Claim 4, characterized in that the hydrolysis of the casein in step ti) of the casein cleavage products is separated by ultrafiltration into a membrane 11a having a CUt-off value not exceeding about 20,000 Oaltons. Process according to one of Claims 1 to 7, characterized in that the casein-free whey protein material 1i obtained in step a) is concentrated and / or lactose is separated, preferably by diafiltration of an ultrafiltration membrane 11a with a cut-off value of about 20,000 Daltons or less, before hydrolysis. Process according to one of Claims 1 to 8, characterized in that the casein-free whey protein is hydrolysed to a degree of hydrolysis which varies between 8 and 18%. Method according to claims 1 to 9, characterized in that the proteinase used is pork pancreatic protein, Aspergillus o ryza en protein, Streptomyces / griseus proteinase, Racillus 1icheniformic proteinase or trypsin. Method according to one of the preceding claims, characterized in that the ultrafiltration in step c) is carried out by means of a memory with a cut-off value of about 0000 Daltons. 2i 39449