PROCESS FOR THE TREATMENT OF WHEY PROTEIN

Abstract: To facilitate the separation off of fat from whey protein con­ centrates and simultanously avoid protein losses, and obtain a whey protein concentrate having improved taste and storage stability a whey protein concentrate is subjected to hydroly­ sis by means of proteolytic enzyme until a degree of hydroly­ sis of up to 4 has been obtained.

Description: Tecnical Field The present invention relates to a process for treating whey proteins in order to facilitate the separation of fats therefrom, and to obtain a product having improved taste and storage stability. Background of the invention. Whey is a residual product obtained in the manufacture of cheese and has due to its high contents of water a small economical value. A typical composition of whey, with small variations, is as follows: Protein 0.6% Other nitrogen compounds 0.2% Lactose 4.6% Ashes 0.6% Water 94.0% The above figures include a fat content of about 0.1 to 0.2%, depending on what type of cheese preparation the whey is derived from. If the whey is dried, i.e. the water content is reduced to some few percent only, the fat content will reach about 3%. The nutritional value of the proteins present in whey is among the highest known, and several methods are today used industrially to separate, and concentrate the protein fraction. The most common method is ultra filtration, wherein lactose, minerals and water are reduced from the standard whey, and the generally present, dried whey protein products contain up to about 80% of protein. As the fat fraction can not be separated off from a protein concentrate without great protein losses, a powder containing 80% of protein will have a fat content of about 7%. Such an amount of fat causes primarily a taste problem as the product will obtain a characteristic, less pleasant taste, which is very difficult to mask. The product exhibits an impaired storage stability, as well, which is a great problem. It is thus desirable to be able to furnish a process, which facilitates a reduction of the fat content in the whey protein concentrate to a minimum, and which gives a product with improved taste and storage stability. The use of whey protein concentrates in foodstuffs is based upon their functional, i.e. emulsifying, and viscosity influencing properties, as well as the nutritional properties of the concentrate. The costs for recovering the proteins will, however, become quite high, as almost 200 litres of whey are needed to give 1 kg of proteins, and as a consequence thereof the most common use will be within the hospital care and health care sectors, as a protein additive. By reducing the fat contents to a minimum the economical conditions to use the the product as a protein additive in conventional foodstuffs for general use should be improved. A conventional centrifugation of standard whey in, e.g., a milk separator can reduce the fat content down to a residual amount of 0.05%, which means a fat content of about 1.5% in a dried whey. After a concentration by means of ultra filtration of the whey the fat elimination can not possibly be carried out by means of centrifugation due to the physical properties of the whey protein concentrate. If one should affect the whey more vigorously than normally, e.g., by a longer staying period in the separator, or the use of ultra centrifuges using higher G-forces, one may separate off fat, but then including great protein losses. Description of the present invention. The present invention thus relates to a process for the removal of fat from whey protein, characterized in that a whey product is subjected to hydrolysis by means of at least one proteolytic enzyme, until a degree of hydrolysis of up to 4.0 has been obtained, whereupon fat present is isolated and removed. The protein product obtained according to the present invention has its functional properties left, and will give clear, slightly opaque solution with water. Further, the protein product is whippable to a stable foam, and can replace white of egg (albumen) in this respect. Moreover, its emulsifying property is excellent, as well as the taste, and thereby highly concentrated protein pastes can be produced. At the process of the present invention one preferably starts with whey proteins, preferably in the form of a whey protein concentrate in order to avoid the handling of too much water, the whey protein concentrate then being obtained in a conventional manner, such as by ultra filtration, and the protein concentrate has thereby suitably a dry matter content of 15 to 50%, preferably 20 to 35%. The whey proteins are made subject to an enzymatic hydrolysis by means of a proteolytic enzyme, or mixture of proteolytic enzymes until the degree of hydrolysis given above has been reached. The term "degree of hydrolysis" (below denoted DH) is defined as the amount, in percentage, of peptide bounds that have been cleaved during the hydrolysis. It is commonly known that a bitter taste appears at the hydrolysis of proteins. This is said to be due to the fact that hydrophobic amino acids or peptide ends are made free and give effect when the protein has been hydrolysed to a certain extent. At a degree of hydrolysis exceeding DH 4 to 5 the bitterness is very pronounced when hydrolysing whey protein. This is a very moderate degree of hydrolysis. However, it is very surprising to find that a degree of hydrolysis of DH up to 4.0, preferably between 0.2 to 4.0, more preferably between about 0.5 and 4.0, gives such a great effect that fat can be easily separated off from the whey proteins in a conventional way, e.g., by means of centrifugation. The conditions during the hydrolysis of the process, such as the type of enzyme used, the amount of enzyme, hydrolysis temperature, hydrolysis time and pH are not critical to the invention as long as the degree of hydrolysis can be achieved. The one skilled in the art can find out, by means of simple preparatory experiments or knows by experience what conditions are to be used and what conditions are optimal at the process. Suitable enzymes used in the process are found on the market, and non-restricting examples of these are a proteolytic enzyme prepared from Bacillus subtilis (Neutrase® 0.5L), and a proteolytic enzyme prepared from Bacillus licheniformis (Alcalase® 0.6L). Further examples are Pepsin 1%, 50°C and 1 h; Papain 3000 1%, 40°C and 2 h; Chymotrypsin 1%, 40°C and 1 h, Pancreatin 4NE 1%, 40°C and 1 h, all at pH 7; an enzyme mixture prepared from Aspergillus oryzae var. pH 9, 1%, 55°C and 90 min, which is inactivated at pH 4 at 68°C for 1 h. The four first mentioned enzymes are inactivated at pH 4, as well. Besides the conditions and the process are as previously mentioned for all types. A mixture of enzymes is also possible. The hydrolysis is finished when the degree of hydrolysis has been reached, and it can be made in a conventional manner, e.g., by inactivation of the enzyme by decreasing the pH, e.g., to pH 4, or by heating the hydrolysis solution, whereby in the latter case care must be taken not to affect the proteins negatively. Then, the fat can be separated off by means of centrifugation. Although not being bound by any theory it is believed that the hydrolysis of the whey proteins leads to such a change of the emylsifying properties of the proteins that a separation off of the fats by means of centrifugation is considerably facilitated. By means of the process according to the present invention it is not only obtained a product with improved taste and improved storage stability, but is also reduces expected protein losses to a minimum. The invention makes it now possible to utilize the high grade proteins of whey for fortifying the nutritional contents in conventional foodstuffs without causing taste problems. It is also easy to eat protein products having an extremely high contents of proteins. This is a great progress within the art. Although a whey protein concentrate may be preferred as a starting material of the present process, any whey quality can be used, such as standard whey obtained directly from the cheese production in the form of sweet as well as acid whey, concentrated whey, which merely is a partly dried whey, and whey protein concentrate, which is a lactose reduced whey protein quality. Standard whey, so called natural whey exists in a lactose reduced variety as well. The invention will now be described more in detail with reference to examples, which are not to be regarded as limiting to the invention. EXAMPLE 1. A whey protein concentrate having a dry matter content of 22.5%, a protein content of 15.2% and a fat content of 1.6% was treated at 50°C for 20 min at pH 8 using a proteolytic enzyme prepared from Bacillus licheniformis and marketed under the trade mark Alcalase® 0.6L. The amount of enzyme was 1.5% calculated on the protein dry matter. After the 20 min hydrolysis the degree of hydrolysis was DH 2.2. After inactivation of the enzyme by decreasing pH to 4 for 60 min, the fat was separated off by centrifugation in a conventional milk separator. After finalized centrifugation the residual fat content reached 0.06%. Then the protein concentration was continued in an ultra filtration equipment until a dry matter content of 39% had been reached. During the final phase demineralized water was added and the concentration took place as a dialysis. The protein content of the dried powder obtained was 98% of the dry matter content, and the fat content was 0.5%. The taste was completely neutral. The whey protein product thus obtained was tested in a whipping test in order to test the functional properties of the protein. Thereby two different tests were applied, viz. a) a foaming test, where 18 g of an 11% protein solution was whipped for 3 min. The protein of the present invention thereby gave 180 ml of foam, compared with the same weight of albumen (white of egg) which gave 175 ml After 30 min the two foams had decreased 30 ml, and b) a whipping test where the inverted value of density is measured (ml/g). Hereby an 11% solution was whipped for 3 min whereupon the ml/g was determined, as well as the loss in ml after 30 min. The reseults are given in the TABLE below. Product ml/g Loss after 30 min ml Protein of the invention 10.2 8 Albumen 10.0 12 Protein of the invention + equal weight of sugar 3.1 4 Albumen + equal weight of sugar 3.5 2 As evident from the Table above the functional properties of the protein product obtained are equal to albumen, or even better. Other functional properties of the present product are that it gives an almost clear solution in water, it may sometimes become a little opaque (blue), that it functions as an emulsifier, mayonnaise can easily be prepared, high protein contents pastes can be prepared and orally administered without any palatibility problem. EXAMPLE 2. A whey protein concentrate having a dry matter content of 35.1%, and a protein content of 27.0% and a fat content of 2.8%, was treated with a proteolytic enzyme prepared from Bacillus subtilis and marketed under the trade mark Neutrase® 0.5L. The amount of enzyme was 2% calculated on the dry protein content. The hydrolysis took place at a temperature of 20°C and at a pH of 7,0. After a reaction time of 70 min the degree of hydrolysis was DH 1.2. Then the enzyme was inactivated by decreasing pH to 4.0 for 1 h, the solution was made neutral and the fat was separated off to a residual amount of 0.06% in a conventional manner. One obtained a dry powder which contained 83.9% of protein calculated on the dry matter and 0.18% of fat. The taste was neutral and the protein product was easily whipped and provided a stable foam. EXAMPLE 3. Example 1 was repeated under the same conditions with the exception that the degree of hydrolysis after finalized hydrolysis was DH 4.1. The final product in the form of a dry powder had a bitter taste, which is difficult to handle. EXAMPLE 4. Example 2 above was repeated under the same conditions, however, with the exception that the hydrolysis was carried out to a degree of hydrolysis of 0.52. Thereby the protein losses exceeded 5%, but the fat content in the final dry protein product was only 0.9%. The protein product gave a stable foam in the whipping test. EXAMPLE 5. A whey protein concentrate according to Example 2 above was treated in accordance with Example 2, with the exception that the hydrolysis was run to a degree of hydrolysation of DH=0.15 only. The residual fat content after centrifugation in a milk separator was 1.0%. The protein obtained still had its functional properties left, and was whippable. EXAMPLE 6. Example 1 above was repeated in all steps with the exception that no proteolytic enzyme was added. The final dry protein product obtained did not show any degree of hydrolysation, and no fat could be separated off when the product solution was centrifuged before final drying. The fat content of the final dried product was about 7%. It is evident from the Examples above that the DH range up to 4.0 is critical at the process of the present invention, and that the fat content is reduced from about 7%, in the case of a conventionally produced whey protein concentrate, to a fat content of the magnitude 0.2 to 1.0% in the case of the product according to the invention. By this decrease in fat contents one has obtained an organoleptically advantageous product with no or small protein losses, and which product can be used as a full grade protein additive in foodstuffs, as well as in high grade feed-stuffs for animal, particularly high grade feedstuffs for young animals needing great protein additions, or high quality protein additions.

Claims: Process for the removal of fat from whey protein, characterized in that a whey product is subjected to a hydrolysis by means of at least one proteolytic enzyme, until a degree of hydrolysis of up to 4.0 has been obtained, whereupon fat present is isolated and removed. Process according to claim 1, wherein the whey product consists of a whey protein concentrate. Process according to claim 2, wherein the whey protein concentrate prior to hydrolysis has a dry matter content of 15 to 50%, preferably 20 to 35%. Process according to claim 1 , wherein the hydrolysis is interrupted by lowering pH, preferably to pH 4. Process according to claim 1 , wherein the hydrolysis takes place at a temperature of above 15°C, but below the inactivation temperature of the enzyme used. Process according to claim 1 , wherein at least 0.5% by weight, preferably 1.5 to 2% by weight of proteolytic enzyme is used calculated on the protein dry matter. Process according to claim 1 , wherein the degree of hydrolysation is about 0.2 to 4, preferably 0.5 to 4. Protein product derived from whey proteins, characterized in that it consists of whey proteins which have been hydrolysed to a degree of hydrolysation of up to 4.0, preferably about 0.2 to 4.0, and which contains less than 1.0% by weight, preferably less than 0.5% by weight of fat, and which protein still possesses its functional properties. Protein product according to claim 8, wherein the degree of hydrolysation is about 0.5 to 4.0.

Inventors: MELLQVIST, ANN, MELLQVIST, CARL-OLOF
Applicants: ALBUGLOBE AKTIEBOLAG
Application year: 1987
Main classification: A23J3
IPC codes: C12P21, A23J3, A23J1, A23C21