Dairy products

Abstract: A process for the preparation of a low fat cheese, containing denatured protein particles with an average particle size of 0.1-40 µm is described. Depending on the particle size of the denatured proteins soft cheese or hard cheese can be made.

Description: This invention relates to a process for the preparation of improved low fat cheese products. In the prevailing appeal among consumers of a healthy diet, particular attention is drawn to reducing the daily intake of animal fat, not only to reduce the calorific content of the diet, but also the content of saturated fatty acids and cholesterol. To this end the high fat content in traditional food products has been reduced in recent years, while attempting to retain the fulsome mouth response characteristic of full fat products. When the amount of fat in cheese is reduced, the textural properties of a hard or semi-hard cheese in particular in the case of Gouda-cheese are changed. Such a reduction makes the cheese firm, increasing the rubbery texture of the cheese which ultimately can be almost inedible due to its extreme toughness. On the other hand reducing fat in soft or fresh cheese results in a loss of creaminess and an enhanced dryness in the mouth is perceived. Here too the product may be almost inedible. A solution to this problem has now been found in a process to prepare low fat cheese products in which in a particular step of the process part of the fat is replaced by hydrated, denatured protein particles in which the particle size is sufficiently small to induce a mouthfeel similar to that of the fat in cheese like products. It has further been found that different kinds of cheese i.e. soft or fresh cheese versus hard or semi-hard cheese require particles with a different particle size. The present invention therefore provides a process for the preparation of improved low fat cheese products, by aggregation of casein in milk in which at least part of the milk fat normally present in the milk is replaced by an amount of hydrated, denatured protein particles with an average particle size between 0.1 and 20 µm, which process is characterised by the fact that the hydrated denatured protein particles are added to skimmed or partly skimmed milk before pasteurization thereof and before the aggregation of the casein c.q. by rennet is carried out and wherein particles with an average particle size of maximum 2 µm are used for the preparation of soft or fresh cheese, and particles with an average particle size between 2-20 µm are used for the preparation of hard or semi-hard cheese. The invention results in improved low fat cheese which contains an amount of hydrated, denatured protein particles, with an average particle size of less than 2.0 µm or within the range of 2-20 µm. A variety of hydrated denatured, protein particles may be used in the process of the invention, e.g. aqueous dispersions of storage vegetable proteins, blood serum, bovine serum and albumen. A prerequisite is, that the particles retain their solid properties during the process. Preferably, denatured whey protein is used, since the resulting cheese product then retains the components of milk and the incorporation of components akin to the cheese system occurs. It was found, that particle sizes substantially above 20 µm are less satisfactory in terms of the mouth response to the product. Suitable protein based, aqueous compositions are described in our earlier EP 352 144. It describes compositions of non-aggregated, heat-denatured colloidal particles with particle size of 0.1-30 µm of heat denatured plant proteins. It also discloses, that these compositions can be used as fat replacers in food, but it does not mention the use of it in cheese. In European Patent Applications 250623 and 323529 suitable small sized, hydrated heat denatured protein particles are also described, which are obtained by intensive shearing. The particle size is 0.1-2.0 µm, whereas less than 2% are above 3.0 µm and it is disclosed, that both the shape of the particles and in particular the particle size are important for the organoleptic properties of the particles. The use of these components as fat-replacer in food is mentioned, but again the use in cheese is not described. According to Chem. Abstr. 80 (1974), no. 19, p. 292, abstr. 106945d it is known to add whey-proteins to milk prior to its pasteurization. However, nothing is disclosed about the influence of the particle size on the product properties of the resulting cheese product. In GB 1,273,943 a process is described, wherein milk protein precipitation products are applied in milk products. However, the precipitation products are made by a process, that avoids partial denaturation of the protein. Food Science and Tech. Abstr. 1976, p. 132-135, no. 76-11-P 2234 discloses the use of denatured whey protein for the preparation of Probaltiiskii cheese. However, nothing is said about the moment of addition of the whey protein. Similar information can be found in J. of Dairy Science 69 , 1986, 2543-2550, although according to this references the whey is added at the end of the ripening process. In US 3,644,326 Pien has disclosed a process for the preparation of cheese, wherein proteins are extracted from lactoserum and re-introduced into the milk during manufacturing. However, no indications can be found, when to add the proteins to the milk. Preferably low fat cheeses are prepared in accordance with the invention with a fat on dry matter content of less than 40% by regulating the fat content of the skimmed milk and by varying the amount of added hydrated, denatured protein particles. In this way either hard, semi-hard, processed, fresh or soft cheeses can be prepared. The particle size of the denatured protein particles is thus chosen depending on the kind of cheese, that is required. If a hard or semi-hard cheese is required the average particle size must be 2-20 µm. If however soft cheeses, such as cottage cheese, fresh cheese, fromage frais, mold ripened cheeses, or processed cheeses, with a smooth, more viscous type of texture is required particles with an average particle size sufficiently small e.g. maximum 2 microns must be used in order to retain the smooth character of the cheese. The denatured whey protein composition is preferably prepared by heating a solution of undenatured whey proteins at a concentration below the gelling concentration, i.e. below 8 wt%, at pasteurisation temperatures or higher, as required. Part of the whey proteins are heat denatured and are acidified to a pH between 4.0 and 5.5, such that particles are formed of less than 20 µm in average size, which can be separated e.g. by centrifugation from the mother liquor. The particles so obtained, containing approximately 85 wt% water can then be neutralised to the pH of milk and may then be combined with a milk composition of reduced fat content to provide a cheese milk. The taste and texture of cheese made from this milk is more or less that of full fat cheese, depending on the extent to which the milk composition is depleted of fat and the amount of whey protein added. The process of the invention lends itself to simple recycling of sweet whey from cheese manufacture, the whey being processed as described to produce a composition of denatured unaggregated protein particles which may then be recycled to the cheese milk. Preferably the amount of denatured protein particles added to the cheese milk is from 1 to 5 wt% based on the fat content of the milk. While it is not intended to limit the scope of the invention claimed by reference to any particular theory regarding the mechanism involved, it is believed that the unfavourable mouth response of skimmed or partly skimmed milk based cheeses prepared from heating milk before cheese making is attributable to the effect of whey protein binding to the casein micelles present in milk as a result of this heating. In addition the clotting process is affected hereby, in particular at milk heating temperatures above 85°C, when cheese making is no longer possible. When instead the whey proteins are heated alone, they are able to react with themselves resulting in the formation of particles of the required dimensions, provided their concentration is below the gelation concentration and heating time and temperature combinations and pH are kept to within the limits required to maintain the average particle size below 20 microns. Example I Cheese whey recovered from Gouda full fat cheese preparations and comprising a 5% solution of undenatured whey proteins, was heated for 2 minutes at 76°C by passage through a plate heat exchanger and cooled to room temperature. It was then acidified to a pH 5.0 by gradual addition of citric acid with rapid agitation to avoid locally high acid concentrations. The acidified whey was then centrifuged at 5000g for 15 minutes, when a supernatant liquor was separated, leaving a concentrate containing 12 wt% protein. The average size of the protein particles in the concentrate, measured with a Coulter Counter particle size analyser was 3.1 microns, consisting largely of unaggregated denatured whey protein particles. The composition was neutralised by adding sufficient aqueous sodium hydroxide (0.1 N) again with agitation to give a final pH of 6.7. Cheese milk was prepared by mixing sufficient skim milk with full fat milk to a fat level of 1.5 wt%, to which the neutralised whey protein concentrate was added at a ratio of 1 part to 50 of the milk composition. The milk mixture so obtained was pasteurised in a conventional manner by passage through a heat-exchanger for 35 seconds at 72°C. Gouda cheese was prepared in a traditional manner from the resulting reduced fat milk composition by adding starter culture and rennet at 31°C. The resulting curd had the same structure as the equivalent full fat cheese and subsequent cutting, wheying-off and washing procedures were unchanged. The cheese was pressed before brining and coated as usual before storage for 10 weeks in a cheese ripening room. Cheese taste and texture of the ripened product were evaluated by a panel on a 5 point scale in comparison with full fat Gouda cheese and with products made in comparative tests in which the above example was repeated a) without adding whey protein, b) with pasteurisation before addition of the whey protein of the cheese milk. The results of the comparison appear on the accompanying table. The fat content on dry matter of the samples A, B and C were respectively: 31%, 32% and 32%. The results must be interpreted in such a way, that the figure that is closest to the figure for sample 48⁺ is the best. From the results mentioned in the Table it can be concluded, that the low fat cheese, that most resembles a full fat cheese is Sample B, but Sample C also has quite satisfactory properties. Sample A is very unsatisfactory. The example was repeated with slight modifications as indicated below. The results of these experiments were quite satisfactory and comparable with those of Samples B and C from the Table. Ex. II centrifugation was replaced by overnight settling and simple decanting of the supernatant. Ex. III less full fat milk was added, resulting in a cheese with FID of 10%. The amount of whey was raised accordingly. Ex. IV the heating temperature for the denaturation of the sweet whey solution was 81°C, heating time 2 mins, resulting in particles of 10 µm. Ex. V heating temperature 90°C; particle size 20 µm Ex. VI protein particle obtained, according to EP 323529 were used.

Claims: Process for the preparation of improved low fat cheese product by aggregation of casein in milk in which at least part of the milk fat normally present in the milk is replaced by an amount of hydrated, denatured protein particles with an average particle size between 0.1 and 20 um wherein the hydrated, denatured protein particles are added to skimmed or partly skimmed milk before pasteurisation thereof and before the aggregation of the casein is carried out and wherein particles with an average particle size of maximum 2 µm are used for the preparation of soft or fresh cheese, and particles with an average particle size between 2-20 µm are used for the preparation of hard or semi-hard cheese. Process according to claim 1, wherein the fat content of the skimmed milk and the amount of added hydrated, denatured protein particles are such, that the low fat cheese product has a fat on dry matter content of less than 40%. Process according to claims 1 or 2, wherein denatured whey protein particles with an average size of maximum 20 µm are used.

Inventors: KLOOSTERMAN JOHANNES, TORENVLIET LIM, VISSER JOHANNES, TORENVLIET, LIM, VISSER, JOHANNES
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1990
Main classification: A23C9
IPC codes: A23C21, A23C19, A23C9