A process for the production of alkali-treated powder possessing an immunological activity

Abstract: A process for producing an alkali-treated yogurt powder possessing immunological activity, which process comprises heating yoghurt in the presence of an alkaline agent such that protein in the yoghurt is solubilised, and drying the resulting treated yoghurt to a powder. The treated yoghurt thus produced is useful in both foods and animal feedstuffs.

Description: This invention relates to a process for the production of yogurt powder possessing an immunological activity, and more particularly to a process for the production of yogurt powder containing an immunological activator derived from the destroyed lactic acid bacteria in the heated yogurt and having a lower adhesion and hygroscopicity. The yogurt powder thus prepared according to the present invention is used as food and feed. Conventionally, since yogurt as food had a short preservation period from production date to expiration date, any yogurt past its expiration date was wasted. Since diversification of customers' needs forced manufacturers to produce many varieties of products, a lot of product loss occurred at the time of the change of manufacturing products. The resulting merchandise loss and expenses for waste described above were serious disadvantages from the point of view of manufacturing cost. In addition, conventional yogurt has other weak points, such as degradation of value and function of food due to autolysis of lactic acid bacteria in the yogurt when kept raw for a long time. The only other way to use the wasted yogurt other than as a food was as a milk substitute to animals by drying it with bran, in a drum dryer and the like. The waste raw yogurt is useful for a milk substitute in liquid feed, however it is not so useful to add to dry feeds, because feeding boxes are messed up and the entire feed deteriorated by microbial contamination. When it is dried by dryers, such as a drum dryer, the product was dried into an agglomeration rather than powder. Its high adhesion and hygroscopicity prevented mixing the product with usual powder feed. Therefore, there was no other way except to feed itself directly. Further, in the ways stated above, an immunological activity derived from the lactic acid bacteria in the yogurt could not be used efficiently. Up to this time, an object of feeding the yogurt is only to increase its palatability for animals and to use it as a nutritious resource. The yogurt powder containing an immunological activity derived from the lactic acid bacteria in the yogurt has not been used as a high value-added feed, much less as food and the like. FR-A-1005 116 describes powdered milk products produced by fermentation of pasteurised milk and addition of sodium carbonate for buffering before freeze drying. Accordingly, it is an object of the present invention to provide yogurt powder which can be used as a feed additive by mixing with feed. It is another object of the present invention to provide a process for the production of yogurt powder which carries a high immunological activity derived from the lactic acid bacteria in the heated yogurt that is usable for food and the like. Accordingly, the present invention provides a process for producing an alkali-treated yogurt powder possessing immunological activity, which process comprises heating yogurt in the presence of an alkaline agent such that protein in the yogurt is solubilised, and drying the resulting treated yogurt to a powder. When yogurt is heated and treated in accordance with the process of the invention a casein portion of the protein therein is solubilised in water. Thereafter, the yogurt is subjected to the addition of a surfactant or to high pressure treatment by use of a high pressure homogenizer or to addition of a drying carrier, solely or in combination, for drying the yogurt by a spray drying method or the like. A preferred embodiment of the invention involves adding a surfactant to the treated yogurt prior to drying. The yogurt powder thus prepared according to the present invention retains an immunological activity derived from the lactic acid bacteria and the like in the heated yogurt. The resulting yogurt powder can be used as a feed additive having immunological activity or as an ingredient for health food. The process of this invention, in any way, can be modified in accordance with usage and purposes. The yogurt used as a starting material in this invention usually includes any yogurt which may be of curd form and of liquid form; for example, yogurt produced for food and drink, product loss, returned yogurt of which tasting periods have expired. Typically, in the process of the invention the yogurt is heated at more than 60°C to sterilize it and to solubilise a casein portion of protein therein smoothly in water. The optimum temperature of the heat treatment is preferably 80 to 95°C. In one aspect, the process comprises heating the yogurt to a temperature of from 60°C to 100°C in the presence of an alkaline agent such that a pH of 7.0 to 9.6 is obtained. The term "alkaline agent" herein includes sodium hydroxide, potassium hydroxide and the like. The pH of the yogurt should preferably reach more than 7.0 to solubilise casein of the yogurt in water. Treatment of the cells' surfaces with the alkaline agent also serves to stabilize the immunological activity of the destroyed lactic acid bacteria in the heated yogurt. The optimum pH is preferably 8.3 to 9.6. The term "surfactant" herein includes a non-ionic surfactant with HLB (hydrophile-lipophile balance) value of more than 7.0. Generally the surfactant is added to the yogurt in an amount of from 0.1 to 10.0% by weight. The surfactant serves to disperse fat smoothly, and treatment of the cells' surfaces with it also stabilizes the immunological activity of the destroyed lactic acid bacteria in the heated yogurt. The surfactant to be used includes, for example, polyoxyethylene sorbitan fatty acid ester and sucrose fatty acid ester. Any of these with 9.0 to 15.0 in HLB is acceptable. The optimum addition is preferably 0.3 to 5% to an amount of the yogurt. The term "high pressure treatment" herein means subjecting the yogurt momentarily to a pressure of about 50 to 1000 kg/cm 2 . Preferably a high pressure homogenizer is used. An effect of this high pressure treatment is that the cells' surfaces are destroyed so that cell walls consisting of sugar-lipid and sugar protein can be easily removed. In the process of the invention a drying carrier may be added to the yogurt. The term "drying carrier" herein includes dextrin and lactose and the like. The drying carrier is added, typically in an amount of more than 2% by weight, to reduce adhesion and hygroscopicity at the moment of drying the yogurt. Preferably, the DE value (dextrose equivalent value) of dextrin is 7.0 to 12.0, and the optimum addition is 5 to 20% by weight of the amount of the yogurt. Concerning the drying method herein, any well-known method, such as freeze drying, spray drying and vacuum drying may be used, but the optimum method in terms of cost is spray drying. The yogurt powder thus prepared according to the present invention not only may be mixed easily with feed, but it also possess a high immunological activity. It can also be used for food and the like. For example, when the resulting yogurt powder is administered slightly to mice before inoculating a fatal amount of E. coli into mice, the administered mice survive, while all or most of the mice in a non-administered group die. These animal tests prove the high immunological activity of the yogurt powder which can provide feed having an immunological activity and ingredients for a new type of food and the like. This invention will be more clearly understood with reference to the following examples and control example. Control Example: One hundred kilograms of yogurt (11% of solid contents) was thrown into a mixer equipped with a jacket to heat up the yogurt until it becomes 85°C. Thereafter, while stirring the yogurt, 10 kilograms of bran was thrown into the mixer to dry the product at 800°C by use of a drum dryer. As a result, 16.8 kilograms of agglomerate substance was obtained. Example 1: One hundred kilograms of yogurt (11% of solid contents) was thrown into a mixer equipped with a jacket, and heated to 90°C. While stirring the yogurt, 40% solution of sodium hydroxide was added to adjust the yogurt to around pH 9.0. 10 kilograms of dextrin was also thrown into the mixer. Furthermore, the mixture was filtered through a sieve with 60 mesh after being mixed well. Finally, the filtrate was dried on a spray dryer under inlet temperatures of 170°C and outlet temperatures of 85°C. As a result, 18.5 kilograms of dried yogurt powder was obtained. Example 2: One hundred kilograms of yogurt (11% of solid contents) was thrown into a mixer equipped with a jacket to heat the yogurt to 90°C. While stirring the yogurt, 40% solution of sodium hydroxide was added to adjust the yogurt to around pH 9.0. Successively, 0.5% of sucrose fatty acid ester was added to an amount of the yogurt, and also 10 kilograms of dextrin was thrown into the mixer. Furthermore, the mixture was filtered through a sieve with 60 mesh after being mixed well. Finally, the filtrate was dried on a spray dryer under inlet temperatures of 170°C and outlet temperatures of 85°C. As a result, 18.5 kilograms of dried yogurt powder was obtained. Example 3: One hundred kilograms of yogurt (11% of solid contents) was thrown into a mixer equipped with a jacket to heat the yogurt to 90°C. While stirring the yogurt, 40% solution of sodium hydroxide was added to adjust the yogurt to around pH 9.0. Successively, 0.5% of sucrose fatty acid ester was added to an amount of the yogurt, and 10 kilograms of dextrin was also thrown into the mixer. Furthermore, the mixture was filtered through a sieve with 60 mesh after being mixed well. Finally, the filtrate was subjected to 100 kg/cm 2 of pressure treatment through a high pressure homogenizer to dry it on a spray dryer under inlet temperatures of 170°C and outlet temperatures of 85°C. As a result, 18.5 kilograms of dried yogurt powder was obtained. In order to investigate the fluidity and hygroscopicity of the dry matters obtained in the above control and test examples, the following two points were measured: (1) angle of repose and (2) successive loss on drying at room temperature. Table 1 shows the results. From this it was found that the yogurt powder herein possessed high fluidity and low hygroscopicity, and that its physical properties were improved in comparison with the control example. Angle of Repose Loss on Drying (%) 0 day 1st day 2nd day Example 1 42° 4.71 4.88 4.99 Example 2 41° 4.65 4.86 4.98 Example 3 36° 4.65 4.72 4.98 Control Example >50° 7.31 11.68 12.66 Experiment 1: In order to observe the life or death of mice inoculated with E. coli, the yogurt powder obtained in the above control and test examples was administered into the abdominal cavities of 10 mice in the amount of 5 mg/per mouse, and thereafter dosages of E. coli in amounts fatal to mice was inoculated into the abdominal cavities of the mice. As a control, only E. coli was inoculated into mice of the same number. Table 2 shows the results. From this, it was confirmed that the yogurt powder herein reinforced the infectious resistance of mice against E. coli, and that this powder possessed a sufficiently higher immunological activity in comparison with the control example. No. Dead after Inoculation Total # Dead Total # Surviving 1st day 2nd day 3rd day Example 1 2 1 0 3 7 Example 2 2 0 0 2 8 Example 3 0 0 0 0 10 Control Exp. 6 1 0 7 3 Control 7 3 0 10 0 Phagocytosis of Neutrophiles Control Control Example Example 3 500 µg Example 3 500 µg (min.) Experiment 2: In order to measure the phagocytosis of neutrophiles in the spleens of mice by a chemiluminescence method on the basis of luminol reaction, the yogurt powder obtained in the above example was floated in physiological saline to administer the floating solution directly into the stomachs of mice with a tube, and the spleens of mice were removed on the third day after the administration to adjust cell sap to 4 x 10 6 cells/ml by 10mM-HEPES added MEM. As a result, the phagocytosis of splenic cells (neutrophiles) of the administered mice increased. Therefore, it was proved that the administration of the yogurt powder activated immunocomplement cells. Figure 1 shows the results.

Claims: A process for producing an alkali-treated yogurt powder possessing immunological activity, which process comprises heating yoghurt in the presence of an alkaline agent such that protein in the yoghurt is solubilised, and drying the resulting treated yoghurt to a powder. A process according to claim 1, which comprises heating the yoghurt to a temperature of from 60°C to 100°C in the presence of an alkaline agent such that a pH of 7.0 to 9.6 is obtained. A process according to claim 1 or 2 which further comprises adding a surfactant to the treated yoghurt prior to drying. A process according to claim 3 wherein the surfactant has an HLB (hydrophile-lipophile balance) value of 7.0 or more. A process according to claim 3 or 4 wherein the surfactant is added to the yoghurt in an amount of from 0.1 to 10.0% by weight. A process according to any one of the preceding claims which further comprises subjecting the treated yoghurt to treatment with a high pressure homogenizer prior to drying. A process according to claim 6 wherein the treated yoghurt is subjected to a pressure of 50 to 1000 kg/cm 2 . A process according to any one of the preceding claims which further comprises adding a drying carrier to the yoghurt. A process according to claim 8 wherein the drying carrier is dextrin or lactose. A process according to any one of the preceding claims wherein the treated yoghurt is dried to a powder by spray-drying.

Inventors: HAMANO ATUSHI, KUROKAWA TOMOHIRO, MAKIYAMA MAYUMI, SASAKI TAKASHI, TANABE HIROSHI, TANI MASAHIDE, HAMANO, ATUSHI, KUROKAWA, TOMOHIRO, MAKIYAMA, MAYUMI, SASAKI, TAKASHI, TANABE, HIROSHI, TANI, MASAHIDE, Kurokawa, Tomohiro, Scientific Feed Lab. Co. Ltd.,
Applicants: NAT FEDERATION AGRIC COOP ASS, SCIENT FEED LAB CO LTD, NATIONAL FEDERATION OF AGRICULTURAL, SCIENTIFIC FEED LABORATORY CO., LTD.
Application year: 1995
Main classification: A23C9
IPC codes: A23C9, A61K35, A23K1, A61P37