Lactic acid bacteria-fermented composition and method for producing the same

Abstract

To provide a lactic acid bacteria-fermented yeast protein-containing composition with reduced off-flavor commonly referred to yeast odor, sensed in yeast-derived protein materials and a method for producing the same, and a method for reducing off-flavor in yeast-derived protein materials.SOLUTION: Culturing lactic acid bacteria in a culture medium containing a suspended yeast-derived protein material makes it possible to reduce the off-flavor derived from yeast in the protein materials, commonly referred to yeast odor, making it available as a protein source.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a yeast protein composition having reduced off-flavors and a method for producing the same. [Background technology]

[0002] In recent years, as the demand for protein increases with the global population growth, there are concerns that the supply will be insufficient. For this reason, much research has been done with the aim of using protein materials derived from plants, microorganisms, insects, etc. as foods. Among them, microorganisms are expected to be a source of protein because they grow quickly, can grow with little nutrition, and are suitable for mass production. Among microorganisms, yeast is also expected to be a source of protein, but it has a unique odor known as yeast odor, which poses challenges in using it as a food. Methods reported for masking the unique odor caused by yeast in food systems include a flavor enhancer for chocolate products that contains yeast extract and 2-furanmethanol and / or 5-methyl-2-furanmethanol as active ingredients (Patent Document 1), and a method for masking the yeast odor by adding flavoring to a yeast extract-containing paste that is characterized by being composed of yeast extract powder, liquid oil and fat, and solid fat (Patent Document 2).

[0003] However, methods for masking the yeast odor by adding food additives or flavorings have tended to be avoided due to consumers' increasing preference for natural foods. Furthermore, no methods have yet been reported for improving the unique odor of yeast as a protein ingredient. For this reason, there has been a demand for a yeast-derived protein composition that satisfies consumer needs and has an improved unique odor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-175963 A [Patent Document 2] JP 2017-184625 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a yeast-derived protein composition that is improved in an off-flavor known as yeast odor, and a method for producing the same, and to provide a method for improving the off-flavor of a yeast-derived protein composition. [Means for solving the problem]

[0006] As a result of intensive research into solving the above-mentioned problems, the inventors discovered that when lactic acid bacteria are cultured in a medium in which a yeast-derived protein material is suspended, the off-flavor of the protein material is suppressed, and thus completed the present invention.

[0007] That is, the present invention relates to the following first to fifth aspects. The first is a lactic acid bacteria-fermented yeast protein-containing composition, which uses as a medium a yeast-derived protein material having a protein content of 40% by weight or more and a dietary fiber content of 4% by weight or more before fermentation by lactic acid bacteria. The second is a method for producing the composition according to the first aspect, which comprises a step of culturing lactic acid bacteria in a medium containing a protein material derived from yeast. Thirdly, there is provided a method for suppressing the off-flavor of a yeast-derived protein material, which comprises adding a yeast-derived protein material having a protein content of 40% by weight or more and a dietary fiber content of 4% by weight or more before fermentation by lactic acid bacteria to a culture medium for lactic acid bacteria and culturing the lactic acid bacteria. Fourthly, there is provided a food or drink comprising the fermentation composition according to the first aspect. Fifth, there is provided a method for producing the food or drink described in the fourth aspect. Effect of the Invention

[0008] According to the present invention, a yeast protein composition in which off-flavors derived from yeast are suppressed can be obtained by suspending a protein material derived from yeast in a medium and culturing lactic acid bacteria in the medium. Furthermore, since the off-flavors derived from yeast are suppressed, the yeast protein composition can be used as a protein source in general foods and supplements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The protein composition of the present invention is made from a yeast-derived protein material and is a protein composition in which the off-flavor expressed as yeast odor is suppressed compared to the original yeast-derived protein material. The yeast odor in the present invention refers to the unique odor or off-flavor of the yeast itself, and the degree of this can be known by sensory evaluation.

[0010] The yeast from which the protein material of the present invention is derived can be any yeast that is generally used in the production of food products such as beer, sake, wine, bread, and seasonings, without any restrictions. Specific examples include budding yeast (Saccharomyces cerevisiae) and torula yeast (Siblindonella jadini; also known as Candida utilis). Among these, torula yeast is preferable.

[0011] The yeast-derived protein material in the present invention may be yeast cells after soluble extract components are separated and removed from the yeast cells. Alternatively, the yeast-derived protein material may be an insoluble fraction obtained by treating the yeast cells after soluble extract components are separated and removed with an enzyme having glucanase activity, and then removing the soluble fraction. The protein content of the insoluble fraction may be 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more, based on the solid content, as the total amino acid content measured by an amino acid analyzer according to a conventional method. Here, the enzyme having glucanase activity may be a commonly available enzyme preparation. The reaction conditions may be the optimal conditions for the enzyme used. The soluble fraction may be removed after the enzyme reaction by a general method such as centrifugation or filtration.

[0012] Moreover, the protein material preferably contains dietary fiber, more preferably 4% by weight or more, and even more preferably 4.5% by weight or more. The amount of dietary fiber can be determined by hydrolysis. Specifically, a sample is hydrolyzed with 1N sulfuric acid at 110°C for 3.5 hours, neutralized, and the resulting hydrolysates, mannose and glucose, are measured by high performance liquid chromatography (HPLC) and converted into glucan and mannan to determine the amount of dietary fiber. The HPLC analysis conditions may be general sugar analysis conditions as long as they allow the measurement of glucose and mannose.

[0013] The composition of the present invention can be produced by adding the above yeast-derived protein material to a medium for culturing lactic acid bacteria. The amount of the yeast-derived protein material added to the medium for culturing lactic acid bacteria can be 5 to 20% by weight, preferably 8 to 15% by weight, and more preferably 9 to 12% by weight.

[0014] As long as the effects of the present invention are not adversely affected, other components may be added to the medium, such as enzyme decomposition products of proteins, inorganic salts, sugars, vitamins, and minerals.

[0015] The lactic acid bacteria used in the production of the composition of the present invention are not particularly limited as long as they are lactic acid bacteria commonly used in the production of foods and beverages, but among them, lactic acid bacteria of the genus Lactobacillus, Lacticaseibacillus, Latilactobacillus, Rigilactobacillus, Lactiplantibacillus, Rimosilactobacillus, Levilactobacillus, Fructilactobacillus, Apilactobacillus, Enterococcus, Lactococcus, Pediococcus, Leuconostoc, Streptococcus, and Bifidobacterium are preferred, lactic acid bacteria of the genus Lactobacillus, Lactiplantibacillus, or Levilactobacillus are more preferred, and Lactiplantibacillus plantarum subsp. plantarum or Levilactobacillus brevis is even more preferred. Furthermore, one of the above-mentioned lactic acid bacteria may be used alone, or a combination of two or more of them may be used.

[0016] The conditions for culturing lactic acid bacteria are not particularly limited as long as the yeast odor of the yeast-derived protein material is suppressed, and the temperature, pH, culture time, and the like generally used in culturing lactic acid bacteria can be appropriately set. For example, in the case of static culture, the fermentation temperature can be 15 to 40°C, preferably 24 to 34°C. The fermentation time can be 12 to 168 hours, preferably 18 to 144 hours, and more preferably 24 to 96 hours. During culture, the pH decreases with the production of organic acid, so that the pH can be adjusted to a suitable pH for the growth of lactic acid bacteria using sodium hydroxide, potassium hydroxide, or the like.

[0017] The lactic acid bacteria culture thus obtained contains a protein composition derived from yeast but with a suppressed yeast odor. Therefore, this culture can be used as the yeast protein composition of the present invention as is. If necessary, excipients and the like may be added to the culture, followed by concentration and drying. The drying method may be a method generally used in food production, such as spray drying, drum drying, or freeze drying. There is no particular limitation on the form, and the composition may be prepared in the form of powder, granules, capsules, tablets, paste, or the like.

[0018] The composition of the present invention may be eaten as it is, or may be added to general foods or supplements. General foods include processed foods such as paste-like foods like curry and stew, and processed foods such as meatballs and fish paste products. It may also be mixed with other protein materials and used as a supplement. The composition of the present invention may be added to food or beverages in any manner, and may be added simultaneously with other raw materials, or may be added separately to produce food or beverages.

[0019] The method for suppressing the off-flavor of a yeast-derived protein material in the present invention is to ferment the yeast-derived protein material with lactic acid bacteria. The method for fermenting with lactic acid bacteria is as described above. EXAMPLES

[0020] The present invention will be specifically described below using examples, but the present invention is not limited to these.

[0021] <Raw materials for the composition of the present invention> Among the protein materials derived from yeast, "KR Yeast" (Mitsubishi Corporation Life Sciences) was used as sample 1, which is the yeast cell after separating and removing soluble extract components from the yeast cell. The protein content of "KR Yeast" was analyzed as total amino acid content using an amino acid analyzer L8800 (Hitachi) according to standard methods, and was found to be 45% by weight. The dietary fiber content was analyzed by HPLC (column: SUGAR SP0810 (Shodex), detector: RI, mobile phase: ultrapure water) and was found to be 4.1% by weight. In addition, the torula yeast cells after separating and removing the soluble extract components were suspended in water at 10% by weight, and a commercially available glucanase preparation was added at 0.05% relative to the cells and allowed to act for 3 hours under optimal enzyme conditions, after which the soluble fraction was removed and the resulting insoluble fraction was dried to obtain Sample 2. The protein and dietary fiber amounts were analyzed using the same method as for Sample 1, and the protein content was 82% by weight and the dietary fiber content was 15.2% by weight.

[0022] <Production of the composition of the present invention> 10 g of sample 1 and 2 g of glucose were added to water, and the mixture was diluted to 100 mL, followed by heat sterilization to prepare a medium. Lactiplantibacillus plantarum subsp. plantarum was seeded therein and cultured at 30° C. for 72 hours under slight stirring conditions. The resulting culture solution was freeze-dried to obtain a powdered sample of Example 1. Moreover, a sample of Example 2 was obtained by carrying out the same procedure except that Streptococcus thermophilus was used as the lactic acid bacterium to be inoculated. The same procedure was carried out except that lactic acid bacteria were not seeded, to obtain a sample of Comparative Example 1. Furthermore, as a sample of Control Example 1, "KR yeast" was used. In addition, 10 g of sample 2 and 2 g of glucose were added to water to make 100 mL, and the mixture was heat sterilized to prepare a medium. Lactiplantibacillus plantarum subsp. plantarum was seeded therein and cultured at 30° C. for 65 hours under slight stirring conditions. The resulting culture solution was freeze-dried to obtain a powdered sample of Example 3. The same procedure was carried out except that Levilactobacillus brevis was used as the lactic acid bacterium to be inoculated, to obtain a sample of Example 4. The same procedure as in Example 2 was carried out except that lactic acid bacteria were not seeded, to obtain a sample of Comparative Example 2.

[0023] <Confirmation test for yeast odor suppression by sensory evaluation> When the odor of the powder of each sample of Example 1, Example 2, and Comparative Example 1 was evaluated by sensory evaluation, the odor derived from yeast was reduced in Examples 1 and 2 compared to Control Example 1. Furthermore, Comparative Example 1 had an odor similar to that of Control Example 1, and compared to Comparative Example 1, the odor derived from yeast was reduced in the samples of Examples 1 and 2, and the yeast odor was improved. Furthermore, when the odors of the powder samples of Example 3, Example 4, and Comparative Example 2 were evaluated, the odor derived from yeast was reduced in Examples 3 and 4 compared to Comparative Example 2. In addition, Comparative Example 2 had a stuffy odor compared to Control Example 1. The samples of Examples 3 and 4 did not have an odor compared to Control Example 1, and the odor derived from yeast was reduced, indicating that the yeast odor of the yeast-derived protein material was improved by fermentation.

[0024] From the above, it was demonstrated that a yeast-derived protein fermentation composition with suppressed yeast odor can be obtained by fermenting a yeast-derived protein material with lactic acid bacteria.

Claims

1. The composition contains a lactic acid bacteria-fermented yeast protein, the medium being a yeast protein material having a protein content of 40% by weight or more and a dietary fiber content of 4% by weight or more before fermentation by lactic acid bacteria.

2. A method for producing the composition according to claim 1, comprising the step of culturing lactic acid bacteria in a medium containing a protein material derived from yeast.

3. The method for suppressing the off-flavor of a yeast-derived protein material is characterized in that a yeast-derived protein material having a protein mass of 40% by weight or more and a dietary fiber mass of 4% by weight or more before fermentation by lactic acid bacteria is added to a culture medium for lactic acid bacteria, and the lactic acid bacteria are cultured.

4. A food or drink comprising the fermented composition according to claim 1.

5. A method for producing the food or drink according to claim 4.