METHOD FOR PRODUCING A FOOD PRODUCT BY FERMENTATION WITH LACTIC ACID BACTERIA

Abstract

A method for producing a lactic acid bacteria fermentation food product is characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing the lactic acid bacteria in a medium containing milk or a dairy product as the main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as the main component before culturing the lactic acid bacteria, or to a fermented liquid during or after culturing.

Description

METHOD FOR PRODUCING A FOOD PRODUCT BY FERMENTATION WITH LACTIC ACID BACTERIA TECHNICAL FIELD The present invention relates to a method for producing a lactic acid bacteria fermentation food product, and more particularly to a method for producing a lactic acid bacteria fermentation food product that has a high proliferation-promoting effect on lactic acid bacteria during production and also has an excellent viability-enhancing effect on lactic acid bacteria during storage. BACKGROUND OF THE INVENTION Until now, food products and beverages containing viable cells, such as yogurts and fermented milks, have been widely consumed and drunk as foods with physiological functions, such as intestinal regulation. For these foods to effectively exhibit these physiological functions, it is necessary to efficiently proliferate lactic acid bacteria during production and also maintain their levels during storage. However, depending on the raw materials, conditions, and other factors, the lactic acid bacteria may not proliferate sufficiently during fermentation or may die during storage, resulting in a decrease in the viable cell count or similar, and thus preventing the expected physiological function from being achieved. With regard to the problem, the applicant has already reported that adding oleic acid to low-fat yogurt increases the viable cell count of lactic acid bacteria in the product and can improve viability during storage (PTL 1). Furthermore, it is described that culturing using a medium supplemented with oleic acid or a butterfat fraction containing oleic acid increases the survival rate of microorganisms in the product and in the bile acid (PTL 2), or that adding buttermilk results in a growth-promoting effect on lactic acid bacteria (PTL 3). However, there has been an application for the establishment of a technique capable of increasing the viable cell count in a product and maintaining the viable cell count in a lactic acid bacteria fermentation food product. List of appointments Patent literature PTL 1: JP-A-2001-45968 PTL 2: JP-A-2000-102380 PTL 3: JP-A-2008-520202 BRIEF DESCRIPTION OF THE INVENTION Technical problem An object of the present invention is to provide a method for producing a lactic acid bacteria fermentation food product that has a high proliferation-promoting effect on lactic acid bacteria during production and also has an excellent viability-enhancing effect during storage. Solution to the problem As a result of intensive studies, the present inventor found that by cultivating lactic acid bacteria in a medium supplemented with a lipase degradation product of an oil or fat, the proliferation of lactic acid bacteria is promoted during production and, in addition, death is suppressed during storage, and therefore, the viable cell count of lactic acid bacteria in the product can be kept high, thus completing the present invention. That is, the present invention is a method for producing a lactic acid bacteria fermentation food product, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as a main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as a main component before culturing the lactic acid bacteria, or to a fermented liquid during or after culturing. Furthermore, the present invention is a method for promoting the proliferation of lactic acid bacteria, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and cultivating lactic acid bacteria in a medium containing milk or a dairy product as the main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as the main component before cultivating the lactic acid bacteria. Furthermore, the present invention is a method for improving the viability of lactic acid bacteria, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as a main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as a main component before culturing the lactic acid bacteria, or to a fermented liquid during or after culturing. Furthermore, the present invention is a proliferation-promoting agent for lactic acid bacteria or a viability-enhancing agent for lactic acid bacteria, characterized by containing a lipase degradation product of an oil or fat as an active ingredient. Advantageous effects of the invention According to the production method of the present invention, the viable cell count in the product after production can be increased by promoting the proliferation of lactic acid bacteria during fermentation, and the viability of the lactic acid bacteria can also be improved by preventing their death during storage. Therefore, the viable cell count of lactic acid bacteria in a lactic acid bacteria fermentation food product can be maintained within a high viable cell count range, allowing their physiological functions to be effectively exhibited. DETAILED DESCRIPTION OF THE INVENTION The method for producing a lactic acid bacteria fermentation food product of the present invention is configured such that when the lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as a main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as a main component before fermenting the lactic acid bacteria, or to a fermented liquid during or after culturing. In the present invention, the lactic acid bacteria to be used in the fermentation are not particularly limited, and bacteria belonging to the genera Lactobacillus, Lactococcus, Streptococcus, Enterococcus, and similar genera may be used. Specific examples of bacteria include Lactobacillus casei, Lactobacillus acidophilus (L. acidophilus), Lactobacillus gasseri (L. gasseri), Lactobacillus helveticus (L. helveticus), and Lactobacillus salivarius (L. salivarius). salivarius), Lactobacillus fermentum (L. fermentum), Lactobacillus yoghurti (L. yoghurti), Lactobacillus delbrueckii subsp. bulgaricus (L. delbrueckii subsp. bulgaricus), Lactobacillus delbrueckii subsp. delbrueckii (L. delbrueckii subsp. delbrueckii), Lactobacillus gallinarum (L. gallinarum), Lactobacillus johnsoni (L. johnsoni), Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus plantarum, Lactococcus raffinolactis, Streptococcus thermophilus, and Enterococcus faecium. Among these, Lactobacillus casei, Lactobacillus gasseri and the like are preferred in terms of a proliferation promoting effect and a viability improving effect, and particularly, Lactobacillus casei is preferred. As Lactobacillus casei, for example, Lactobacillus casei YIT 9029 strain (FERM BP-1366, deposit date: May 18, 1987) and the like. Note that in the present invention, the lactic acid bacteria to be used in fermentation also include bacteria belonging to the genus Bifidobacterium, which are anaerobic bacteria, in addition to the commonly referred to lactic acid bacteria as described above. Such bacteria belonging to the genus Bifidobacterium are not particularly limited, and are exemplified by Bifidobacterium breve, Bifidobacterium pseudocatenulatum, Bifidobacterium bifidum, Bifidobacterium longum, Bifidobacterium infantis, Bifidobacterium adolescentis, Bifidobacterium catenulatum, Bifidobacterium angulatum, Bifidobacterium gallicum, Bifidobacterium lactis, Bifidobacterium animalis, and similar bacteria. Among these, Bifidobacterium bifidam, Bifidobacterium breve, and similar bacteria are preferred, and Bifidobacterium bifidam is particularly preferred.Such as Bifidobacterium bifidum, for example, Bifidobacterium bifidum YIT 10347 (FERM BP-10613, deposit date: June 23, 2005) and similar. The aforementioned Lactobacillus casei YGT 9029 strain and Bifidobacterium bifidum YIT 10347 are currently deposited with the International Patent Organizations Depository, National Institute of Technology and Evaluation (#120, 2-5-8 Kazusakamatari, Kisarazu-shi, Chiba-ken, 292-0818, Japan). In the present invention, one or two or more species of lactic acid bacteria may be used. The lactic acid bacteria mentioned above are grown in a medium containing milk or a dairy product as the main component (hereafter sometimes referred to simply as the medium).Milk or dairy product as the main component of the medium is not particularly restricted as long as it is milk itself or a dairy product produced using milk as a raw material, and for example, an animal milk medium composed of cow's milk, goat's milk, sheep's milk, whole milk powder, skimmed milk powder, cream, compound cream, whey protein concentrate (WPC), whey protein isolate (WPI), casein, α-lactoglobulin, β-lactoglobulin, total milk protein (TMP), or the like, or a liquid milk derived from plants such as soy milk, and among these, skimmed milk powder, whole milk powder, animal milk such as cow's milk, or a dairy product produced using animal milk as a raw material is preferably used in terms of fermentability.In addition to the components mentioned above, the medium may include a carbohydrate such as glucose, fructose or sucrose, another agent that promotes the proliferation of lactic acid bacteria such as an oolong tea extract or a tencha (sweet tea) extract, vitamins such as vitamin A, a group of B vitamins, vitamin C and vitamin E, various types of peptides, amino acids, calcium salts, magnesium or similar substances, etc. In the present invention, a lipase degradation product of an oil or fat (hereinafter sometimes simply referred to as the lipase degradation product) is added to the aforementioned medium in advance of culturing lactic acid bacteria, or it is added to a fermented liquid during or after culturing. Herein, the lipase degradation product is preferably added to the medium before culturing or to the fermented liquid after culturing, and more preferably to the medium before culturing. The lipase to be used is not particularly restricted, but a lipase derived from a microorganism of the genus Candida, the genus Rhizopus, the genus Penicillium, or the genus Aspergillus is preferably used, and one or two or more of these types may be used.Examples of commercially available products of such a lipase derived from a microorganism include, for example, Amano Lipase AY 30G (derived from Candida rugosa), Neurase F3G (derived from Rhizopus niveus), Amano Lipase MER (derived from Rhizopus oryzae), Amano Lipase DF 15 (derived from Rhizopus oryzae), Amano Lipase R (derived from Penicillium roqueforti), Amano Lipase A 6 (derived from Aspergillus niger) (all manufactured by Amano Enzyme Co., Ltd.), and similar products. Among these, a lipase derived from a microorganism of the genus Candida is preferred because it provides an excellent growth-promoting effect during lactic acid bacteria cultivation and an excellent viability-enhancing effect during storage. The type of oil or fat that a lipase can degrade is not particularly limited; examples include vegetable oil or fat, milk fat, and similar substances. One, two, or more types of these fats and oils can be used, but vegetable oil or fat is preferred due to its ability to promote the growth of lactic acid bacteria during cultivation, improve viability during storage, and enhance flavor. The vegetable oil or fat that can be degraded by a lipase is not particularly limited; for example, olive oil, sesame oil, rice bran oil, safflower oil, soybean oil, corn oil, rapeseed oil, palm oil, cottonseed oil, peanut oil, sunflower oil, or similar oils are all acceptable. However, olive oil, sunflower oil, or similar oils are preferred due to their ability to promote the growth of lactic acid bacteria during cultivation, improve viability during storage, and enhance flavor. Such vegetable oil or fat is preferably used at 100% by mass without adjusting the concentration for workability or similar reasons, and is prepared by sterilization as needed. Furthermore, among the oils or fats that will be degraded by a lipase, milk fat is not particularly restricted and can be, for example, a material containing milk fat, such as milk or a dairy product, which is the main component of the medium, and for example, cow's milk, goat's milk, sheep's milk, whole milk powder, skimmed milk powder, cream, compound cream, or similar. However, among these, cream, whole milk powder, butter, or similar products may be preferred from the standpoint of promoting the proliferation of lactic acid bacteria during their cultivation and improving viability during storage. Such milk fat is preferably used with a fat concentration adjusted to approximately 3 to 50% by mass, based on workability or similar considerations, and is prepared by sterilization treatment as required. The lipase degradation product used in the present invention is obtained by adding the lipase to the oil or fat to induce a reaction. The amount of lipase added is preferably 0.9 to 2.4% by mass, and more preferably 1.2 to 1.8% by mass with respect to the oil or fat. The reaction temperature is generally 30 to 60°C, and preferably 40 to 50°C, and the reaction is generally allowed to proceed for 4 to 48 hours, and preferably for approximately 12 to 24 hours at that temperature. Within these ranges, an excellent proliferation-promoting effect is obtained during the fermentation of lactic acid bacteria, as well as an excellent viability-enhancing effect during storage. Furthermore, these ranges are also preferred from the standpoint of cost and feasibility.Once the reaction is complete, sterilization treatment is carried out as needed. However, to prevent solidification of the milk fat during sterilization, it is preferable to add a neutralizer to the reaction mixture before the reaction is complete. Potassium hydroxide, sodium hydroxide, potassium carbonate, sodium bicarbonate, or similar neutralizers are used, but adding potassium carbonate or sodium bicarbonate sometimes generates bubbles; therefore, potassium hydroxide or sodium hydroxide are preferred. Adding such a neutralizer neutralizes the reaction mixture to a pH of 6.5 to 7.5, preferably 6.5 to 7.0.The neutralizer can be added at any time, provided it is after the sterilization treatment of the oil or fat, which will be carried out before the addition of the lipase, and before the sterilization treatment after the lipase reaction is complete. However, if the neutralizer is added at the beginning of the lipase reaction, the reaction may not continue long enough. Therefore, the neutralizer is preferably added during the period between two hours before the reaction is complete and before the sterilization treatment after the reaction is complete. The lipase degradation product, once the reaction is complete, is in the form of an aqueous solution or a paste and can be used as is, but it is preferable to use it after spray drying or a similar method. The lipase degradation product obtained by degrading oil or fat using a lipase can normally contain free fatty acids and their monoglycerides, diglycerides, and triglycerides. This lipase degradation product is added beforehand to the aforementioned medium containing milk or a dairy product as the main component, or it is added to a fermented liquid during or after culturing. The amount of lipase degradation product added is not particularly limited, but it is preferably 3 to 100 ppm, more preferably 5 to 80 ppm, and particularly preferably 5 to 40 ppm in terms of free fatty acids. In this description, the term free fatty acids means free butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid, and the amount in terms of free fatty acids is a value converted to the total content of these free fatty acids, and is obtained from the HPLC-measured value of each free fatty acid content described below.When it is within this range, a fermented food product is obtained that has an excellent proliferation-promoting effect on lactic acid bacteria during production and an excellent viability-enhancing effect during storage, and also has an excellent taste. In a medium to which the lipase degradation product has been added beforehand in this manner, the aforementioned lactic acid bacteria are inoculated and cultured, or the lipase degradation product is added to a fermented liquid during or after the culture. The culture can be carried out, for example, at approximately 20 to 50°C for approximately 8 to 48 hours. Furthermore, the culture can be carried out under anaerobic conditions as required. Note that by carrying out the culture in the medium supplemented with the lipase degradation product, the proliferation of lactic acid bacteria can be promoted, and the cell count of lactic acid bacteria in the fermented liquid after the culture is complete can be increased to, for example, 1.2 × 10⁹ cfu / ml or more, preferably 1.5 × 10⁹ cfu / ml.The fermented liquid obtained through cultivation can be transformed into a final product by subjecting it to a homogenization treatment as needed, and then adding and mixing a separately prepared syrup solution and further adding a flavor or similar. Note that in the present invention, the lactic acid bacteria fermentation food product includes beverages such as fermented milks and lactic acid bacteria beverages from dairy products specified by the Ministerial Ordinance on Milk and Dairy Products on Composition Standards, etc., hard yogurts, soft yogurts, natural yogurts, and more, kefir, cheese, and the like. Furthermore, the lactic acid bacteria fermentation food product of the present invention includes beverage products using different lactic acid bacteria, such as plain, flavored, fruit, sweet, soft, beverage, solid (hard), and frozen fermented milks, and the like, lactic acid bacteria beverages, kefir, cheese, and the like. Furthermore, in the lactic acid bacteria fermentation food product of the present invention, in addition to the syrup solution or similar, arbitrary components such as various types of other food materials, for example, various types of carbohydrates, a thickener, an emulsifier, and various types of vitamins can be mixed in as needed. As such, food materials can be mixed specifically carbohydrates such as sucrose, glucose, fructose, palatinose, trehalose, lactose, xylose, and maltose, sugar alcohols such as sorbitol, xylitol, erythritol, lactitol, palatinit, reduced starch syrup, and reduced maltose starch syrup, high-intensity sweeteners such as aspartame, somatin, sucralose, acesulfame K, and stevia, various types of thickeners (stabilizers) such as agar, gelatin, carrageenan, guar gum, xanthan gum, pectin, locust bean gum, gellan gum, carboxymethyl cellulose,Soybean polysaccharides and propylene glycol alginate, emulsifiers such as fatty acid esters of sucrose, fatty acid esters of glycerol, fatty acid esters of polyglycerol, fatty acid esters of sorbitan, and lecithin, milk fat such as cream, butter, and sour cream, acidulants such as citric acid, lactic acid, acetic acid, malic acid, tartaric acid, and gluconic acid, various vitamins such as vitamin A, B vitamins, vitamin C, and vitamin E, minerals such as calcium, magnesium, zinc, iron, and manganese, and flavors such as yogurt, berry, orange, quince, perilla, citrus, apple, mint, grape, apricot, pear, custard, peach, melon, banana, tropical, herbal, black tea, and coffee. The lactic acid bacteria fermentation food product thus obtained from the present invention has excellent viability during storage and, therefore, for example, even if the fermentation food product is stored at 10°C for 3 weeks, it can maintain a viable cell rate of 150% or more, preferably 200% or more, compared to a lactic acid bacteria fermentation food product not using the present invention, and can exhibit a high viability rate. As described above, the lipase degradation product of an oil or fat promotes the growth of lactic acid bacteria when added to the medium and can therefore be used as a growth promoter for lactic acid bacteria when used as an active ingredient. As a medium to which the growth promoter is added, other than the previously mentioned medium containing milk or a dairy product as an active ingredient, any medium known for its use in culturing lactic acid bacteria can be used without limitation, such as MRS medium, SPC medium, and similar media.By adding the proliferation-promoting agent of the present invention in an amount preferably of 3 to 100 ppm, and more preferably of 5 to 40 ppm in terms of free fatty acids to said medium, an excellent proliferation-promoting effect on lactic acid bacteria can be obtained. Furthermore, the lipase degradation product of an oil or fat enhances the viability of lactic acid bacteria during storage when added to the medium or fermented liquid during or after cultivation. Therefore, it can be used as a viability enhancer for lactic acid bacteria when used as an active ingredient. The medium to which the viability enhancer is added, other than the aforementioned medium containing milk or a dairy product as an active ingredient, can be any medium known for its use in cultivating lactic acid bacteria. Examples include MRS medium, SPC medium, and similar media.By adding the viability-enhancing agent of the present invention in an amount preferably from 3 to 100 ppm, and more preferably from 5 to 40 ppm in terms of free fatty acids to said medium, an excellent viability-enhancing effect on lactic acid bacteria can be obtained. It is preferred that additional yeast and an emulsifier be incorporated into the growth promoter and the viability enhancer for lactic acid bacteria. Furthermore, a flavoring agent or any of the various types of solvents may be incorporated into the growth promoter and the viability enhancer for lactic acid bacteria as required. The yeast used in the growth promoter and viability enhancer for lactic acid bacteria is not particularly restricted, but, for example, a yeast such as a high-mineral yeast is preferred. The yeast content in the growth promoter and viability enhancer for lactic acid bacteria is not particularly restricted, but is, for example, 1.0 to 10% by mass, and preferably 3.0 to 8.0% by mass. The emulsifier used in the growth promoter and viability enhancer for lactic acid bacteria is not particularly restricted, but, for example, a polyglycerol fatty acid ester, a sucrose fatty acid ester, a polysorbate, xanthan gum, guar gum, or similar emulsifiers may be used. The content of the emulsifier / thickening stabilizer in the growth promoter and viability enhancer for lactic acid bacteria is not particularly restricted, but is, for example, 0.2 to 1.0% by mass, and preferably 0.3 to 0.5% by mass in the case of a thickening stabilizer such as xanthan gum or guar gum. A method for preparing the proliferation-promoting agent and the viability-enhancing agent for lactic acid bacteria is not particularly limited, but, for example, it is preferred to carry out the preparation in the following manner: a mixture obtained by mixing a lipase degradation product of an oil or fat, a solvent such as propylene glycol, an emulsifier, and a dispersion obtained by dispersing yeast in a solvent such as water, and the resulting mixture is further stirred and mixed. EXAMPLES The present invention will henceforth be described in more detail with reference to the examples, but the present invention is not limited to these examples. The measurement of free fatty acid content in the following examples was performed by HPLC under the following conditions. (HPLC conditions) To 3.5 g of the sample, 1 mL of a methanolic solution of tridecanoic acid (50 pg / mL) was added as an internal reference standard, along with 15 mL of acetonitrile. After shaking and centrifugation, 3.5 mL of the supernatant was collected, the acetonitrile was removed using a centrifugal evaporator, and the volume was brought up to approximately 5 mL with methanol. The resulting mixture was filtered through a 0.45 µm filter. To 5 volumes of the resulting solution, 1 volume of an acetone solution (1 mg / mL) of ADAM (9-antryldiazomethane, manufactured by Funakoshi Co., Ltd.) was added, and the resulting mixture was allowed to stand at room temperature in a dark place for 90 minutes or more and analyzed by high-performance liquid chromatography.A total of nine types of free fatty acids were used as standard substances: butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. The sum of these nine types of free fatty acids was taken as the total free fatty acids. The analysis was performed under the following conditions. (Conditions of analysis) Column: UK-C8 Union produced by Imtakt Corporation Column temperature: 30°C Flow rate: 1.0 mL / min Mobile phase: Liquid A (acetonitrile / water = 65 / 35) and liquid B (acetonitrile / water = 85 / 15) were used and elution was performed with 100% liquid A for 0-9 min, a linear gradient from 0 to 100%, liquid B for 9-28 min, and 100% liquid B for 28-46 min. Injection quantity: 10 pL Excitation wavelength: 365 nm Fluorescence wavelength: 412 nm PRODUCTION EXAMPLE 1 Preparation of the cream lipase degradation product paste 3880 g of fresh cream (solids content: 51.7%) was sterilized at 98°C for 30 minutes. 15 g of Amano 30G lipase AY and 135 g of water were stirred and mixed to prepare liquid A. Liquid A was added to the sterilized fresh cream, and the enzymatic reaction was allowed to proceed for 20 hours. Once the reaction was complete, the reaction solution was neutralized by adding a 50% by mass aqueous potassium hydroxide solution until the pH reached 6.7. After neutralization, sterilization was carried out at 95°C for 15 minutes, yielding a cream lipase degradation product paste. The free fatty acid content of the cream lipase degradation product paste was measured by HPLC and found to be 38.38% by mass. PRODUCTION EXAMPLE 2 Preparation of cream lipase degradation product powder 3880 g of fresh cream (solids content: 51.7%) was sterilized at 98°C for 30 minutes. 15 g of Amano 30G lipase AY and 135 g of water were stirred and mixed to prepare liquid A. Liquid A was added to the sterilized fresh cream, and an enzymatic reaction was allowed to proceed for 20 hours. Once the reaction was complete, the reaction solution was neutralized by adding a 50% by mass aqueous potassium hydroxide solution until the pH reached 6.7. After neutralization, sterilization was carried out at 95°C for 15 minutes, yielding a cream lipase degradation product paste. 342.8 g of skimmed milk powder, 306.4 g of cream lipase degradation product paste and 1154.5 g of water were shaken and mixed, and the resulting mixture was spray-dried to obtain cream lipase degradation product powder.When the free fatty acid content in the cream lipase degradation product powder was measured in the same way as in Production Example 1, it was 20.47% by mass. PRODUCTION EXAMPLE 3 Preparation of an aqueous solution of lipase degradation product in whole milk powder: 0.12 g of whole milk powder (solids content: 95%) were dissolved in 100 g of water, and the resulting solution was sterilized at 98°C for 30 minutes. 0.12 g of AY Amano 30G lipase was added, and an enzymatic reaction was allowed to proceed at 50°C for 20 hours. Once the reaction was complete, the reaction solution was neutralized by adding a 50% by mass aqueous potassium hydroxide solution until the pH reached 6.7. After neutralization, sterilization was carried out at 95°C for 15 minutes, yielding an aqueous solution of lipase degradation product in whole milk powder. When the free fatty acid content in the aqueous solution of the lipase degradation product in whole milk powder was measured in the same way as in Production Example 1, it was 3.59% by mass. PRODUCTION EXAMPLE 4 Preparation of lipase degradation product powder in whole milk powder: 40 g of whole milk powder (solids content: 95%) was dissolved in 157.56 g of water, and the resulting solution was sterilized at 98°C for 30 minutes, yielding liquid A. 0.12 g of AY Amano 30G lipase and 0.108 g of water were stirred and mixed to prepare liquid B. Liquid B was added to liquid A, and the enzymatic reaction was allowed to proceed at 50°C for 20 hours. Once the reaction was complete, the reaction solution was neutralized by adding a 50% by mass aqueous potassium hydroxide solution until the pH reached 6.7. After neutralization, sterilization was carried out at 95°C for 15 minutes. After cooling, the resulting mixture was spray-dried to obtain a powder of lipase degradation product in whole milk powder.When the free fatty acid content in the lipase degradation product powder in whole milk powder was measured in the same way as in Production Example 1, it was 15.55% by mass. PRODUCTION EXAMPLE 5 Preparation of lipase degradation product paste in butter 3000 g of butter (solids content: 83%) was melted at 50°C and then sterilized at 98°C for 30 minutes. 37.5 g of Amano 30G lipase AY and 337.5 g of water were stirred and mixed to prepare liquid A. Liquid A was added to the sterilized butter, and the enzymatic reaction was allowed to proceed at 50°C for 20 hours. After the reaction was complete, the reaction solution was sterilized at 95°C for 15 minutes, yielding a butter lipase degradation product paste. The free fatty acid content of the butter lipase degradation product paste was measured by HPLC and found to be 47.1% by mass. PRODUCTION EXAMPLE 6 Preparation of lipase degradation product powder in butter 3000 g of butter (solids content: 83%) was melted at 50°C and then sterilized at 98°C for 30 minutes. 37.5 g of Amano 30G lipase AY and 337.5 g of water were stirred and mixed to prepare liquid A. Liquid A was added to the sterilized butter, and an enzymatic reaction was allowed to proceed at 50°C for 20 hours. Once the reaction was complete, the reaction solution was sterilized at 95°C for 15 minutes, yielding a paste of lipase degradation product in butter. 25 g of skimmed milk powder, 0.2 g of potassium hydroxide, 10 g of butter lipase degradation product paste and 114.8 g of water were stirred and mixed, and the resulting mixture was spray-dried to obtain butter lipase degradation product powder.When the free fatty acid content in the cream lipase degradation product powder was measured in the same way as in Production Example 1, it was 14.6% by mass. EXAMPLE 1 Production of food product by fermentation of lactic acid bacteria A medium containing 16% w / v skimmed milk powder, 10% w / v glucose, and 0.2% w / v oolong tea extract was mixed with the lipase degradation product paste from cream obtained in Production Example 1 to bring the total fatty acid content to 16.5 ppm. This was followed by sterilization at 100°C for 62 minutes, resulting in a culture medium. Separately, the Lactobacillus casei strain YGT 9029 was inoculated at 0.5% v / v into a 10% w / v skimmed milk powder solution and cultured at 37°C for 24 hours, resulting in a culture solution. The culture solution was inoculated at 0.5% v / v into the culture medium and cultured at 35°C, and the culture was completed when the acidity reached 24 mL / 9 g, thereby obtaining a food product from the fermentation of the lactic acid bacteria.In addition, for comparison, a lactic acid bacteria fermentation food product was obtained in the same manner as described above, except that a medium without added lipase degradation product was used. The viable cell count (cfu / ml) in each of the lactic acid bacteria fermentation food products at the end of the culture and after storage at 10°C for 14 and 21 days was measured in BCP medium. These results are shown in Table 1. TABLE 1 Viable cell count Without addition Lipase degradation product paste in cream at the end of culture 7.9 x 10⁸ 1.2 x 10⁹ after storage for 14 days 7.3 x 10⁸ 1.1 x 10⁹ after storage for 21 days 6.0 x 10⁸ 9.8 x 10⁸ When lactic acid bacteria were cultured in the medium, adding cream lipase degradation product paste to the medium significantly increased the viable cell count at the end of the culture and the viable cell count after storage compared to the case where lipase degradation product was not added to the medium. EXAMPLE 2 Production of food product by fermentation of lactic acid bacteria To a medium containing 16% w / v of skimmed milk powder, 2.2% w / v of glucose, 5.1% w / v of fructose, and 0.2% w / v of an oolong tea extract, each of the cream lipase degradation product pastes obtained in Production Example 1, the cream lipase degradation product powder obtained in Production Example 2, the aqueous solution of whole milk lipase degradation product powder obtained in Production Example 3, and the whole milk lipase degradation product powder obtained in Production Example 4 was added so that the total free fatty acid content was 27.7 ppm, followed by sterilization at 100°C for 62 minutes, thus obtaining a culture medium. Separately, the Lactobacillus casei strain YGT 9029 was inoculated at 0.5% v / v into a 10% w / v nonfat dry milk solution and cultured at 37°C for 24 hours, yielding a culture solution. This culture solution was inoculated at 0.5% v / v into the culture medium and cultured at 35°C. The culture was considered complete when the acidity reached 24 mL / 9 g, resulting in a lactic acid fermentation food product. The viable cell count (cfu / ml) in each of the lactic acid fermentation food products at the end of the culture and after storage at 10°C for 14 days was measured on BCP medium. Furthermore, the flavor of each of the lactic acid bacteria fermentation food products was evaluated according to the following evaluation criteria. These results are shown in Table 2. TABLE 2 Type of lipase degradation product: Lipase degradation product paste in cream; Lipase degradation product powder in cream; Aqueous solution of lipase degradation product in whole milk powder; Lipase degradation product powder in whole milk powder. Viable cell count at the end of culture: 1.3 x 10⁹; 1.3 x 10⁹; 1.3 x 10⁹; 1.2 x 10⁹. Viable cell count after storage for 14 days: 1.2 x 10⁹; 1.2 x 10⁹; 1.3 x 10⁹; 1.3 x 10⁹. Flavor: BBBB Evaluation Criteria for Taste (Evaluation): (Content) A: very good B: Okay C: a little bad D: bad Even when any of the lipase degradation products were added, the proliferation of lactic acid bacteria in production was promoted to the same extent as in Example 1, and viability during storage was also improved. Furthermore, with regard to taste, food products with a favorable flavor were obtained. EXAMPLE 3 Production of food product by fermentation of lactic acid bacteria To a medium containing 16% w / v of skimmed milk powder, 2.2% w / v of glucose, 5.1% w / v of fructose and 0.2% w / v of an oolong tea extract, each of the lipase degradation product pastes in cream obtained in Production Example 1, the lipase degradation product paste in butter obtained in Production Example 5 and the lipase degradation product powder in butter obtained in Production Example 6 was added so that the total free fatty acid content was 53.5 ppm, followed by sterilization at 100°C for 62 minutes, thus obtaining a culture medium. Separately, the Lactobacillus casei strain YIT 9029 was inoculated at 0.5% v / v into a 10% w / v fat-reduced milk powder solution and cultured at 37°C for 24 hours, yielding a culture solution. The culture solution was inoculated at 0.A 5% v / v concentration was added to the culture medium and cultured at 35°C. The culture was considered complete when the acidity reached 24 mL / 9 g, resulting in a lactic acid bacteria fermentation food product. For comparison, a lactic acid bacteria fermentation food product was also obtained using the same method as described above, except that a medium without added lipase degradation product was used. The viable cell count (cfu / ml) in each lactic acid bacteria fermentation food product was measured on BCP medium at the end of the culture and after storage at 10°C for 14 and 21 days.Furthermore, the percentage of viable cell count when using each of the lipase degradation products was calculated by assuming the viable cell count in the lactic acid bacteria fermentation food product to which no lipase degradation product was added was 100%. Additionally, the flavor of each of the lactic acid bacteria fermentation food products was evaluated according to the same evaluation criteria as in Example 2. These results are shown in Table 3. TABLE 3 Type of lipase degradation product None Lipase degradation product paste in cream Lipase degradation product paste in butter Lipase degradation product powder in butter Additional amount of lipase degradation product* 0 53.5 ppm 53.5 ppm 53.5 ppm Viable cell count at the end of culture 1.1 x 10⁹ (100%) 1.7 x 10⁹ (155%) 1.7 x 10⁹ (155%) 1.6 x 10⁹ (145%) Viable cell count after storage for 14 days 9.6 x 10⁸ (100%) 1.6 x 10⁹ (167%) 1.6 x 10⁹ (167%) 1.6 x 10⁹ (167%) Viable cell count after storage for 21 days 7.4 x 10⁸ (100%) 1.5 x 109 (203%) 1.6 x 109 (216%) 1.6 x 109 (216%) Flavor BC Ca BA *: Total free fatty acid content When lactic acid bacteria are cultured in the medium, adding the lipase degradation product of a milk fat to the medium significantly increases the viable cell count at the end of the culture and the viable cell count after storage compared to the case where the lipase degradation product was not added to the medium. PRODUCTION EXAMPLE 7 Preparation of lipase degradation product paste in fats or vegetable oil: The raw materials were mixed in a 250 ml heat-resistant bottle according to the formulation shown in Table 4, and then stirred at 50°C for 20 hours. After stirring, the enzyme was inactivated by heating to 90–95°C for 15 minutes. The resulting material was solidified in a refrigerator and then melted at 50°C. A layer of supernatant oil was collected and transformed into a lipase degradation product paste in fats or vegetable oil. The amount of free fatty acids in each of the lipase degradation product pastes in fats or vegetable oil was measured by HPLC. The results are also shown in Table 5. TABLE 4 Vegetable oil or fat 175.0 g □AY Amano raisins 30 g 2.5 g Water 22.5 g Total 200.0 g TABLE 5 Vegetable oil or fat. Amount of free fatty acids (g / kg). Olive oil 691. Sunflower oil 700. PRODUCTION EXAMPLE 8 Preparation of lipase degradation product powder in fats or vegetable oil Among the lipase degradation product pastes in vegetable oil or fat obtained in Production Example 7, the lipase degradation product paste in vegetable oil or fat obtained using sunflower oil was spray-dried to obtain a lipase degradation product powder in sunflower oil. EXAMPLE 4 Production of food product by fermentation of lactic acid bacteria To a medium containing 16% w / v of skimmed milk powder, 2.2% w / v of glucose, 5.1% w / v of fructose and 0.2% w / v of an oolong tea extract, each of the olive oil lipase degradation product pastes and sunflower oil lipase degradation product paste obtained in Production Example 7, and the sunflower oil lipase degradation product powder obtained in Production Example 8 was added so that the total free fatty acid content was 17.4 ppm, followed by sterilization at 100°C for 62 minutes, thus obtaining a culture medium. Separately, the Lactobacillus casei strain YIT 9029 was inoculated at 0.5% v / v into a 10% w / v fat-reduced milk powder solution and cultured at 37°C for 24 hours, yielding a culture solution. The culture solution was inoculated at 0.A 5% v / v concentration was added to the culture medium and cultured at 35°C. The culture was considered complete when the acidity reached mL / 9 g, resulting in a lactic acid bacteria fermentation food product. For comparison, a lactic acid bacteria fermentation food product was also obtained using the same method described above, except that a medium without added lipase degradation product was used. The viable cell count (cfu / ml) in each lactic acid bacteria fermentation food product was measured on BCP medium at the end of the culture and after storage at 10°C for 14 and 21 days.Furthermore, the percentage of viable cell count when using each of the lipase degradation products was calculated by assuming the viable cell count in the lactic acid bacteria fermentation food product to which no lipase degradation product was added was 100%. Additionally, the flavor of each of the lactic acid bacteria fermentation food products was evaluated according to the same evaluation criteria as in Example 2. These results are shown in Table 6. TABLE 6 Type of lipase degradation product None Lipase degradation product paste in olive oil Lipase degradation product paste in sunflower oil Lipase degradation product powder in sunflower oil Additional amount of lipase degradation product* 0 17.4 ppm 17.4 ppm 17.4 ppm Viable cell count at the end of culture 1.1 x 10⁹ (100%) 1.9 x 10⁹ (173%) 1.7 x 10⁹ (155%) 1.7 x 10⁹ (155%) Viable cell count after storage for 14 days 9.6 x 10⁸ (100%) 1.5 x 10⁹ (156%) 1.5 x 10⁹ (156%) 1.7 x 10⁹ (177%) Viable cell count after storage for 21 days 7.4 x 10⁸ (100%) 1.5 x 109 (203%) 1.5 x 109 (203%) 1.5 x 109 (203%) BAAA flavor *: Total free fatty acid content When lactic acid bacteria are cultured in the medium, adding the lipase degradation product of a vegetable oil or fat significantly increases both the viable cell count at the end of the culture and the viable cell count after storage compared to the case where the lipase degradation product was not added. Furthermore, a significant effect can be confirmed at low concentrations compared to oil derived from dairy fat or lipase degradation products in fat. Additionally, the lipase degradation product of a vegetable oil or fat is also found to improve the flavor of the lactic acid bacteria fermentation product. PRODUCTION EXAMPLE 9 Preparation of a proliferation-promoting agent / viability-enhancing agent for lactic acid bacteria 16.2 g of the lipase degradation product in olive oil prepared in Production Example 7, 87.5 g of propylene glycol, and 4.0 g of xanthan gum were shaken and mixed to prepare Liquid A. Separately, 649.7 g of water, 41.8 g of yeast extract, 200.0 g of a flavoring agent, and 0.8 g of citric acid were shaken and mixed to prepare Liquid B. Liquid A and Liquid B were then shaken and mixed to obtain a growth promoter / viability enhancer for lactic acid bacteria. The growth-promoting agent / viability-enhancing agent for lactic acid bacteria could be stored stably at 10°C or less for 1 month. EXAMPLE 5 Production of food product by fermentation of lactic acid bacteria In a medium obtained by thermal sterilization of an aqueous solution containing 14% w / w whole milk powder, 4% w / w skimmed milk powder and 0.1% w / w milk peptide (LE80GF-US, manufactured by Nippon Shinyaku Co., Ltd.) at 135°C for 3 seconds, a starter of the Bifidobacterium bifidum YGG 10347 strain was inoculated so that the initial cell count was approximately 2 x 107 cfu / ml and cultured at 37°C in the air atmosphere until the pH reached 4.8 to 4.9, thereby obtaining a fermented liquid of bifidobacteria. Separately, the lipase degradation product in whole milk powder obtained in Production Example 4 was added to an aqueous solution containing 7% w / w sucrose and 1% w / w sodium carboxymethylcellulose (CMC122Y, manufactured by Daicel Corporation) so that the total free fatty acid content was 45 ppm, followed by heat sterilization at 121°C for 3 seconds, resulting in a syrup.Forty parts by mass of the bifidobacteria fermented liquid thus obtained were subjected to a homogenization treatment at 15 MPa, and subsequently added to and mixed with 60 parts by mass of syrup, yielding a lactic acid bacteria fermentation food product containing bifidobacteria. The viable cell count (cfu / ml) of the strain was determined. The presence of Bifidobacterium bifidum YIT 10347 in the lactic acid bacteria fermentation food product containing bifidobacteria was measured in TOS medium at the end of the culture and after storage at 10°C for 21 days. Furthermore, when the percentage of viable cell count was calculated using each of the lipase degradation products, assuming the viable cell count in the lactic acid bacteria fermentation food product without added lipase degradation product was 100%, the viable cell count after 21 days of storage was 233%. Additionally, when the taste of each of the fermentation food products was evaluated according to the same evaluation criteria as in Example 2, the taste was rated as B. These results are shown in Table 7. TABLE 7 Lipase Degradation Product Type None Lipase Degradation Product Powder in Whole Milk Powder Additional Amount of Lipase Degradation Product* 0 45 ppm Viable Cell Count at End of Culture 4.0 x 108 (100%) 4.0 x 108 (100%) Viable Cell Count After 21 Days of Storage 2.1 x 107 (100%) 4.9 x 107 (233%) Flavor BB *: Total free fatty acid content When producing the lactic acid bacteria fermentation food product containing bifidobacteria, adding the lipase degradation product to the fermented liquid after cultivation significantly increased the viable cell count after storage compared to the case where no lipase degradation product was added to the fermented liquid. Industrial applicability According to the production method of the present invention, a proliferation-promoting effect is achieved in lactic acid bacteria during fermentation, and a viability-enhancing effect is obtained during storage. Therefore, the viable cell count in the lactic acid bacteria fermentation food product can be maintained within a high range, allowing the bacteria's physiological functions to be effectively exhibited. Consequently, the method of the present invention is useful for producing a functional or similar food product.

Claims

1- A method for producing a lactic acid bacteria fermentation food product, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as a main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as a main component before culturing the lactic acid bacteria, or to a fermented liquid during or after culturing. 2 - The method for producing a food product by fermentation of lactic acid bacteria according to claim 1, further characterized in that the oil or fat is a vegetable oil or fat. 3 - The method for producing a food product by fermentation of lactic acid bacteria according to claim 2, further characterized in that the vegetable oil or fat is olive oil or sunflower oil.

4. - The method for producing a food product by fermentation of lactic acid bacteria according to claim 1, further characterized in that the oil or fat is a milk fat. 5 - The method for producing a lactic acid bacteria fermentation food product according to claim 4, further characterized in that the milk fat is derived from butter, cream or whole milk powder. 6 - The method for producing a lactic acid bacteria fermentation food product according to any of claims 1 to 5, further characterized in that the medium containing milk or a dairy product as a main component is a medium containing, as a main component, animal milk or a dairy product made using animal milk as a raw material. 7- The method for producing a lactic acid bacteria fermentation food product according to any of claims 1 to 6, further characterized in that the lactic acid bacteria are LactobaciHus case / . 8- A method for promoting the proliferation of lactic acid bacteria, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as the main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as the main component before culturing the lactic acid bacteria. 9- A method for improving the viability of lactic acid bacteria, characterized in that when a lactic acid bacteria fermentation food product is produced by inoculating and culturing lactic acid bacteria in a medium containing milk or a dairy product as a main component, a lipase degradation product of an oil or fat is added to the medium containing milk or a dairy product as a main component before culturing the lactic acid bacteria, or to a fermented liquid during or after culturing. 10- A proliferation-promoting agent for lactic acid bacteria, characterized by comprising a lipase degradation product of an oil or fat as an active ingredient. 11- The growth-promoting agent for lactic acid bacteria according to claim 10, further characterized in that it additionally comprises yeast and an emulsifier. 12 - An agent for improving the viability for lactic acid bacteria, characterized by comprising a lipase degradation product of an oil or fat as an active ingredient. 13- The viability enhancer for lactic acid bacteria according to claim 12, further characterized in that it additionally comprises yeast and an emulsifier.