Method for increasing viscosity of rice bran fermented by lactic acid bacteria

Abstract

To provide a viscosity increasing method of a rice bran lactic acid fermented product excellent in flavor and texture, and using rice bran containing much exopolysaccharide having health function derived from lactic acid, and ingestible by a person affected by lactose intolerance or milk allergy.SOLUTION: In a viscosity increasing method of a rice bran lactic acid fermented product, rice bran is used as a raw material, and saccharified rice bran obtained by subjecting the same to a saccharification treatment with rice malt or saccharifying enzyme is fermented by using lactic acid bacterium producing exopolysaccharide.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a rice bran lactic acid bacteria fermentation product using lactic acid bacteria that produce exopolysaccharides.

[0002] A type of lactic acid bacteria contained in fermented milk such as yogurt is known to produce exopolysaccharides, which have been proven to have health benefits such as regulating the intestines, stimulating the immune system, and suppressing the onset of allergies such as hay fever.

[0003] Yogurt obtained by fermentation using Lactobacillus cremoris, a lactic acid bacterium isolated by the applicant (product name "Caspian Sea Yogurt", applicant's registered trademark, Registration No. 5761425), also has excellent health benefits such as intestinal regulation, immune activation, skin function improvement, and mitigation of elevated blood sugar levels, and the applicant's research has revealed that these health benefits are derived from the exopolysaccharides produced by the Lactobacillus cremoris (Patent Documents 1 to 3).

[0004] Furthermore, the applicant of the present application has disclosed a method for increasing the production of exopolysaccharides by Lactobacillus cremoris by adding whey protein or soy protein to milk and fermenting it with Lactobacillus cremoris (Patent Document 4). However, there is a need for a method for further increasing the production of exopolysaccharides.

[0005] Meanwhile, yogurt has various health benefits and many people enjoy its health benefits. However, people who are lactose intolerant or have a milk allergy cannot consume yogurt. Therefore, there is a need for the development of a food product that can be consumed by people who are lactose intolerant or have a milk allergy and that has the health benefits of yogurt as an alternative to yogurt.

[0006] In order to solve the above problems, many proposals have been made for lactic acid bacteria fermented products using soybeans as a raw material. The applicant of the present application has also disclosed a method for producing fermented soy milk products in which soy milk is used as a raw material and fermented with lactic acid bacteria that produce exopolysaccharides (Patent Documents 5 and 6). However, fermented soy milk products have a grassy smell and an astringent taste, which has led to some problems in that they do not suit the tastes of some consumers.

[0007] Therefore, there is a need for the development of new lactic acid bacteria fermentation products with excellent flavor that use ingredients other than milk and soybeans.One such product that has been proposed is a lactic acid bacteria fermentation product using rice bran and its manufacturing method (Patent Documents 7 to 9). However, rice bran has a unique unpleasant odor and unpleasant taste (astringent, harsh, bitter), so further improvement in flavor is required. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 3715640 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-256312 [Patent Document 3] Japanese Patent Application Publication No. 2018-168082 [Patent Document 4] Patent No. 5060431 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-192632 [Patent Document 6] Patent No. 6209177 [Patent Document 7] Patent No. 61-53008 [Patent Document 8] Japanese Patent Application Publication No. 60-94057 [Patent Document 9] Japanese Patent Application Publication No. 8-280341 Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a method for producing a rice bran lactic acid bacteria fermentation product using rice bran that contains a large amount of exopolysaccharides having health functions derived from lactic acid bacteria, and has an excellent flavor and can be taken by people with lactose intolerance or milk allergy. [Means for solving the problem]

[0010] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have discovered that a rice bran saccharified product, which is made from rice bran using rice koji and then fermented with lactic acid bacteria capable of producing exopolysaccharides, can produce a yogurt-like rice bran lactic acid bacteria fermented product containing a large amount of exopolysaccharides, known as rice bran yogurt, and have completed the present invention. Furthermore, the present inventors have discovered that while rice bran as a raw material has the unpleasant odor and unpleasant taste (astringent, harsh, bitter) characteristic of rice bran, the rice bran lactic acid bacteria fermented product obtained by the present invention can improve these unpleasant odors and tastes by using rice koji and lactic acid bacteria capable of producing exopolysaccharides, and have completed the present invention.

[0011] That is, the present invention relates to the following methods [1] to [4] for increasing the viscosity of a rice bran fermentation product with lactic acid bacteria. [1] This relates to a method for increasing the viscosity of rice bran lactic acid bacteria fermentation products, which comprises gelatinizing rice bran by adding water and heating, saccharifying the gelatinized product using rice koji or a saccharifying enzyme, and then fermenting the gelatinized product using lactic acid bacteria capable of producing exopolysaccharides. [2] The method according to [1], which has the effect of improving the unpleasant odor or unpleasant taste of rice bran. [3] The method according to [1] or [2], wherein the lactic acid bacterium is Lactococcus lactis subsp. cremoris FC (FERM AP-20185). [4] The method according to [1] or [2], wherein the rice bran fermentation product is a viscous substance similar to solid yogurt or a liquid substance similar to drinkable yogurt. [Effects of the Invention]

[0012] According to the method of the present invention, a yogurt-like rice bran lactic acid bacteria fermentation product containing a large amount of exopolysaccharides made from rice bran can be provided, allowing people with lactose intolerance or milk allergies to enjoy the health benefits of the exopolysaccharides contained in yogurt. Furthermore, the rice bran lactic acid bacteria fermented product obtained by the method of the present invention has the unpleasant odor and taste of rice bran improved, making it possible to provide a rice bran lactic acid bacteria fermented food with excellent flavor. Furthermore, since rice bran is rich in various vitamins, essential amino acids such as lysine, minerals such as iron, and dietary fiber, the rice bran lactic acid bacteria fermentation product obtained by the method of the present invention also allows the intake of useful nutrients derived from rice bran. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the following description.

[0014] The method of the present invention uses rice bran as a raw material, rice koji for saccharifying the rice bran, and exopolysaccharide-producing lactic acid bacteria for lactic acid fermentation of the rice bran saccharified product. (Rice bran raw material) In the present invention, rice bran is used as the main raw material. The raw material rice bran refers to the outer part of brown rice grains, and rice bran obtained by polishing brown rice to a weight polishing ratio of 90% or more is generally called "red bran," rice bran obtained by polishing brown rice to a weight polishing ratio of about 80 to 90% is called "medium white bran," and rice bran obtained by polishing rice to a weight polishing ratio of less than 80% is called "white bran." The rice polishing ratio by weight is a value calculated using the following formula (1). Furthermore, the term "white rice" below refers to brown rice after polishing as described below. Weight polishing ratio (%) = (weight of white rice / weight of brown rice) × 100 (1) In the present invention, any type of rice bran can be used. Nakashiroka is particularly preferred because the final rice bran lactic acid bacteria fermentation product contains a large amount of exopolysaccharides, has almost no unpleasant odor or taste of rice bran, and has an excellent flavor. When white bran is used, the fermentation product has almost no unpleasant odor or taste of rice bran and has an excellent flavor, but the amount of exopolysaccharides with health benefits is lower than that of red bran and medium-white bran. When red bran is used, the amount of exopolysaccharides is high, but the fermentation product has an unpleasant taste, resulting in an inferior flavor compared to white bran and medium-white bran.

[0015] (Rice koji) In the present invention, rice koji is used to saccharify rice bran. The rice koji used may be either rice koji for amazake (sweet sake) or rice koji for sake brewing, and is not particularly limited. By using rice koji in the saccharification process, the amount of exopolysaccharides produced in the fermented product increases, thereby improving the unpleasant odor and taste of the fermented product. Furthermore, by using rice koji, desirable aroma components are produced by the rice koji during the saccharification process, thereby improving the unpleasant odor and taste of the rice bran. In the saccharification treatment of rice bran, saccharifying enzymes such as α-amylase and glucoamylase can also be used. However, when saccharifying enzymes are used, the amount of exopolysaccharides produced in the fermentation product is less than when rice koji is used, and the desirable aroma components that are produced when rice koji is used are not produced, so the unpleasant odor and taste of rice bran are not improved to a degree that is inferior to that achieved with rice koji in the fermentation product.

[0016] (Exopolysaccharide-producing lactic acid bacteria) In the present invention, lactic acid bacteria capable of producing exopolysaccharides are used to ferment the saccharification product of rice bran with rice koji. The lactic acid bacteria are not particularly limited as long as they are exopolysaccharide-producing bacteria, and the use of exopolysaccharide-producing bacteria can improve the unpleasant odor and unpleasant taste of the rice bran in the fermented product compared to non-exopolysaccharide-producing bacteria. In particular, when the exopolysaccharide is viscous, the unpleasant odor and taste of rice bran can be more effectively reduced by the viscosity. For example, when the lactic acid bacteria capable of producing exopolysaccharides are Lactococcus lactis subsp. cremoris FC (FERM AP-20185) or Streptococcus thermophiles T38 (proprietary of Fujicco Co., Ltd.), the unpleasant odor and taste of the fermented rice bran can be significantly reduced. Lactococcus lactis subsp. cremoris FC (FERM AP-20185) is deposited at the International Patent Organism Depositary of the National Institute of Advanced Industrial Science and Technology. In the present invention, the lactic acid bacteria capable of producing exopolysaccharides may be used alone or in combination of two or more kinds.

[0017] (Manufacturing method) In the method of the present invention, rice bran is gelatinized by adding water and heating, and then the gelatinized rice bran is saccharified using rice koji to obtain rice bran saccharified product.The rice bran saccharified product is then completed by inoculating lactic acid bacteria capable of producing exopolysaccharides into the rice bran saccharified product and fermenting it.

[0018] (Galactosylation of rice bran) After adding water to rice bran, the rice bran is gelatinized by heat treatment. The heating conditions (temperature and time) are not particularly limited as long as the starch contained in the rice bran is gelatinized. However, if the heat treatment also serves as a sterilization treatment for the raw rice bran, it is preferable to carry out the heat treatment at 80°C or higher. The amount of water to be added is not particularly limited as long as the rice bran can absorb the water sufficiently, and can be adjusted according to the final fermented product. For example, if the fermented product is to be a viscous product like solid yogurt, 2 to 5 parts by weight of water can be added to 1 part by weight of rice bran, and if the fermented product is to be a liquid product like a yogurt drink, the amount of water can be increased and adjusted accordingly.

[0019] (Saccharification treatment) Rice bran saccharified product is obtained by adding rice koji to gelatinized rice bran and then maintaining the temperature at a suitable temperature for saccharification. The saccharification conditions (temperature and time) are not particularly limited as long as the starch contained in the rice bran is saccharified. However, a treatment temperature of 50 to 65°C is preferred to promote the enzymatic reactions of amylase, protease, and other enzymes contained in the rice koji and to prevent contamination by lactic acid bacteria and putrefactive bacteria. For example, the rice bran saccharified product can be obtained by appropriately adjusting the saccharification time to 4 to 24 hours. The resulting rice bran saccharified product is then heat-treated to stop the saccharification reaction and inactivate the enzymes contained in the rice koji. In the saccharification treatment, the amount of rice koji to be added to the gelatinized rice bran is not particularly limited, and can be determined appropriately taking into consideration the time required for the saccharification treatment and the flavor and physical properties of the final rice bran lactic acid bacteria fermentation product. In order to accelerate the saccharification and homogenize the rice bran saccharified product, homogenization treatment can be carried out before or after the saccharification treatment. Furthermore, the rice bran saccharified product may be centrifuged or filtered to remove oil and fat components before the subsequent lactic acid fermentation step. By separating and removing the oil and fat components before lactic acid fermentation, it is possible to prevent the oil and fat components from becoming rancid or toxic due to oxidation and decomposition, and to suppress deterioration in the flavor of the final fermented product.

[0020] (Lactic acid fermentation) The rice bran saccharified product is inoculated with lactic acid bacteria capable of producing exopolysaccharides, and then fermented to obtain a rice bran lactic acid bacteria fermented product. In the fermentation treatment, the fermentation conditions (temperature and time) are not particularly limited as long as they are within the optimal growth temperature range for the lactic acid bacteria used, and can be appropriately determined taking into account the flavor and physical properties of the final rice bran lactic acid bacteria fermentation product obtained. The amount of lactic acid bacteria to be inoculated into the rice bran saccharified product during the fermentation treatment is not particularly limited, and can be determined appropriately taking into consideration the time required for lactic acid fermentation and the flavor and physical properties of the final rice bran fermented product. 4 (cfu / g) or more, preferably 10 6 ~10 8For example, when the number of lactic acid bacteria is in the range of 10 (cfu / g) per 100 parts by weight of the rice bran saccharified product, 7 A starter having a cell density of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, of which the cell density is 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, is inoculated. In addition, when the starter is Lactococcus lactis subsp. cremoris FC, its optimum temperature is around 25°C, so the number of lactic acid bacteria is 10 7 When 3 parts by weight of a starter having a bacterial count of 100 (cfu / g) or more is inoculated, the rice bran lactic acid bacteria fermentation product can be obtained by fermenting at 25°C for 3 to 72 hours. Furthermore, the rice bran lactic acid bacteria fermentation product can be homogenized as needed, and the homogenization treatment can produce a rice bran lactic acid bacteria fermentation product that is smooth and thick to the touch. The rice bran lactic acid bacteria fermentation product has an excellent flavor with the unpleasant odor and unpleasant taste (astringency, harshness, bitterness) specific to rice bran improved, and furthermore, due to the viscosity of the exopolysaccharides produced by the lactic acid bacteria having the ability to produce exopolysaccharides, it has a smooth mouthfeel and an excellent texture.

[0021] Furthermore, the rice bran lactic acid bacteria fermentation product obtained by the method of the present invention can be further supplemented with additives such as sweeteners, fruit pulp, fruit juice, flavorings, and acidulants, if necessary, to produce yogurt-like foods, yogurt-like drinks, and the like with various flavors.

[0022] Thus, the method of the present invention makes it possible to obtain a rice bran lactic acid bacteria fermentation product that contains a large amount of exopolysaccharides derived from lactic acid bacteria that have health benefits, has improved unpleasant odors and tastes (astringency, harshness, bitterness) that are specific to rice bran, and is rich in useful nutrients from rice bran. [Example]

[0023] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0024] (Materials and conditions) The examples and comparative examples of the present invention were carried out using the following materials and conditions unless otherwise specified. To gelatinize rice bran, 1 part by weight of rice bran was mixed with 5 parts by weight of water, and then the mixture was heated at 85°C for 10 minutes with stirring to gelatinize the rice bran, thereby obtaining gelatinized rice bran liquid. The rice bran used was medium-sized white rice bran (rice polishing ratio: 82-88% by weight) provided by the sake brewery, and rice flour ("Hanbeiya Rice Flour" manufactured by Hanbeiya Co., Ltd.) was used as a control for the rice bran. Next, 50 parts by weight of rice koji per 100 parts by weight of rice bran was added to the gelatinized rice bran solution, and the mixture was saccharified at 55°C for 15 hours with stirring, followed by heating at 85°C for 30 minutes to inactivate the enzymes contained in the rice koji, yielding a rice bran saccharified solution. The rice koji used was commercially available rice koji for amazake ("Plus Koji Rice Koji" manufactured by Marukome Co., Ltd.). As a control for rice koji, the same part by weight of pregelatinized rice ("Alpha Rice" manufactured by Kodama Co., Ltd.) as the rice koji was used, and 0.05 parts by weight of α-amylase ("Uniase BM-8" manufactured by Yakult Pharmaceutical Co., Ltd.: 64,000 units / g) and 0.1 parts by weight of glucoamylase ("Uniase 30" manufactured by Yakult Pharmaceutical Co., Ltd.: 2,000 units / g) were used as liquefaction and saccharification enzymes. The pregelatinized rice and α-amylase were then added to the pregelatinized rice bran liquid, which was then heated from room temperature to 85°C in approximately 30 minutes. This was then cooled to below 60°C, after which glucoamylase was added. As with the rice koji, this was followed by a saccharification treatment at 55°C for 15 hours and then a heat treatment at 85°C for 30 minutes to obtain a rice bran saccharified liquid. Finally, the lactic acid bacteria fermentation treatment of the rice bran saccharified liquid was carried out by adding 3 parts by weight of lactic acid bacteria starter (10 lactic acid bacteria count) to 100 parts by weight of rice bran saccharified liquid. 7 cfu / g) were added and fermented at 25°C for 8 hours for Lactobacillus cremoris and at 37°C for 6 hours for Lactobacillus thermophilus to obtain rice bran lactic acid bacteria fermentation products. After fermentation, the rice bran lactic acid bacteria fermentation products were stored at 10°C and subjected to the sensory evaluation described below. The lactic acid bacteria used were Lactococcus lactis subsp. cremoris FC (hereinafter referred to as Cremoris FC) and Streptococcus thermophilus T38 (proprietary of Fujicco Co., Ltd.) (hereinafter referred to as Thermophilus T38) as exopolysaccharide-producing bacteria, and Lactococcus lactis subsp. cremoris C4 (proprietary of Fujicco Co., Ltd.) (hereinafter referred to as Cremoris C4) as a control non-exopolysaccharide-producing bacterium.

[0025] (Evaluation method) The examples and comparative examples of the present invention obtained by the above methods were evaluated by the following methods. [Sensory evaluation] The sensory evaluation of the rice bran lactic acid bacteria fermented product was conducted by 14 trained sensory panelists who were selected as superior tasters in a five-taste discrimination test. The panelists stirred the rice bran lactic acid bacteria fermented product five times with a spoon, put it in their mouths, and evaluated the flavor and texture. Flavor was evaluated based on the presence and strength of unpleasant odors and tastes (astringent, harsh, bitter) and pleasant flavors (sweetness, pleasant aroma), while texture was evaluated based on the presence and strength of viscosity (thickness) compared to regular yogurt, using a five-point scale based on Table 1. The average scores of each panelist were used to give an overall evaluation according to the evaluation criteria shown in Table 2.

[0026] [Table 1]

[0027] [Table 2]

[0028] Examples 1 and 2, Comparative Examples 1 and 2: Comparison between exopolysaccharide-producing bacteria and non-exopolysaccharide-producing bacteria Under the conditions shown in Table 3 below, medium-sized white rice bran was used as the raw material, and this was saccharified using rice koji to obtain a rice bran saccharified liquid. Various lactic acid bacteria were then inoculated into the saccharified liquid and fermented with lactic acid bacteria. The resulting rice bran lactic acid bacteria fermented product was then subjected to a sensory evaluation using the method described in paragraph

[0025] .

[0029] [Table 3]

[0030] The results in Table 3 show that lactic acid fermentation using exopolysaccharide-producing bacteria not only increases the viscosity of the rice bran lactic acid fermentation product, but also improves the unpleasant odor and taste (astringency, harshness, bitterness) that are characteristic of rice bran, resulting in an excellent flavor and texture. Furthermore, it was found that when Cremoris FC was used, the unpleasant odor and taste of rice bran could be improved to a level comparable to that of rice flour.

[0031] Example 1 and Comparative Example 3: Comparison of rice bran saccharification treatment Under the conditions shown in Table 4 below, medium-sized white rice bran was used as the raw material, and this was saccharified using rice koji or saccharifying enzymes and gelatinized rice to obtain rice bran saccharified liquid, which was then inoculated with Lactobacillus cremoris FC and fermented with lactic acid bacteria.The resulting rice bran lactic acid bacteria fermented product was then subjected to a sensory evaluation using the method shown in paragraph

[0025] .

[0032] [Table 4]

[0033] The results in Table 4 show that using rice koji during the saccharification process of rice bran increases the viscosity of the rice bran lactic acid bacteria fermentation product compared to enzyme-treated rice bran, and also reduces the unpleasant odor and taste (astringency, harshness, bitterness) that are characteristic of rice bran, greatly improving the flavor and resulting in an excellent texture and flavor.

[0034] Example 1 and Comparative Example 1: Comparison of exopolysaccharide production For the rice bran lactic acid bacteria fermentation product of Example 1 and the rice flour lactic acid fermentation product of Comparative Example 1, the amount of extracellular polysaccharides was measured per 100 g of each fermentation product using the following method, taking the increase (difference) in the amount of polysaccharides from before fermentation to after fermentation as the amount of extracellular polysaccharides. 1) Protein removal: 100 g of each saccharified solution (before fermentation) and 100 g of the fermented product (after fermentation) were added with an equal volume of 20% (V / V) trichloroacetic acid to form a suspension, which was then centrifuged (15,000 rpm, 10 minutes) to collect the supernatant, which was then centrifuged again under the same conditions to obtain the supernatant. 2) Recovery of polysaccharide fraction: After removing fats and oils from the supernatant, 1.5 volumes of 4°C ethanol were added and mixed, followed by centrifugation (15,000 rpm, 20 minutes). The supernatant was discarded and the polysaccharide fraction was recovered. 3) Purification: After adding 60% (V / V) ethanol at 4°C to the polysaccharide fraction and mixing, the mixture was centrifuged (15,000 rpm, 20 minutes), and the supernatant was discarded. This process was repeated again to recover the polysaccharide fraction. 4) Quantification of polysaccharides: Polysaccharide fractions were quantified colorimetrically using the phenol-sulfuric acid method.

[0035] [Table 5]

[0036] The results in Table 5 clearly show that the rice bran fermentation product obtained by the method of the present invention contains more exopolysaccharides than the rice flour fermentation product. [Industrial Applicability]

[0037] The method of the present invention can provide a rice bran lactic acid bacteria fermentation product that contains a large amount of exopolysaccharides having health functions, is improved in the unpleasant odor and taste specific to rice bran, has excellent flavor and texture, and allows the intake of useful nutrients derived from rice bran.

Claims

1. A method for promoting exopolysaccharide production in a rice bran lactic acid bacteria fermentation product, comprising: gelatinizing rice bran by heating with water, saccharifying the resulting product using rice koji or a saccharifying enzyme, and then fermenting the product using Lactococcus lactis subsp. cremoris FC (FERM AP-20185) as a lactic acid bacterium capable of producing exopolysaccharides; and using the saccharified rice bran to promote exopolysaccharide production.

2. A method for promoting an increase in the viscosity of a rice bran lactic acid bacteria fermentation product, comprising: gelatinizing rice bran by heating with water, saccharifying the resulting product using rice koji or a saccharifying enzyme, and then fermenting the product using Lactococcus lactis subsp. cremoris FC (FERM AP-20185) as a lactic acid bacterium capable of producing exopolysaccharides; and using the saccharified rice bran to promote an increase in viscosity.

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