LU503470B1

LU503470B1 - METHOD FOR MANUFACTURING RICE BRAN FOOD RICH IN γ-AMINOBUTYRIC ACID (GABA)

Info

Publication number: LU503470B1
Application number: LU503470A
Authority: LU
Inventors: Chi-Fai Chau; Tsai-Chien Sun
Original assignee: Univ Nat Chung Hsing
Priority date: 2023-02-13
Filing date: 2023-02-13
Publication date: 2023-08-14

Abstract

The present application provides a method for manufacturing rice bran food rich in γ-aminobutyric acid, which comprises fermenting rice bran with a monosodium glutaminate substrate under a predetermined condition to obtain rice bran ferment rich in γ-aminobutyric acid; and then manufacturing the rice bran ferment and cooked rice bran into the rice bran food rich in γ-aminobutyric acid. The method for manufacturing rice bran food rich in γ-aminobutyric acid of the present application does not require addition of microorganisms or chemicals to produce the rice bran food rich in γ-aminobutyric acid, and thus can effectively reduce manufacturing costs and improve safety.

Description

METHOD FOR MANUFACTURING RICE BRAN FOOD RICH IN y-AMINOBUTYRIC ACID (GABA)

TECHNICAL FIELD

[0001] The present application relates to a method for manufacturing functional food and specifically to a method for manufacturing rice bran food rich in y-aminobutyric acid (GABA).

BACKGROUND

[0002] Rice bran, i.e., bran of brown rice, is a by-product of the process of crushing brown rice into white rice. Rice bran comprises about 25-30% dietary fiber and about 20% rice germ.

Therefore, it comprises fat, protein, minerals, carbohydrates, y-oryzanol and y-aminobutyric y acid (GABA) and the like. In recent years, research has pointed out that rice bran has anti-tumor, hypoglycemic and cholesterol-lowering functions.

[0003] Methods known in the art for preparing y-aminobutyric acid include chemical synthesis, plant tissue metabolism and microbial fermentation. As for the chemical synthesis, although it has fast reaction speed and high yield, removal of toxic components in products are complicated and reaction conditions are not easy to control, resulting in high cost and poor safety, and thus it cannot be applied to food. As for the plant tissue metabolism, it has high safety but the yield is too low, which is not conducive to mass production. As for the microbial fermentation, it can obtain a high amount of y-aminobutyric acid but the operation procedure is complicated. If microorganisms such as E. coli are used for synthesis, there will be safety concerns. If the fermentation production is performed with strains having higher safety, the safety issue can be solved but there are still problems of poor availability and high cost of the strains.

SUMMARY

[0004] The primary object of the present application provides a method for manufacturing rice bran food rich in y-aminobutyric acid, which may comprise converting monosodium glutaminate into y-aminobutyric acid using glutamate decarboxylase in rice bran, and mixing the resultant with cooked rice bran to yield the rice bran food rich in y-aminobutyric acid, thereby achieving the effect of improving process safety and reducing manufacturing costs.

[0005] Thus, in order to achieve the above object, the present application discloses a method 1 for manufacturing rice bran food rich in y-aminobutyric acid, which comprises the following std4903470

[0006] Step a: fermenting a rice bran material with a monosodium glutamate (MSG)-containing substrate under a predetermined condition to obtain a rice bran ferment.

[0007] Step b: mixing and manufacturing the rice bran ferment and cooked rice bran into the rice bran food rich in y-aminobutyric acid.

[0008] Wherein, the substrate comprises 50 mM or more monosodium glutamate, preferably 50 mM monosodium glutaminate.

[0009] Wherein, the predetermined condition includes a reaction temperature of 30°C, a reaction time of 2 hours and a pH of 6.0.

[0010] In one embodiment of the present application, the rice bran material is prepared from rice through milling and screening processes. Specifically, the rice bran material is prepared by the following steps:

[0011] Step al: milling fresh rice into fresh rice bran;

[0012] Step a2: screening out rice bran that does not meet a predetermined screening standard from the fresh rice bran, the remainder being the rice bran material.

[0013] Wherein, the predetermined screening standard is a size not less than 40 mesh.

[0014] In one embodiment of the present application, the rice bran ferment obtained from step a is a powder. Generally, when drying the liquid obtained after fermentation, a powdered rice bran ferment can be obtained.

[0015] In one embodiment of the present application, in the step b, after mixing the rice bran ferment and the cooked rice bran, milling and screening processes are performed to yield the rice bran food rich in y-aminobutyric acid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows the yield of y-aminobutyric acid after fermentation of a crude enzyme liquid of rice bran at different reaction times and different reaction temperatures.

[0017] Figure 2 shows the yield of y-aminobutyric acid after fermentation of a crude enzyme liquid of rice bran at different pH values.

[0018] Figure 3 shows the yield of y-aminobutyric acid after fermentation of a crude enzyme liquid of rice bran in a substrate containing different amounts of monosodium glutamine.

DETAILED DESCRIPTION

[0019] The present application discloses a method for manufacturing rice bran food rich in y-aminobutyric acid, which comprises fermenting rice bran with a substrate containing 2 monosodium glutaminate under a predetermined condition to obtain rice bran ferment ridH/$R3470 y-aminobutyric acid; and then manufacturing the rice bran ferment and cooked rice bran into the rice bran food rich in y-aminobutyric acid. In another word, the cost of y-aminobutyric acid can be reduced and the use of chemicals in the process can be avoided through the method for manufacturing rice bran food rich in y-aminobutyric acid disclosed in the present application.

[0020] In one embodiment of the present application, fermenting the rice bran and the substrate containing 50 mM monosodium glutaminate under a reaction temperature of 30°C, a reaction time of 2 hours and a pH of 6.0 may improve the yield of y-aminobutyric acid.

[0021] Rice bran comprises about 20% rice germ and the rice germ is rich in endogenous glutamate decarboxylase (GAD), which can convert glutamic acid into y-aminobutyric acid.

Therefore, the method for manufacturing rice bran food rich in y-aminobutyric acid disclosed in the present application comprises screening rice germ from the rice bran and taking the rice germ as a source of glutamate decarboxylase to perform fermentation and convert the monosodium glutaminate in the substrate into y-aminobutyric acid, thereby obtaining the rice bran food rich in y-aminobutyric acid.

[0022] Wherein, the screening uses a sieve or other tools that take size as a screening criteria.

[0023] The “y-aminobutyric acid”, as disclosed in the present application, refers to a natural active ingredient with a molecular formula CsH9NO» and a molecular weight of 103.12, belongs to non-protein amino acid, and has an amino group located in y position. Researches show that y-aminobutyric acid has a variety of physiological activities, including improving brain function, enhancing memory, anti-stress, anti-depression, anti-fatigue, lowering blood pressure, improving menopausal symptoms, improving chronic alcohol-related diseases, activating liver and kidney function, etc.

[0024] The “coked rice bran”, as disclosed in the present application, refers to a product obtained after a coking procedure of fresh rice bran which aims to reduce the undesirable odor of fresh rice bran, wherein the coking procedure 1s steaming, boiling, baking, roasting or the like.

[0025] In one embodiment of the present application, a method for manufacturing rice bran food rich in y-aminobutyric acid 1s provided, and comprises the following steps:

[0026] Step 101: preparing an organic rice bran material

[0027] Organic rice is milled to obtain fresh rice bran, and then a 40 mesh sieve is used to remove rice bran of less than 40 mesh, leaving rice bran of more than 40 mesh as the rice bran material for subsequent use.

[0028] Step 102: preparing a fermentation broth 3

[0029] A substrate containing monosodium glutaminate (MSG) is added into the rice 23470 material from step 101. pH is adjusted to 6. Fermentation is carried out at 30°C for 2 hours.

Subsequently, enzyme is inactivated by heating to stop the fermentation reaction and obtain a fermentation broth.

[0030] Wherein, the substrate comprises 50 mM or more monosodium glutamate.

[0031] Step 103: preparing dried fermentation powder

[0032] The fermentation broth from step 102 is dried, for example, through lyophilization, to yield a fermentation powder.

[0033] Step 104: preparing rice bran food rich in y-aminobutyric acid

[0034] Cooked rice bran is added to a predetermined amount of the fermentation powder from step 103. Milling is performed. Then screening is performed by an 80 mesh sieve to yield rice bran food rich in y-aminobutyric acid.

[0035] In order to verify technical features and efficacy of the present application, a number of examples and drawings will be given for detailed description below.

[0036] Example 1: preparing an enzyme liquid of rice bran

[0037] 20 g of screened rice bran was added to 100 mL of phosphate buffer (20 mM, pH 6.0) and homogenized at 4°C for 1 min. The homogenized liquid was centrifuged at 5000 g for 10 min to separate the upper layer liquid, i.e., an enzyme liquid of rice bran, for subsequent use.

[0038] Example 2: Experiment (I) for production condition of y-aminobutyric acid

[0039] To 4 mL of 20 mM phosphate buffer (pH 6.0, containing 50 mM monosodium glutamate), 2 mL enzyme liquid of rice bran was added. Reactions were carried out at 25, 30 or 35°C, respectively, for 0, 0.5, 1, 2 or 4 hours. After the reaction, the enzyme was inactivated by heating in a hot water bath for 5 min. Concentration was carried out at 5000 g for 10 min to obtain an upper layer liquid. The content of y-aminobutyric acid was detected in the upper layer liquids obtained at the different temperatures and reaction times. Results are shown in Figure 1.

[0040] As shown in Figure 1, when reacting the enzyme liquid of rice bran and the monosodium glutamate-containing substrate at 30°C for 2 hours, the yield of y-aminobutyric acid (511 pg/mL) was higher than other reaction temperatures and reaction times. Thus, the optimum reaction condition for producing y-aminobutyric acid by the enzyme liquid of rice bran and the monosodium glutamate-containing substrate is a reaction temperature of 30°C and a reaction time of 2 hours.

[0041] Example 3: Experiment (II) for production condition of y-aminobutyric acid

[0042] 4 mL of 20 mM phosphate buffer (containing 50 mM monosodium glutamate) was adjusted to different pH values: 4.0, 5.0, 6.0 or 7.0. The enzyme liquid of rice bran was added to the 4 the phosphate buffers having different pH. Reactions were carried out at 30°C for 2 hours. After /RE3470 reaction, the enzyme was inactivated by heating in a hot water bath for 5 min. Concentration was carried out at 5000 g for 10 min to obtain an upper layer liquid. The content of y-aminobutyric acid was detected in the upper layer liquids. Results are shown in Figure 2.

[0043] As shown in Figure 2, as compared to other monosodium glutamate-containing phosphate buffers, when fermentation with the enzyme liquid of rice bran was carried out in the phosphate buffer (containing 50 mM monosodium glutamate) having a pH value of 6 as a substrate, higher amount of y-aminobutyric acid (682.5 ug/mL) can be obtained.

[0044] Example 4: Experiment (III) for production condition of y-aminobutyric acid

[0045] 4 mL of 20 mM phosphate buffers (pH 6.0) having different content (0, 50, 100 or 150 mM) of monosodium glutamate were prepared. The enzyme liquid of rice bran was added to the phosphate buffers having different content of monosodium glutamate. Reactions were carried out at 30°C for 2 hours. After the reaction, the enzyme was inactivated by heating in a hot water bath for 5 min. Concentration was carried out at 5000 g for 10 min to obtain an upper layer liquid.

The content of y-aminobutyric acid was detected in the upper layer liquids. Results are shown in

Figure 3.

[0046] As shown in Figure 3, as compared to the phosphate buffer having 75 or 100 mM monosodium glutamate, when fermentation with the enzyme liquid of rice bran was carried out in the phosphate buffer having 50 mM monosodium glutamate, the yield of y-aminobutyric acid was higher (672 pg/mL).

[0047] As can be seen from the results of above Examples 2-4, reacting the enzyme liquid of rice bran and the substrate containing 50 mM monosodium glutaminate under a reaction temperature of 30°C, a reaction time of 2 hours and a pH of 6.0 may produce a fermentation broth having the highest y-aminobutyric acid content. The rice bran food rich in y-aminobutyric acid was produced by mixing the fermentation broth in a liquid or solid state with cooked rice bran. 5

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method for manufacturing rice bran food rich in y-aminobutyric acid, which comprises the following steps: step a: mixing a rice bran material with a monosodium glutamate (MSG)-containing substrate and performing fermentation under a predetermined condition to obtain a rice bran ferment after the fermentation; and step b: mixing and manufacturing the rice bran ferment and cooked rice bran into the rice bran food rich in y-aminobutyric acid.

2. The method of claim 1, wherein in the step a, the substrate comprises 50 mM or more monosodium glutamate.

3. The method of claim 1, wherein the predetermined condition includes a reaction temperature of 30°C, a reaction time of 2 hours and a pH of 6.0.

4. The method of claim 1, wherein in the step a, the rice bran ferment is dried into a rice bran ferment powder.

5. The method of claim 1, wherein in the step b, after mixing the rice bran ferment and the cooked rice bran, a milling process and a screening process are sequentially performed to yield the rice bran food rich in y-aminobutyric acid.

6. The method of claim 1, wherein in the step a, the rice bran material is prepared by the following steps: step al: milling fresh rice into fresh rice bran; and step a2: screening out rice bran that does not meet a predetermined screening standard from the fresh rice bran, the remainder being the rice bran material. 6