Novel brown rice powder preparation method

Abstract

The invention relates to a preparation method of novel coarse rice powder, which utilizes cellulase to improve the component proportion in rice bran dietary fiber, and utilizes amylase to denature starch, so that the solubility and compatibility of the whole system are improved. During roughening, a wax layer on the surface of the brown rice is ground away, and components influencing the taste are removed. Cellulose in the brown rice cortex is treated through alkali and cellulase, starch is dextrinized with low DE value through amylase, the effect of hydrophilic colloid during starch gelatinization can be achieved, a relatively short glucose chain can be generated to interact with components in the system, and the compatibility of the brown rice flour system is improved. By adding cellulase, more soluble dietary fibers can be generated, the absorption rate of the fibers is increased, and the processing performance of the coarse rice powder is improved; the brown rice powder is added into a NaOH solution for treatment, fibers can be softened, the taste is improved, and processing is convenient. Compared with an existing rice extruding method, the equipment investment and the energy consumption can be reduced.

Description

Technical Field

[0001] The invention relates to a novel method for preparing brown rice flour, and belongs to the technical field of rice processing. Background Art

[0002] Brown rice is obtained by removing the husk from rice grains through a rice husker. Brown rice is mainly composed of three parts: cortex, endosperm and embryo. Compared with polished white rice, brown rice is rich in dietary fiber, minerals, VE and B vitamins. It also contains a variety of active ingredients such as γ-aminobutyric acid, glutathione, oryzanol, etc., and is a green and healthy food. Since the cortex of brown rice is rich in fiber and has a rough taste, it is often difficult for consumers to accept it. In order to make full use of the nutrients of brown rice, it has become a current research hotspot to use ultra-fine grinding, biological enzymes, extrusion and puffing technologies to process brown rice to improve the characteristics of brown rice flour. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a novel method for preparing brown rice flour.

[0004] The technical solution adopted by the present invention is:

[0005] A method for preparing novel brown rice flour comprises the following steps:

[0006] (1) sieving the brown rice to remove impurities and pick out incomplete grains to obtain clean brown rice, and storing it in a refrigerator at 4° C. for later use;

[0007] (2) taking 200 g of clean brown rice and milling it with a sand roller rice mill to obtain brown rice with a milling rate of 2.00% to 2.50%;

[0008] (3) adding brown rice to cyclone milling, adding 0.3% to 0.5% (w / w) NaOH solution to the brown rice flour, the mass ratio of the brown rice flour to the NaOH solution being 1:3 to 6, stirring at 25° C. to 35° C. for 5 h; then adjusting the pH to 5 to 8 with 0.1 mol / L hydrochloric acid, centrifuging at 3000 r / min for 15 min, removing the supernatant to obtain a preliminarily treated brown rice flour, drying the brown rice flour at 40° C. for 24 h, and passing through a 100 mesh sieve;

[0009] (4) adding distilled water to the brown rice flour, adjusting the pH to 6.0, and making a 5% to 20% uniform emulsion;

[0010] (5) The emulsion is transferred into a round-bottom flask, heated to 50° C. under stirring, and then 0.01% to 0.05% of cellulase is added to the total emulsion, and the reaction time is 0.5 h to 2.5 h;

[0011] (6) Continue to raise the temperature to 80°C to 100°C, add 50 μL to 300 μL of α-amylase, the concentration of α-amylase is 20000 U / mL to 60000 U / mL, and the reaction time is 3 min to 10 min;

[0012] (7) After the reaction is completed, 0.1 mol / L hydrochloric acid is added to adjust the pH to ≤ 3 to inactivate the enzyme and terminate the reaction; after cooling to room temperature, the pH is adjusted to neutral, dried at 40° C. for 24 h, and passed through a 100-mesh sieve to obtain the target product.

[0013] Preferably, in step (5), the amount of cellulase added is 0.03% of the total amount of the emulsion, and the reaction time is 1.5 h; in step (6), the amount of α-amylase added is 150 μL, and the concentration of α-amylase is 30,000 U / mL.

[0014] Beneficial effects of the present invention:

[0015] (1) The novel brown rice flour preparation method of the present invention comprises the following steps: firstly, the waxy layer on the surface of brown rice is removed by whitening and browning, thereby removing the components that affect the taste; then, cellulase is used to improve the components in the dietary fiber of brown rice bran, thereby increasing the content of soluble dietary fiber; and amylase is used to denature the starch, thereby improving the solubility and compatibility of the entire system.

[0016] (2) The present invention adds cellulase, and produces more soluble dietary fiber through the treatment of cellulose in the brown rice cortex by alkali and cellulase, thereby increasing the absorption rate of fiber and improving the processing performance of brown rice flour; and the brown rice flour is treated with NaOH solution to soften the fiber, improve the mouthfeel and facilitate processing.

[0017] (3) The present invention adopts the process of roughing and compared with the existing method of extruding raw materials, the advantages are obvious. Roughing is conducive to subsequent enzymolysis, otherwise the enzyme may be hindered and unable to react with the substrate; roughing does not affect other parts and components of brown rice, while extrusion has a greater impact on the components and structure of the entire brown rice powder. The starch in the extruded brown rice powder has been completely gelatinized, which is different from the dextrin with a lower DE value obtained after the starch in the brown rice powder of the present invention is treated. Amylase dextrinizes the starch with a low DE value, which can not only play the role of hydrophilic colloid when starch is gelatinized, but also produce relatively short glucose chains to interact with the components in the system, which can improve the compatibility of the brown rice powder system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Scanning electron microscope images of dextrin (MD) in the product of the present invention and rice flour (GRF) and starch (GRS) in brown rice flour. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0020] Embodiment 1 A kind of preparation method of novel brown rice powder

[0021] (1) Brown rice is sieved through an 18-mesh sieve to remove rice grains, rice husks, and other impurities, and incomplete grains to obtain clean brown rice, which is then stored in a refrigerator at 4°C.

[0022] (2) taking 200 g of clean brown rice, grinding it with a TM05C sand roller rice mill (40# sand roller, rotation speed 1060 r / min) for 16 to 25 s to obtain brown rice with a grinding reduction rate of 2.00%;

[0023] (3) adding the brown rice to a low-temperature continuous hammer cyclone mill for milling; adding 0.4% (w / w) NaOH solution to the brown rice flour, with the mass ratio of the brown rice flour to the NaOH solution being 1:4, stirring at 30° C. for 5 h, then adjusting the pH to about 7 with 0.1 mol / L hydrochloric acid, centrifuging at 3000 r / min for 15 min, removing the supernatant (repeated 3 times) to obtain preliminarily treated brown rice flour, drying the brown rice flour at 40° C. for 24 h, and then passing through a 100-mesh sieve;

[0024] (4) adding distilled water to the sifted brown rice flour, adjusting the pH to 6.0, and making a 15% uniform emulsion;

[0025] (5) The emulsion was transferred into a 500 mL round-bottom flask equipped with a paddle, heated to 50°C while stirring, and then 0.03% of the total emulsion amount of cellulase was added for 1.5 h;

[0026] (6) Continue to raise the temperature to 80-100°C, add 100 μL of thermostable α-amylase, the concentration of α-amylase is 40000U / mL, and react for 3-10 minutes; after the reaction, add 0.1 mol / L hydrochloric acid to adjust the pH to ≤3, inactivate the enzyme and terminate the reaction. After cooling to room temperature, adjust the pH to neutral, then dry at 40°C for 24 hours, and pass through a 100-mesh sieve to obtain the target product.

[0027] Embodiment 2, a kind of preparation method of novel brown rice flour

[0028] (1) Brown rice is sieved through an 18-mesh sieve to remove rice grains, rice husks, and other imperfect grains. The resulting brown rice is then stored in a refrigerator at 4°C.

[0029] (2) taking 200 g of clean brown rice, grinding it with a TM05C sand roller rice mill (40# sand roller, rotation speed 1060 r / min) for 16 to 25 s to obtain brown rice with a grinding reduction rate of 2.00%;

[0030] (3) adding brown rice to a low-temperature continuous hammer cyclone mill for milling; adding 0.5% (w / w) NaOH solution to the obtained brown rice flour, with the mass ratio of brown rice flour to NaOH solution being 1:5, stirring at 30° C. for 5 h, then adjusting the pH to about 7 with 0.1 mol / L HCl, centrifuging at 3000 r / min for 15 min, removing the supernatant (repeated 3 times) to obtain preliminarily treated brown rice flour, drying the brown rice flour at 40° C. for 24 h, and passing through a 100-mesh sieve.

[0031] (4) adding distilled water to the dry brown rice powder, adjusting the pH to 6.0, and making a 12% uniform emulsion;

[0032] (5) The emulsion was transferred into a 500 mL round-bottom flask equipped with a paddle, heated to 50°C while stirring, and 0.04% of the total emulsion amount of cellulase was added for 1.0 h;

[0033] (6) Continue to raise the temperature to 80-100°C, add 200 μL of thermostable α-amylase, the concentration of α-amylase is 40000U / mL, and react for 3-10 minutes. After the reaction is completed, add 0.1 mol / L hydrochloric acid to adjust the pH to ≤3, inactivate the enzyme and terminate the reaction; after cooling to room temperature, adjust the pH to neutral; dry at 40°C for 24 hours, and pass through a 100-mesh sieve to obtain the target product.

[0034] Product Performance Analysis

[0035] Performance analysis of the product of Example 1

[0036] Example 1: Brown rice was obtained, with a milling rate of 2.00%, a husk retention rate of 34.5%, and a germ retention rate of 99.3%.

[0037] 1. The role of cellulase

[0038] The rice bran in the brown rice flour product was extracted and analyzed to find that the cellulose content in the processed rice bran dietary fiber was reduced by 30% and the hemicellulose content was reduced by 12% compared with the original content, indicating that the addition of cellulase in the present invention can produce more soluble dietary fiber, increase the fiber absorption rate, and improve the processing performance of the brown rice flour.

[0039] 2. The role of amylase

[0040] The starch in the brown rice flour was extracted and analyzed to find that the starch was hydrolyzed into maltodextrin with a molecular weight of 7.309×10 6 , dispersion coefficient M w / M n It is 4.575, and the viscosity of the 15% (w / w) emulsion is 104.96 mPa·s.

[0041] The polydispersity coefficient of a polymer is usually expressed as M w / M n The ratio reflects the relative molecular weight distribution range of the polymer. Usually the weight average molecular weight of native starch is 10 6 -10 8 After enzyme treatment, the molecular structure is destroyed, the content of high molecular weight components decreases, and the content of low molecular weight components increases, which leads to the M w reduce.

[0042] Thermodynamic properties show that maltodextrin has no obvious endothermic enthalpy, indicating that starch has been fully gelatinized after enzymatic hydrolysis. Maltodextrin dilute solution shows a shear thinning trend at low shear frequency and Newtonian fluid properties at high shear frequency.

[0043] Figure 1 The scanning electron microscope images of dextrin (MD) in the product of the present invention and rice flour (GRF) and starch (GRS) in brown rice flour are compared. It can be seen that the starch and protein of rice flour (GRF) in the brown rice flour are aggregated, and the starch GRS is relatively dispersed, and the low DE value dextrin obtained by treatment also retains the granular state of starch.

Claims

1. a preparation method of novel brown rice powder, characterized in that: The method comprises the following steps: (1) sieving the brown rice to remove impurities and pick out incomplete grains to obtain clean brown rice, and storing it in a refrigerator at 4° C. for later use; (2) taking 200 g of clean brown rice and milling it with a sand roller rice mill to obtain brown rice with a milling rate of 2.00% to 2.50%; (3) adding brown rice to cyclone milling, adding 0.3% to 0.5% (w / w) NaOH solution to the brown rice flour, the mass ratio of the brown rice flour to the NaOH solution being 1:3 to 6, stirring at 25° C. to 35° C. for 5 h; then adjusting the pH to 5 to 8 with 0.1 mol / L hydrochloric acid, centrifuging at 3000 r / min for 15 min, removing the supernatant to obtain a preliminarily treated brown rice flour, drying the brown rice flour at 40° C. for 24 h, and passing through a 100 mesh sieve; (4) adding distilled water to the brown rice flour, adjusting the pH to 6.0, and making a 5% to 20% uniform emulsion; (5) The emulsion is transferred into a round-bottom flask, heated to 50° C. under stirring, and then 0.01% to 0.05% of cellulase is added to the total emulsion, and the reaction time is 0.5 h to 2.5 h; (6) Continue to raise the temperature to 80°C to 100°C, add 50 μL to 300 μL of α-amylase, the concentration of α-amylase is 20000 U / mL to 60000 U / mL, and the reaction time is 3 min to 10 min; (7) After the reaction is completed, 0.1 mol / L hydrochloric acid is added to adjust the pH to ≤ 3 to inactivate the enzyme and terminate the reaction; after cooling to room temperature, the pH is adjusted to neutral, dried at 40° C. for 24 h, and passed through a 100-mesh sieve to obtain the target product.

2. the preparation method of novel brown rice powder according to claim 1, is characterized in that: In step (5), the amount of cellulase added is 0.03% of the total amount of the emulsion, and the reaction time is 1.5 h.

3. the preparation method of novel brown rice powder according to claim 1, is characterized in that: In step (6), the amount of α-amylase added is 150 μL, and the concentration of α-amylase is 30,000 U / mL.

Images