A method to improve the nutritional value of brown rice and lower its glycemic index.

Abstract

This invention relates to the field of grain processing technology, and in particular to a method for improving the nutritional value of brown rice and reducing its glycemic index. The invention uses brown rice as raw material, processing it through a process of mist-wetting for nutrient enrichment, integrated microwave gelatinization and drying, tempering, and milling to produce semi-cooked rice (parboiled rice). The brown rice processed by the method provided by this invention is clean and odorless, slows down the rate of water penetration, prevents grain cracking, reduces the rate of broken rice during subsequent milling, and, under the action of endogenous enzymes, enriches nutrients such as GABA, flavonoids, and free amino acids. Furthermore, the bran layer of the dried brown rice is easily separated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rice processing, in particular to a method for improving the nutrition of brown rice and reducing the glycemic index of brown rice. BACKGROUND

[0002] The traditional process of steamed brown rice is to soak the rice for a certain period of time, then steam, dry, hull and mill. Because the rice contains many impurities, the impurities will penetrate into the rice during the soaking process, affecting the smell and quality. In addition, due to the rapid penetration of water during the soaking process of brown rice using the traditional process, stress is generated, and cracks appear on the brown rice. During the subsequent milling process, the broken rice rate is too high, and the nutritional ingredients are reduced. The brown rice that has been fully humidified using the traditional steam gelatinization process is more prone to breakage of the brown rice skin layer compared to the rice, resulting in rice adhesion, affecting the subsequent drying and milling process. SUMMARY

[0003] To solve the above problems, the present application provides a method for improving the nutrition of brown rice and reducing the glycemic index of brown rice. The brown rice processed by the method provided by the present application is clean and odorless, the water penetration rate during the humidification process of the brown rice can be slowed down, the rice grains do not crack, the subsequent milling broken rice rate is reduced, and under the action of endogenous enzymes, the nutritional ingredients such as GABA, flavonoids and free amino acids are enriched, and the brown rice skin layer after drying is easy to separate.

[0004] To achieve the above purpose, the present application provides the following technical scheme:

[0005] The present application provides a method for improving the nutrition of brown rice and reducing the glycemic index of brown rice, comprising the following steps:

[0006] The brown rice is humidified by atomization to obtain wet brown rice;

[0007] The wet brown rice is subjected to microwave gelatinization to obtain gelatinized brown rice; the microwave gelatinization time is 20-25 min; during the microwave gelatinization process, the wet brown rice has a flat thickness of 5-6 cm, and the microwave power is 15-20 kw;

[0008] The gelatinized brown rice is subjected to microwave drying to obtain dried brown rice; during the microwave drying process, the gelatinized brown rice has a flat thickness of 0.8-1 cm, and the microwave power is 7-15 kw; the water content of the dried brown rice is <15%.

[0009] Preferably, the water content of the wet brown rice is 29-31%.

[0010] Preferably, the atomization humidification environment temperature is 20-30℃, and the time is 10-20h.

[0011] Preferably, the atomization humidification device comprises a roller 8, a mist guide pipe 4, an atomizer 5, a bracket 6 and a motor 1; the inner wall of the roller 8 is provided with more than three roller blades 9; one end of the roller 8 in the horizontal direction is connected with the motor 1, and the other end is open; the connection between the roller 8 and the motor 1 is arranged on the bracket 6; one end of the mist guide pipe 4 extends into the roller along the opening of the roller 8 in the horizontal direction, and the other end is connected with the atomizer 5.

[0012] Preferably, a heat preservation interlayer 3 is arranged between the inner wall of the roller 8 and the outer cylinder; a material inlet and outlet 2 communicating the inner wall and the outer cylinder of the roller 8 is arranged on the roller 8; a material collector 7 is further arranged on the bracket 6; the material collector 7 is arranged directly below the roller 8.

[0013] Preferably, the method further comprises: after the dried brown rice is placed for 1-2 hours, cold air is cooled to 20-25 DEG C to obtain cooled brown rice.

[0014] Preferably, the moisture content of the cooled brown rice is less than 14%.

[0015] Preferably, after the cooled brown rice is obtained, the skin layer of the cooled brown rice is removed to obtain edible semi-cooked rice.

[0016] Preferably, the removing method comprises grinding.

[0017] Preferably, after the skin layer of the cooled brown rice is removed, edible rice bran is collected.

[0018] Beneficial effects:

[0019] 1. The present application adopts a mist humidification process (i.e. atomization humidification) to humidify brown rice, which can slow down the water penetration rate, and the rice grains do not crack, and the subsequent grinding rate of broken rice is reduced (the subsequent grinding rate of broken rice is 60-70% when traditional soaking humidification is adopted, and the subsequent grinding rate of broken rice is 10-20% when the mist humidification process is adopted); and the activity of various endogenous enzymes (amylase, protease, glutamic acid decarboxylase, etc.) can be activated, and the enrichment of nutritional ingredients and active ingredients is promoted, and GABA, flavonoids, free amino acids, etc. are significantly increased.

[0020] 2. The present application adopts a microwave gelatinization and drying integrated process, the microwave material thickness in the gelatinization stage is thick (5-6 cm) and the power is high (15-20 kw), which is beneficial to heat accumulation and internal starch gelatinization of brown rice, and the microwave material thickness in the drying stage is thin (0.8-1 cm) and the power is low (7-15 kw), which can quickly remove water.

[0021] 3. The brown rice processed using the method of the present invention is clean and odorless. The fatty acid value of the edible rice bran obtained by milling is significantly lower than that of the rice bran milled from the raw brown rice, and it is relatively stable during storage, which solves the problem of poor stability of rice bran and is more suitable for processing rice bran food.

[0022] 4. Compared with rice, brown rice treated by the method of the present invention has significantly increased resistant starch, and the blood sugar rise is slowed after consumption, making it more suitable for people with high blood sugar or diabetes. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0024] Figure 1 This is a schematic diagram of the structure of the atomizing humidification device used in the embodiment of the present invention; wherein, 1 is a motor, 2 is a material inlet and outlet, 3 is a heat insulation jacket, 4 is a mist guide pipe, 5 is an atomizer, 6 is a bracket, 7 is a material collector, 8 is a drum, and 9 is a drum blade. Detailed Implementation

[0025] This invention provides a method for improving the nutritional value of brown rice and reducing its glycemic index, comprising the following steps:

[0026] Brown rice is humidified by atomization to obtain wet brown rice;

[0027] The wet brown rice is microwaved to gelatinize it, resulting in gelatinized brown rice. The microwave gelatinization time is 20-25 minutes. During the microwave gelatinization process, the thickness of the wet brown rice is 5-6 cm, and the microwave power is 15-20 kW.

[0028] The gelatinized brown rice is microwave-dried to obtain dried brown rice. During the microwave drying process, the thickness of the gelatinized brown rice is 0.8-1 cm, and the microwave power is 7-15 kW. The moisture content of the dried brown rice is <15%.

[0029] The present invention preferably uses clean, odorless brown rice as raw material, which can reduce the odor of the subsequently prepared dried brown rice or semi-cooked rice.

[0030] This invention involves atomizing and humidifying brown rice to obtain wet brown rice. In this invention, the ambient temperature for atomizing and humidifying is preferably 20–30°C, more preferably 25–35°C, and even more preferably 30°C; the time is preferably 10–20 hours, and even more preferably 17 hours; the moisture content of the wet brown rice is preferably 29%–31%, and even more preferably 30%.

[0031] like Figure 1As shown, the atomization humidification device of the present application preferably comprises a roller 8, a mist guide pipe 4, an atomizer 5, a support 6 and a motor 1; the inner wall of the roller 8 is preferably provided with more than three roller blades 9, which can make the brown rice continuously roll under the action of the roller blades 9; the inner wall and the outer cylinder of the roller 8 are preferably provided with a heat preservation interlayer 3 for maintaining the temperature in the roller; the roller 8 is preferably provided with a material inlet and outlet 2 communicating with the inner wall and the outer cylinder of the roller 8, which is preferably a material inlet and outlet with a switch to control the inlet and outlet of the material, and when it is turned to the top, the material is fed, and when it is turned to the bottom, the material is discharged; one end of the roller 8 in the horizontal direction is preferably connected with the motor 1, so that the roller 8 rotates under the drive of the motor 1, and the other end is preferably open; the connection between the roller 8 and the motor 1 is arranged on the support 6; one end of the mist guide pipe 4 is preferably inserted into the roller along the horizontal opening of the roller 8, and the other end is preferably connected with the atomizer 5; the mist generated by the atomizer 5 is evenly attached to the surface of the rolling brown rice in the roller 8 through the mist guide pipe 4, so that the brown rice slowly absorbs water, and the amount of spraying can be adjusted according to the amount of material; the support 6 is preferably further provided with a material collector 7; the material collector 7 is preferably arranged directly below the roller 8 for collecting the wet brown rice.

[0032] If the brown rice is humidified by traditional soaking, due to the rapid penetration of water, stress is generated, the rice grains crack, and the broken rice rate is too high in the subsequent milling process. The present application uses atomization to humidify the brown rice, slows down the water penetration rate, and the rice grains do not crack, reducing the subsequent milling broken rice rate. Moreover, at about 30℃, a variety of endogenous enzyme (amylase, protease, glutamic acid decarboxylase, etc.) activities can be activated to promote the enrichment of nutritional and active ingredients, and GABA, flavonoids, free amino acids, etc. are significantly increased.

[0033] After obtaining the wet brown rice, the present application carries out microwave gelatinization on the wet brown rice to obtain gelatinized brown rice. In the process of microwave gelatinization of the present application, the wet brown rice is laid flat with a thickness of 5-6 cm, and the microwave power is 15-20 kw, more preferably 18 kw; the microwave gelatinization time is 20-25 min, more preferably 23 min; the microwave gelatinization device is preferably a continuous microwave equipment, and the conveying speed of the wet brown rice on the continuous microwave equipment is preferably 0.3-0.4 m / min, more preferably 0.35 m / min. The purpose of microwave gelatinization of the present application is to gelatinize the wet brown rice. The moisture content of the wet brown rice is about 30%, and the moisture content is sufficient. The material thickness is set to 5-6 cm, which is beneficial to internal heat accumulation. The material is more, the microwave power is higher, the material temperature is controlled at 60-80℃, and the starch gelatinization temperature is reached. The conveying speed is slow, 0.3-0.4 m / min, the microwave time is 20-25 min, which ensures that the internal starch is completely gelatinized, and the moisture content is reduced to 20%-25%.

[0034] After the gelatinized brown rice is obtained, the gelatinized brown rice is subjected to microwave drying to obtain dried brown rice. In the microwave drying process, the thickness of the gelatinized brown rice is 0.8-1 cm, the microwave power is 7-15 kw, preferably 8-13 kw, and more preferably 10 kw; and the moisture content of the dried brown rice is less than 15%. In the present application, the microwave drying device is preferably a continuous microwave device, and the conveying speed of the gelatinized brown rice on the continuous microwave device is preferably 0.3-0.6 m / min, further preferably 0.4-0.5 m / min, and more preferably 0.45 m / min; and the microwave drying time is preferably 15-20 min. The purpose of the secondary microwave is drying, so the material thickness is reduced to 0.8-1.0 cm, the material is thinner, the microwave power is reduced, the conveying speed is increased, and the drying temperature is not higher than 90°C (70-90°C).

[0035] After the dried brown rice is obtained, the dried brown rice is preferably allowed to stand for 1-2 h, and then cooled to 20-25°C (room temperature) by cold air to obtain cooled brown rice. In the present application, the standing time is preferably 1-2 h, and more preferably 1.5 h; and the moisture content of the cooled brown rice is less than 14%. By standing for 1-2 h, the moisture in the dried brown rice can be balanced. After starch ripening, room temperature or low temperature storage will cause aging, thereby increasing the resistant starch content in the brown rice and slowing down the blood glucose rise after eating.

[0036] After the cooled brown rice is obtained, the husk of the cooled brown rice is preferably removed to obtain edible parboiled rice. In the present application, the removal method preferably includes milling, and the milled rice bran is edible rice bran which can be collected for processing rice bran food.

[0037] The traditional process of steamed rice is to soak the rice for a certain period of time, and then to process it by steaming, drying, hulling and milling. Because the rice contains many impurities, the odor penetrates into the rice during the soaking process, affecting the odor and quality. The present application innovatively uses brown rice as raw material to process parboiled rice (steamed rice) by mist nutrition enrichment, microwave gelatinization and drying integration, tempering and milling.

[0038] Using the traditional steaming process to ripen brown rice, because the brown rice husk is relatively thin compared to the rice hull, it is easy to break the skin under the action of hot steam, causing starch overflow and rice adhesion, affecting the subsequent drying and milling process. The present application uses a microwave gelatinization and drying integration process, which uses high-power microwave to gelatinize the internal starch of the brown rice, and then uses low-power microwave to remove water. After drying, the moisture content is controlled to be less than 15%. After tempering to balance the moisture, the moisture content is cooled to room temperature and controlled to be less than 14%. Finally, moderate milling is performed to obtain transparent and nutritious steamed rice.

[0039] In order to further illustrate the present application, a method for improving the nutrition of brown rice and reducing the glycemic index of brown rice provided by the present application is described in detail below in combination with the accompanying drawings and examples, but they cannot be understood as limiting the scope of protection of the present application.

[0040] Example 1

[0041] After the brown rice is cleaned, it is placed in a rotating drum as shown in Figure 1 , atomized water vapor is introduced into the drum, and the brown rice in the drum is continuously rolled and slowly and uniformly humidified. The temperature in the drum is controlled at 30°C (the temperature is controlled by introducing hot air if it is too low). The atomization time is 17h. After the brown rice is slowly absorbed and fully saturated (the moisture content reaches 30%), it is subjected to primary microwave cooking. A continuous microwave device (purchased from Shandong Shengrun Machinery Co., Ltd., model WB-15) is used. The material thickness is 6cm, the microwave power is 18kw, the material conveying speed is 0.35m / min, and the primary microwave time is 23min. The moisture content is reduced to 24%. Due to the sufficient material thickness and slow conveying speed, the heat storage time is sufficient, the rice kernels are fully gelatinized, and they are transparent.

[0042] After primary microwave, secondary microwave drying is performed. The material thickness is 0.8cm, the microwave power is 10kw, and the material conveying speed is 0.45m / min. The moisture content in the gelatinized brown rice is reduced to 13%. It is then transferred to a transfer bin for slow recovery and moisture balance for 1.5h, and then cold air cooling is performed. The temperature of the brown rice is reduced to room temperature, and the moisture content is reduced to 11% (referring to LS / T 3271-2023 steamed rice). Finally, it is transferred to a milling device for milling to remove the skin and obtain transparent semi-cooked rice. The broken rice rate of the product after milling is 12%.

[0043] Comparative Example 1

[0044] A method similar to Example 1, except that the brown rice is directly soaked in water at 30°C for 17h, and the moisture content reaches 31%. After steaming for 25min, the moisture content increases to 40%. Some rice kernels crack, starch spills out, and the rice kernels are deformed and adhered. Subsequent drying is difficult. Due to the high moisture content, the drying energy consumption also increases, and some rice kernels are still adhered. Due to the deformation of the rice kernels after drying, the broken rice rate is too large during subsequent milling, reaching 69%.

[0045] Comparative Example 2

[0046] A method similar to Example 1, except that the brown rice was directly soaked in water at 30°C for 17 h, the moisture content reached 31%, the material thickness was 3 cm, the conveying speed was 0.3 m / min, the moisture content was reduced to 19%, the gelatinization was not complete due to insufficient material thickness and insufficient heat storage, and part of the rice grains turned white due to rapid water loss (the product requires transparency, and the white grains are unqualified), the material thickness was 1 cm, the microwave power was 15 kw, the conveying speed was 0.6 m / min, the moisture content was rapidly dried to 12%, the white rice grains increased, and after 1 h of slow cooling to room temperature, the moisture content was reduced to 10%, and the broken rice rate was 45% after milling.

[0047] Comparative Example 3

[0048] A method similar to Example 1, except that the brown rice was directly soaked in water at 20°C for 17 h, the moisture content reached 28%, the material thickness was 4 cm, the conveying speed was 0.4 m / min, the moisture content was reduced to 15%, the gelatinization was not complete due to insufficient material thickness and insufficient heat storage, part of the rice grains turned white due to rapid water loss (the product requires transparency, and the white grains are unqualified), the material thickness was 0.8 cm, the microwave power was 15 kw, the conveying speed was 0.4 m / min, the moisture content was rapidly dried to 10%, the white rice grains increased, and even part of the rice grains were overheated and had a burnt smell, after 1 h of slow cooling to room temperature, the moisture content was reduced to 9%, and the broken rice rate was 42% after milling.

[0049] Test Example

[0050] The nutritional components of the semi-cooked rice prepared in Example 1 and Comparative Examples 1-3 and the rice processed by the traditional method, and the fatty acid content in rice bran were determined. Among them, GABA was determined according to NY / T 2890-2016 "Determination of γ-aminobutyric acid in rice by high performance liquid chromatography"; free amino acids were determined according to GB 5009.124-2016 "Determination of amino acids in food safety national standards food"; resistant starch was determined according to NY / T2638-2014 "Determination of resistant starch in rice and products by spectrophotometry"; the glycemic index was determined according to WS / T 652-2019 "Determination of food glycemic index"; and the flavonoids were determined as follows:

[0051] The content of flavonoids in the sample was determined by high performance liquid chromatography-mass spectrometry. The liquid chromatography conditions were as follows: Waters HSST3 chromatographic column (50x2.1mm, 1.8μm); mobile phase A was 0.1% formic acid in ultrapure water, and mobile phase B was 0.1% formic acid in acetonitrile; the flow rate was controlled at 0.3mL / min; the column temperature was kept at 40℃; the sample injection amount was 2μL each time; the elution gradient was as follows: 0.0min water / acetonitrile (90:10V / V), 2.0min water / acetonitrile (90:10V / V), 6.0min water / acetonitrile (40:60V / V), 9.0min water / acetonitrile (40:60V / V), 9.1min water / acetonitrile (90:10V / V), 12.0min water / acetonitrile (90:10V / V). The mass spectrometry conditions were as follows: electrospray ion source, sheath gas 40arb; auxiliary gas 10arb; ion spray voltage -2800V; temperature 350℃; ion transfer tube temperature 320℃. Sixteen kinds of flavonoids were detected, and the determination was performed in triplicate. The results are shown in Tables 1 and 2.

[0052] Table 1 Comparison results of nutritional components and broken rice rate

[0053]

[0054]

[0055] Note: The rice is obtained by traditional methods such as hulling, milling, polishing and color selection, and the variety is the same as that of the product of the application, which is Suijing 18.

[0056] Table 2 Comparison results of fatty acid values in different rice bran (mg / 100g)

[0057] Indicator Rice bran Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Fatty acid value (initial) 272.23 190.72 195.47 198.66 224.6 Fatty acid value (storage 15 days) 707.00 195.91 219.42 221.07 308.1

[0058] Note: The rice is obtained by traditional methods such as hulling and milling.

[0059] As shown in Tables 1 and 2, under suitable temperature and humidity conditions, the internal glutamic acid decarboxylase activity of brown rice is activated, which promotes the enrichment of GABA, and the increase of protease activity promotes the decomposition of protein into amino acids, so that the content of free amino acids is increased. The microwave temperature of 70-90℃ inhibits the activity of fat oxidase in brown rice, the fatty acid value of the rice bran obtained after milling is increased, and the storage stability is improved. The microwave temperature of 60-80℃ is higher than the gelatinization temperature of rice starch (59℃), and the starch is completely gelatinized under sufficient water and gelatinization time, so that the rice is transparent and hard after drying, and the broken rice rate is reduced. The gelatinized rice starch is stored at room temperature for a period of time, and starch retrogradation occurs, so that the content of resistant starch is increased, and the glycemic index is reduced.

[0060] Although the above embodiments have been described in detail, it should be understood that these are only some embodiments of the present application, but not all embodiments. Other embodiments can be obtained on the basis of the above embodiments without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. A method for improving the nutritional quality and reducing the glycemic index of brown rice, characterized in that, The method comprises the following steps: The brown rice is atomized and humidified to obtain humidified brown rice; the atomized and humidified environment temperature is 30℃, and the time is 10-20h; the water content of the humidified brown rice is 29%-31%; The humidified brown rice is subjected to microwave gelatinization to obtain gelatinized brown rice; the microwave gelatinization time is 20-25min; during the microwave gelatinization, the flat laying thickness of the humidified brown rice is 5-6cm, and the microwave power is 15-20kw; The gelatinized brown rice is subjected to microwave drying to obtain dried brown rice; during the microwave drying, the flat laying thickness of the gelatinized brown rice is 0.8-1cm, and the microwave power is 7-15kw; the water content of the dried brown rice is <15%; After the dried brown rice is placed for 1-2h, the cold air is cooled to 20-25℃ to obtain cooled brown rice; the water content of the cooled brown rice is <14%; After the cooled brown rice is obtained, the skin layer of the cooled brown rice is removed to obtain edible semi-cooked rice.

2. The method of claim 1, wherein, The atomized and humidified device comprises a roller (8), a mist guide pipe (4), an atomizer (5), a bracket (6) and a motor (1); the inner wall of the roller (8) is provided with more than three roller blades (9); one end of the roller (8) in the horizontal direction is connected with the motor (1), and the other end is open; the connection between the roller (8) and the motor (1) is arranged on the bracket (6); one end of the mist guide pipe (4) extends into the roller along the opening in the horizontal direction of the roller (8), and the other end is connected with the atomizer (5).

3. The method of claim 2, wherein, A heat preservation interlayer (3) is arranged between the inner wall of the roller (8) and the outer cylinder; a material inlet and outlet (2) communicating the inner wall and the outer cylinder of the roller (8) is arranged on the roller (8); a material collector (7) is further arranged on the bracket (6); the material collector (7) is arranged directly below the roller (8).

4. The method of claim 1, wherein, The removing method comprises grinding.

5. The method of claim 1, wherein, After the skin layer of the cooled brown rice is removed, edible rice bran is collected.

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