Low-gi instant mixed-grain rice and processing method thereof

Abstract

The application discloses a low-GI instant miscellaneous grain rice and a processing method thereof, and belongs to the technical field of deep processing of agricultural products.The instant miscellaneous grain rice is prepared by mixing different types of whole grain miscellaneous grains with good low-GI characteristics and a small amount of high-quality rice in a certain proportion and adopting radio frequency rapid curing-reverse pressure curing sterilization technology, the average hardness value of the processed instant miscellaneous grain rice product is 4.3 kgf, the average viscosity value is 0.62 kgf, the average elasticity value is 0.74 kgf, the product has a softer and stickier taste, the product GI is less than 55, and the product belongs to low-GI food.The method has a short technological process, simple equipment, high utilization rate, small occupied space, low investment, low energy consumption, no pollution, short production period, is suitable for automatic continuous production and industrialization popularization.

Description

TECHNICAL FIELD

[0001] The application relates to low-GI instant mixed-grain rice and a processing method thereof, and belongs to the technical field of deep processing of agricultural products. BACKGROUND

[0002] When the human body takes in easily digestible starch or high-glycemic index (GI) food, the blood sugar will rise sharply, the secretion and release of insulin will be promoted, and the conversion of blood sugar into fat will be accelerated, thereby causing high blood lipids and obesity, and obesity is a high-risk factor for diseases such as hypertension and diabetes. Especially for type 2 diabetes patients, eating GI food such as rice at each meal will cause rapid postprandial blood sugar rise, and must be controlled by taking medicine or reducing the intake of staple food, thereby seriously affecting the quality of life.

[0003] Currently, low-GI instant rice is being researched by scholars or enterprises. For example, patent CN 111264757 A discloses a preparation method of low-GI instant rice, which is characterized in that low-GI rice and mixed grains are used as main raw materials, and high-temperature fluidization process is combined with conventional high-temperature high-pressure sterilization process for processing. Although this technology can realize low GI of the product, the high-temperature fluidization process combined with the conventional high-temperature high-pressure process is used, so that the equipment investment is large, the energy consumption is high, and the processing cost is high in the processing process. Meanwhile, the raw material rice used in the formula is a low-GI rice variety, which lacks innovation, and the low-GI rice is expensive, so that the overall cost of the product is high, and the product is not easy to popularize.

[0004] Patent CN 113712148 A discloses a low-GI black hulless barley mixed-grain instant rice and a preparation method thereof, which is characterized in that microwave fluidization technology is used to perform high-temperature fluidization treatment on black hulless barley, oatmeal, black rice, green beans and other mixed grains, then soaking, cooking, heat preservation and cooling are performed, and finally the finished product is obtained through packaging and high-pressure sterilization. Although this product can achieve the effect of low GI, the process flow is long, the processing period is long, the equipment investment is large, and the energy consumption is high in the processing process, so that it is difficult to realize integrated and continuous production. Meanwhile, the process adopts the method of first cooking and cooling, then packaging and high-temperature high-pressure sterilization, and the conventional high-temperature high-pressure is used, which will seriously damage the sensory of the product and affect the eating quality of the product.

[0005] Patent CN 115708562 A discloses an anti-aging regenerative highland barley instant rice and its preparation method, which is characterized by using high-temperature fluidization technology combined with conventional high-temperature high-pressure sterilization process. Compared with the method disclosed in patent CN 113712148 A, the complex process flow is shortened. However, the high-temperature fluidization technology combined with conventional high-temperature high-pressure sterilization process still has similar problems as the method in patent CN 111264757 A, such as large equipment investment, long process chain, high energy consumption, high processing cost, and the like. In addition, conventional high-temperature high-pressure treatment can easily cause bag expansion, damage the product's sensory, and shorten the shelf life.

[0006] Patents CN100455207C and CN1172597A disclose a production method of instant nutritious rice, which also mentions reverse pressure sterilization technology. However, the patent does not provide any information on how the technology is implemented and the parameters.

[0007] Patent CN 1121478A discloses a steaming bag instant rice and its production process, which is characterized by first steaming the rice at 1.0 Kg / cm2, 115 ℃ or 1.2 Kg / cm2, 120 ℃ or 1.5 Kg / cm2, 125 ℃ for 5-8 min, then maintaining the pressure for 18-22 min, and then applying a water vapor pressure slightly greater than the previous pressure to the bagged rice for reverse pressure, with a time of about 8-12 min. This method can achieve one-time sterilization and cooking for rice and other easily cooked single materials. However, for mixed grain materials, different grains have different textures and cooking conditions, and it is difficult to achieve the same cooking effect. The process is not suitable for instant mixed grain rice.

[0008] Patent CN 107692031 A discloses a method for processing anti-reversion instant rice using indica rice, which is characterized by using indica rice as raw material, screening and removing impurities, soaking and microwave pretreatment, superheated steam pretreatment and shaping, vacuum quantitative packaging, and reverse pressure microwave cooking to obtain instant rice. This invention uses indica rice (rice) as raw material, and combines microwave pretreatment, superheated steam pretreatment, and reverse pressure microwave cooking. The process is complex, the equipment investment is large, the energy consumption of superheated steam is high, and the equipment investment and processing energy consumption of reverse pressure microwave cooking are higher than those of reverse pressure steam cooking. In addition, whether this process is suitable for instant mixed grain rice has not been studied.

[0009] The nutrition and physicochemical indexes of cereals will change after being processed by different processes, and different processing methods have different absorption degrees and effects on maintaining blood glucose homeostasis. Different production methods have different GI values, and different combinations of ingredients also have different GI values. The instant miscellaneous grain rice products in the prior art have two problems: one is that in order to ensure the taste, only a small amount of miscellaneous grains is added to be mixed with a large proportion of rice, which cannot achieve the low GI effect; and the other is that the miscellaneous grain cereals are simply mixed according to the taste, so that the effect is ignored while the taste is ensured. SUMMARY

[0010] Technical problem: In order to solve the above problems existing in the prior art, the present application develops a low GI instant miscellaneous grain rice and a processing method. The present application develops a low GI instant miscellaneous grain rice with suitable taste, rich nutrition, convenience and full-grain by mixing high-quality whole grain miscellaneous grains with high-quality rice, and invents a key technology of radio frequency rapid curing-reverse pressure curing sterilization. The radio frequency rapid curing technology is used to make the miscellaneous grains achieve rapid curing effect, so that the miscellaneous grains and rice can be cooked together, the flavor and curing uniformity of the product are improved, and the continuous reverse pressure curing sterilization technology is used to make the product achieve commercial sterile state during curing. The reverse pressure technology avoids the product bag swelling caused by high temperature during the curing and sterilization process, ensures the sensory of the product, improves the product quality, and prolongs the shelf life of the product. The problems of high processing cost, complicated process, long processing period, high cost, poor sensory and edible characteristics of the product, short shelf life and other problems of the product processed by the prior art are solved.

[0011] Technical solution

[0012] The present application reduces the GI of the instant miscellaneous grain rice to below 55, significantly improves the sensory and edible quality of the product, prolongs the shelf life of the product, and invents a key technology of radio frequency rapid curing-reverse pressure curing sterilization, so that different miscellaneous grains can be cooked together, the palatability of the product is improved, and the continuous reverse pressure curing sterilization technology is used to avoid the product bag swelling problem during the processing process and the damage to the sensory of the product caused by the traditional steaming and cooking process. The quality of the low GI instant miscellaneous grain rice is greatly improved.

[0013] The first object of the present application is to protect a processing method of low GI instant miscellaneous grain rice, and the specific steps include:

[0014] (1) raw material pretreatment;

[0015] (2) radio frequency rapid curing: the pretreated miscellaneous grains obtained in step (1) are subjected to rapid curing treatment by using a radio frequency system device, so that the miscellaneous grains achieve rapid curing effect;

[0016] (3) Reverse pressure pre-ripening: the mixed grains after the radio frequency quick ripening treatment in step (2) are added with water according to the ratio, then are packed in high-temperature cooking bags and sealed, and are placed in a vertical reverse pressure sterilization pot, water is injected to cover the surface of the cooking bags, and reverse pressure parameters, pre-ripening temperature parameters and pre-ripening time are set to perform reverse pressure pre-ripening treatment;

[0017] (4) Reverse pressure ripening sterilization: after the reverse pressure pre-ripening treatment in step (3) is completed, reverse pressure parameters, ripening sterilization temperature parameters and ripening sterilization time are re-set to perform further ripening and sterilization treatment;

[0018] (5) Circulating water cooling: circulating water is connected to cool to obtain a low-GI instant mixed grain rice product.

[0019] In an embodiment, the step (1) specifically refers to selecting whole grain mixed grains, removing solid impurities, different kinds of grains, worm-eaten grains, imperfect grains, broken grains and smutty grains, and then performing washing treatment to remove dust on the surface to obtain pretreated mixed grains.

[0020] In an embodiment of the present application, the mixed grains in step (1) are highland barley, oat, buckwheat, brown rice, konjac rice, wherein the proportion of highland barley is 10% to 30%, the proportion of oat is 20% to 40%, the proportion of buckwheat is 10% to 30%, the proportion of brown rice is 5% to 15%, the proportion of rice is 10% to 30%, and the proportion of konjac rice is 2% to 10%. Preferably, in the mixed grains, the proportion of highland barley is 20%, the proportion of oat is 30%, the proportion of buckwheat is 15%, the proportion of brown rice is 10%, the proportion of rice is 20%, and the proportion of konjac rice is 5%.

[0021] In an embodiment of the present application, the radio frequency system device is used for quick ripening treatment in step (2), and the temperature is set to 90 to 150℃ and the radio frequency time is 3 to 10 minutes during the treatment process.

[0022] In an embodiment of the present application, the radio frequency system device is used for quick ripening treatment in step (2), and the plate spacing is set to 5 to 15 cm during the treatment process, and further, the plate spacing is 15 cm.

[0023] In an embodiment of the present application, in the radio frequency quick ripening in step (2), the treatment conditions of highland barley and oat are radio frequency temperature 120℃ and radio frequency time 5 minutes, and the treatment conditions of brown rice and buckwheat are radio frequency temperature 120℃ and radio frequency time 4 minutes.

[0024] In an embodiment of the present application, in step (3), the ratio of mixed grain rice formula to water is 1: (1.5 to 1.7).

[0025] In an embodiment of the present application, in step (3), the reverse pressure pre-ripening temperature is 100±1℃, and the additional reverse pressure is 0.08 to 1.4 Mpa.

[0026] In one embodiment of the present application, in step (3), the reverse pressure pre-aging time is 10-40 min.

[0027] In one embodiment of the present application, in step (4), the reverse pressure aging sterilization temperature is 121±1℃, and the additional reverse pressure is 0.15-0.20 Mpa.

[0028] In one embodiment of the present application, in step (4), the reverse pressure aging sterilization time is 20-60 min.

[0029] In one embodiment, the step (5) is specifically maintaining the reverse pressure parameters unchanged after the reverse pressure aging sterilization in step (4) is completed, connecting a circulating water, setting a water circulating cooling time, until the temperature is reduced to below 45℃, opening the vertical reverse pressure sterilization pot, and obtaining the low GI instant mixed grain rice product.

[0030] In one embodiment of the present application, in step (5), the cooling method adopted is circulating water cooling, and the cooling time is 3-10 min.

[0031] A second object of the present application is to provide a low GI instant mixed grain rice prepared by the above method.

[0032] Advantages and effects of the present application:

[0033] The present application develops a processing method of low GI instant mixed grain rice, and simultaneously prepares a low GI instant mixed grain rice, which has unique flavor, rich nutrition, convenience, GI<55, belongs to low GI food, and can effectively control blood sugar load for long-term consumption by high blood sugar people, and can achieve the effect of relieving or even improving high blood sugar.

[0034] The present application firstly adopts the radio frequency rapid aging technology combined with the continuous reverse pressure aging sterilization technology to process the instant mixed grain rice product, firstly adopts the radio frequency system equipment to rapidly age the mixed grains, the radio frequency rapid aging technology processing makes the mixed grains achieve the effect of rapid aging, realizes the same cooking and aging of the mixed grains and rice, and improves the product flavor and aging uniformity. The continuous aging sterilization technology is adopted, the product achieves the commercial sterile state during the aging, the reverse pressure technology avoids the product bag expansion phenomenon due to high temperature in the aging sterilization process, ensures the product sense, improves the product quality, and prolongs the product shelf life. The cooling process adopts the circulating water cooling method, compared with the traditional cooling method, the cooling speed is faster and safer, and the cooling time can be shortened to less than 7 min. The method process flow is short, the equipment is simple, the utilization rate is high, the land occupation space is small, the investment is less, the energy consumption is low, there is no pollution, the production cycle is short, it is suitable for automatic continuous production, and is suitable for industrialization promotion.

[0035] After the radio frequency rapid aging treatment of the application, the steaming aging time is shortened by 17%~33% on average, the hardness value is reduced by 40%~52% on average, the viscosity value is increased by 52%~69% on average, and the elasticity value is increased by 16%~58% on average, achieving the effect of cooking and aging with rice. The average hardness value of the instant mixed grain rice product is 4.3 kgf, the average viscosity value is 0.62 kgf, and the average elasticity value is 0.74, and the taste is softer and more glutinous.

[0036] The application has simple production process, no pollution, is suitable for industrialized production, improves the flavor and palatability of mixed grains, is convenient and fast, makes the mixed grains not difficult to eat and make, has important significance for the popularization of mixed grain industry and the solution of the diet of diabetes group, and has good social and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The in-vitro digestion curve of the low GI instant mixed grain rice prepared in Example 1 and the samples of Comparative Examples 5 and 6.

[0038] Figure 2 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (one) in Example 1.

[0039] Figure 3 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (two) in Example 1.

[0040] Figure 4 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (three) in Example 1.

[0041] Figure 5 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (four) in Example 1.

[0042] Figure 6 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (five) in Example 1.

[0043] Figure 7 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (six) in Example 1.

[0044] Figure 8 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (seven) in Example 1.

[0045] Figure 9 The human blood glucose detection curve of the low GI instant mixed grain rice (i.e. "low GI new product") volunteer (eight) in Example 1.

[0046] Figure 10 Blood glucose test curve of the low GI instant mixed-rice (i.e. "low GI new product") volunteer (No. 1) in Example 1.

[0047] Figure 11 Blood glucose test curve of the low GI instant mixed-rice (i.e. "low GI new product") volunteer (No. 2) in Example 1.

[0048] Figure 12 Blood glucose test curve of the low GI instant mixed-rice (i.e. "low GI new product") volunteer (No. 3) in Example 1.

[0049] Figure 13 Blood glucose test curve of the low GI instant mixed-rice (i.e. "low GI new product") volunteer (No. 4) in Example 1.

[0050] Figure 14 Hardness value of the products with different rice-water ratios in Example 4.

[0051] Figure 15 Change of the pot temperature with time in Example 6. DETAILED DESCRIPTION

[0052] 1. Experimental instruments:

[0053] The vertical pressure sterilization pot referred in the following examples can be purchased from Jiangsu Qianqiu Agricultural Science and Technology Development Co., Ltd., and the full-automatic vertical pressure sterilization pot QZD080L. The radio frequency system equipment referred in the following examples can be purchased from Beihua Epoch High Frequency Equipment Co., Ltd., and the tunnel type radio frequency test machine GJS-6(4)B-27II-JY.

[0054] 2. Texture parameter determination:

[0055] The texture parameter determination process referred in the following examples:

[0056] Hardness value: indicates the hardness of the rice, the larger the value, the harder the rice, and the smaller the value, the softer the rice.

[0057] Elasticity value: indicates the elasticity of the rice, the larger the value, the better the elasticity of the rice, and vice versa.

[0058] Adhesiveness value: indicates the adhesiveness of the rice, the larger the value, the greater the adhesiveness of the rice, and the easier the rice is to form a cluster.

[0059] Cooking time: the time required when the grain is cooked until no white core appears.

[0060] The hardness, springiness and cohesiveness values are measured using a STA1A rice flavor meter (Satake, Japan): (30.0 ± 0.1) g of grains is accurately weighed in a stainless steel pot, which is covered with a rice washing cover and rinsed with water for about 30 s, and the pot is sealed with filter paper. The pot is then placed in a rice cooker for cooking. After the grains are cooked, they are allowed to rest for 2 h at room temperature. Then, 7 g of cooked grains is weighed into a stainless steel sample ring with a diameter of 30 mm and a height of 9 mm, and a rice cake is formed by pressing the sample with a rice press. The sample is placed in a measuring groove and inserted into the flavor meter for measurement. The front and back of each sample are measured once (2 times in total). The hardness, springiness and cohesiveness values of the grains are measured in triplicate for each sample.

[0061] Cooking time determination: The cooking time of the rice is determined using the glass plate-white core method. 10 g of instant cooked grain sample is weighed and added to 100 mL of boiling water for cooking. During the cooking process, 8 grain samples are randomly taken every 2 min and placed on a glass plate, and then pressed to observe the change in the core of the grains. When no white core appears in the grains, the cooking time is determined.

[0062] 3. In vitro digestion method to determine GI

[0063] The sample is dried and ground to 40 mesh. 200 mg of rice powder is placed in a 20 mL glass bottle with a stopper, 10 mL of 0.2 mol / L acetic acid buffer (pH = 6.0) is added, and the mixture is gelatinized by magnetic stirring in boiling water at 100°C for 30 min. The mixture is cooled to 37°C, 5 mL of 0.2 mol / L acetic acid buffer (pH = 6.0) is added, and the mixture is stirred evenly. Then, 5 mL of mixed enzyme solution (containing α-amylase 10 U / mg and AMG enzyme 3260 U / mL) is added, and the mixture is incubated at 37°C. At 0, 10, 20, 30, 60, 90, 120 and 180 min, 0.1 mL of enzyme hydrolysis solution is taken and 9 times the volume of anhydrous ethanol is added to inactivate the enzyme. After centrifugation at 4000 g for 10 min, the glucose content in the supernatant is determined by a GOPOD kit (Megazyme). The percentage of hydrolyzed starch is obtained by multiplying the glucose content by 0.9. The starch digestion curve of the rice noodles is plotted with the digestion time (t) as the abscissa and the starch hydrolysis rate (%) as the ordinate. The area under the curve (AUC) from 0 to 180 min is calculated, the hydrogenation index (HI) is calculated, and the GI value of the sample is further calculated.

[0064] HI (%) = 100 - (0.862 x GI + 8.198)

[0065] GI = 0.862HI + 8.198

[0066] 4. Food glycemic index determination method for determining the GI of human body

[0067] The GI value of the sample is determined according to the method of WS / T 652-2019 issued by the National Health Commission on June 11, 2019.

[0068] The technical solutions of the application will be described in detail below in combination with the drawings and specific embodiments.

[0069] Example 1: A low GI instant mixed grain rice and its processing method

[0070] The method comprises the following process steps:

[0071] (1) Each selected 1000g high-quality highland barley, oat, brown rice, buckwheat, remove solid impurities, foreign particles, insect damaged particles, imperfect particles, broken particles, and diseased particles in the raw materials, and then perform washing treatment to remove the surface dust, and obtain the pretreated mixed grain;

[0072] (2) The pretreated mixed grain obtained in step (1) is subjected to rapid cooking treatment by using a continuous radio frequency system device, and the plate spacing is set to 15 cm. Among them, the treatment conditions of highland barley and oat are 120℃, 5min, and the treatment conditions of brown rice and buckwheat are 120℃, 4min.

[0073] (3) The mixed grain after rapid cooking treatment in step (2) is mixed according to highland barley: oat: buckwheat: brown rice: rice: konjac rice = 20:30:15:10:20:5, and is sealed according to rice: water = 1:1.6, and the packaging specification is 150g / bag. The sealed cooking bag is placed in a vertical pressure sterilization pot, the pot cover is covered, pre-cooking is carried out, the pre-cooking temperature is set to 100±1℃, the additional pressure is set to 0.1Mpa, and the pre-cooking time is set to 20min;

[0074] (4) After the pressure pre-cooking treatment in step (3) is completed, the pressure parameters, cooking and sterilization temperature parameters, and cooking and sterilization time are re-set for further cooking and sterilization treatment. The pressure cooking and sterilization temperature is set to 121±1℃, the additional pressure is set to 0.18Mpa, and the pressure cooking and sterilization time is set to 35min;

[0075] (5) After the pressure cooking and sterilization in step (4) is completed, the pressure parameters remain unchanged, the circulating water is connected, the water circulating cooling time is set to 7min, and the temperature is reduced to below 45℃. Open the vertical pressure sterilization pot to obtain a low GI instant mixed grain rice product.

[0076] Comparative Example 1: An instant mixed grain rice and its processing method

[0077] Omitting the step of quick cooking of mixed grains in Example 1 (i.e. step 2) to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0078] Comparative Example 2: An instant mixed grain rice and a processing method thereof

[0079] Using ordinary cooking to replace steps (3), (4) of Example 1 to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0080] Among them, ordinary cooking refers to the preparation method of mixed grain rice reported in CN112089006A, and the specific conditions are: 40min of normal pressure cooking, 25min of heat preservation.

[0081] Comparative Example 3: An instant mixed grain rice and a processing method thereof

[0082] Omitting the pre-cooking step of Example 1 (i.e. step 3) to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0083] Comparative Example 4: An instant mixed grain rice and a processing method thereof

[0084] Omitting the sterilization and reverse pressure cooking step of Example 1 (i.e. step 4) to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0085] Comparative Example 5: An instant mixed grain rice and a processing method thereof

[0086] Omitting the reverse pressure pre-cooking and sterilization steps of Example 1 (i.e. steps 3, 4), using the reverse pressure cooking method reported in CN1121478A to replace steps (3), (4) of Example 1 to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0087] Among them, the specific conditions of the reverse pressure cooking method are: 7min of cooking at 0.12Mpa, 120℃, 20min of heat preservation, then increasing the pressure to 0.17Mpa, 10min of heat preservation.

[0088] Comparative Example 6: An instant mixed grain rice and a processing method thereof

[0089] Omitting the reverse pressure pre-cooking and sterilization steps of Example 1 (i.e. steps 3, 4), using the reverse pressure microwave cooking reported in CN107692031A to replace steps (3), (4) of Example 1 to obtain instant mixed grain rice products, other experimental steps are consistent with Example 1.

[0090] Among them, the specific conditions of the reverse pressure microwave cooking are: microwave intensity is 0.5kw / kg, reverse pressure is 0.21Mpa, cooking temperature is 121℃, and heat preservation time is 20min.

[0091] The texture index and in vitro simulated GI value of the instant mixed grain rice prepared by Example 1 and Comparative Examples 1-6 were determined, and the results are shown in Table 1. At the same time, the in vitro digestion curves of the samples of Example 1 and Comparative Examples 5 and 6 were determined, and the results are shown in Table 2. Figure 1 The human GI of the product of Example 1 was determined, and the results are shown in Table 3 and Figure 1. Figure 2 The human GI of the product of Example 1 was determined, and the results are shown in Table 3 and Figure 1.

[0092] Table 1: Comparison of product indexes

[0093]

[0094] As can be seen from Table 1, the average hardness value of the low GI instant mixed grain rice product prepared in Example 1 is 4.3 kgf, the average viscosity value is 0.62 kgf, the average elasticity value is 0.74 kgf, the taste is softer and more glutinous, the in vitro simulated GI value is 53.5, and the in vivo GI value is 51.2, which belongs to low GI food; the product prepared in Comparative Example 1 has obvious mixed grain undercooked phenomenon due to the fact that the raw materials are not subjected to radio frequency fast cooking treatment, and the differences in cooking time and conditions of the mixed grains result in the final product; the product prepared in Comparative Example 2 has obvious bag swelling and shrinkage deformation due to the lack of external counter pressure, and the product is obviously hard and has poor palatability; the product prepared in Comparative Example 3 has insufficient cooking due to the lack of pre-cooking process, and the product has poor palatability due to insufficient viscosity; the product prepared in Comparative Example 4 is obviously undercooked due to the lack of 121℃ intensified cooking and sterilization process; the products prepared in Comparative Examples 5 and 6 both use counter pressure technology, but the products have problems of hard or unevenly soft and rotten taste, and insufficient viscoelasticity of the mixed grains, and cannot achieve low GI. In summary, the product prepared in Example 1 has the best palatability and achieves low GI, and the radio frequency fast cooking treatment of the raw materials, counter pressure pre-cooking and counter pressure cooking and sterilization steps in the preparation process are the core and key steps and cannot be omitted, and Comparative Examples 2-6 cannot achieve this effect, which shows that the counter pressure sterilization technology and counter pressure microwave cooking technology reported at present are not suitable for the processing of low GI instant mixed grain rice.

[0095] Example 2: Determination of the conditions of radio frequency fast cooking treatment of highland barley, oat, buckwheat and brown rice

[0096] Brown rice was used as the treatment object, and the pre-experiment was carried out to determine the plate spacing parameters of the radio frequency system, and the method steps were as follows:

[0097] (1) 1000 g of brown rice was selected, and the stones, soil blocks, foreign particles, insect damaged particles, imperfect particles, broken particles and diseased particles in the raw materials were removed to obtain pretreated raw materials;

[0098] (2) The mixed grains obtained in step (1) were soaked in water for 10 min, drained, and spread on a conveyor belt with a thickness of 1 cm.

[0099] (3) Start the radio frequency system, and send the drained and leveled miscellaneous grains in step (2) into the radio frequency cavity through the conveying belt, the plate spacing of the radio frequency system is set to 5, 10, 15, 20, and 25 cm respectively, the radio frequency temperature is set to 110℃, the radio frequency time is set to 6 min, experiments are carried out respectively, and the sample cooking time is measured respectively, and the results are shown in Table 2.

[0100] Table 2 Cooking time of brown rice treated by radio frequency with different plate spacing

[0101]

[0102] As shown in Table 2, when the plate spacing is in the range of 5-15 cm, the cooking time of brown rice is significantly shortened, and the effect of cooking and ripening with rice is achieved. When the plate spacing is 20 cm and 25 cm, the treatment effect is not ideal, although the cooking time is slightly shortened, but it cannot achieve the effect of cooking and ripening with rice. Therefore, the plate spacing setting range should be 5-15 cm, and the optimal plate spacing is 15 cm considering the equipment capacity.

[0103] The method for determining the quick cooking treatment parameters of each miscellaneous grain raw material comprises the following process steps:

[0104] (1) Select 1000g of highland barley, oat, buckwheat and brown rice respectively, remove stones, soil blocks, foreign particles, insect damaged particles, imperfect particles, damaged particles and diseased particles in the raw materials to obtain pretreated raw materials;

[0105] (2) Soak the miscellaneous grains obtained in step (1) in water for 10 minutes respectively, drain and spread on the conveying belt with a thickness of 1 cm;

[0106] (3) Start the radio frequency system, and according to the pre-experiment results, the plate spacing is fixed at 15 cm, the drained and leveled miscellaneous grains in step (2) are sent into the radio frequency cavity through the conveying belt, the radio frequency temperature is set to 90℃, 100℃, 110℃, 120℃ and 130℃ respectively, and the radio frequency time is set to 3 min, 4 min, 5 min, 6 min and 7 min respectively, and experiments are carried out respectively;

[0107] Take untreated raw materials and quick-cooked miscellaneous grains under different conditions to measure their cooking time and texture index, and the measurement results are shown in Tables 3-11.

[0108] Table 3 Cooking time of different untreated miscellaneous grain raw materials and rice

[0109]

[0110] Table 4 Cooking time of different miscellaneous grains under 90℃ condition with radio frequency time

[0111]

[0112] Table 5 Changes of cooking time of different coarse cereals with radio frequency time under 100℃

[0113]

[0114] Table 6 Changes of cooking time of different coarse cereals with radio frequency time under 110℃

[0115]

[0116] Table 7 Changes of cooking time of different coarse cereals with radio frequency time under 120℃

[0117]

[0118] From Tables 3-7, it can be seen that the radio frequency temperature setting of 90℃ cannot achieve the effect of rapid cooking of coarse cereals, and the cooking time is even prolonged. The main reason is that the temperature of 90℃ mainly plays a drying role, making the internal structure of coarse cereals more compact, and thus more difficult to cook. The radio frequency treatment of 100℃ reduces the cooking time, but it is not obvious. The radio frequency treatment of 110℃ significantly shortens the cooking time of different coarse cereals. The cooking time of brown rice and buckwheat is basically close to that of rice at 6min, but the texture of highland barley and oat with tough skin is still longer. The radio frequency treatment of 120℃ significantly shortens the cooking time of different coarse cereals. The cooking time of brown rice and buckwheat is 4-5min, and the cooking time of highland barley and oat is 5-6min, which is basically close to 30min, achieving the effect of cooking and cooking together with rice. Considering comprehensively, the best rapid cooking conditions of brown rice and buckwheat are 120℃ and 4min, and the best rapid cooking conditions of highland barley and oat are 120℃ and 5min.

[0119] Table 8 Cooking time, hardness value, viscosity value and elasticity value of brown rice treated at 120℃ for 4min

[0120]

[0121] Table 9 Cooking time, hardness value, viscosity value and elasticity value of buckwheat treated at 120℃ for 4min

[0122]

[0123] Table 10 Cooking time, hardness value, viscosity value and elasticity value of highland barley treated at 120℃ for 5min

[0124]

[0125] Table 11 Cooking time, hardness value, viscosity value and elasticity value of oat treated at 120℃ for 5min

[0126]

[0127] From Tables 8-11, it can be seen that the brown rice treated at 120°C for 4 min has an average reduction of 22.2% in cooking time, an average reduction of 40.3% in hardness value, an average increase of 69.2% in viscosity value, and an average increase of 22.8% in elasticity value; the buckwheat treated at 120°C for 4 min has an average reduction of 17.8% in cooking time, an average reduction of 41.2% in hardness value, an average increase of 66.7% in viscosity value, and an average increase of 16.4% in elasticity value; the highland barley treated at 120°C for 5 min has an average reduction of 33.0% in cooking time, an average reduction of 51.6% in hardness value, an average increase of 52.6% in viscosity value, and an average increase of 58.3% in elasticity value; and the oat treated at 120°C for 5 min has an average reduction of 30.9% in cooking time, an average reduction of 46.3% in hardness value, an average increase of 67.5% in viscosity value, and an average increase of 36.8% in elasticity value. In summary, after the RF fast cooking treatment, the cooking time of the coarse cereals is reduced by an average of 17%-33%, the hardness value is reduced by an average of 40%-52%, the viscosity value is increased by an average of 52%-69%, and the elasticity value is increased by an average of 16%-58%. The indicators of the treated coarse cereals are close to those of rice, achieving the effect of cooking and ripening together with rice.

[0128] Example 3: Determination of the formula of low-GI instant coarse cereal rice

[0129] A low-GI instant coarse cereal rice is developed to determine the formula proportion of coarse cereals, rice, and konjac rice through pre-experiments. First, gradient cooking experiments are carried out with rice and different coarse cereals to determine the overall proportion of coarse cereals in the formula based on the influence of hardness value on the palatability of the product. Second, konjac rice is used to replace part of the rice, and cooking experiments are carried out under the condition of the determined overall proportion of coarse cereals to further determine the proportion of rice and konjac rice in the formula. The experimental results are shown in Tables 12 and 13.

[0130] Table 12 Influence of coarse cereal proportion on product sensory

[0131]

[0132] Table 13 Influence of rice and konjac rice proportion on product sensory

[0133]

[0134] From the results of Table 12, it can be seen that, whether it is single grain or mixed grain, when the proportion of grain in the formula is higher than 75%, the hardness value of the product will increase significantly, and the palatability will become poor. Considering the product taste and product characteristics comprehensively, the overall proportion of grain in the formula is determined to be 75%. From the results of Table 13, it can be seen that, with the increase of the substitution ratio of konjac rice in rice, the hardness value of the product shows an upward trend. When the ratio of rice to konjac rice is higher than 4:1, the hardness value of the product has no significant difference. When it is lower than 4:1, the hardness value of the product increases significantly, and the palatability becomes poor. Considering the product taste and product characteristics comprehensively, the proportions of rice and konjac rice in the formula are determined to be 20% and 5% respectively.

[0135] According to the pre-experiment, the addition amount of rice in the formula is determined to be 20%, the addition amount of konjac rice is 5%, and the total proportion of barley, oat, brown rice and buckwheat is 75%. With the addition amount of barley, oat, brown rice and buckwheat after quick cooking treatment as factors, a four-factor three-level orthogonal optimization test design is carried out. According to the standards shown in Table 14, the comprehensive scores are determined from five dimensions of smell, appearance structure, palatability, taste and texture to determine the optimal formula. The results are shown in Tables 15 and 16.

[0136]

[0137] Table 14 Sensory evaluation table of grain rice

[0138] Table 15 Orthogonal test factor and level design

[0139]

[0140] The orthogonal optimization screening test design of the low GI instant grain rice components is carried out. The results are shown in Table 16.

[0141] Table 16 Analysis results of orthogonal optimization experiment

[0142]

[0143] From the range R in Table 16, R A > R D > R C > R B Therefore, the primary and secondary relationships of the factors affecting the comprehensive score of the formula are as follows: barley > brown rice > buckwheat > oat. The best combination of the experimental results is A2B2C2D2, i.e. the best formula is barley: oat: buckwheat: brown rice: rice: konjac rice = 20:30:15:10:20:5.

[0144] Example 4: Determination of rice-water ratio parameter

[0145] Except for changing the ratio of rice to water in step (3), the other experimental steps are consistent with Example 1, and a low GI instant mixed grain rice is prepared. The best ratio of rice to water is determined by sensory evaluation from the aspects of smell, color, softness, elasticity, viscosity, taste, and cold rice texture, etc. The results are shown in Table 17 and Figure 3

[0146] Table 17 Sensory evaluation of products under different conditions of the ratio of rice to water

[0147]

[0148] As can be seen from the results in Table 17, with the decrease of the ratio of rice to water, the sensory evaluation of the mixed grain rice shows a trend of first increasing and then decreasing. The product has higher palatability when the ratio of rice to water is 1:1.5 to 1:1.7, and the best ratio of rice to water is 1:1.6. The hardness of the samples under different conditions is measured, and the results are shown in Table 18. Figure 3 Figure 3 As can also be seen, the hardness of the product shows a downward trend with the change of the ratio of rice to water, and the hardness that is too high or too low will affect the palatability of the product. The best hardness of the product is about 4.4 kgf. In summary, the best ratio of rice to water is 1:1.6.

[0149] Example 5: Determination of the parameters of the reverse pressure process

[0150] Except for changing the pre-maturation reverse pressure parameters, pre-maturation time, maturation sterilization reverse pressure parameters, and maturation sterilization time in steps (3) and (4), the other experimental steps are consistent with Example 1. The pre-maturation temperature is set to 100±1℃, and the maturation sterilization temperature is set to 121±1℃. The pre-maturation reverse pressure parameters, pre-maturation time, maturation sterilization reverse pressure parameters, and maturation sterilization time are used as factors for a four-factor three-level orthogonal optimization test design. The best process parameters are determined by sensory evaluation from the aspects of product appearance (whether the bag is inflated, broken, or shrunk), smell, color, softness, elasticity, viscosity, taste, and cold rice texture, etc.

[0151] Table 18 Design of orthogonal test factors and levels

[0152]

[0153] The orthogonal optimization screening test design of the reverse pressure process of the low GI instant mixed grain rice components is shown in Table 19, and the statistical results of the inflation rate and shrinkage deformation rate of the samples in the process are shown in Table 20.

[0154] Table 19 Analysis results of the orthogonal optimization experiment

[0155]

[0156] Table 20 Inflation rate and shrinkage rate of samples under different experimental conditions ​​

[0157]

[0158] From the range value R in Table 19, we can see that R C >R D >R A >R B Therefore, the order of importance of the factors affecting the overall score of the formula is as follows: maturation sterilization back pressure > maturation sterilization time > pre-maturation back pressure > pre-maturation time. The optimal combination of experimental results is A1B2C3D2, that is, the optimal process combination of back pressure pre-maturation and back pressure maturation sterilization is: pre-maturation back pressure set to 0.1 MPa, pre-maturation time set to 20 min, maturation sterilization back pressure set to 0.18 MPa, and maturation sterilization time set to 35 min.

[0159] As shown in Table 20, under a back pressure of 0.14 MPa for sterilization, 5-10% of the samples in experiments 1, 6, and 8 experienced bag bulging, while the remaining samples showed varying degrees of shrinkage. This indicates that the back pressure of 0.14 MPa for sterilization was significantly insufficient, leading to violent expansion during the high-temperature treatment and even bag bulging or rupture. Unruptured samples experienced shrinkage of the retort pouch due to rapid cooling, affecting the product's sensory characteristics. Under a back pressure of 0.16 MPa for sterilization, samples in experiments 2, 4, and 9 all showed varying degrees of shrinkage, indicating that the back pressure of 0.16 MPa was also insufficient, leading to violent expansion during the high-temperature treatment and shrinkage of the retort pouch due to rapid cooling, affecting the product's sensory characteristics. Under a back pressure of 0.18 MPa for sterilization, the sensory characteristics of samples in experiments 3, 5, and 7 were unaffected, indicating that the optimal back pressure for sterilization was 0.18 MPa.

[0160] Example 6: Determination of Cooling Method and Parameters

[0161] After processing according to the optimal formula, optimal rapid cooking process, and optimal back-pressure pre-cooking and cooking sterilization process in Example 1, the mixture was cooled using a circulating water cooling method. The back-pressure parameters were kept constant, and circulating cooling water was introduced. Cooling was performed for 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min, respectively, and the temperature inside the pot was measured using a sensor. The results are as follows: Figure 4 As shown.

[0162] Depend on Figure 4 It can be seen that the temperature inside the pot reaches 45℃ after 7 minutes of circulating water cooling. Under this temperature condition, opening the lid will result in a suitable temperature that will not cause burns to the human body. In addition, considering energy consumption and water consumption, the optimal cooling time is determined to be 7 minutes. The cooling effect under this condition is compared with that of traditional cooling methods, as shown in Table 21.

[0163] Table 21 Comparison of the effects of different cooling methods

[0164]

[0165] From the comparison results in Table 21, it can be seen that the circulating water bath cooling method can greatly shorten the cooling time, shorten the production cycle and reduce the time cost.

[0166] The above-described specific embodiments further specifically describe the technical problems solved by the present application, technical solutions and beneficial effects. It should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A processing method for low-GI instant mixed grain rice, characterized in that, The method includes the following steps: (1) Raw material pretreatment; (2) Radio frequency rapid cooking: The pre-treated grains obtained in step (1) are subjected to rapid cooking treatment using radio frequency system equipment, so that the grains achieve the effect of rapid cooking; (3) Back pressure pre-cooking: After the grains in step (2) radio frequency cooking are processed, water is added according to the ratio and they are packaged into high temperature cooking bags and sealed. Then they are placed in a vertical back pressure sterilizer and water is added until the liquid level covers the surface of the cooking bag. Back pressure parameters, pre-cooking temperature parameters and pre-cooking time are set for back pressure pre-cooking treatment. The back pressure pre-cooking temperature is 100±1℃, the external back pressure is 0.1Mpa, and the back pressure pre-cooking time is 20min. (4) Back pressure cooking and sterilization: After the back pressure pre-cooking treatment in step (3) is completed, the back pressure parameters, cooking and sterilization temperature parameters, and cooking and sterilization time are reset for further cooking and sterilization treatment; (5) Circulating water cooling: Connect to circulating water and cool to obtain low-GI ready-to-eat mixed grain rice products.

2. The method according to claim 1, characterized in that, In step (4), the back pressure cooking and sterilization temperature is 121±1℃, the applied back pressure is 0.15~0.20Mpa, and the back pressure cooking and sterilization time is 20~60min.

3. The method according to claim 1, characterized in that, In step (1), the specific process involves selecting whole grains, removing solid impurities, foreign grains, insect-damaged grains, imperfect grains, broken grains, and diseased grains from the raw materials, and then washing them to remove surface dust to obtain pre-treated grains. The grains are barley, oats, buckwheat, brown rice, and konjac rice, with barley accounting for 20%, oats accounting for 30%, buckwheat accounting for 15%, brown rice accounting for 10%, rice accounting for 20%, and konjac rice accounting for 5%.

4. The method according to claim 1, characterized in that, In step (2), the radio frequency curing temperature is 120℃, the radio frequency time is 3~10min, and the electrode spacing is 5~15cm.

5. The method according to claim 4, characterized in that, The electrode spacing is 15cm.

6. The method according to claim 1, characterized in that, In step (2), the radio frequency ripening conditions for barley and oats are 120°C for radio frequency and 5 min for radio frequency, while the conditions for brown rice and buckwheat are 120°C for radio frequency and 4 min for radio frequency.

7. The method according to claim 1, characterized in that, In step (3), the ratio of grains to water is 1: (1.5~1.7).

8. The method according to claim 1, characterized in that, The specific step (5) is as follows: after the back pressure cooking and sterilization in step (4) is completed, the back pressure parameters are kept unchanged, circulating water is connected, the water circulation cooling time is set until the temperature drops below 45°C, the vertical back pressure sterilization pot is opened, and a low-GI ready-to-eat mixed grain rice product is obtained; wherein, the cooling method used is the circulating water cooling method, and the cooling time is 3~10min.

9. A low-GI instant mixed grain rice, characterized in that, It is prepared by the method described in any one of claims 1-8.

Images