Method for improving digestion resistance of rice based on endogenous protein distribution regulation and control technology

Abstract

The invention discloses a method for improving the digestion resistance of rice based on an endogenous protein distribution regulation and control technology. Comprising the following steps: A, soaking rice and water according to a certain proportion; b, draining the unhulled rice obtained in the step A, and cooking; c, freezing the unhulled rice obtained in the step B at low temperature; d, drying the rice obtained in the step C at high temperature; and E, unshelling, milling, grinding and sieving the unhulled rice obtained in the step D, and measuring the contents of the fast digestible starch, the slow digestible starch and the resistant starch in the rice. According to the invention, the content of slowly digestible starch and resistant starch in the rice is effectively increased by a simple, effective, low-cost, convenient and feasible method, and the effect of reducing the content of rapidly digestible starch in the rice is achieved by regulating the distribution of endogenous proteins in the rice through the generation and sublimation of ice crystals in a low-temperature freezing and high-temperature drying combined process for the first time; the digestion resistance of the rice is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of food technology, in particular to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology. Background Art

[0002] Rice is mainly consumed in the form of polished white rice. Due to over-processing, polished white rice not only loses nutrients seriously, but also the starch is digested quickly after entering the human body, resulting in a rapid increase in blood sugar after a meal, which is not conducive to blood sugar homeostasis and human health. In order to improve the resistance of rice to digestion, rice is usually treated specifically to increase its slowly digestible starch and resistant starch content to achieve the purpose of a balanced diet. The starch digestion process refers to the digestion and hydrolysis of starch under the action of digestive enzymes, which is divided into three stages: enzyme diffusion stage, enzyme binding stage and enzyme hydrolysis stage, among which the enzyme binding stage is the main stage that affects the starch digestion characteristics. According to the classification of traditional nutrition, starch in food can be divided into three categories according to its digestion characteristics in the human body: rapidly digestible starch (RDS), which is quickly digested and absorbed in the mouth, duodenum and near the small intestine within 20 minutes and causes blood sugar to rise. The rapid increase in blood sugar levels may cause damage to some cells, tissues and organs; slowly digestible starch (SDS), which is slowly digested in the small intestine within 20 to 120 minutes, so that the postprandial blood sugar response will not rise rapidly but rise slowly, and can continuously and slowly release energy, reduce the secretion of postprandial insulin, improve the postprandial blood sugar load, and help control the complications of patients with type 2 diabetes; resistant starch (RS), starch that cannot be digested and absorbed in the human small intestine after 120 minutes, enters the large intestine and is fermented by the internal flora of the large intestine to produce short-chain fatty acids, thereby promoting intestinal health.

[0003] At present, the technology for improving the digestion resistance of rice mainly combines exogenous substances such as polysaccharides or polyphenols with starch, changes the molecular structure of starch by adding debranching enzymes or by extrusion, ultrasound, microwave, and high-pressure treatment, but pays little attention to the effect of endogenous proteins on starch digestion characteristics. The protein content in rice is about 6% to 9%, mainly filled between starch particles in the form of independent protein bodies. The present invention uses low-temperature freezing combined with high-temperature drying process for the first time to regulate protein distribution to achieve the purpose of increasing the content of slowly digestible starch and resistant starch. Ice crystals are rapidly generated during low-temperature freezing, and ice crystals are rapidly sublimated during high-temperature drying. The action of ice crystals destroys a large number of hydrogen bonds in the secondary structure of proteins, increases the hydrophobic interaction that maintains the three-dimensional structure of proteins, and breaks the disulfide bonds that maintain the stability of proteins, resulting in the destruction of the three-dimensional structure of proteins, protein denaturation, and stretching and opening of peptide chains. At the same time, starch and protein peptide chains attract and bind to each other through electrostatic interactions, hydrophobic forces, van der Waals forces, and hydrogen bonds to form a complex. Due to the close combination with starch molecules, proteins are greatly retained in the subsequent rice milling process. The protein with fully destroyed structure attaches to the surface of starch granules and forms a complex with starch, which becomes a physical barrier that hinders the binding of digestive enzymes, reduces the action sites of enzymes, and thus enhances the rice's resistance to digestion. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology. The present invention effectively increases the content of slowly digestible starch and resistant starch in rice with a low-cost and simple method, and for the first time proposes a method for improving the digestion resistance of rice by regulating the distribution of endogenous proteins in rice.

[0005] The object of the present invention is achieved through the following solutions:

[0006] The present invention provides a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, comprising the following steps:

[0007] A. Wash and drain the rice and soak it in water according to a certain ratio, wherein the rice includes either non-glutinous rice or indica rice;

[0008] B. draining the rice obtained in step A and then steaming it;

[0009] C. freezing the rice obtained in step B at low temperature;

[0010] D. drying the rice obtained in step C at high temperature;

[0011] E. Shelling, milling, grinding and sieving the rice obtained in step D to obtain rice flour. If rice or rice flour is used to perform the above steps AD, the starch digestibility obtained by directly processing rice cannot be achieved. This is because rice bran contains a large amount of protein and lipid, which is closely combined with starch during the low-temperature freezing-high-temperature drying process, resulting in a large amount of retention during the rice milling process; and directly processing rice or rice flour cannot achieve this purpose.

[0012] Preferably, in step A, the mixing ratio of rice to water is 1:1.2-1.5 (w / v).

[0013] Preferably, in step A, the soaking temperature is 60-65° C., and the soaking time is 4-6 hours.

[0014] Preferably, in step B, the cooking temperature is 95-100° C. and the cooking time is 10-15 min.

[0015] Preferably, in step C, the low-temperature freezing temperature is -18 to -20°C, and the low-temperature freezing time is 12 to 15 hours.

[0016] Preferably, in step D, the high temperature drying temperature is 90-100° C., and the high temperature drying time is 11-12 hours.

[0017] Preferably, in step E, the rice is husked and then milled at a milling rate of 10% to 15%.

[0018] Preferably, in step E, the rice flour is ground into rice flour and then sieved through a 100-150 mesh screen to obtain rice flour.

[0019] Preferably, the method further comprises the step of determining the content of resistant starch in the rice after step E. Further, the content of fast-digestible starch, the content of slow-digestible starch and the content of resistant starch in the rice flour are determined.

[0020] The present invention destroys the protein structure by adding a process of low-temperature freezing combined with high-temperature drying after boiling to destroy the interaction between proteins through the formation and sublimation of ice crystals, so that the protein structure is loose, unfolded, and attached to the surface of starch particles. At the same time, the electrostatic interaction, hydrophobic force, van der Waals force and hydrogen bond force between starch and protein are promoted by the action of ice crystals to enhance the interaction between starch and protein and generate starch-protein complexes. The protein wrapped on the surface of starch particles forms a physical barrier that hinders the enzyme binding stage, reduces the action sites of digestive enzymes, and thus improves the digestion resistance of rice starch.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The method of the present invention has simple steps, is easy to implement, has high production efficiency and low operating cost;

[0023] (2) The present invention regulates the distribution of endogenous protein in rice through a low-temperature freezing-high-temperature drying process, significantly improving the digestion resistance of rice starch. The prepared rice has a lower content of rapidly digestible starch, a higher content of slowly digestible starch and resistant starch, and greatly improves the nutritional value of rice. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 This is a confocal laser scanning image of the distribution of endogenous proteins in japonica rice grains;

[0026] Figure 2 This is a confocal laser scanning image of the distribution of endogenous proteins in indica rice grains. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0028] The following examples and comparative examples relate to the determination method of fast digestible starch, slow digestible starch and resistant starch content, specifically, rice flour (500 mg, dry basis) is suspended in 10.0 g distilled water. After sufficient stirring, the starch suspension is boiled in a boiling water bath for 25 min, and the first 15 min needs to be vortexed every 1 min to prevent starch from agglomerating. After cooling, 10.0 mL of buffer, 15 glass beads and 500 mg of guar gum are added to the gelatinized sample, and the mixture is vortexed evenly and balanced in a water bath shaker at 80 rpm and 37 ° C for 15 min. 5.0 mL of freshly prepared enzyme mixture (porcine pancreatic α-amylase and amyloglucosidase) is added to the sample, and the sample tube is placed in a water bath shaker at 37 ° C and 80 rpm to start the decomposition of starch. 500 μL of the reaction solution is sampled in a 20 mL, 80% (v / v) alcohol tube after 20 min and 120 min, and the enzyme is fully vortexed to inactivate the enzyme. The alcohol tube was centrifuged at room temperature and 4000 rpm for 15 minutes, and the supernatant was taken and quantified using a D-glucose assay kit at 20 minutes and 120 minutes (G 20 , G 120 )The amount of glucose released by enzymatic hydrolysis.

[0029] The calculation formulas for the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) are as follows:

[0030]

[0031] %RS = total starch content - (%RDS + %SDS).

[0032] Rice protein was prepared from rice flour by alkali dissolution and acid precipitation. The protein sample was placed in a desiccator and dried with P2O 5 Dry and balance for more than two weeks for later use. First, take an appropriate amount of dried potassium bromide crystals and grind them into powder in a mortar. Load the powder into a tablet press and press it into a tablet. Put the tablet into a slide slot and then put it into an infrared spectrometer for analysis and reference. Then weigh 1 mg of the dried protein sample, add potassium bromide at a mass ratio of 1:100, grind it into a uniform powder in a mortar, press it into a thin sheet, and then perform full-band (400-4000cm) infrared spectrometer analysis. -1 ) scanning. Infrared spectrum processing: Origin8.5 software was used for plotting, and PeakFit v4.12 software was used for the amide I band region (1600-1700 cm -1 The spectrum of each segment was analyzed. The baseline was corrected first, and the Savitsk-Golay function was used for smoothing. Then, the Gaussian deconvolution was used, and then the second-order derivative fitting was used. The percentage of the secondary structure in each part was calculated by the area occupied by each sub-peak.

[0033] Weigh 40 mg of protein, add 4 mL of reaction buffer (containing 2.5% SDS, 92 mM glycine, 4.1 mM EDTA and 86 mM Tris-HCl, pH 8.0), homogenize for 0.5 min on a high-speed homogenizer every 10 min, repeat three times, add 0.04 mL of DTNB solution (4 mg / mL), mix quickly, react at 25°C in the dark for 30 min, and then centrifuge (20,000×g, 4°C, 15 min). Determine the absorbance of the supernatant at 412 nm, and calculate the content of free thiol groups according to the formula:

[0034] -SH (μmol / g) = 73.53 x A 412 ⅹD / C

[0035] Where: A 412 is the absorbance value at a wavelength of 412 nm; D is the dilution factor; C is the final protein content of the sample, mg / mL.

[0036] Example 1

[0037] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the steps are as follows:

[0038] Step 1: Wash the japonica rice and soak it in a ratio of rice to water (1:1.2, w / v) at a temperature of 60° C. for 4 h.

[0039] Step 2: Dry the rice soaked in step 1 under natural conditions at a temperature of 10° C. for 4 days.

[0040] Step 3: Shelling, milling and grinding the rice dried in step 2, and then passing through a 100-mesh sieve to obtain rice flour.

[0041] Step 4: Determine the fast-digestible starch content, the slow-digestible starch content and the resistant starch content of the rice flour in step 3.

[0042] Implementation effect: The rice prepared in this embodiment has a fast digestible starch content of 70.19%, a slow digestible starch content of 5.20%, and a resistant starch content of 7.69%. In the confocal laser scanning results, the protein is marked with green by Nile blue. Figure 1 It can be seen that this example shows a weaker fluorescence signal, indicating that the protein content is low. Although the protein is distributed around some starch granules, there are still many aggregates.

[0043] Example 2

[0044] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology. The method adds a cooking step on the basis of Example 1, and the steps are as follows:

[0045] Step 1: Wash the japonica rice and soak it in a ratio of rice to water (1:1.2, w / v) at a temperature of 60° C. for 4 h.

[0046] Step 2: Steam the rice soaked in step 1 at a temperature of 95° C. for 10 minutes.

[0047] Step 3: Dry the rice soaked in step 2 under natural conditions at a temperature of 10° C. for 4 days.

[0048] Step 4: Shelling, milling and grinding the rice dried in step 3, and then passing through a 100-mesh sieve to obtain rice flour.

[0049] Step 5: Determine the fast-digestible starch content, the slow-digestible starch content and the resistant starch content of the rice flour in step 4.

[0050] Implementation effect: The rice prepared in this embodiment has a fast-digestible starch content of 70.57%, a slow-digestible starch content of 3.69%, and a resistant starch content of 8.76%. The fast-digestible starch content in this embodiment is slightly lower than that in Example 1, the slow-digestible starch content is significantly lower than that in Example 1, and the resistant starch content is higher than that in Example 1. Figure 1 The confocal laser scanning results showed that the fluorescence signal of this example was enhanced compared with that of Example 1, indicating an increase in protein content. The distribution of proteins around starch granules was relatively dispersed, but there were still many protein aggregates.

[0051] Example 3

[0052] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology. The method adds a low-temperature freezing step on the basis of Example 2, and the steps are as follows:

[0053] Step 1: Wash the japonica rice and soak it in a ratio of rice to water (1:1.2, w / v) at a temperature of 60° C. for 4 h.

[0054] Step 2: Steam the rice soaked in step 1 at a temperature of 95° C. for 10 minutes.

[0055] Step 3: Immediately freeze the rice obtained by cooking in step 2 at a low temperature, with the freezing temperature being -18°C and the freezing time being 12 hours.

[0056] Step 4: Dry the rice soaked in step 3 under natural conditions at a temperature of 10° C. for 4 days.

[0057] Step 5, shelling, milling and grinding the rice dried in step 4, and then passing through a 100-mesh sieve to obtain rice flour.

[0058] Step 6: Determine the fast-digestible starch content, the slow-digestible starch content and the resistant starch content of the rice flour in step 5.

[0059] Implementation effect: The rice prepared in this embodiment has a fast-digestible starch content of 70.42%, a slow-digestible starch content of 3.02%, and a resistant starch content of 9.13%. The fast-digestible starch content and the slow-digestible starch content of this embodiment are similar to those of embodiment 2, and the resistant starch content is significantly higher than that of embodiment 2. Figure 1 The confocal laser scanning results showed that compared with Example 2, the fluorescence signal of this example was enhanced, indicating an increase in protein content, a more dispersed distribution of protein around starch granules, and a significant reduction in protein aggregation.

[0060] Example 4

[0061] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the method is the same as that of Example 3, except that;

[0062] In step 4, the drying method of the soaked polished round-grained rice is changed from sun drying under natural conditions to high-temperature drying in an oven, the drying temperature is 90° C., and the drying time is 11 h.

[0063] Implementation effect: The rice prepared in this embodiment has a fast-digestible starch content of 68.24%, a slow-digestible starch content of 4.93%, and a resistant starch content of 9.82%. The fast-digestible starch content in this embodiment is significantly lower than that in Example 3, while the slow-digestible starch content and the resistant starch content are significantly higher than those in Example 3. Figure 1 The confocal laser scanning results showed that compared with Example 3, the fluorescence signal of this example was significantly enhanced, indicating that the protein content was greatly increased, and the distribution of protein around the starch granules was obviously dispersed, showing a network structure.

[0064] Table 2 shows the changes in protein structure in rice during different treatment processes. Compared with Examples 1, 2 and 3, the α-helical structure and β-turn ratio of Example 4 are higher. Low-temperature freezing-high-temperature drying induces the transformation of β-folding and random coiled structures to α-helical β-turns. The decline in β-folding content can indicate a decrease in the number of hydrogen bonds, and hydrogen bonds are the main chemical bonds that maintain the secondary structure of proteins. The decline in its content indicates that a large number of hydrogen bonds are destroyed. The helical-folding transition buries polar groups inside the molecule and exposes hydrophobic groups, increasing hydrophobicity. Compared with Examples 1, 2 and 3, the free sulfhydryl content of Example 4 increases significantly, indicating more disulfide bond ruptures. Ice crystals are rapidly generated during low-temperature freezing, and ice crystals are rapidly sublimated during high-temperature drying. The effect of ice crystals causes a large number of hydrogen bonds in the secondary structure of proteins to be destroyed, and the hydrophobic interactions that maintain the three-dimensional structure of proteins are increased. The disulfide bonds that maintain protein stability are broken, resulting in the destruction of the three-dimensional structure of proteins, protein denaturation, and peptide chain stretching and opening.

[0065] Example 5

[0066] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the method is the same as that in Example 1, except that;

[0067] In step 1, japonica rice is replaced with indica rice.

[0068] Implementation effect: The rice prepared in this embodiment has a fast-digestible starch content of 68.70%, a slow-digestible starch content of 3.23%, and a resistant starch content of 11.73%. Figure 2The confocal laser scanning results showed that the present embodiment presented a weaker fluorescence signal, indicating that the protein content was low. Although the protein was distributed around some starch granules, there were still many aggregates.

[0069] Example 6

[0070] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the method is the same as that of Example 2, except that;

[0071] In step 1, japonica rice is replaced with indica rice.

[0072] Implementation effect: The content of fast-digestible starch in the rice prepared in this embodiment is 68.58%, the content of slow-digestible starch is 2.12%, and the content of resistant starch is 12.29%. The fast-digestible starch in this embodiment is not much different from that in Example 5, the content of slow-digestible starch is significantly lower than that in Example 5, and the content of resistant starch is higher than that in Example 5. Figure 2 The confocal laser scanning results showed that the fluorescence signal of this example was enhanced compared with that of Example 5, indicating an increase in protein content. The distribution of proteins around starch granules was relatively dispersed, but there were still many protein aggregates.

[0073] Example 7

[0074] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the method is the same as that of Example 3, except that;

[0075] In step 1, japonica rice is replaced with indica rice.

[0076] Implementation effect: The content of fast-digestible starch in the rice prepared in this embodiment is 66.87%, the content of slow-digestible starch is 4.14%, and the content of resistant starch is 12.45%. The content of fast-digestible starch in this embodiment is significantly lower than that in Example 6, while the content of slow-digestible starch and resistant starch is higher than that in Example 6. Figure 2 The confocal laser scanning results showed that compared with Example 6, the fluorescence signal of this example was enhanced, indicating an increase in protein content, a more dispersed distribution of protein around starch granules, and a significant reduction in protein aggregation.

[0077] Example 8

[0078] This embodiment relates to a method for improving the digestion resistance of rice based on endogenous protein distribution regulation technology, and the method is the same as that of Example 4, except that;

[0079] In step 1, japonica rice is replaced with indica rice.

[0080] Implementation effect: The content of fast-digestible starch in the rice prepared in this embodiment is 63.50%, the content of slow-digestible starch is 5.88%, and the content of resistant starch is 12.94%. The content of fast-digestible starch in this embodiment is significantly lower than that in Example 7, while the content of slow-digestible starch is significantly higher than that in Example 7, and the difference in resistant starch is not much. Figure 2 The confocal laser scanning results showed that compared with Example 7, the fluorescence signal of this example was significantly enhanced, indicating that the protein content was greatly increased, and the distribution of protein around the starch granules was the most dispersed, showing a network structure that tightly wrapped the starch granules.

[0081] Comparative Example 1

[0082] This comparative example relates to a method for improving the digestion resistance of rice, and the steps are as follows:

[0083] Step 1: Shell the washed polished japonica rice, mill it, grind it, and pass it through a 100-mesh sieve to obtain rice flour.

[0084] Step 2: Determine the fast-digestible starch content, the slow-digestible starch content and the resistant starch content of the rice flour in step 1.

[0085] Implementation effect: The content of fast-digestible starch in the rice prepared in this comparative example is 79.09%, the content of slow-digestible starch is 4.00%, and the content of resistant starch is 5.02%. The content of fast-digestible starch in this comparative example is significantly higher than that in Example 4, while the content of resistant starch is significantly lower than that in Example 4. Figure 1 The confocal laser scanning results showed that compared with Example 4, this comparative example showed almost no fluorescent signal, indicating that the protein content was low, the protein was obviously aggregated, and the wrapping effect on the starch granules could not be observed.

[0086] Comparative Example 2

[0087] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 4, except that:

[0088] In step 3, the low-temperature freezing is changed to relatively low-temperature refrigeration, the refrigeration temperature is 4°C, and the refrigeration time is 12 hours.

[0089] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 70.48%, a slow-digestible starch content of 3.62%, and a resistant starch content of 9.24%. The fast-digestible starch content of this example is slightly higher than that of Example 4, while the resistant starch content is slightly lower than that of Example 4. Figure 2 ,The confocal laser scanning results showed that compared with Example 4, the fluorescence signal of this comparative example was ,lower, indicating that the protein content was lower and the protein was more ,aggregated.

[0090] Comparative Example 3

[0091] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 4, except that:

[0092] In step 3, the low-temperature freezing is changed to ultra-low-temperature freezing, the freezing temperature is -40°C, and the freezing time is 12 hours.

[0093] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 69.88%, a slow-digestible starch content of 4.21%, and a resistant starch content of 9.46%. The fast-digestible starch content of this example is slightly higher than that of Example 4, while the resistant starch content is slightly lower than that of Example 4. Figure 2 The confocal laser scanning results show that there is no significant difference between this comparative example and Example 4. However, compared with Example 4, this comparative example has higher energy consumption and higher cost.

[0094] Comparative Example 4

[0095] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 4, except that:

[0096] In step 4, high temperature drying is changed to low temperature drying, the drying temperature is 60° C., and the drying time is 11 h.

[0097] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 70.05%, a slow-digestible starch content of 3.81%, and a resistant starch content of 9.31%. The fast-digestible starch content of this example is slightly higher than that of Example 4, while the resistant starch content is slightly lower than that of Example 4. Figure 2 ,The confocal laser scanning results showed that compared with Example 4, the fluorescence signal of this comparative example was ,lower, indicating that the protein content was lower and the protein was more ,aggregated.

[0098] Comparative Example 5

[0099] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of comparative example 1, except that:

[0100] In step 1, japonica rice is replaced with indica rice.

[0101] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 72.61%, a slow-digestible starch content of 3.26%, and a resistant starch content of 9.89%. The fast-digestible starch content of this example is significantly higher than that of Example 8, while the resistant starch content is significantly lower than that of Example 8. Figure 2 The confocal laser scanning results showed that compared with Example 8, this comparative example showed almost no fluorescent signal, indicating that the protein content was low, the protein was obviously aggregated, and the wrapping effect on the starch granules could not be observed.

[0102] Comparative Example 6

[0103] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 8, except that:

[0104] In step 3, the low-temperature freezing is changed to relatively low-temperature refrigeration, the refrigeration temperature is 4°C, and the refrigeration time is 12 hours.

[0105] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 68.05%, a slow-digestible starch content of 3.89%, and a resistant starch content of 10.01%. The fast-digestible starch content of this example is slightly higher than that of Example 8, while the resistant starch content is slightly lower than that of Example 8. Figure 2 ,The confocal laser scanning results showed that the fluorescence signal of this comparative example was lower than that of Example 8, indicating that the protein content was lower and the protein was more aggregated.

[0106] Comparative Example 7

[0107] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 8, except that:

[0108] In step 3, the low-temperature freezing is changed to ultra-low-temperature freezing, the freezing temperature is -40°C, and the freezing time is 12 hours.

[0109] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 64.88%, a slow-digestible starch content of 5.29%, and a resistant starch content of 11.88%. The fast-digestible starch content of this example is slightly higher than that of Example 8, while the resistant starch content is slightly lower than that of Example 8. Figure 2 , the confocal laser scanning results show that there is no significant difference between this comparative example and Example 8. However, compared with Example 8, this comparative example has higher energy consumption and higher cost.

[0110] Comparative Example 8

[0111] This comparative example relates to a method for improving the digestion resistance of rice, which is the same as that of Example 8, except that:

[0112] In step 4, high temperature drying is changed to low temperature drying, the drying temperature is 60° C., and the drying time is 11 h.

[0113] Implementation effect: The rice prepared in this comparative example has a fast-digestible starch content of 66.36%, a slow-digestible starch content of 4.35%, and a resistant starch content of 11.29%. The fast-digestible starch content of this example is slightly higher than that of Example 8, while the resistant starch content is slightly lower than that of Example 8. Figure 2,The confocal laser scanning results showed that the fluorescence signal of this comparative example was lower than that of Example 8, indicating that the protein content was lower and the protein was more aggregated.

[0114] Table 1 In vitro digestibility of japonica rice and indica rice after different treatments

[0115]

[0116] Different letters in the same column (same rice variety) represent significant differences (p<0.05).

[0117] Table 2 Structural changes of proteins in japonica rice and indica rice after different treatments

[0118]

[0119]

[0120] Different letters in the same column (same rice variety) represent significant differences (p<0.05).

[0121] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for improving rice digestion resistance based on endogenous protein distribution regulation technology, the method comprising the following steps: A. washing and draining the rice and then soaking it in water according to a certain ratio, wherein the rice comprises at least one of polished round-grained rice and indica rice; B. draining the rice obtained in step A and then steaming it; C. freezing the rice obtained in step B at low temperature; D. drying the rice obtained in step C at high temperature; E. Shelling, milling, grinding and sieving the rice obtained in step D to obtain rice flour.

2. The method for improving rice digestion resistance based on endogenous protein distribution regulation technology according to claim 1, characterized in that: In step A, rice and water are mixed at a ratio of w / v=1:1.2-1.

5.

3. The method for improving rice digestion resistance based on endogenous protein distribution regulation technology according to claim 1, characterized in that, In step A, the soaking temperature is 60-65° C., and the soaking time is 4-6 hours.

4. The method for improving rice digestion resistance based on endogenous protein distribution regulation technology according to claim 1, characterized in that: In step B, the cooking temperature is 95-100° C. and the cooking time is 10-15 minutes.

5. The method for improving rice digestion resistance based on endogenous protein distribution regulation technology according to claim 1, characterized in that: In step C, the low-temperature freezing temperature is -18 to -20°C, and the low-temperature freezing time is 12 to 15 hours.

6. The method for improving rice digestion resistance based on endogenous protein distribution regulation technology according to claim 1, characterized in that: In step D, the high temperature drying temperature is 90-100° C., and the high temperature drying time is 11-12 hours.

7. The method for regulating the distribution of endogenous proteins to improve the digestion resistance of rice according to claim 1, characterized in that: In step E, the rice is husked and then milled at a milling rate of 10% to 15%.

8. The method for regulating the distribution of endogenous proteins to improve the digestion resistance of rice according to claim 1, characterized in that: In step E, the rice flour is ground into rice flour and then sieved through a 100-150 mesh screen to obtain rice flour.

9. The method for regulating the distribution of endogenous proteins to improve the digestion resistance of rice according to claim 1, characterized in that: The method further comprises the step of determining the content of resistant starch in the rice after step E.

10. The method for regulating the distribution of endogenous proteins to improve the digestion resistance of rice according to claim 9, characterized in that: The contents of rapidly digestible starch, slowly digestible starch and resistant starch in rice flour were determined.

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