Preparation of Recombinant Rice with Low Glycemic Index from a Raw Material of Resistant Starch

Abstract

The present disclosure disclosed is a preparation method for low glycemic index resistance starch recombinant rice, which belongs to the technical field of food. The method of the present disclosure is as follows: after starch and lipid in an alcohol aqueous system are complexed under low temperature, variable-temperature crystallization is performed, so that a low glycemic index resistance starch is prepared, and then, with the low glycemic index resistance starch as a main material, low glycemic index recombinant rice is prepared by the extrusion technique. The low glycemic index resistance starch prepared by utilizing the method of the present disclosure has the functions of controlling postprandial blood glucose, protecting and transporting fatty acid, retarding starch retrogradation and so on. The low glycemic index recombinant rice prepared by utilizing the method of the present disclosure is suitable for being eaten by patients with type II diabetes.

Claims

1. A preparation method for low glycemic index resistance starch, comprising: dispersing rice starch into an ethanol solution A to obtain a starch solution; the starch solution being subjected to a first incubation under 35 C. to 50 C. and adding an NaOH solution to the starch solution for conducting a first reaction to obtain a reaction mixture A; dissolving fatty acid in an ethanol solution B to a fatty acid solution; preheating the fatty acid solution under 45 C. to 55 C., and then adding it into the reaction mixture A for conducting a second reaction to obtain a reaction mixture B; regulating a pH of the reaction mixture B to become neutral and then cooling the reaction mixture B to obtain a cooled reaction mixture B; and the cooled reaction mixture B being subjected to a second incubation under 20 C. to 30 C., and then conducting post-processing to obtain a low glycemic index starch-lipid complexed resistance starch.

2. The preparation method according to claim 1, wherein a volume percentage concentration of the ethanol solution A is 50% to 60%.

3. The preparation method according to claim 1, wherein a mass volume concentration of the starch solution is 15% to 25%.

4. The preparation method according to claim 1, wherein the first incubation is conducted in a 35-50 C. thermostatic water bath oscillator; and the time of the first reaction is 20 to 30 minutes.

5. The preparation method according to claim 1, wherein a speed of adding the NaOH solution is 1 mL/min to 3 mL/min; and a concentration of the NaOH solution is 0.5 mol/L to 1.5 mol/L.

6. The preparation method according to claim 1, wherein a ratio of starch mass to NaOH mass to ethanol volume in the reaction mixture A is 1.0 g:(0.3-0.5) g:(2.4-3.3) mL.

7. The preparation method according to claim 1, wherein mass of the fatty acid is 5% to 15% of mass of the rice starch.

8. The preparation method according to claim 1, wherein a volume percentage concentration of the ethanol solution B is 60% to 70%.

9. The preparation method according to claim 1, wherein a ratio of starch mass to fatty acid mass to NaOH mass to ethanol volume in the reaction mixture B is 1 g:(0.05-0.15) g:(0.3-0.5) g:(2:0-3.6) mL.

10. The preparation method according to claim 1, wherein the preheating is conducted in a 45-55 C. thermostatic water bath; and the time of the preheating is 3 to 10 minutes.

11. The preparation method according to claim 1, wherein a speed of adding the fatty acid solution into the reaction mixture A is 0.2 mL/min to 0.5 mL/min.

12. The preparation method according to claim 1, wherein the time of the second reaction is 45 to 90 minutes.

13. The preparation method according to claim 1, wherein the second incubation is conducted in a 20-30 C. water bath; and the time of the second incubation is 0.5 to 1 hour.

14. A low glycemic index resistance starch prepared by applying the preparation method for low glycemic index resistance starch according to claim 1.

15. A method for preparing food, drugs and health-care products, characterized by adopting the low glycemic index resistance starch according to claim 14 as a material.

16. A preparation method for low glycemic index recombinant rice by using the low glycemic index resistance starch according to claim 14.

17. The preparation method according to claim 16, comprising: mixing rice flour, the low glycemic index resistance starch, soybean polysaccharide, propylene glycol alginate, sodium alginate and xanthan gum to obtain extruded material powder; adding water to the extruded material powder and blending them to obtain extruded material slurry; sending the extruded material slurry into an extruder; and performing extrusion granulation while a temperature is controlled, thereby obtaining the low glycemic index convenient rice.

18. The preparation method according to claim 17, wherein a mass ratio of the rice flour to the low glycemic index resistance starch to the soybean polysaccharide to the propylene glycol alginate to the sodium alginate to the xanthan gum is (50-70):(35-50):(0.25-0.75):(0.1-0.2):(0.1-0.2):(0.2-0.4).

19. Low glycemic index recombinant rice prepared by using the preparation method according to claim 17.

Description

DETAILED DESCRIPTION

[0103] An assay method involved in the following examples is as follows:

[0104] Determination of resistant starch content (adopting the Englyst method):

[0105] 200 mg of sample is weighed and put into a 50 mL centrifuge tube, 2 mL of water is added, and after uniform blending, the blend is put into a 37 C. thermostatic water bath and oscillated (rotational speed: 160 rpm); the blend is added with 4 mL of pepsin solution (containing 0.5 g of pepsin and 0.5 g of guar gum dispersed in 100 mL of 5 mol/L hydrochloric acid solution) to react for 30 minutes, five glass beads and 2 mL of 0.5 mol/L sodium acetate solution (pH=5.2) are then added into each testing centrifuge tube, and oscillation is continued for 30 minutes; 2 mL of mixed enzyme solution (8 g of pancreatin and 1.96 mL of glucoamylase (260 U/mL) dispersed in 44.8 mL of water) is then added, and after 120 minutes of hydrolysis, 0.1 mL of sample is extracted and added into 0.9 mL of 90% ethanol to inactivate enzyme; after 5 minutes of centrifuging at 10000 g, supernate is extracted, a glucose oxidase kit (GOD-POD) is adopted to determine the content of glucose with water without sample as a blank sample, parallel determination is conducted for each sample three times, and a mean value is obtained.

[0106] Resistant starch (RS) is starch which cannot be digested and absorbed by the small intestine within 120 minutes, and the specific formula is as follows:

RS %=(TGG.sub.120)0.9100%/TS

[0107] In the formula, G.sub.120 is glucose/mg released after 120 minutes of enzymolysis, TG is total glucose/mg in the sample, and TS is the dry basis mass/mg of total starch in the sample.

[0108] Determination of in-vitro simulated glycemic index (adopting the Goni method):

[0109] 200 mg of sample is weighed and put into a 50 mL centrifuge tube, 2 mL of water is added, and after uniform blending, the blend is put into a 37 C. thermostatic water bath and oscillated (rotational speed: 160 rpm); the blend is added with 4 mL of pepsin solution (containing 0.5 g of pepsin and 0.5 g of guar gum dispersed in 100 mL of 5 mol/L hydrochloric acid) to react for 30 minutes, five glass beads and 2 mL of 0.5 mol/L sodium acetate solution (pH=5.2) are then added into each testing centrifuge tube, and oscillation is continued for 30 minutes; 2 mL of mixed enzyme solution (8 g of pancreatin and 1.96 mL of glucoamylase (260 U/mL) dispersed in 44.8 mL of water) is then added, and time is accurately counted; after 0, 30, 60, 90, 120 and 180 minutes of oscillation for hydrolysis, 0.1 mL of sample is extracted and added into 0.9 mL of 90% ethanol to inactivate enzyme; after 5 minutes of centrifuging at 10000 g, supernate is extracted, a glucose oxidase kit (GOD-POD) is adopted to determine the content of glucose with water without sample as a blank sample, parallel determination is conducted for each sample three times, and a mean value is obtained; the digestion rate of the sample is marked with the hydrolysis rate (%) of the sample within 0 to 180 minutes, and a graph is drawn to calculate the area under the curve (AUC) of hydrolysis.

[0110] A calculation formula for the hydrolysis index (HI) and glycemic index of a sample is as follows:

[00001]$\mathrm{HI}=\frac{\mathrm{AUC}.Math..Math.\left(\mathrm{sample}\right)}{\mathrm{AUC}.Math..Math.\left(\mathrm{reference}\right)}100.Math.\%.Math..Math.\mathrm{GI}=0.549\mathrm{HI}+37.91$

EXAMPLE 1

Preparation of Low Glycemic Index Resistance Starch

[0111] Specific steps are as follows:

[0112] (1) Each raw material is obtained according to the formula of table 1;

[0113] (2) the rice starch is weighed and dispersed into a 55% (v/v) ethanol solution A, so that a 20% (w/v) starch solution is prepared, the temperature of the starch solution is kept in a 45 C. thermostatic water bath oscillator, meanwhile, a 1.0 mol/L NaOH solution is added at a rate of 2 mL/min, and reaction is sufficiently conducted for 25 minutes;

[0114] (3) the fatty acid is dissolved in a 65% (v/v) ethanol solution B until the ratio of starch mass to NaOH mass to ethanol solution A volume to fatty acid mass to ethanol solution B volume in the reaction mixture is shown as table 1, subsequently the solution is preheated in a 50 C. thermostatic water bath for 5 minutes and then added into the starch solution system at a rate of 0.4 mL/min, reaction is sufficiently conducted for 75 minutes, and a 1.0 mol/L HCl solution is then added to regulate pH to become neutral;

[0115] (4) after the reaction is complete, the starch-lipid complex is immediately transferred into a 20 C. environment and quickly cooled for 3 minutes, and the temperature of the starch-lipid complex is then kept in a 25 C. water bath for 1 hour;

[0116] (5) after temperature keeping is complete, centrifuging is performed at 10000 g for 5 minutes, and after supernate is removed, a crude product is obtained; and

[0117] (6) after being washed with distilled water three times, the crude product is dried in 40 C. blast for 24 hours and then ground until it can pass through a 100-mesh sieve, and thereby a starch-lipid complexed resistant starch product is obtained.

TABLE-US-00001 TABLE 1 Raw Material Formula Rice Ethanol solution Fatty Ethanol solution starch/g NaOH/g A/mL acid/g B/mL A 1.0 0.4 3.0 0.1 3.0 B 1.0 0.1 3.0 0.1 3.0 C 1.0 0.8 3.0 0.1 3.0 D 1.0 0.5 2.4 0.15 2.0 E 1.0 0.4 5.0 0.1 5.0 F 1.0 0.4 3.0 0.02 3.0
Among them, the concentration of the ethanol solution A is 55% (v/v); and the concentration of the ethanol solution B is 65% (v/v).

[0118] The resistant starch content and glycemic index of the obtained low glycemic index resistance starch are assayed, and the assay result is shown in table 2.

TABLE-US-00002 TABLE 2 Resistant Starch Content and In-vitro Simulated Glycemic Index Assay Result Resistant starch content (%) In-vitro simulated glycemic index A 66.2 0.4 34.3 0.3 B 42.7 0.1 56.1 0.5 C 39.4 0.2 63.2 0.1 D 52.7 0.3 38.6 0.2 E 48.6 0.5 42.3 0.4 F 35.8 0.1 69.1 0.2

[0119] It can be known from the result that all the factors including the NaOH, the ethanol solution A, the fatty acid and the ethanol solution B will affect the complexing effect of starch and lipid and the content of the resistant starch, so a product with high resistant starch content and low in-vitro simulated glycemic index needs to be prepared within the ratio defined by the present disclosure.

EXAMPLE 2

Preparation of Low Glycemic Index Resistance Starch

[0120] Specific steps are as follows:

[0121] (1) the rice starch is weighed and dispersed into a 55% (v/v) ethanol solution A, so that a 20% (w/v) starch solution is prepared, the temperature of the starch solution is kept in a 45 C. thermostatic water bath oscillator, meanwhile, a 1.0 mol/L NaOH solution is added at a rate of 2 mL/min until the ratio of starch mass to NaOH mass to ethanol volume in the reaction mixture A is 1.0:0.4:3.0, and reaction is sufficiently conducted for 25 minutes;

[0122] (2) the fatty acid is dissolved in a 65% (v/v) ethanol solution B until the ratio of starch mass to fatty acid mass to NaOH mass to ethanol volume in the reaction mixture B is 1.0 g:0.1 g:0.4 g:3.0 mL, the solution is preheated in a 50 C. thermostatic water bath for 5 minutes and then added into the starch solution system at a rate of 0.4 mL/min, reaction is sufficiently conducted for 75 minutes, and a 1.0 mol/L of HCl solution is then added to regulate pH to become neutral;

[0123] (3) the specific operation conditions of low-temperature complexing and cooling crystallization are adjusted according to table 3;

[0124] (4) after temperature keeping is complete, centrifuging is performed at 10000 g for 5 minutes, and after supernate is removed, a crude product is obtained; and

[0125] (5) after being washed with distilled water three times, the crude product is dried in 40 C. blast for 24 hours and then ground until it can pass through a 100-mesh sieve, and thereby a starch-lipid complexed resistant starch product is obtained.

TABLE-US-00003 TABLE 3 Operation Conditions of Low-temperature Complexing and Variable-temperature Crystallization Techniques Water bath Quick cooling Quick bath temperature Reaction temperature/ cooling temperature/ keeping time/min C. time/min C. time/min A 60 4 5 25 60 B 45 4 3 25 30 C 60 80 5 25 60 D 60 4 3 25 30 E 60 20 5 20 60 F 60 20 2 10 15

[0126] Among them, the ratio of the starch to the fatty acid to the NaOH to the ethanol in the reaction mixture B is 1.0:0.1:0.4:3.0 (m:m:m:V).

[0127] The resistant starch content and glycemic index of the obtained low glycemic index resistance starch are assayed, and the assay result is shown in table 4.

TABLE-US-00004 TABLE 4 Resistant Starch Content and In-vitro Simulated Glycemic Index Assay Result Resistant starch content In-vitro simulated glycemic (%) index A 67.4 0.2 33.8 0.1 B 53.7 0.1 38.4 0.5 C 37.2 0.3 57.1 0.2 D 55.9 0.4 39.5 0.3 E 60.1 0.1 35.7 0.2 F 46.3 0.2 43.9 0.4

[0128] It can be known from the result that all the factors including starch and lipid complexing time, quick cooling temperature and time in the variable-temperature crystallization technique, water bath temperature and temperature keeping time will affect the complexing effect of starch and lipid and the content of the resistant starch, so a product with high resistant starch content and low in-vitro simulated glycemic index needs to be prepared within the conditions defined by the present disclosure.

EXAMPLE 3

Preparation of Low Glycemic Index Recombinant Rice

[0129] Specific steps are as follows:

[0130] (1) Each raw material is obtained according to the formula of table 5 (here, low glycemic index resistance starch is the low glycemic index resistance starch obtained according to the group A in example 2);

[0131] (2) the raw materials are uniformly mixed by using a stirrer and then added with distilled water which is 35% of the mass of the materials, water is added for conditioning, and after uniform mixing is performed again, a mixture is obtained;

[0132] (3) after conditioning is complete, the mixture is sent into a twin-screw extruder, the solid feeding speed is 3 kg/h before extrusion is started, the four temperatures of the twin-screw extruder are respectively set as 60 C., 80 C., 90 C. and 100 C., the rotational speed of the screws is 110 rpm, the die aperture of the discharge hole of the extruder is 6 mm, and the rotational speed of a cutting machine at the discharge hole is 250 rpm;

[0133] (4) extrusion granulation is performed by the twin-screw extruder, a cutter is used for cutting at the die, and thereby grainy granules or spherical or rod-like granules with a grain size of 4 mm in length are obtained;

[0134] (5) finally, the prepared rice granule product is dried by adopting a hot-air fluidized bed, drying temperature is 110 C., drying time is 12 minutes, and moisture is controlled at 8% after drying; and

[0135] (6) after drying, the rice granule product is then cooled and packaged, and thereby low glycemic index recombinant rice is obtained.

TABLE-US-00005 TABLE 5 Raw Material Formula Low glycemic index Propylene Rice resistance Soybean glycol Sodium Xanthan flour starch polysaccharide alginate alginate gum A 60 40 0.5 0.15 0.15 0.3 B 70 35 0.5 0.15 0.15 0.3 C 50 50 0.5 0.15 0.15 0.3 D 80 20 0.5 0.15 0.15 0.3 E 60 40 0.25 0.1 0.1 0.2 F 60 40 0.75 0.2 0.2 0.4

[0136] Among them, the rice flour used is rice flour capable of passing through a 100-mesh sieve; the soybean polysaccharide used is soluble soybean polysaccharide; and the low glycemic index resistance starch used is the low glycemic index resistance starch prepared by adopting the conditions of the group A in example 1 and example 2.

[0137] The glycemic index of the obtained low glycemic index recombinant rice is assayed, and the assay result is shown in table 6.

TABLE-US-00006 TABLE 6 Glycemic Index Assay Result Glycemic index A 48.3 0.2 B 53.9 0.4 C 42.6 0.5 D 67.2 0.3 E 50.4 0.1 F 51.5 0.2

[0138] It can be known from the result that the ratio of the rice flour to the low glycemic index resistance starch will affect the in-vitro simulated glycemic index of the recombinant convenient rice, and the low-glycemic index recombinant convenient rice needs to be prepared within the ratio defined by the present disclosure.

EXAMPLE 4

Preparation of Low Glycemic Index Recombinant Rice

[0139] Specific steps are as follows:

[0140] (1) According to the ratio of 60:40:0.5:0.15:0.15:0.3, rice flour, low-lycemic index resistant starch (here, the low-lycemic index resistant starch is the low-lycemic index resistant starch obtained according to the group A in example 2), soybean polysaccharide, propylene glycol alginate, sodium alginate and xanthan gum are weighed, so that raw materials are obtained;

[0141] (2) the raw materials are uniformly mixed by using a stirrer and then added with distilled water which is 35% of the mass of the materials, water is added for conditioning, and after uniform mixing is performed again, a mixture is obtained;

[0142] (3) after conditioning is complete, the mixture is sent into a twin-screw extruder, the solid feeding speed is 3 kg/h before extrusion is started, the four temperatures of the twin-screw extruder, the rotational speed of the screws and the die aperture of the discharge hole of the extruder are set according to operation conditions of the extrusion technique in table 7, and the rotational speed of a cutting machine at the discharge hole is set as 250 rpm;

[0143] (4) extrusion granulation is performed by the twin-screw extruder, a cutter is used for cutting at the die, and thereby spherical or rod-like granules are obtained;

[0144] (5) finally, the prepared rice granule product is dried by adopting a hot blast fluidized bed, drying temperature is 110 C., drying time is 12 minutes, and moisture is controlled at 8% after drying; and

[0145] (6) after drying, the rice granule product is then cooled and packaged, and thereby low glycemic index recombinant rice is obtained.

TABLE-US-00007 TABLE 7 Operation Conditions of Extrusion Technique Screw Screw Screw Screw Rotational Die temperature temperature temperature temperature speed of aperture/m 1/ C. 2/ C. 3/ C. 4/ C. screws/rpm m A 60 80 90 110 110 4 B 55 70 85 100 110 4 C 70 85 100 120 110 4 D 60 80 90 110 150 4 E 60 80 90 110 70 4 F 60 80 90 110 110 10

[0146] Among them, the mass ratio of the rice flour used to the prepared low glycemic index resistance starch to the soybean polysaccharide to the propylene glycol alginate to the sodium alginate to the xanthan gum is 60:40:0.5:0.15:0.15:0.3.

[0147] The resistant starch content and glycemic index of the obtained low glycemic index recombinant rice are assayed, and the assay result is shown in table 8.

TABLE-US-00008 TABLE 8 Glycemic Index Assay Result Glycemic index A 47.6 0.3 B 51.9 0.1 C 53.3 0.2 D 56.7 0.4 E 57.9 0.2 F 55.8 0.1

[0148] It can be known from the result that all the factors including the four sections of screw temperatures, the rotational speed of the screws and the die aperture in the extrusion process will affect the in-vitro simulated glycemic index of the recombinant convenient rice, and the low-glycemic index recombinant convenient rice needs to be prepared within the conditions defined by the present disclosure.

[0149] Although the present disclosure has been disclosed as above with the preferred examples, the examples are not intended to limit the present disclosure. Any person skilled in the art can make various changes and embellishments without departing from the spirit and scope of the present disclosure, so the protection scope of the present disclosure shall be based on the definition of the claims.