Low-GI rice noodles based on sugarcane polyphenol-soybean protein isolate load and preparation method of low-GI rice noodles

Abstract

The invention belongs to the technical field of rice product processing, and particularly relates to low-GI rice noodles based on sugarcane polyphenol-soybean protein isolate load and a preparation method of the low-GI rice noodles. The method comprises the following steps: mixing rice flour with a sugarcane polyphenol-soybean protein isolate load to obtain mixed rice flour; and adding water into the mixed rice flour to obtain rice milk, heating and gelatinizing the rice milk into dough, and performing extrusion forming to obtain the low-GI rice noodles. The invention innovatively develops a method for preparing the rice noodles by loading the sugarcane polyphenols on the soybean protein isolate and mixing the sugarcane polyphenols with the rice flour, the sugarcane polyphenols effectively enhance the stability and effect of the sugarcane polyphenols under the carrier action of the soybean protein isolate, and the sugarcane polyphenol-soybean protein isolate load is added into the rice flour, so that the rice noodles are more stable in taste. According to the method, the digestibility of starch in the prepared rice noodles can be remarkably reduced, the GI value of the rice noodles can be effectively reduced, meanwhile, the texture and eating experience of the prepared rice noodles can be ensured, and full balance of the taste and functionality of the rice noodles is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of rice product processing, and particularly relates to a low GI rice noodle based on a sugarcane polyphenol-soy protein isolate loading material and a preparation method thereof. Background Art

[0002] Rice noodles, as a traditional food, are widely popular because of their good taste and easy digestion. However, the GI value of ordinary rice noodles is high, which is not suitable for diabetic patients and people who need to control blood sugar. In order to lower the GI value of rice noodles, researchers tried to add ingredients with blood sugar-lowering function to rice noodles.

[0003] Sugarcane polyphenols are a natural plant polyphenol with multiple biological activities such as antioxidant, anti-inflammatory, and hypoglycemic effects. However, sugarcane polyphenols are very sensitive to the external environment and are easily affected by factors such as temperature and light, which limits their application in food.

[0004] Therefore, developing a method that can effectively mix sugarcane polyphenols and stably retain their activity has become a focus in the field of rice product processing. By evenly distributing sugarcane polyphenols in rice noodles, not only the GI value of rice noodles can be reduced, but also the nutritional value of rice noodles can be increased, providing a healthier and safer food choice for diabetic patients and healthy consumers. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a low GI rice noodle based on sugarcane polyphenol-soy protein isolate loading material and a preparation method thereof, so as to effectively reduce the GI value of the rice noodle, making it more suitable for consumption by diabetic patients and people who need to control blood sugar.

[0006] To achieve the above objectives, the technical solutions adopted by the present invention include:

[0007] In a first aspect, the present invention provides a method for preparing low GI rice noodles based on a sugarcane polyphenol-soy protein isolate loading material, comprising the following steps:

[0008] S1, mixing rice flour with sugarcane polyphenol-soy protein isolate loading material to obtain mixed rice flour;

[0009] S2, adding water to the mixed rice flour to obtain rice milk, heating and gelatinizing into agglomerates, extruding to obtain the low GI rice noodles;

[0010] The mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:(0.5-1.5).

[0011] Sugarcane polyphenols, as a natural plant active ingredient, have a significant hypoglycemic effect, but because they are highly sensitive to the external environment and are easily affected by factors such as temperature and light, their active ingredients are easily degraded, limiting their stability and application in food. Therefore, in order to solve the application problem of sugarcane polyphenols in food, the present invention innovatively develops a method for preparing rice noodles by loading sugarcane polyphenols with soy protein isolate and mixing them with rice flour. The soy protein isolate can effectively protect the sugarcane polyphenols and reduce their contact with the external environment, thereby maintaining the stability of its active ingredients. The soy protein isolate can provide certain adhesion and elasticity, thereby improving the texture of the rice noodles to a certain extent and enhancing the edible taste of the rice noodles.

[0012] Through experimental research, it was found that the rice noodles added with the sugarcane polyphenol-soy protein isolate loading material can not only effectively reduce the digestibility of starch in the rice noodles, significantly reduce the GI value of the rice noodles, and thus reduce its blood sugar response, but also ensure the texture and eating experience of the prepared rice noodles. The successful application of this innovative method not only opens up a new way for the food application of sugarcane polyphenols, but also provides a useful reference for the development of low GI foods.

[0013] Preferably, the mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:(0.5-1).

[0014] Through experimental research, it was found that the precise regulation of the dosage ratio of rice flour and sugarcane polyphenol-soy protein isolate loading material is the key to ensuring the balance of functionality and taste of rice noodles. When the two are compounded in the above preferred dosage range to prepare rice noodles, the digestibility of starch in rice noodles can be effectively reduced, thereby significantly reducing the GI value of rice noodles, while increasing the toughness and chewiness of rice noodles, and effectively reducing the cooking loss and breaking rate of rice noodles during cooking; when the loading material ratio is too high, it will significantly affect the taste and structure of rice noodles, causing the rice noodles to be too loose or have a poor taste, thus affecting the eating experience. When the loading material dosage is too low, the loading material will be insufficiently stable, and the sugar-lowering effect of sugarcane polyphenols cannot be fully exerted.

[0015] Preferably, the preparation method of the sugarcane polyphenol-soy protein isolate loading material comprises the following steps: dissolving sugarcane polyphenol in water to obtain a sugarcane polyphenol solution, then dissolving soy protein isolate in water to obtain a soy protein isolate solution, then adding the sugarcane polyphenol solution to the soy protein isolate solution under water bath conditions, stirring, centrifuging to obtain the supernatant, and freeze-drying to obtain the sugarcane polyphenol-soy protein isolate loading material.

[0016] Preferably, the mass ratio of the sugarcane polyphenols to the soy protein isolate is 1:(5-10).

[0017] Preferably, the mass ratio of the sugarcane polyphenols to the soy protein isolate is 1:8.

[0018] Through experimental exploration, it was found that when the above method is used to prepare the sugarcane polyphenol-soy protein isolate loading material, the dosage ratio of the two is in the preferred range of 1: (5-10) of the present invention, especially when the optimal ratio is 1: 8, it can effectively ensure that the sugarcane polyphenol is fully wrapped and protected, significantly improve its loading rate, while maintaining its activity and prolonging its stability in rice noodles. In addition, the use of the above preferred ratio of the two is more conducive to forming a loading material that is uniform, stable and has good release performance, so that the sugarcane polyphenol can be gradually released during the digestion process, thereby giving full play to the hypoglycemic effect; when the proportion of sugarcane polyphenol is too high, it will lead to the degradation and instability of the sugarcane polyphenol, thereby affecting its effect, and when the proportion of soy protein isolate is too high, the concentration of sugarcane polyphenol will be diluted, resulting in a weakening of its hypoglycemic effect.

[0019] Preferably, in step S2, the mass ratio of water to mixed rice flour is (1-1.5):1, and the heating gelatinization temperature is 90-95°C.

[0020] Preferably, in the method for preparing the sugarcane polyphenol-soy protein isolate loading material, the water bath condition is 55-65° C., the stirring time is 2.5-3.5 h, and the centrifugation condition is: centrifugation at a speed of 3500-4500 r / min for 8-12 min.

[0021] Preferably, the preparation method further comprises the following steps: steaming the extruded rice noodles for 4-5 minutes, cooling and aging to obtain the low GI rice noodles; the specific conditions of the aging are: aging for 6-8 hours at a temperature of 18-22°C and a humidity of 90-95%.

[0022] Preferably, the length of the rice noodles after extrusion molding is 15-20 cm and the diameter is 1-2 mm.

[0023] In a second aspect, the present invention provides low GI rice noodles prepared by the preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention innovatively develops a method for preparing rice noodles by loading sugarcane polyphenols on soy protein isolate and mixing the mixture with rice flour. Under the carrier effect of soy protein isolate, the sensitivity of sugarcane polyphenols to the external environment is reduced, thereby enhancing the stability and effect of sugarcane polyphenols. In addition, adding the sugarcane polyphenol-soy protein isolate load to rice flour can significantly reduce the digestibility of starch in the prepared rice noodles and effectively reduce the GI value. At the same time, the texture and eating experience of the prepared rice noodles can also be ensured. Therefore, the method of the present invention not only provides a healthier dietary choice for diabetic patients, but also provides new ideas and possibilities for the development of functional foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The content of starch components digested in vitro by rice noodles with different recipes;

[0027] Figure 2 This is a diagram showing the starch hydrolysis rate of rice noodles with different recipes at different time periods;

[0028] Figure 3 It is the infrared spectrum curve diagram of Example 4-6 and Comparative Example 3-4;

[0029] Figure 4 The cross-sectional SEM (500x) images of rice noodles are respectively those of Comparative Examples 3-4 and Examples 4-6. DETAILED DESCRIPTION

[0030] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] Unless otherwise specified, the raw materials used in the examples and comparative examples are all conventional raw materials available in the art and can be purchased through commercial channels. The experimental operations not specifically specified in the examples and comparative examples are all conventional operations in the art or can be understood or known by those skilled in the art based on the existing technology or common knowledge they master.

[0032] Example 1

[0033] The present invention provides a method for preparing a sugarcane polyphenol-soy protein isolate loading material, comprising the following steps:

[0034] Dissolve 1 g of sugarcane polyphenol powder in 8 ml of water to obtain a sugarcane polyphenol aqueous solution, dissolve 8 g of soy protein isolate in 40 ml of water, heat in a water bath at 60°C and stir to fully dissolve, add the sugarcane polyphenol aqueous solution to the soy protein isolate aqueous solution and continue stirring for 3 hours, let it stand and cool, then centrifuge at 4000 r / min for 10 minutes, and freeze-dry the supernatant to obtain a sugarcane polyphenol-soy protein isolate load powder.

[0035] Example 2

[0036] This embodiment provides a method for preparing a sugarcane polyphenol-soy protein isolate loading material, comprising the following steps:

[0037] Dissolve 1 g of sugarcane polyphenol powder in 8 ml of water to obtain a sugarcane polyphenol aqueous solution, dissolve 5 g of soy protein isolate in 40 ml of water, heat in a water bath at 55°C and stir to fully dissolve, add the sugarcane polyphenol aqueous solution to the soy protein isolate aqueous solution and continue stirring for 2.5 hours, let it stand and cool, then centrifuge at 3500 r / min for 12 minutes, and freeze-dry the supernatant to obtain a sugarcane polyphenol-soy protein isolate load powder.

[0038] Example 3

[0039] This embodiment provides a method for preparing a sugarcane polyphenol-soy protein isolate loading material, comprising the following steps:

[0040] Dissolve 1 g of sugarcane polyphenol powder in 8 ml of water to obtain a sugarcane polyphenol aqueous solution, dissolve 10 g of soy protein isolate in 40 ml of water, heat in a water bath at 65°C and stir to fully dissolve, add the sugarcane polyphenol aqueous solution to the soy protein isolate aqueous solution and continue stirring for 3 hours, let it stand and cool, then centrifuge at 4500 r / min for 8 minutes, and freeze-dry the supernatant to obtain a sugarcane polyphenol-soy protein isolate load powder.

[0041] Example 4

[0042] The present invention provides a method for preparing low GI rice noodles based on a sugarcane polyphenol-soy protein isolate loading material, comprising the following steps:

[0043] S1, mixing rice flour and the sugarcane polyphenol-soy protein isolate loading material prepared in Example 1 at a mass ratio of 100:0.5 to obtain composite rice flour;

[0044] S2, mixing water and composite powder at a mass ratio of 1.2:1 to obtain rice slurry, heating the rice slurry in a water bath to gelatinize at 90°C to obtain rice dough, stirring for 10 minutes, and extruding the rice dough through a noodle machine to a length of 15-20cm and a diameter of 1-2mm to obtain rice noodles. Steaming the formed rice noodles in a steamer for 5 minutes, cooling at room temperature, and then aging in a thermostat at a temperature of 20°C and a humidity of 95% for 7 hours to obtain the sugarcane polyphenol-soy protein isolate loaded low GI rice noodles.

[0045] Example 5

[0046] The present invention provides a method for preparing low GI rice noodles based on a sugarcane polyphenol-soy protein isolate loading material, which differs from Example 4 only in that the mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material prepared in Example 1 is 100:1, and the rest of the preparation methods are the same.

[0047] Example 6

[0048] The present invention provides a method for preparing low GI rice noodles based on a sugarcane polyphenol-soy protein isolate loading material, which differs from Example 4 only in that the mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material prepared in Example 1 is 100:1.5, and the rest of the preparation methods are the same.

[0049] Comparative Example 1

[0050] This comparative example provides a method for preparing a sugarcane polyphenol-soy protein isolate loading material, which differs from Example 1 only in that the mass ratio of the sugarcane polyphenol to the soy protein isolate is 1:3, that is, the added amount of sugarcane polyphenol is 1g, and the added amount of the soy protein isolate is 3g, and the rest is the same as Example 1.

[0051] Comparative Example 2

[0052] This comparative example provides a method for preparing a sugarcane polyphenol-soy protein isolate loading material, which differs from Example 1 only in that the mass ratio of the sugarcane polyphenol to the soy protein isolate is 1:15, that is, the added amount of sugarcane polyphenol is 1 g, and the added amount of the soy protein isolate is 15 g, and the rest is the same as Example 1.

[0053] Comparative Example 3

[0054] This comparative example provides a method for preparing low GI rice noodles based on sugarcane polyphenol-soy protein isolate loading material, which differs from Example 4 only in that: in this comparative example, ordinary semi-dry rice noodles are prepared without adding sugarcane polyphenol-soy protein isolate loading material, and the rest of the operations are the same as those in Example 4.

[0055] Comparative Example 4

[0056] This comparative example provides a method for preparing low GI rice noodles based on sugarcane polyphenol-soy protein isolate loading material, which differs from Example 4 only in that in this comparative example, rice flour is directly mixed with sugarcane polyphenol in a mass ratio of 100:0.5 to obtain composite rice noodles, and the remaining operations are the same as those in Example 4.

[0057] Comparative Example 5

[0058] This comparative example provides a method for preparing low GI rice noodles based on sugarcane polyphenol-soy protein isolate loading material, which is different from Example 4 only in that the mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:0.2.

[0059] Comparative Example 6

[0060] This comparative example provides a method for preparing low GI rice noodles based on sugarcane polyphenol-soy protein isolate loading material, which is different from Example 4 only in that the mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:2.

[0061] Effect Example 1

[0062] This effect example uses the sugarcane polyphenol-soy protein isolate loading material prepared by the preparation method described in Examples 1-3 and Comparative Examples 1-2 as samples, and measures the loading rate of sugarcane polyphenol therein. Gallic acid is used as a standard, and the polyphenol content of the sugarcane polyphenol aqueous solution and the sugarcane polyphenol-soy protein isolate loading material aqueous solution is measured using GB / T831-2008 "Folin phenol reagent colorimetry", and then the loading rate is calculated using the following formula, loading rate (%) = (polyphenol content of sugarcane polyphenol aqueous solution / polyphenol content of sugarcane polyphenol-soy protein isolate loading material) * 100%. Each group of samples is repeated 3 times, and the final measurement results are averaged. The specific results are shown in Table 1.

[0063] Table 1

[0064] Sample source Load rate / % Sample source Load rate / % Example 1 80.94±0.18 Comparative Example 1 72.64±0.11 Example 2 78.64±0.14 Comparative Example 2 77.51±0.16 Example 3 80.78±0.17

[0065] As shown in Table 1, the technical solution of the present invention can effectively coat sugarcane polyphenols in soy protein isolate, and the polyphenol loading rate reaches more than 78%. In particular, the polyphenol loading efficiency of the load described in Example 1 is the best, reaching 80.94%. When the dosage ratio of sugarcane polyphenols to soy protein isolate in Comparative Examples 1-2 exceeds the specified range of the present invention, the polyphenol loading rate is significantly reduced compared with the embodiment. This is because the soy protein isolate combines with polyphenols through hydrogen bonds, hydrophobic interactions, electrostatic interactions, etc. to form a coating structure. If the soy protein isolate content is insufficient, the interaction between the two will not be strong enough, resulting in the inability of the sugarcane polyphenol molecules to be completely coated or loaded. If the soy protein isolate content is too high, the coating structure may be unstable. In addition, too much protein may also weaken the interaction between polyphenol molecules, thereby affecting the coating effect.

[0066] Effect Example 2

[0067] In this effect example, rice noodles prepared by the preparation methods described in Examples 4-6 and Comparative Examples 3-5 were used as samples, and their starch hydrolysis index (HI) and glycemic index (pGI) were measured.

[0068] The pGI determination method is as follows: the sample is steamed at the optimal steaming time, the water is drained after steaming, the rice noodles are cut into several small ends of 5 mm, 500 mg is weighed and placed in a 250 ml conical flask, 5 glass beads are added, 15 ml of pH 5.2 sodium acetate buffer is added, 10 ml of α-amylase (290 U / mL) and saccharifying enzyme (15 U / mL) are added after stirring, and the conical flask is placed in a 37°C constant temperature water bath oscillating box with a speed of 130 r / min. The enzymatic hydrolysis reaction starts and the time is counted, and 0.1 ml of the enzymatic hydrolyzate is accurately drawn into a centrifuge tube at 0, 10, 20, 30, 60, 120, and 180 min time periods, and 0.4 ml of anhydrous ethanol is added for inactivation. The inactivated enzyme solution was centrifuged at 4000r / min for 10min, and the supernatant was subjected to a glucose kit and its absorbance was measured at 505nm using an ELISA reader to determine the glucose content of the enzyme solution at different time periods, and the glucose content was converted into starch content using the following formula:

[0069]

[0070] Wherein: W, starch hydrolysis rate, %; Gt, glucose content in digestion at different time periods, mg; 0.9, conversion coefficient of glucose to starch; TS, total starch content, mg.

[0071] The calculation formula of the content of each component of digestible starch is:

[0072]

[0073] Wherein: G20, glucose content in the hydrolyzate after 20 min of hydrolysis (mg); FG, free glucose content in the sample (mg); G120, glucose content in the hydrolyzate after 120 min of hydrolysis (mg); TS, total starch content in the sample (mg).

[0074] The starch digestibility curve was fitted to a first-order equation:

[0075] Ct=C∞(1-e -kt )

[0076] Where: Ct, starch hydrolysis rate at time t, %; C∞, final starch hydrolysis rate, %; k, first-order rate constant of starch digestion in vitro, min-1. The area under the hydrolysis curve (AUC) was obtained by integrating the established kinetic equation within (0-180min). The hydrolysis index HI was obtained by comparing the AUC of the sample with the AUC of the reference sample (white bread).

[0077] The glycemic index is calculated based on the method of AKERBERG et al.:

[0078] GI=0.862HI+8.198

[0079] The eGI of the rice noodles of Examples 4-6 and Comparative Examples 3-5 were calculated. The results are as follows: Figure 1 The changes in the digestion kinetic parameters of rice noodles prepared with different recipes are shown in Table 2.

[0080] Table 2

[0081] Sample name C∞ <![CDATA[K(min -1 )]]> HI(%) GI Example 4 0.54±0.06 0.0556 51.62±0.53 52.69±0.48 Example 5 0.53±0.04 0.0554 50.39±0.56 51.64±0.35 Example 6 0.54±0.08 0.0419 49.48±0.36 50.85±0.41 Comparative Example 3 0.84±0.09 0.0288 71.48±0.19 69.81±0.16 Comparative Example 4 0.56±0.05 0.0418 53.88±0.22 54.64±0.22 Comparative Example 5 0.66±0.02 0.0588 58.44±0.33 58.57±0.33

[0082] Foods can be divided into three categories according to their GI values: high GI foods (GI ≥ 70), medium GI foods (55 < GI < 70) and low GI foods (GI ≤ 55).

[0083] like Figure 1 As shown in Table 2, the digestibility rate (C∞) of the rice noodles starch prepared in the embodiment of the present invention is significantly lower than that of the ordinary rice noodles and the rice noodles to which only sugarcane polyphenols are added.

[0084] The content of digestible starch components Figure 2 As shown, in Examples 4-6, with the increase in the amount of soy protein isolate loaded with sugarcane polyphenols, the RS content in the rice noodles further increased to 48.13%, while the SDS and RDS further decreased to 22.54% and 29.33%. The decrease in the digestibility of rice noodles may be due to the fact that the addition of polyphenols promotes the formation of a difficult-to-digest composite structure of starch after cooking, which further inhibits the combination of digestive enzymes and starch, thereby inhibiting digestion and reducing blood sugar response.

[0085] In addition, as the amount of sugarcane polyphenol-soy protein isolate loading material added increases, the starch digestibility of the rice noodles prepared by the present invention gradually decreases. When the added amount reaches 1%, the starch digestibility is significantly lower than that of the rice noodles to which only sugarcane polyphenol is added. When the added amount is 1.5% in Example 6, the pGI value is 50.85±0.41, which is less than 55, and has reached the requirement of low GI food, and is suitable for consumption by diabetic patients. When the sugarcane polyphenol-soy protein isolate loading material of the present invention is not added in Comparative Example 3, the pGI value of the prepared ordinary rice noodles is significantly higher than that of Examples 4-6. When only sugarcane polyphenol is added in Comparative Example 4, the pGI value of the prepared composite rice noodles is significantly higher than that of Examples 4-6. The pGI value of the rice noodles also increased to a certain extent compared with the example. When the amount of the load in Comparative Example 5 was lower than the preferred range of the present invention, the digestibility of starch in the rice noodles could not be effectively reduced, resulting in a pGI value significantly higher than that of the example. The above results all show that the present invention uses sugarcane polyphenols under the carrier effect of soy protein isolate, which can effectively reduce its loss or degradation during the preparation process, thereby enhancing the stability and hypoglycemic effect of sugarcane polyphenols, and when the sugarcane polyphenol-soy protein isolate load is compounded with rice flour within the preferred range of the present invention, the digestibility of starch in the prepared rice noodles can be better reduced, and its GI value can be effectively reduced.

[0086] Effect Example 3

[0087] In this effect example, the rice noodles prepared by the preparation methods described in Examples 4-6 and Comparative Examples 3-5 are used as samples, and the water absorption rate and cooking loss are used as indicators to measure the cooking quality of the samples. The specific method is as follows.

[0088] Select 20 semi-dried rice noodles with a length greater than 15 cm, place them in a 1L beaker, add 0.6L of water, and then heat to boil. After the steaming is completed at the optimal cooking time, drain the water. Select rice noodles with a length less than 7.5 cm and greater than 7.5 cm, and weigh them m1 and m2 respectively, and calculate the breakage rate according to the following formula.

[0089] Strip breaking rate = m1 / (m1+m2)×100%

[0090] Where: m1-the mass of semi-dry rice noodles with a length less than 7.5 cm; m2-the mass of semi-dry rice noodles with a length greater than 7.5 cm.

[0091] Select 10 semi-dried rice noodles with a length of 20 cm and weigh them as m0. Put the semi-dried rice noodles in a 1L beaker, add 0.6L water, heat and boil, record the best cooking time, drain the cooked rice noodles and weigh them as m1, then dry them to constant weight as m2, and calculate the cooking loss and water absorption rate according to the following formula. Each sample was measured three times. The specific results are shown in Table 3.

[0092] Cooking loss = 1-m2 / [m0(1-M)]×100%

[0093] Water absorption rate = (m1-m0) / m0×100%

[0094] Wherein: M-water content of semi-dry rice flour, %; m0-mass of semi-dry rice flour before cooking, g; m1-mass of semi-dry rice flour after cooking, g; m2-dry weight of semi-dry rice flour after cooking, g.

[0095] Table 3

[0096]

[0097] The cooking characteristics of the rice noodles fortified with the sugarcane polyphenol-soy protein isolate loading material were evaluated from the three indicators of water absorption rate, cooking loss and breaking rate. As can be seen from Table 3, the sugarcane polyphenol-soy protein isolate loading material in Examples 4-6 can effectively reduce the breaking rate of rice noodles within a specific addition amount range, and significantly reduce the cooking loss and water absorption rate compared with Comparative Example 4. This is because the interaction between starch, protein and sugarcane polyphenols through hydrogen bonds weakens the interaction between starch and water molecules, thereby making the gel structure compact. As the sugarcane polyphenol-soy protein isolate loading material increases, the water absorption rate increases slightly. This is due to the effect of the hydrophilic groups of sugarcane polyphenols themselves, and the cooking loss and breaking rate gradually decrease, which shows that the rice noodles of Examples 4-6 have obvious advantages in cooking quality.

[0098] Effect Example 4

[0099] In this effect example, rice noodles prepared by the preparation methods described in Examples 4-6 and Comparative Examples 3-4 and 6 are used as samples to explore their texture characteristics, and the specific method is as follows.

[0100] 15 semi-dried rice noodles with a length of 20 cm were selected from each group of samples. After the optimal cooking time, the water was drained and 5 rice noodles were selected and placed on the texture analyzer. The measurement mode was TPA mode. The probe model was P / 36R, the pre-measurement speed was 2 mm / s, the measurement speed was 1 mm / s, the post-measurement speed was 1 mm / s, the compression ratio was 50%, the compression interval was 3s, and each sample was measured 3 times. The experimental results are shown in Table 4.

[0101] Table 4

[0102] Sample name hardness elasticity Adhesiveness Chewability Example 4 2044.322±90.832a 0.944±0.017a 1545.90±118.13ab 1319.78±106.84ab Example 5 2074.871±65.673a 0.920±0.019a 1584.93±28.10a 1458.90±48.33a Example 6 1908.627±127.620a 0.912±0.028a 1249.16±228.39c 1278.68±88.75b Comparative Example 3 1729.810±62.984b 0.908±0.019a 1237.15±29.33c 1227.10±53.60b Comparative Example 4 1703.591±78.846b 0.852±0.013b 1233.45±0.01c 1050.66±4.31d Comparative Example 6 1621.431±67.26c 0.822±0.011c 1258.37±0.02c 1125.57±5.61c

[0103] As can be seen from Table 4, when the amount of sugarcane polyphenol-soy protein isolate loading material added in Examples 4-6 is within the preferred range of the present invention, the hardness, elasticity, adhesiveness and chewiness of the rice noodles can be effectively enhanced, so that the texture characteristics of the rice noodles can be improved; when the loading material in Comparative Example 6 is further increased and exceeds the specified range of the present invention, the texture characteristics are significantly reduced, which is mainly due to the destructive effect of soy protein isolate on the starch structure. When no sugarcane polyphenol-soy protein isolate loading material is added in Comparative Example 3 and only sugarcane polyphenol is added in Comparative Example 4, the prepared rice noodles show a certain degree of reduction in hardness, elasticity, adhesiveness and chewiness; the above results all show that when the sugarcane polyphenol-soy protein isolate loading material is added to rice flour within a specific dosage range, the digestibility of starch in the prepared rice noodles can be significantly reduced, and the GI value can be effectively reduced. At the same time, the texture and eating experience of the prepared rice noodles can be ensured, and the functionality and taste of the rice noodles can be fully balanced.

[0104] Effect Example 5

[0105] In this effect example, the rice noodles prepared by the preparation methods described in Examples 4-6 and Comparative Examples 3-4 were used as samples, freeze-dried, crushed, and passed through a 100-mesh sieve. The short-range ordered structure of the samples was analyzed by Fourier transform infrared spectroscopy. -1 The scanning was performed within the wave number range of 32 times, with a scanning frequency of 4 cm -1 FTIR spectra were obtained with a resolution of 1.5 Å.

[0106] According to the detection results of Fourier transform infrared spectroscopy (FTIR) Figure 3 ), we can infer the effect of different treatment methods on the molecular structure of starch. 1045cm -1 and 1022cm -1 The absorption peaks near 995cm represent the ordered and disordered structures of starch, respectively, while the absorption peaks at 995cm -1 The absorption peak near 1045cm is the bending vibration of C-OH. -1 / 1022cm -1 and 1022cm -1 / 995cm -1 The peak intensity ratio of 1045 cm-1 can be used to determine the change in the order and disorder of starch. The results are shown in Table 5. -1 / 1022cm -1 In terms of the ratio of , all the treated starch samples (Examples 4-6) are higher than the control example, which shows that the degree of order of the treated starch samples is improved, indicating that the complex optimizes the molecular arrangement of starch through hydrogen bonding, hydrophobic interaction and cross-linking effect, indicating that the microscopic properties of rice noodles are improved, and the functionality and processing performance of the product are improved. The increase in ordered structure helps the cooking resistance and elasticity of rice noodles, improves its texture, and makes it less likely to break during the cooking process; the reduction in disordered structure may slow down the in vitro digestion rate of starch.

[0107] Table 5

[0108] Example 4 Example 5 Example 6 Comparative Example 3 Comparative Example 4 1045 / 1022 0.664 0.684 0.720 0.650 0.654 1022 / 995 1.056 1.045 1.033 1.075 1.073

[0109] Effect Example 6

[0110] In this effect example, rice noodles prepared by the preparation methods described in Examples 4-6 and Comparative Examples 3-4 were used as samples. After freeze-drying, the samples were cut to obtain a cross-sectional area. Double-sided carbon tape was used to fix the samples on a sample holder. The samples were gold-plated for 60 seconds using a sputtering coating machine, and images were observed and photographed at an acceleration voltage of 9 kV and 500 times.

[0111] Depend on Figure 4The results show that the rice noodles prepared in Comparative Example 3 have a relatively compact structure, fewer pores, and uneven pore shapes and sizes. Comparative Example 4 is similar to Comparative Example 3, but is still relatively compact overall. The pores of the rice noodles described in the examples become uniform, and the pore sizes are still inconsistent, but are significantly more uniform than the comparative examples. As the amount of soy protein isolate loaded with sugarcane polyphenols increases, the pore structure of the rice noodles gradually increases, becomes larger, and is more evenly distributed.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing low GI rice noodles based on sugarcane polyphenol-soy protein isolate loading material, characterized in that: The following steps are involved: S1, mixing rice flour with sugarcane polyphenol-soy protein isolate loading material to obtain mixed rice flour; S2, adding water to the mixed rice flour to obtain rice milk, heating and gelatinizing into agglomerates, extruding to obtain the low GI rice noodles; The mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:(0.5-1.5).

2. The preparation method according to claim 1, characterized in that The mass ratio of the rice flour to the sugarcane polyphenol-soy protein isolate loading material is 100:(0.5-1).

3. The preparation method according to claim 1, characterized in that: The preparation method of the sugarcane polyphenol-soy protein isolate loading material comprises the following steps: dissolving sugarcane polyphenol in water to obtain a sugarcane polyphenol solution, then dissolving soy protein isolate in water to obtain a soy protein isolate solution, then adding the sugarcane polyphenol solution to the soy protein isolate solution under water bath conditions, stirring, centrifuging to obtain a supernatant, and freeze-drying to obtain the sugarcane polyphenol-soy protein isolate loading material.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the sugarcane polyphenols to the soy protein isolate is 1:(5-10).

5. The preparation method according to claim 4, characterized in that: The mass ratio of the sugarcane polyphenols to the soy protein isolate is 1:

8.

6. The preparation method according to claim 1, characterized in that: In the step S2, the mass ratio of water to mixed rice flour is (1-1.5):1, and the heating and gelatinization temperature is 90-95°C.

7. The preparation method according to claim 3, characterized in that: In the preparation method of the sugarcane polyphenol-soy protein isolate loading material, the water bath condition is 55-65° C., the stirring time is 2.5-3.5 hours, and the centrifugal condition is: centrifugation at a speed of 3500-4500 r / min for 8-12 minutes.

8. The preparation method according to claim 1, characterized in that: The preparation method further comprises the following steps: steaming the extruded rice noodles for 4-5 minutes, cooling and aging to obtain the low GI rice noodles; the specific conditions of the aging are: aging for 6-8 hours at a temperature of 18-22° C. and a humidity of 90-95%.

9. Low GI rice noodles prepared by the preparation method according to any one of claims 1 to 8.

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