Low gi high springiness chestnut starch gel and method of making same

Abstract

The application provides a low-GI high-elasticity chestnut starch gel and a preparation method thereof, and the preparation method comprises the following steps: preparing a chestnut starch water dispersion, heating and reacting, cooling and grinding to obtain modified starch; dispersing the modified starch by using an ionic liquid containing sodium chloride, citric acid and fructose, and homogenizing to obtain a premix; covering a film on the premix, punching holes, and multi-stage frequency conversion heating to obtain a starch gelatinization liquid; mixing the starch gelatinization liquid with ethanol to obtain a starch fluid; and extruding the starch fluid into a mold, drying and solidifying to form a product, which is obtained. The chestnut starch gel prepared by the method has a V-shaped structure, a low GI value and high elasticity.

Description

Technical Field

[0001] This invention relates to the field of starch gel processing technology, specifically to a low-GI, high-elasticity chestnut starch gel and its preparation method. Background Technology

[0002] Starch gelation refers to the process by which starch combines with water molecules at high temperatures, causing the starch to swell, undergo structural changes, and form a gel-like substance. Starch is widely available and inexpensive. After high-temperature hydration and gelation, it possesses a helical, multi-level network structure, making it suitable as an encapsulation carrier for active ingredients in pharmaceuticals and health foods, such as enzymes and QQ candies. Compared to animal gels, chestnut starch gel is odorless, but it suffers from problems such as weak gelation and easy collapse after traditional cooking and heating, as well as high calorie content. Therefore, it is necessary to develop a chestnut starch gel and its preparation method to expand the applications of chestnut starch. Summary of the Invention

[0003] Therefore, it is necessary to provide a low-GI, high-elasticity chestnut starch gel and its preparation method, which can significantly reduce the GI value of chestnut starch and improve its elasticity.

[0004] The present invention adopts the following technical solution:

[0005] This invention provides a method for preparing low-GI, high-elasticity chestnut starch gel, comprising the following steps: preparing an aqueous dispersion of chestnut starch, heating it to 100-110°C for reaction, cooling, and grinding to obtain modified starch; dispersing the modified starch in an ion-soluble aqueous solution containing sodium chloride, citric acid, and fructose to obtain a starch emulsion; homogenizing the starch emulsion to obtain a premix; coating and perforating the premix with a film, and heating it using multi-stage frequency conversion to obtain a starch gelatinized liquid; mixing ethanol into the starch gelatinized liquid and maintaining it at 50-70°C to obtain a starch fluid; extruding the starch fluid into a mold, drying, and solidifying it to obtain the final product.

[0006] In some embodiments, the water content of the chestnut starch aqueous dispersion is 20-25%.

[0007] In some embodiments, the sodium chloride content in the ionic aqueous solution is 0.1–0.4 g / 100 mL, the citric acid content is 0.3–0.5 g / 100 mL, and the fructose content is 3–6 g / 100 mL. Preferably, the mass ratio of sodium chloride, citric acid, and fructose is 1:2:20.

[0008] In some embodiments, the homogenization process parameters are: rotation speed 4000-4500 rpm, homogenization time 5-10 min.

[0009] In some embodiments, the process parameters for the multi-stage frequency conversion heating are: 100% irradiation for 15-20s, 80% irradiation for 10-20s, and 20% irradiation for 20-30s.

[0010] In some embodiments, the starch fluid contains 3-5% ethanol (by volume). Preferably, the starch fluid also contains pigments or active ingredients.

[0011] In some embodiments, the process parameters for drying and curing are: temperature 50-60°C, humidity 70-80%, wind speed 0.5-1m / s, and drying time 3-5h.

[0012] Compared with the prior art, the core advantage of this invention is:

[0013] This invention employs hydrothermal treatment to modify starch, ionic liquids to enhance the gelling properties of emulsions, variable frequency irradiation heat transfer to prepare V-crystal gel, hot flow extrusion degassing injection molding, and constant temperature and humidity solidification processes to produce a high-elasticity, low-calorie, low-glycemic index V-crystal chestnut starch gel, aiming to serve as a plant-based carrier for health foods and thereby expand the application of chestnut starch. Attached Figure Description

[0014] Figure 1 Photographs of chestnut starch gels prepared in Examples 1 to 3.

[0015] Figure 2 A comparison graph showing the changes in glucose content after simulated digestion of chestnut starch and chestnut starch gel prepared in Example 1.

[0016] Figure 3 A comparison diagram showing the changes in crystal structure between chestnut starch and the chestnut starch gel prepared in Example 1.

[0017] Figure 4 This is a photograph of chestnut starch gel prepared in Example 8 using the same process parameters as in Example 1 but with a different mold. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0019] Explanation of the source of key experimental materials:

[0020] Chestnut starch: Select Qianxi chestnuts, cut them into pieces, grind them into a paste, and soak them in a 0.2wt% food-grade sodium hydroxide aqueous solution at a material-to-liquid ratio of 1:2 (w / w). Extract the paste with alkali at 4℃ for 12 hours, then pass it through a 100-mesh sieve, wash it twice with water, and dry it with hot air at 45℃ to obtain chestnut starch.

[0021] Example 1

[0022] This embodiment provides a method for preparing starch gel, including the following steps:

[0023] (1) Adjust the moisture content of chestnut starch to 20%, stir it thoroughly, seal it in a 100mL hydrothermal reactor with a volume filling of 80%, let it stand for 12h, then heat it to 100℃ at 10℃ / min, maintain it for 4h, cool it at room temperature, grind it, and pass it through an 80-mesh sieve to obtain modified starch.

[0024] (2) Weigh 0.2g sodium chloride, 0.4g citric acid and 4g fructose, add them to tap water and stir. Make up to 100mL to obtain an ionic liquid.

[0025] (3) Take 15g of modified starch and dissolve it in 85mL of ionic liquid to obtain starch emulsion.

[0026] (4) The starch emulsion was dispersed and homogenized at 4500 rpm for 10 min.

[0027] (5) Place the homogenized starch emulsion in a glass container with a thickness of 2-3 cm, cover the surface with plastic wrap and poke holes, adjust the frequency conversion microwave to 100% irradiation for 20 s, then stir slowly; irradiate at 80% for 20 s to gelatinize the starch and improve transparency; irradiate at 20% for 20-30 s (amylose dissolves and double helix deconstructs), then take it out and add 3-5 ml of anhydrous ethanol, stir to form a viscous paste-like fluid, keep warm at 60℃ for 5-10 min to obtain starch fluid (containing 3-5% anhydrous ethanol).

[0028] (6) Float the food-grade silicone mold on the surface of the liquid in a water bath at 40-50°C and preheat for 5 minutes. The starch fluid is then injected into the mold through extrusion and gently vibrated. The melt flow index is 50-100 g / min.

[0029] (7) Place the entire mold into a constant temperature and humidity chamber, set the temperature to 55-60℃, humidity to 70-80%, wind speed to 0.5-1m / s, and drying time to 3h to obtain starch gel.

[0030] Example 2

[0031] This embodiment provides a starch gel, the preparation method of which is basically the same as that of Example 1, except that the anhydrous ethanol in step (5) is replaced with an anhydrous ethanol solution containing 0.5g resveratrol.

[0032] Example 3

[0033] This embodiment provides a starch gel, the preparation method of which is basically the same as that of Example 1, except that the anhydrous ethanol in step (5) is replaced with an anhydrous ethanol solution containing 0.2g of carotene.

[0034] Example 4

[0035] This embodiment provides a starch gel, the preparation method of which is basically the same as that of Example 1, except that in step (2), 100 mL of ionic liquid contains 0.4 g sodium chloride, 0.4 g citric acid and 4 g fructose.

[0036] Comparative Example 1

[0037] This comparative example provides a starch gel, the preparation method of which is basically the same as that of Example 1, except that in step (2), the ionic liquid does not contain sodium chloride.

[0038] Comparative Example 2

[0039] This comparative example provides a starch gel, the preparation method of which is basically the same as that of Example 1, except that in step (2), 100 mL of ionic liquid contains 0.8 g sodium chloride, 0.4 g citric acid and 4 g fructose.

[0040] The starch gels prepared in the above experimental examples were tested respectively:

[0041] (1) The starch gel samples prepared in the above experimental examples (after drying for 3 hours) were photographed respectively. The cross-sectional image was broken open by hand to simulate cutting or tearing by teeth. The internal texture was dense and uniform, without air bubbles.

[0042] (2) The values ​​of L*, a*, and b* were measured using a colorimeter.

[0043] (3) Hardness, elasticity and chewiness were tested on starch gel using a TA texture analyzer with a P36R probe in TPA mode at a test speed of 2 mm / s and a compression ratio of 30%.

[0044] (4) The glycemic index was obtained by recording the amount of glucose produced at each time period through in vitro digestion simulation and calculating it based on GI = 39.71 + 0.549HI. (Reference: Wang Huaibin, Peng Xingguang, Liu Hongsheng, et al. Research progress on in vitro and in vivo prediction methods of glycemic index of carbohydrate foods [J]. Food Science, 2023, 44(15): 407-417.)

[0045] Wherein, HI: Hydrolysis Index, represents the ratio of starch hydrolysis rate to glucose hydrolysis rate in food. Foods with a GI value <55 are considered low-GI, those between 56-69 are medium-GI, and those 70 and above are high-GI. T0: Initial gelatinization temperature; Tp: Peak gelatinization temperature; ΔH: Enthalpy of gelatinization. The table shows that an increase in gelatinization temperature after processing indicates improved product thermal stability, a decrease in enthalpy of gelatinization (improved resistance to retrogradation), and an increase in the proportion of V crystals.

[0046] (5) The crystal structure was determined by X-ray diffraction in the 4–45° range at 5°min. -1 The crystallinity was obtained by scanning and calculated using MDI Jade 6.0 software. Relative crystallinity is the ratio of the area of ​​the crystalline region to the area of ​​the amorphous region; V-crystal ratio is the ratio of the area of ​​the V-crystal to the total crystalline region. (Reference: Chen Cuilan, Zhang Benshan, Chen Fuquan. A new method for calculating starch crystallinity [J]. Food Science, 2011, 32(09):68-71.)

[0047] Color difference and texture characteristics, Example 5, Example 7 table notes, different letters in the same column indicate statistically significant differences in data (p<0.05).

[0048] Color difference and textural properties

[0049]

[0050]

[0051] The changes in glucose content over time during in vitro simulated digestion are shown in the table below. Before processing, the glucose content refers to chestnut starch (raw material); after processing, it refers to the chestnut starch gel product obtained in Example 1.

[0052] Comparison of thermal stability and glycemic index before and after processing

[0053]

[0054] Experimental Example 5

[0055] Referring to the method steps and process parameters of Example 1, this experiment investigated the effect of temperature conditions (unheated, 80℃, 100℃, 120℃, 130℃, 150℃) on the modified starch composition. The test results are shown in the table below:

[0056]

[0057] The optimal heating temperature for modified starch, based on the SDS and RS content, is 100℃. The higher the resistant component, the lower the GI value.

[0058] Experimental Example 6

[0059] Referring to the method steps and process parameters of Example 1, this experiment investigated the effects of different sugars (unsweetened, fructose, glucose, and sucrose) on the elasticity of chestnut starch gel. The test results are shown in the table below:

[0060] performance Unsweetened fructose glucose sucrose elasticity 3.66±0.13 4.39±0.21 3.68±0.27 3.75±0.18

[0061] Experimental Example 7

[0062] Referring to the method steps and process parameters of Example 1, this experiment investigated the effect of citric acid addition on the elasticity of chestnut starch gel. The test results are shown in the table below:

[0063] Citric acid addition amount pH of ionic liquids elasticity 0％ <![CDATA[7.8±0.04 a ]]> <![CDATA[2.77±0.66 d ]]> 0.2％ <![CDATA[6.5±0.06 b ]]> <![CDATA[4.01±0.21 c ]]> 0.4％ <![CDATA[5.4±0.04 c ]]> <![CDATA[5.0±0.14 b ]]> 0.6％ <![CDATA[2.3±0.05 d ]]> <![CDATA[6.8±0.32 a ]]>

[0064] As the amount of citric acid increases, the pH value of the system decreases, but the elasticity of the starch gel increases. In order not to affect the taste, the preferred addition amount is 0.4%.

[0065] Experimental Example 8

[0066] Referring to the method and process parameters of Example 1, this experiment investigated the effects of different microwave process parameters (mold adjusted to a cylindrical shape) on the state and elasticity of chestnut starch gel. The test results are shown in the table below:

[0067]

[0068]

[0069] Furthermore, it's worth noting that traditional heating (100℃ for 30 minutes) results in weak starch gels with rough surfaces that easily stick together, poor elasticity, and a tendency to crumble and disintegrate. Multi-stage frequency conversion microwave heating, on the other hand, provides shorter heating times and produces chestnut starch gels with higher strength.

[0070] It should be noted that the above embodiments are only for further elaboration and explanation of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention. The method of the present invention is only a preferred embodiment and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a low-GI, high-elasticity chestnut starch gel, characterized in that, Includes the following steps: Prepare an aqueous dispersion of chestnut starch, seal and heat to 100-110℃ for 4 hours, cool, grind to obtain modified starch; The modified starch was dispersed in an aqueous ion-containing solution containing sodium chloride, citric acid and fructose to obtain a starch emulsion; The starch emulsion was homogenized to obtain a premixed solution; The premixed liquid is coated with a film and perforated, then heated by multi-stage frequency conversion to obtain a starch gelatinized liquid; Ethanol was mixed into the starch gelatinized liquid and kept at 50-70°C to obtain starch fluid. The starch fluid is extruded into a mold, dried, and cured to form the desired shape. The water content of the chestnut starch aqueous dispersion is 20-25%; The sodium chloride content in the ionic aqueous solution is 0.1–0.4 g / 100 mL, the citric acid content is 0.3–0.5 g / 100 mL, and the fructose content is 3–6 g / 100 mL. The process parameters for the multi-stage frequency conversion heating are: 100% irradiation for 15-20s, 80% irradiation for 10-20s, and 20% irradiation for 20-30s.

2. The method for preparing low-GI high-elasticity chestnut starch gel according to claim 1, characterized in that, The mass ratio of sodium chloride, citric acid, and fructose is 1:2:

20.

3. The method for preparing low-GI high-elasticity chestnut starch gel according to claim 1, characterized in that, The homogenization process parameters are: rotation speed 4000-4500 rpm, homogenization time 5-10 min.

4. The method for preparing low-GI high-elasticity chestnut starch gel according to claim 1, characterized in that, The starch fluid also contains pigments or active components.

5. The method for preparing low-GI high-elasticity chestnut starch gel according to claim 1, characterized in that, The process parameters for drying, curing, and molding are: temperature 50-60℃, humidity 70-80%, wind speed 0.5-1m / s, and drying time 3-5h.

6. The low-GI, high-elasticity chestnut starch gel prepared by the preparation method according to any one of claims 1-5.

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