Low-GI Chinese chestnut powder and preparation method thereof

Abstract

The invention discloses low-GI Chinese chestnut powder and a preparation method thereof. The method comprises the following steps: firstly selecting mature Chinese chestnuts without diseases and insect pests, performing pretreatment such as shelling and color protection, then sequentially performing heat-moisture treatment, enzymolysis treatment (ultrasonic treatment can be selected to enhance the effect), drying and crushing, then compounding with low-GI-value raw materials (such as oat flour, tartary buckwheat flour, konjaku flour and the like), and finally performing nitrogen filling or vacuum packaging. The GI value of the obtained low-GI Chinese chestnut powder is lower than 55, and the low-GI Chinese chestnut powder can remarkably reduce the blood sugar rising speed of a human body after meal and is suitable for diabetics, obese people and people paying attention to health to eat. The method is simple in process operation, can be produced by using existing equipment, reduces the cost, retains the nutritional ingredients and flavor of the Chinese chestnuts while reducing the GI value, and is good in taste. Through verification of embodiments, the product is good in taste, color and nutrition, and process parameters can be optimized according to actual production conditions during industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and particularly relates to a low-GI chestnut powder and a preparation method thereof. Background Art

[0002] The high incidence of related chronic diseases (type II diabetes) caused by overnutrition has become a social public health problem that cannot be ignored. As a diet adjustment method with high safety and no toxic side effects, low glycemic index (low-GI) foods have good advantages in preventing and controlling diabetes. Reducing the GI value of residents' traditional staple foods can better intervene in the treatment of type II diabetes. The glycemic index (GI) is a physiological index that measures the degree of blood sugar increase after the human body ingests food (mainly foods with high starch or other carbohydrate content). Low-GI foods generally require a GI value below 55. Some of its components can prolong the residence time of food in the human gastrointestinal tract, delay the digestion and absorption rate, and help maintain postprandial blood sugar balance. Long-term consumption of low-GI foods is of great significance for the intervention treatment of diabetic patients.

[0003] Chestnuts are rich in nutritional value, with a high starch content, and contain various nutrients such as proteins, fats, crude fibers, reducing sugars, total sugars, ash, various vitamins and minerals. They have a unique sweet, fragrant and glutinous flavor, and can adapt to various processing technologies, such as blanching, baking, pulverizing, etc. These technologies help to remove the outer shell and astringent skin of chestnuts for further processing and treatment. However, due to the fast digestion and absorption of raw chestnut starch, especially the high content of rapidly digestible starch, it belongs to high-GI foods, which easily leads to too rapid blood sugar increase and restricts the development of the chestnut starch industry. Summary of the Invention

[0004] The present invention aims to at least partly solve the technical problems that the existing chestnut products are restricted in their industrial development due to high GI values and cannot meet the healthy diet needs of diabetic patients and obese people. For this purpose, the object of the present invention is to provide a low-GI chestnut powder, a preparation method thereof and an application.

[0005] The high incidence of chronic diseases such as type II diabetes caused by overnutrition in residents, and low-GI foods have significant advantages in preventing and controlling diabetes. Chestnuts are rich in nutrition, but the digestion and absorption of raw chestnut starch are fast and the content of rapidly digestible starch is high, belonging to high-GI foods, which greatly restricts the development of the chestnut starch industry.

[0006] Preparation method of low-GI chestnut powder of the present invention. First, raw materials are selected and pretreated. Chestnuts with good maturity and no pests and diseases are selected, the outer shell and inner skin are removed, then they are washed and drained, and cut into thin slices or small pieces with a thickness of 2-5 mm. Then, the chestnut kernels are soaked in a color protection solution with an ascorbic acid concentration of 3 mmol / L, a citric acid concentration of 35 mmol / L, and a cysteine (Cys) concentration of 0.75 mmol / L for raw material color protection. Then, the pretreated chestnut raw materials are put into a heat-moisture treatment device and treated for 2-3 hours under the conditions of a temperature of 100-120 °C and a relative humidity of 75%-90% to increase the resistance by changing the starch structure, and then cooled to room temperature to obtain pretreated chestnut kernels. After that, when the chestnuts are cooled to 40-60 °C, a suitable enzyme preparation (such as pullulanase, α-amylase, etc.) is added at 0.2%-1.0% of the weight of the raw materials, and enzymolysis is carried out for 2-6 hours under the condition of a pH value of 4.5-6.5. During enzymolysis, stirring is carried out at 80-150 revolutions per minute. After enzymolysis, the chestnut slurry is heated to 90-100 °C and kept for 5-10 minutes to inactivate the enzyme; if ultrasonic treatment is selected, after enzymolysis, the chestnut material is placed in an ultrasonic device, immersed in water, the ultrasonic frequency is set at 20-50 kHz, and the power is 200-800 W, and treated for 10-30 minutes. Then, the treated chestnut material is dried at 50-70 °C until the moisture content is 8%-12%, and ground into fine powder with a mesh size of 60-100. Raw materials with low GI values (such as oat powder, tartary buckwheat powder, konjac powder, etc.) are selected and compounded with the ground chestnut powder, and the compounding ratio is chestnut powder: low-GI raw material = 3-6:1. Stirring is carried out at 100-180 revolutions per minute in a stirring device for 10-20 minutes. Finally, the final product is vacuum-packed or nitrogen-filled and stored in a cool, dry, and well-ventilated place.

[0007] It was found during the research process that through the above series of treatments, the structure of chestnut starch can be effectively changed. Heat-moisture treatment changes the internal structure of starch granules and increases resistance; enzymolysis treatment can further decompose starch, and ultrasonic treatment can enhance the effect of reducing the GI value; compounding with low-GI raw materials can further reduce the overall GI value. The low-GI chestnut powder obtained after these treatments has a detected GI value lower than 55, which is significantly lower than that of traditional chestnut powder, and maintains good performance in terms of taste, color, and nutritional components.

[0008] The low-GI chestnut powder processed by the present invention can significantly reduce the rising speed of postprandial blood glucose in the human body, providing an ideal food choice for diabetic patients, obese people, and people concerned about health, and contributing to healthy diet management. The process operation is relatively simple, and existing food processing equipment can be used for production, reducing production costs and equipment investment, and having high economic and social benefits. While reducing the GI value, the product retains the nutritional components and flavor of chestnuts, has a good taste, and improves the acceptance of consumers.

[0009] Specifically, the present invention provides the following technical solutions:

[0010] In the first aspect of the present invention, a preparation method of low-GI chestnut powder is provided, including: (1) Raw material selection and pretreatment: Select chestnuts with good maturity and no pests or diseases, remove the outer shell and inner skin, wash them clean and drain the water, and cut them into thin slices or small pieces of 2-5 mm; (2) Raw material color protection: Immerse chestnut kernels in a color protection solution with a concentration of 3 mmol / L of ascorbic acid, 35 mmol / L of citric acid, and 0.75 mmol / L of Cys; (3) Hydrothermal treatment: Put the pretreated chestnuts into a hydrothermal treatment device, set the temperature at 100-120 °C and the relative humidity at 75%-90%, treat for 2-3 hours, and then naturally cool to room temperature after completion; (4) Enzymatic hydrolysis treatment: For chestnuts cooled to 40-60 °C, add a suitable enzyme preparation (such as pullulanase, α-amylase, etc.) according to 0.2%-1.0% of the weight of the raw materials, and carry out enzymatic hydrolysis for 2-6 hours (depending on the optimal activity environment of the enzyme) under the condition of pH value 4.5-6.5. Stir at 80-150 revolutions per minute during enzymatic hydrolysis, and then heat the chestnut slurry to 90-100 °C and keep it for 5-10 minutes to inactivate the enzyme; (5) Ultrasonic treatment (optional): After enzymatic hydrolysis, if ultrasonic treatment is selected, place the chestnut material in an ultrasonic device, add water to submerge it, set the ultrasonic frequency at 20-50 kHz and the power at 200-800 W, and treat for 10-30 minutes; (6) Drying and pulverization: Dry the treated chestnut material at 50-70 °C to reduce the water content to 8%-12%, and then pulverize it into fine powder of 60-100 mesh; (7) Raw material compounding: Select raw materials with low GI values (such as oat powder, tartary buckwheat powder, konjac powder, etc.) and compound them with the pulverized chestnut powder, and the compounding ratio is chestnut powder: low-GI raw material = 3-6:1. (8) Nitrogen filling packaging: The final product is packaged by vacuum packaging or nitrogen filling packaging. The packaging specifications are set according to market demand. The product is stored in a cool, dry and ventilated place, avoiding direct sunlight and high temperature and high humidity.

[0011] Through the above series of treatments, the structure of chestnut starch can be changed, and the GI value of the product can be reduced. Compounding with low-GI raw materials further optimizes the product characteristics, and nitrogen filling or vacuum packaging ensures the product quality and shelf life. This preparation method has strong operability and can provide suitable food choices for relevant people.

[0012] According to the embodiments of the present invention, the preparation method of the above-mentioned low-GI chestnut powder may further include the following technical features:

[0013] In some embodiments of the present invention, during the hydrothermal treatment in step (3), the temperature is preferably 110 °C and the relative humidity is preferably 85%. Under this condition, the change of starch structure is more sufficient, the GI value of the product can be reduced more effectively, and the flavor and nutritional components of chestnuts can be better retained.

[0014] In some embodiments of the present invention, during the enzymatic hydrolysis treatment in step (4), if pullulanase is used, its dosage accounts for 0.5% of the weight of the chestnut raw material, the pH value is adjusted to 5.5, the enzymatic hydrolysis temperature is 50 °C, and the enzymatic hydrolysis time is 4 hours. Such a parameter combination can enable pullulanase to exert a better enzymatic hydrolysis effect, fully act on chestnut starch, and improve the product quality.

[0015] In some embodiments of the present invention, during the ultrasonic treatment in step (5), the ultrasonic frequency is 30 kHz, the power is 500 W, and the treatment time is 20 minutes. Such ultrasonic parameters can more effectively destroy the chestnut starch structure, enhance the effect of reducing the GI value, and at the same time avoid adverse effects on the nutritional components and flavor of chestnuts caused by over-treatment.

[0016] In some embodiments of the present invention, during the drying in step (6), the temperature is controlled at 60 °C, and after pulverization, an 80-mesh fine powder is obtained. Such a drying temperature and pulverization mesh number can not only ensure the drying effect and stability of the product, but also enable the product to have a good taste and instant solubility.

[0017] In some embodiments of the present invention, during the raw material compounding in step (7), the compounding ratio of chestnut powder to oat powder is 3:1. At this ratio, it can not only significantly reduce the GI value of the product, but also enable the product to have the nutrition and flavor of both chestnuts and oats, improving the comprehensive quality of the product.

[0018] In some embodiments of the present invention, before step (1), it further includes screening the selected chestnuts to remove shriveled and deteriorated chestnuts. Through this pretreatment step, the quality of the raw material can be further improved, ensuring the quality consistency of the final product.

[0019] In some embodiments of the present invention, before packaging in step (8), the product is subjected to quality inspection, and the inspection items include GI value, moisture content, microbial indicators, etc. Only the products with all indicators meeting the standards are packaged to ensure the quality and safety of the products on the market.

[0020] In the second aspect of the present invention, a preparation method of low-GI chestnut powder is provided, including: 1) Select chestnuts with good maturity and no pests and diseases, remove the outer shell and inner skin, wash, drain, and cut into thin slices or small pieces of 2-5 mm, and soak in a color protection solution for color protection; 2) Perform hydrothermal treatment at 110°C and a relative humidity of 85%, and cool to room temperature; 3) After cooling to 50°C, add pullulanase at 0.5% of the weight of the chestnut raw material, adjust the pH value to 5.5, enzymolyze at 50°C for 4 hours, with a stirring speed of 120 revolutions per minute, and inactivate the enzyme after enzymolysis; 4) Perform ultrasonic treatment on the enzymolyzed material, with an ultrasonic frequency of 30 kHz and a power of 500 W, and treat for 20 minutes; 5) Dry at 60°C until the moisture content is 10%, and pulverize into 80-mesh fine powder; 6) Compound the chestnut powder and oat powder in a ratio of 3:1, and stir evenly; 7) Use vacuum packaging or nitrogen filling packaging.

[0021] In the third aspect of the present invention, a low-GI chestnut powder is provided. The low-GI chestnut powder is prepared by the preparation method described in any embodiment of the first aspect of the present invention or the preparation method described in the second aspect of the present invention. The GI value of this low-GI chestnut powder is lower than 55, which can effectively delay the rising speed of postprandial blood glucose in the human body. It is suitable for diabetic patients, obese people, and people concerned about health to eat, and retains the nutritional components and flavor of chestnuts, with a good taste. Description of the Drawings

[0022] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand in the description of the embodiments with reference to the following drawings, where:

[0023] Figure 1 is a schematic flow chart of the preparation process of low-GI chestnut powder provided according to an embodiment of the present invention; Detailed Embodiments

[0024] The embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the described embodiments are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0025] The present invention provides a method for preparing low-GI chestnut powder, comprising: (1) raw material selection and pretreatment, selecting chestnuts with good maturity and no pests and diseases, removing the outer shell and inner skin, washing, draining, and cutting into thin slices or small pieces; (2) raw material color protection, soaking chestnut kernels with a color protection liquid in a specific ratio; (3) hydrothermal treatment, treating at a certain temperature and humidity for a period of time and then cooling; (4) enzymatic hydrolysis treatment, adding an enzyme preparation after cooling and carrying out enzymatic hydrolysis under suitable conditions, and then inactivating the enzyme, and ultrasonic treatment can be optionally used to further disrupt the starch structure; (5) drying and pulverizing, drying the material and pulverizing it into fine powder of a specific mesh number; (6) raw material compounding, selecting raw materials with low GI values and compounding them with chestnut powder in proportion and stirring evenly; (7) nitrogen filling packaging, using vacuum or nitrogen filling packaging, setting the packaging specifications according to market demand and storing in a suitable environment.

[0026] It should be noted that the chestnuts used in the present invention should be selected with good maturity and no pests and diseases, and their sources can be directly purchased from formal channels or directly obtained from the production areas. Although there will be certain differences in the nutritional components and starch characteristics of chestnuts from different production areas and varieties, chestnut powder meeting the low-GI requirements can be prepared by the method of the present invention. In at least some embodiments of the present invention, to ensure the stable quality of the product, chestnut varieties with plump grains and relatively high starch content can be preferably selected.

[0027] In the raw material color protection step, the color protection liquid used is composed of ascorbic acid with a concentration of 3 mmol / L, citric acid with a concentration of 35 mmol / L, and Cys with a concentration of 0.75 mmol / L. This color protection liquid can effectively prevent chestnuts from oxidizing and discoloring during the processing and maintain a good color. In actual operation, the color protection liquid can be prepared in proportion according to the amount of chestnut raw materials to ensure that the chestnut kernels are completely immersed in the color protection liquid.

[0028] When carrying out hydrothermal treatment, a steam treatment device or other devices with corresponding temperature and humidity control functions can be used. Set the temperature at 100-120°C, the relative humidity at 75%-90%, and the treatment time at 2-3 hours. This process will change the starch structure, increase the resistance, and thus reduce the GI value. After the treatment is completed, let it cool naturally to room temperature. If it is necessary to accelerate the cooling speed, it can also be carried out in an environment with good ventilation.

[0029] During enzymatic hydrolysis, enzyme preparations such as pullulanase and α-amylase can be selected, and the addition amount is 0.2%-1.0% of the weight of the chestnut raw material. Enzymatic hydrolysis is carried out for 2-6 hours under the condition of pH value of 4.5-6.5, depending on the optimal activity environment of the selected enzyme. During the enzymatic hydrolysis process, continuous stirring is carried out at a speed of 80-150 revolutions per minute to ensure sufficient contact between the enzyme and the substrate. During the enzyme inactivation treatment, the chestnut pulp is heated to 90-100°C and maintained for 5-10 minutes. If ultrasonic treatment is selected, after the enzymatic hydrolysis is completed, the chestnut material is placed in an ultrasonic device, an appropriate amount of water is added to submerge the material, the ultrasonic frequency is set to 20-50 kHz, the power is 200-800 W, and the ultrasonic treatment time is 10-30 minutes.

[0030] During the drying and pulverization process, equipment such as a hot air drying oven can be used to dry the material at 50-70°C to reduce the moisture content to 8%-12%. The dried material is pulverized into fine powder of 60-100 mesh by a pulverizer, and the pulverization degree will affect the taste and instant solubility of the product.

[0031] When formulating the raw materials, the selected raw materials with low GI value include oat flour, tartary buckwheat flour, konjac flour, etc.).

[0032] The packaging link adopts vacuum packaging or nitrogen filling packaging, and the packaging specification can be set to 200-500 grams per bag according to market demand. The product should be stored in a cool, dry and well-ventilated environment, avoiding direct sunlight and high temperature and high humidity, preventing the product from deteriorating, and ensuring the quality and shelf life of the product.

[0033] The solution of the present invention will be explained below in conjunction with the embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific techniques or conditions, they are carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. Those raw materials and equipment not specified in terms of the manufacturer can be conventional products obtained through commercial purchase.

[0034] Example 1

[0035] (1) Raw material preparation: Select 100 kg of fresh chestnuts. After manually removing the outer shell and inner skin, rinse them 3 times with clean water, cut them into thin slices 3 mm thick, and drain the water.

[0036] (2) Hydrothermal treatment: Put the chestnut thin slices into a steam treatment device, set the temperature to 110°C, the relative humidity to 85%, and the treatment time to 30 minutes. After the treatment is completed, quickly take out the chestnut thin slices and cool them to 50°C in a well-ventilated environment.

[0037] (3) Enzymatic hydrolysis treatment: Add 0.5 kg of pullulanase (enzyme activity is 1000 PUN / g) to the cooled chestnut slices, adjust the pH value to 5.5 with 0.1 mol / L citric acid - sodium citrate buffer, and stir and hydrolyze at a speed of 120 revolutions per minute in a constant temperature water bath at 50 °C for 4 hours.

[0038] (4) Ultrasonic treatment: After the enzymatic hydrolysis is completed, transfer the chestnut material to the ultrasonic equipment, add an appropriate amount of water to submerge it, set the ultrasonic frequency to 30 kHz, the power to 500 W, and the ultrasonic treatment time to 20 minutes.

[0039] (5) Drying and pulverization: Dry the chestnut material after ultrasonic treatment in a hot air drying oven at 60 °C until the moisture content is 10%, and then pulverize it into 80 - mesh fine powder with a pulverizer.

[0040] (6) Raw material compounding: Weigh 60 kg of chestnut powder, add 10 kg of oat powder and 5 kg of tartary buckwheat powder, put them into a stirrer, and stir at a speed of 150 revolutions per minute for 15 minutes to make them fully mixed.

[0041] (7) Packaging: Vacuum - pack the compounded low - GI chestnut powder, with 300 g per bag.

[0042] Example 2

[0043] (1) Raw material preparation: Prepare 200 kg of chestnuts, cut them into slices with a thickness of 2 mm after processing, and wash and drain.

[0044] (2) Hydrothermal treatment: In the hydrothermal treatment equipment, set the temperature to 105 °C, the relative humidity to 80%, the treatment time to 35 minutes, and cool to 45 °C.

[0045] (3) Enzymatic hydrolysis treatment: Add 1 kg of α - amylase (enzyme activity is 800 U / g), adjust the pH value to 5.0, hydrolyze at 55 °C for 3 hours, and the stirring speed is 100 revolutions per minute.

[0046] (4) Drying and pulverization: Without ultrasonic treatment, directly dry at 55 °C until the moisture content is 9%, and pulverize into 70 - mesh powder.

[0047] (5) Raw material compounding: Take 100 kg of chestnut powder and mix it with 25 kg of tartary buckwheat powder and 5 kg of konjac powder, stir at a speed of 120 revolutions per minute for 18 minutes.

[0048] (6) Packaging: Nitrogen - filled packaging, 250 g per bag.

[0049] Example 3

[0050] (1) Raw material preparation: Take 300 kg of chestnut raw materials, process them into slices with a thickness of 5 mm and drain.

[0051] (2) Hydrothermal treatment: Treat at 120°C and relative humidity of 90% for 15 minutes, and then cool to 60°C.

[0052] (3) Enzymatic hydrolysis treatment: Add 1.5 kg of compound enzyme preparation (pullulanase and α-amylase are mixed at a ratio of 1:1), pH value 6.0, hydrolyze at 60°C for 2 hours, and stir at 150 revolutions per minute.

[0053] (4) Ultrasonic treatment: Ultrasonic frequency 40 kHz, power 600 W, treat for 10 minutes.

[0054] (5) Drying and pulverization: Dry at 70°C until the moisture content reaches 8%, and pulverize into 90-mesh powder.

[0055] (6) Raw material compounding: Mix 150 kg of chestnut powder with 30 kg of konjac powder, 10 kg of tartary buckwheat powder, and 5 kg of oat powder, stir for 10 minutes, and the stirring speed is 180 revolutions per minute.

[0056] (7) Packaging: Vacuum pack into 500 g / bag.

Claims

1. A method for preparing low GI chestnut powder, characterized in that: The following steps are involved: (1) Raw material selection and pretreatment: Select chestnuts that are well-matured and free of pests and diseases, remove the shell and inner skin, wash and drain the water, and cut into thin slices or small pieces with a thickness of 2-5 mm; (2) Raw material color protection: Soak chestnut kernels in a color protection solution with a ratio of 3 mmol / L ascorbic acid, 35 mmol / L citric acid, and 0.75 mmol / L cysteine ​​(Cys); (3) Wet heat treatment: Place the pretreated chestnut raw material into a wet heat treatment device, set the temperature at 100-120°C, the relative humidity at 75%-90%, treat for 2-3 hours, and naturally cool to room temperature after the treatment; (4) Enzymatic hydrolysis: After the wet heat treatment, the chestnuts are cooled to 40-60° C., and an enzyme preparation is added at 0.2%-1.0% of the weight of the chestnut raw material. Enzymatic hydrolysis is performed at a pH of 4.5-6.5 for 2-6 hours. The stirring speed during the enzymatic hydrolysis is 80-150 rpm. After the enzymatic hydrolysis, the chestnut pulp is heated to 90-100° C. and kept for 5-10 minutes to inactivate the enzyme; (5) Drying and crushing: Dry the processed chestnut material at 50-70°C to reduce the moisture content to 8%-12%, and then crush it into 60-100 mesh fine powder; (6) Raw material compounding: select low GI raw materials and mix them with the crushed chestnut powder, the compounding ratio is chestnut powder: low GI raw materials = 3-6:1, and stir in a stirring device at a speed of 100-180 rpm for 10-20 minutes; (7) Nitrogen-filled packaging: The final product is packaged in a vacuum package or in a nitrogen-filled package. The packaging specifications are set according to market demand. The product is stored in a cool, dry, well-ventilated environment, avoiding direct sunlight and high temperature and humidity.

2. The method for preparing low GI chestnut powder according to claim 1, characterized in that: The enzyme preparation is one or more of pullulanase and α-amylase.

3. The method for preparing low GI chestnut powder according to claim 1, characterized in that: The method also includes an ultrasonic treatment step: after the enzymatic hydrolysis is completed, the chestnut material is placed in an ultrasonic device, an appropriate amount of water is added to immerse the material, the ultrasonic frequency is set to 20-50kHz, the power is set to 200-800W, and the ultrasonic treatment time is set to 10-30 minutes.

4. The method for preparing low GI chestnut powder according to claim 1, characterized in that: The raw materials with low GI value are one or more of oat flour, buckwheat flour and konjac flour.

5. A low GI chestnut powder obtained by the preparation method according to any one of claims 1 to 4.

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