High-fiber low-glycemic cereal food and preparation method thereof

Abstract

The present invention relates to the technical field of food processing and particularly provides a high-fiber low-glycemic cereal food and a preparation method thereof, the high-fiber low-glycemic cereal food comprises the following raw materials in parts by weight: 15-40 parts of common corn flour, 15-40 parts of high straight-chain corn flour, 5-20 parts of iron stick yam flour, 5-20 parts of wheat aleurone layer powder, 5-15 parts of modified corn bran powder, 3-10 parts of red date powder, 3-10 parts of Chinese wolfberry powder and 3-10 parts of mulberry powder. 2-5 parts of erythritol and 3-10 parts of skimmed milk powder; according to the scheme, the cereal food which is low in glycemic index, high in dietary fiber content, rich in nutrition and excellent in taste is prepared by taking multiple cereals as main raw materials and combining with various medicinal and edible auxiliary materials through a bacterium-enzyme synergistic treatment and extrusion puffing technology; the cereal food prepared by the preparation method disclosed by the invention has the blood glucose generation index of less than or equal to 55, the fiber content of more than or equal to 10%, crispy, smooth and fine taste and rich fragrance, can be used as meal replacement food for diabetic people, old people and healthy people, and has wide market prospects and application values.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a high-fiber, low-glycemic grain food and its preparation method. Background Technology

[0002] In recent years, with the improvement of living standards and changes in dietary structure, people's diets have gradually become more refined. However, overly refined diets lead to insufficient dietary fiber intake and increased glycemic load, resulting in a significant increase in the incidence of chronic metabolic diseases such as obesity and diabetes, seriously threatening human health. Studies have shown that long-term intake of high glycemic index (GI) foods is one of the important factors leading to the occurrence and development of diabetes. For diabetic patients, low-GI foods can effectively reduce postprandial blood glucose levels, increase satiety, and slow down blood glucose fluctuations, thereby helping to control the condition, especially for blood glucose management in patients with type II diabetes. Therefore, the development of low-GI foods has become an important development direction for the food industry.

[0003] Grain foods, as an important part of people's daily diet, are usually refined and contain a large amount of starch, resulting in a high glycemic index (GI), making them unsuitable for people with abnormal glucose metabolism. Furthermore, although the dietary fiber and other components in whole grain foods have positive effects on alleviating chronic metabolic diseases such as diabetes, their coarse texture and poor palatability result in relatively low actual production and consumption. Therefore, developing a low-GI, high-fiber, and palatable grain food by optimizing raw material formulations and improving processing techniques is key to solving the current predicament. Summary of the Invention

[0004] To address the common issues of high glycemic index (GI) and low dietary fiber content in currently processed grain foods, as well as the rough texture and poor sensory appeal of whole grain foods, which fail to meet the needs of specific groups (such as diabetics and the elderly) for low-GI, high-fiber, and nutritionally balanced foods, this invention provides a high-fiber, low-GI grain food and its preparation method. Using multiple grains as the main raw material, combined with various medicinal and edible auxiliary materials, and through synergistic microbial and enzyme treatment and extrusion puffing technology, a grain food with a low GI, high dietary fiber content, rich nutrition, and excellent taste is prepared. Its GI is ≤55, dietary fiber content ≥10%, and it has a crisp, smooth, and delicate texture with a rich aroma. This grain food can be used as a meal replacement for diabetics, the elderly, and healthy individuals, and has broad market prospects and application value.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention first provides a high-fiber, low-glycemic grain food, the raw material composition of which is: 15-40 parts of ordinary corn flour, 15-40 parts of high amylose corn flour, 5-20 parts of Chinese yam powder, 5-20 parts of wheat aleurone layer powder, 5-15 parts of modified corn bran powder, 3-10 parts of jujube powder, 3-10 parts of wolfberry powder, 3-10 parts of mulberry powder, 2-5 parts of erythritol, and 3-10 parts of skim milk powder.

[0006] High-amylose corn flour is a functional food ingredient made from corn with high amylose content, and its amylose content is significantly higher than that of ordinary corn flour (≥50%). High-amylose corn flour has a high content of slow-digesting starch (SDS) and resistant starch (RS), and is a low-GI food. It can effectively inhibit the rise in postprandial blood glucose and reduce insulin response, thereby significantly improving human glucose metabolism.

[0007] The aleurone layer of wheat, located between the wheat endosperm and the seed coat, accounts for approximately 7%-9% of the total weight of wheat grains. It is a highly nutritious natural component, rich in protein, B vitamins, dietary fiber, minerals, and other bioactive ingredients, offering excellent nutritional and health benefits. Studies have shown that the wheat aleurone layer plays an important role in preventing diabetes, cardiovascular disease, intestinal diseases, and certain cancers, making it a functional food ingredient with significant development potential.

[0008] Corn husks are a byproduct of corn starch processing, mainly composed of cellulose, hemicellulose, lignin, protein, and ash. They are rich in dietary fiber, making them a high-quality source. Furthermore, corn husks contain antioxidants such as phytosterols and phenols, exhibiting antioxidant and anti-inflammatory biological activities, and can be used as raw materials for functional foods or dietary supplements. However, due to their poor edibility and processing adaptability, their effective utilization rate is low. Therefore, this invention employs steam explosion technology to modify corn husks. The modified corn husks used in this invention are obtained by passing the corn husks through a 20-mesh sieve, collecting the material remaining on the sieve, treating it under a steam pressure of 0.6-1.2 MPa for 40-120 seconds, depressurizing, and then drying it with hot air at 50°C for at least 12 hours.

[0009] The above treatment breaks down the stubborn natural structural barrier of corn husks, enabling the separation and transformation of components, thereby significantly enhancing its functional properties and application value. The most prominent changes are the increase in soluble dietary fiber content and the substantial enhancement of prebiotic function, which is of great significance for developing functional foods that promote gut health.

[0010] Yam is a traditional plant used for both food and medicine, with a long history of cultivation and consumption. It is rich in protein, starch, vitamins, choline, allantoin, saponins, and other active ingredients, possessing properties that strengthen the spleen and stomach, regulate immunity, reduce inflammation, lower blood sugar and blood pressure, and promote metabolism. Due to its mild and nourishing characteristics, yam is widely used in the dietary management of the elderly and patients. Iron yam is a superior variety of yam that combines food and medicine, its core advantage being its significantly stronger nourishing effects than ordinary yam. It is richer in active ingredients such as yam polysaccharides and saponins, which more effectively strengthen the spleen and stomach, promote body fluid production and benefit the lungs, tonify the kidneys and astringe essence, and have better effects on enhancing immunity and regulating blood sugar. Furthermore, it has a powdery, sweet taste and a firm, dense texture, with a higher nutritional density, making it a nourishing food that combines excellent therapeutic value with a superior taste.

[0011] Mulberries are a functional fruit used both as food and medicine, and are often processed into juice, jam, wine, and canned goods. They are rich in vitamins, amino acids, trace elements, and various active ingredients, such as anthocyanins, flavonoids, active polysaccharides, chlorogenic acid, and resveratrol. Studies have shown that mulberries possess multiple health benefits, including antioxidant, anti-inflammatory, anti-cancer, anti-diabetic, anti-aging, immune-regulating, and fatigue-relieving properties, making them a natural functional food ingredient with significant development potential.

[0012] Goji berries are a traditional plant used for both food and medicine. They are often processed into dried fruit, medicinal wine, powder, and tablets for consumption or medicinal purposes. They contain sugars, proteins, fatty acids, vitamins, minerals, and various phytochemicals, such as phenols, carotenoids, and alkaloids. These components endow goji berries with various biological functions, including antioxidant, anti-inflammatory, immunomodulatory, and liver-protective properties, making them promising for applications in functional foods and health products.

[0013] Red dates are a commonly used ingredient in traditional Chinese medicine and food, as announced by the National Health and Family Planning Commission, possessing both nutritional and health-promoting functions. Rich in phenolic substances, triterpenoids, saponins, and alkaloids, they exhibit various physiological functions, including lowering blood lipids, anti-inflammation, liver protection, anti-fatigue, anti-oxidation, anti-cancer, immune enhancement, and intestinal protection, making them an important functional food ingredient.

[0014] Erythritol is a natural sugar alcohol whose main function is as a healthy sweetener. It provides a pure, sugary sweetness while producing almost no calories, not raising blood sugar levels, and is less likely to cause gastrointestinal discomfort. It can also prevent tooth decay, so it is widely used in sugar-free foods and beverages to meet consumers' demand for healthy eating.

[0015] Skim milk powder is a powder produced by spray drying after removing most of the fat from fresh milk. Its core function is to provide high-quality protein, calcium, and B vitamins, while greatly reducing fat and calorie intake. It is widely used in milk powder, baked goods, beverages, meat products and other fields. It can enhance the nutritional value of products (such as high calcium and high protein) and improve their structure (such as flavor and thickening). It is an economical and multifunctional basic raw material.

[0016] Furthermore, the present invention provides a method for preparing the above-mentioned high-fiber, low-glycemic grain food, the specific steps of which are as follows: (1) Pretreatment: Clean and impurity-free ordinary corn, high amylose corn, iron yam, wheat aleurone layer, modified corn husk, red dates, wolfberry and mulberry are crushed separately to obtain ordinary corn flour, high amylose corn flour, iron yam powder, wheat aleurone layer powder, modified corn husk powder, red date powder, wolfberry powder and mulberry powder; (2) Mixing: Mix the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone layer powder, modified corn bran powder, red date powder, wolfberry powder, mulberry powder, erythritol, and skim milk powder in proportion to obtain mixed powder; (3) Enzyme treatment: Add an appropriate amount of water to the mixed powder in step (2), add a certain proportion of compound enzyme preparation, and enzymatically hydrolyze under suitable conditions. After the enzymatic hydrolysis is completed, dry the material at 50-60℃ to obtain the enzymatically hydrolyzed mixture. (4) Solid-state fermentation: Add a certain proportion of water to the enzymatic hydrolysis mixture in step (3), mix evenly, sterilize, and cool naturally to room temperature to obtain the fermentation substrate; inoculate highly active freeze-dried Lactobacillus plantarum powder onto the fermentation substrate, carry out solid-state fermentation under suitable conditions, and after the fermentation is completed, dry the fermentation substrate at 50-60℃, pulverize it and pass it through a 60-100 mesh sieve to obtain the raw material powder. (5) Extrusion puffing: Adjust the moisture content of the raw material powder in step (4), and obtain high-fiber, low-glycemic index grain food by twin-screw extrusion puffing, segmentation and drying.

[0017] Furthermore, in step (1), the particle size of the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone layer flour, modified corn bran flour, jujube flour, wolfberry flour and mulberry flour mentioned in the raw material configuration is 60-100 mesh.

[0018] Furthermore, the compound enzyme preparation mentioned in step (3) is xylanase and cellulase, with a mass ratio of 1-3:0.5-1.5, and the addition ratio of the compound enzyme preparation is 0.5%-1.5% of the dry weight of the mixed powder, and the moisture content is adjusted to 55-65wt%.

[0019] Furthermore, the enzymatic hydrolysis conditions described in step (3) are a temperature of 40-50℃, a pH of 4.5-5.5 adjusted using a 0.1M citrate-sodium citrate buffer system, and enzymatic hydrolysis for 2-6 hours under these conditions, with samples taken every 30-60 minutes. The reducing sugar content is determined using the DNS method. When the increase in reducing sugar between two consecutive detection intervals is <5%, it can be determined as the end point of enzymatic hydrolysis.

[0020] Furthermore, the solid-state fermentation process described in step (4) involves mixing the enzymatic hydrolysis mixture with deionized water at a weight ratio of 1:0.5-1, sterilizing at 121-123℃ for 15-25 minutes, and naturally cooling to room temperature to obtain the fermentation substrate. For inoculation, highly active freeze-dried *Lactobacillus plantarum* powder is used, without the need for a pre-activation step, and is inoculated onto the fermentation substrate at an inoculation rate of 0.5-1.5% by mass; the powder contains ≥1×10⁻⁶ bacteria at the time of inoculation. 11 CFU / g, fermented in a micro-aerobic environment with an oxygen concentration of 0.5-2%, at a temperature controlled at 30-37℃, for a fermentation time of 6-24h.

[0021] Furthermore, the moisture content of the raw material powder in step (5) is adjusted to 10%-25%; the extrusion puffing process is as follows: the temperatures of zones I, II, III and IV of the extrusion puffing machine are set to 50-70℃, 60-80℃, 100-120℃ and 140-160℃ respectively, the screw speed is 170-210r / min, and the feeding speed is 150-190r / min.

[0022] Furthermore, the drying process described in step (5) involves placing the segmented grain food in a hot air circulating oven, controlling the drying temperature at 40-60℃, and the drying time at 30-60 min, so that the product moisture content is ≤10%, and then cooling it to room temperature to obtain a high-fiber, low-glycemic grain food.

[0023] Furthermore, the high-fiber, low-glycemic grain foods prepared above can retain their shaped form, such as spheres or strips, which can be used for ready-to-eat snacks or products that need to maintain a specific shape to enhance chewiness or visual appeal; they can also be further pulverized to suit scenarios that require powder, granules, or preparation for consumption, such as meal replacement powders and grain porridge, thereby improving product solubility and portability.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The grain food of the present invention can meet the basic nutritional and energy needs of the human body, and is rich in a variety of functional components that help regulate blood sugar. It has slow digestion characteristics and can significantly delay the rate of postprandial blood sugar rise, making it suitable for the meal replacement needs of people with high blood sugar and the elderly. Among them, the combination of wheat aleurone layer and modified corn husk significantly increases the dietary fiber content, achieving complementarity and synergistic effect of dietary fiber components and functions. It not only enhances satiety and improves intestinal flora, but also synergistically regulates immune function and metabolic balance, effectively preventing obesity and related chronic diseases.

[0025] (2) This invention employs a synergistic bacterial-enzyme technology, utilizing the synergistic effect of *Lactobacillus plantarum* and a complex enzyme preparation (cellulase, xylanase) to degrade anti-nutritional factors in raw materials and release functional components, significantly improving the palatability of the product. Further combined with an optimized extrusion puffing process, the product is given a crisp texture and uniform pore structure while retaining the nutritional components of the raw materials. The introduction of the enzymatic hydrolysis-fermentation-extrusion ternary synergistic process not only ensures good solubility of the product through appropriate modification of the material formulation but also constructs an excellent water-holding structure through sufficient biotransformation, thereby synergistically achieving the ideal functional characteristics of the product. This process has advantages such as high processing efficiency, high raw material utilization, and low production cost, making it suitable for large-scale production.

[0026] (3) Based on the grain base, this invention innovatively adds a variety of medicinal and edible ingredients such as yam, mulberry, wolfberry, and red date. Through scientific formulation, the synergistic effect of multiple bioactive components (such as polysaccharides, saponins, anthocyanins, and phenolic substances) is achieved, further enhancing the hypoglycemic, antioxidant, and anti-inflammatory functions. In addition, by adding erythritol and skim milk powder, the flavor and taste of the product can be effectively improved, enhancing sensory acceptability.

[0027] (4) The cereal food of the present invention is a convenient food that provides balanced nutrition while meeting the needs of a fast-paced life. The product design covers high-quality flavor and multiple forms (stick, ball, flake, granule, powder, etc.), which can meet the preferences of different consumption scenarios and groups. It is especially suitable for diabetes management, weight control and elderly nutrition supplementation, and has a broad market prospect. Attached Figure Description

[0028] Figure 1 The starch hydrolysis curves of the cereal foods in Examples 1-5 are shown. Figure 2 The starch hydrolysis curves of the cereal foods in Comparative Examples 1-4 are shown. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to specific embodiments. These embodiments are only used to illustrate the technical solution of the present invention in more detail and should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, all percentages in the following embodiments are mass percentages. The highly active freeze-dried Lactobacillus plantarum powder used was purchased from Minsheng Zhongke Jiayi (Shandong) Biotechnology Co., Ltd.

[0030] Example 1: A high-fiber, low-glycemic grain food and its preparation method A high-fiber, low-glycemic grain food has the following raw material composition: 32 parts ordinary corn flour, 24 parts high amylose corn flour, 8 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0031] Its preparation method includes the following steps: (1) Pretreatment: Clean and impurity-free ordinary corn, high amylose corn, iron yam, wheat aleurone layer, modified corn husk, red dates, wolfberries and mulberries are ground into powder using a pulverizer and passed through a 70-mesh sieve to obtain ordinary corn powder, high amylose corn powder, iron yam powder, wheat aleurone layer powder, modified corn husk powder, red date powder, wolfberry powder and mulberry powder; The modified corn husks were obtained by passing the corn husks through a 20-mesh sieve, collecting the material on the sieve, and then subjecting it to steam explosion treatment at a pressure of 0.8 MPa for 60 seconds. After depressurization, the material was dried in hot air at 50°C for 12 hours before being collected. (2) Mixing: Mix the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone powder, modified corn bran powder, red date powder, wolfberry powder, mulberry powder, erythritol, and skim milk powder in the above proportions, and mix evenly with a mixer to obtain a mixed powder; (3) Enzyme treatment: Adjust the moisture content of the mixed powder to 60wt%, and then add the compound enzyme preparation obtained by mixing xylanase and cellulase in a ratio of 2:1 to the mixed powder and mix evenly. The addition ratio of the compound enzyme preparation is 1% of the dry weight of the mixed powder. The pH is controlled at 4.8-5.2 (using a 0.1M citric acid-sodium citrate buffer system). Enzymatic hydrolysis is carried out at 50℃ for 6h. After the enzymatic hydrolysis is completed, the material is dried at 50℃ to obtain the enzymatic hydrolysate mixture. (4) Solid-state fermentation: Add a certain proportion of water to the enzymatic hydrolysis mixture described in step (3). Mix the enzymatic hydrolysis mixture and deionized water at a weight ratio of 1:0.8 until homogeneous. Sterilize at 121°C for 20 minutes and allow to cool naturally to room temperature to obtain the fermentation substrate. The highly active freeze-dried Lactobacillus plantarum powder does not require activation. Inoculate it into the fermentation substrate at an inoculation rate of 1% and place it in a constant temperature chamber for solid-state fermentation. The fermentation temperature is controlled at 37°C and the fermentation time is 18 hours. After fermentation, dry the fermentation substrate at 60°C for 24 hours, pulverize it, and pass it through a 70-mesh sieve to obtain the raw material powder. (5) Extrusion puffing: Adjust the moisture content of the raw material powder in step (4) to 20%, add the raw material powder to the twin-screw extrusion puffing machine, set the temperature of the twin-screw extrusion puffing machine I, II, III and IV zones to 50℃, 60℃, 110℃ and 150℃ respectively, screw speed 180r / min, feeding speed 165r / min; The extruded and puffed grain bars are cut into pieces using a rotary cutter, placed in an oven, dried at 50°C for 60 minutes, and dried until the moisture content is ≤10%. After cooling to room temperature, they are pulverized to obtain powdered grain food.

[0032] Example 2: A high-fiber, low-glycemic grain food and its preparation method A high-fiber, low-glycemic grain food has the following raw material composition: 32 parts ordinary corn flour, 24 parts high amylose corn flour, 8 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0033] The preparation method is the same as in Example 1, except that the ratio of compound enzyme preparation added in step (3) enzyme treatment is 1.5% of the dry weight of mixed powder.

[0034] Example 3: A high-fiber, low-glycemic grain food and its preparation method A high-fiber, low-glycemic grain food has the following raw material composition: 32 parts ordinary corn flour, 24 parts high amylose corn flour, 8 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0035] The preparation method is the same as in Example 1, except that the fermentation time in step (4) solid-state fermentation is 12h.

[0036] Example 4: A high-fiber, low-glycemic grain food and its preparation method A high-fiber, low-glycemic grain food has the following raw material composition: 26.6 parts ordinary corn flour, 18.6 parts high amylose corn flour, 13.8 parts Chinese yam flour, 11.1 parts wheat aleurone layer flour, 9.8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0037] The preparation method is the same as in Example 1, except for the raw material ratio.

[0038] Example 5: A high-fiber, low-glycemic grain food and its preparation method A high-fiber, low-glycemic grain food has the following raw material composition: 16 parts ordinary corn flour, 32 parts high amylose corn flour, 16 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0039] The preparation method is the same as in Example 1, except for the raw material ratio.

[0040] Comparative Example 1 A type of grain food has the following raw material composition: 32 parts ordinary corn flour, 24 parts high amylose corn flour, 8 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0041] Specific preparation process and parameters: (1) Pretreatment: Ordinary corn, high amylose corn, iron yam, wheat aleurone layer, modified corn husk, red dates, wolfberry and mulberry are crushed and ground into powder by a pulverizer, passed through a 70-mesh sieve, and the sieve material is taken for later use; The modified corn husks were obtained by passing the corn husks through a 20-mesh sieve, collecting the material on the sieve, and then subjecting it to steam explosion treatment at a pressure of 0.8 MPa for 60 seconds. After depressurization, the material was dried in hot air at 50°C for 12 hours before being collected. (2) Mixing: Mix the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone powder, modified corn bran powder, red date powder, wolfberry powder, mulberry powder, erythritol, and skim milk powder in the above proportions, and mix evenly with a mixer to obtain a mixed powder; (3) Extrusion puffing: Adjust the moisture content of the mixed powder to 20wt%, add the mixed powder to the twin-screw extruder, set the temperature of the twin-screw extruder I, II, III and IV zones to 50℃, 60℃, 110℃ and 150℃ respectively, screw speed 180r / min, and feeding speed 165r / min; The extruded and puffed grain bars are cut into pieces using a rotary cutter, placed in an oven, dried at 50°C for 60 minutes, and dried until the moisture content is ≤10%. After cooling to room temperature, they are pulverized to obtain powdered grain food.

[0042] Comparative Example 2 A type of grain food has the following raw material composition: 32 parts ordinary corn flour, 24 parts high amylose corn flour, 8 parts Chinese yam flour, 8 parts wheat aleurone layer flour, 8 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0043] Specific preparation process: (1) Pretreatment: ordinary corn, high amylose corn, iron yam, wheat aleurone layer, modified corn bran, red dates, wolfberry and mulberry are ground into powder using a pulverizer, passed through a 70-mesh sieve, and the sieve-passed material is used for later use; The modified corn husks were obtained by passing the corn husks through a 20-mesh sieve, collecting the material on the sieve, and then subjecting it to steam explosion treatment at a pressure of 0.8 MPa for 60 seconds. After depressurization, the material was dried in hot air at 50°C for 12 hours before being collected. (2) Mixing: Mix the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone powder, modified corn bran powder, red date powder, wolfberry powder, mulberry powder, erythritol, and skim milk powder in the above proportions, and mix evenly with a mixer to obtain a mixed powder; (3) Solid-state fermentation: Add a certain proportion of water to the mixed powder, mix the mixed powder and deionized water at a weight ratio of 1:0.4, sterilize at 121℃ for 20 minutes, and cool naturally to room temperature to obtain the fermentation substrate. The highly active freeze-dried Lactobacillus plantarum powder does not need to be activated. Inoculate it into the fermentation substrate at an inoculation rate of 1%, place it in a constant temperature chamber for solid-state fermentation, control the fermentation temperature at 37℃, and ferment for 18 hours. Dry the above fermentation substrate at 60℃ for 24 hours, pulverize it and pass it through a 70-mesh sieve to obtain the raw material powder. (4) Extrusion puffing: Adjust the moisture content of the raw material powder to 20wt%, add the raw material powder to the twin-screw extrusion puffing machine, set the temperature of the twin-screw extrusion puffing machine I, II, III and IV zones to 50℃, 60℃, 110℃ and 150℃ respectively, screw speed 180r / min, feeding speed 165r / min; The extruded and puffed grain bars are cut into pieces using a rotary cutter, placed in an oven, dried at 50°C for 60 minutes, and dried until the moisture content is ≤10%. After cooling to room temperature, they are pulverized to obtain powdered grain food.

[0044] Comparative Example 3 A type of grain food has the following raw material composition: it consists of the following raw materials in parts by weight: 32 parts of ordinary corn flour, 24 parts of high amylose corn flour, 8 parts of Chinese yam powder, 8 parts of wheat aleurone layer powder, 8 parts of modified corn bran powder, 4 parts of jujube powder, 4 parts of wolfberry powder, 4 parts of mulberry powder, 3.2 parts of erythritol, and 4.8 parts of skim milk powder.

[0045] Specific preparation process: (1) Pretreatment: ordinary corn, high amylose corn, iron yam, wheat aleurone layer, modified corn bran, red dates, wolfberry and mulberry are ground into powder using a pulverizer, passed through a 70-mesh sieve, and the sieve-passed material is used for later use; The modified corn husks were obtained by passing the corn husks through a 20-mesh sieve, collecting the material on the sieve, and then subjecting it to steam explosion treatment at a pressure of 0.8 MPa for 60 seconds. After depressurization, the material was dried in hot air at 50°C for 12 hours before being collected. (2) Mixing: Mix the ordinary corn flour, high amylose corn flour, Chinese yam flour, wheat aleurone layer powder, modified corn bran powder, red date powder, wolfberry powder, mulberry powder, erythritol and skim milk powder in the above proportions, and mix evenly with a mixer to obtain mixed powder; (3) Enzyme treatment: Adjust the moisture content of the mixed powder to 60wt%, then mix xylanase and cellulase in a 2:1 ratio and add them to the mixed powder and mix evenly. The ratio of the compound enzyme preparation added is 1% of the dry weight of the mixed powder. The pH is controlled at 4.8-5.2 (using a 0.1M citric acid-sodium citrate buffer system). Enzymatic hydrolysis is carried out at 50℃ for 6 hours. After the enzymatic hydrolysis is completed, the material is dried at 50℃ to obtain the enzymatic hydrolysate mixture. The above enzymatically hydrolyzed mixture was dried at 50°C for 24 h, pulverized, and passed through a 70-mesh sieve to obtain raw material powder; (4) Extrusion puffing: Adjust the moisture content of the raw material powder to 20%, add the raw material powder to the twin-screw extrusion puffing machine, set the temperature of the twin-screw extrusion puffing machine I, II, III and IV zones to 50℃, 60℃, 110℃ and 150℃ respectively, screw speed 180r / min, feeding speed 165r / min; The extruded and puffed grain bars are cut into pieces using a rotary cutter, placed in an oven, dried at 50°C for 60 minutes, and dried until the moisture content is ≤10%. After cooling to room temperature, they are pulverized to obtain powdered grain food.

[0046] Comparative Example 4 A high-fiber, low-glycemic grain food has the following raw material composition: 20 parts ordinary corn flour, 17 parts high amylose corn flour, 8 parts Chinese yam flour, 25 parts wheat aleurone layer flour, 10 parts modified corn bran flour, 4 parts jujube powder, 4 parts wolfberry powder, 4 parts mulberry powder, 3.2 parts erythritol, and 4.8 parts skim milk powder.

[0047] The preparation method is the same as in Example 1, except for the raw material ratio.

[0048] Experimental Example 1 The glycemic index, fiber content, and sensory quality of the cereal foods prepared in Examples 1-5 and Comparative Examples 1-4 were determined (taking powdered cereal foods as an example). In order to ensure that cereal products meet the standards of low glycemic index and high fiber content, the formula is determined by the glycemic index and fiber content.

[0049] 1. Measurement of glycemic index The method for measuring the glycemic index is as follows: Weigh 200 mg of sample into a 50 mL glass tube, add 2 mL of water, and incubate at 80 ℃ for 5 min to gelatinize. Then add 13 mL of 0.2 mol / L acetate-sodium acetate buffer (pH 5.2), and equilibrate at 37 ℃ for 10 min. Add 0.2 mL of mixed enzyme solution (290 U / mL porcine pancreatic α-amylase and 15 U / mL saccharifying enzyme), and shake at 37 ℃ (150 r / min) while accurately timing. Collect the supernatant for enzyme inactivation treatment, and determine the glucose content at 540 nm using the 3,5-dinitrosalicylic acid method. Plot a starch hydrolysis curve. Calculate the starch hydrolysis index (HI) and eGI based on the area under the hydrolysis curve.

[0050] HI = (AUC) 样品 ÷AUC 白面包 )×100%; eGI=0.862×HI+8.1981.

[0051] 2. Determination of fiber content The enzyme was determined according to the enzyme gravimetric method in the national standard GB 5009.88-2023.

[0052] 3. Sensory evaluation Ten sensory evaluators were selected to conduct sensory evaluations according to the scoring criteria table (Table 1).

[0053] Table 1 Sensory Evaluation Criteria for Cereal Foods

[0054] The results of glycemic index, fiber content and sensory quality determination of the cereal foods prepared in Examples 1-5 and Comparative Examples 1-4 are shown in Table 2.

[0055] Table 2. eGI value, fiber content, and sensory scores of cereal foods

[0056] Figure 1 and Figure 2 The starch hydrolysis curves for Examples 1-5 and Comparative Examples 1-4 are shown below. The curves indicate that the starch hydrolysis rate of the cereal food increases rapidly in the first 20 minutes of digestion; most of the starch digestion is completed by 90 minutes. Furthermore, Comparative Examples 1-3 show significantly higher rates than the Examples, indicating that the rapidly digestible starch content in the Comparative Examples is higher than in the Examples, and also confirming that the combined process of the Comparative Examples using only a single process is less effective than that of the Examples. Comparative Example 4, due to its higher proportion of aleurone layer and corn husk, exhibits a significantly lower starch hydrolysis rate throughout the digestion process compared to other Comparative Examples, and even lower than some Examples. This suggests that the dietary fiber and other components abundant in the aleurone layer and corn husk effectively slow down the enzymatic hydrolysis process of starch, not only reducing the content of rapidly digestible starch but also potentially increasing the proportion of resistant or slowly digestible starch.

[0057] A comprehensive analysis of the data in Table 2 shows that different treatment methods significantly affected the product's eGI value, dietary fiber content, and sensory quality. Example 1 (enzymatic hydrolysis-extrusion-solid-state fermentation combination) exhibited the best overall performance, with a low eGI value (42.92), the highest sensory score (90.42), and a high fiber content (13.49%). Compared to Example 1, Example 2, due to the addition of 1.5% of the compound enzyme preparation (the upper limit of the range), resulted in an increased eGI value and decreased sensory quality, indicating that precise control of enzymatic hydrolysis is necessary. Example 3, due to its shortened fermentation time, showed a significantly increased eGI value, demonstrating that sufficient fermentation is crucial for reducing the glycemic index. Comparative Example 1 (extrusion only) had the highest eGI value (50.06) and the lowest fiber content (8.69%), highlighting the limitations of single processing. Comparative Example 2 (extrusion + fermentation) and Comparative Example 3 (enzymatic hydrolysis + extrusion) both had higher eGI values ​​than Example 1, indicating that the combined effect of the two technologies alone is not as significant as the synergistic effect of the three. In addition, the raw material ratio also needs to be optimized and balanced. For example, although Comparative Example 4 obtained the lowest eGI (39.12) and the highest fiber content (25.21%), the excessive fiber content caused its sensory score to plummet to 65.43, resulting in poor product palatability.

[0058] In summary, the enzymatic hydrolysis-extrusion-fermentation synergistic process used in Example 1 can significantly reduce the product's GI value and moderately increase the fiber content while maintaining excellent sensory acceptance to the greatest extent. It is an effective strategy for achieving balanced optimization of high-fiber, low-GI cereal foods and can be used as a preferred formulation for high-fiber, low-glycemic cereal foods.

[0059] Experimental Example 2 The water solubility index (WSI) and water absorption index (WAI) of the cereal foods prepared in Examples 1-5 and Comparative Examples 1-4 were determined using the following methods: Take approximately 2 g of sample, denoted as M0, and place it in a centrifuge tube of known mass (M1). Add 20 mL of distilled water and shake vigorously for 2 min until the sample is completely dispersed into a suspension. Incubate the suspension in a 30 ℃ water bath for 30 min, shaking every 10 min. After the water bath, centrifuge at 4000 r / min for 15 min. Slowly pour the supernatant into a small aluminum box of known mass (M2) and dry at 105 ℃ to constant weight (M3). Simultaneously weigh the total weight of the centrifuge tube and the precipitate, M4. The formulas for calculating WAI and WAI are as follows: Water solubility index (g / g) = M3 - M2 / M0 Water absorption index (g / g) = M4 - M1 / ​​M0 The WSI and WAI results of the cereal foods prepared in Examples 1-5 and Comparative Examples 1-4 are shown in Table 3.

[0060] Table 3 WSI and WAI for cereal foods

[0061] As shown in Table 3, different processing techniques and formulations significantly affected the functional properties (WSI and WAI) of the product. Overall, Example 1 (enzymatic hydrolysis-extrusion-fermentation co-processing) achieved the best balance between WSI and WAI, indicating the formation of ideal water-soluble components and water-holding structures. In Example 2, both WSI and WAI decreased significantly, confirming that the upper limit for the amount of compound enzyme preparation added is 1.5%. Excessive enzymatic hydrolysis will over-degrade water-soluble components and destroy the network structure, leading to deterioration of functional properties. Example 3, with its shortened fermentation time, had a significantly lower WAI than Example 1, indicating that sufficient fermentation time is crucial for microbial synthesis of hydrophilic substances and modification of fiber structures to improve water-holding capacity. Notably, Comparative Example 4 (high-fiber formulation) had the highest WAI, significantly better than the other groups, highlighting the decisive role of increasing corn husk and aleurone layer content in enhancing the product's water-holding capacity. However, its WSI did not increase significantly at the same time, indicating that the increased amount in this formulation mainly consisted of insoluble fiber. In contrast, neither single extrusion (Comparative Example 1) nor binary processes (Comparative Examples 2 and 3) can achieve synergistic optimization of WSI and WAI. In summary, the ternary synergistic process of enzymatic hydrolysis-fermentation-extrusion adopted in Example 1 can ensure good solubility through appropriate modification of the formulation and construct an excellent water-holding structure through sufficient biotransformation, which is the key to achieving the ideal functional characteristics of the product.

[0062] Comprehensive verification has shown that the cereal products prepared by this invention achieve both low GI and high dietary fiber characteristics, and possess excellent sensory quality. The product not only meets the dual standards of low GI (glycemic index ≤ 55) and high dietary fiber, but also, through scientific formulation and optimized processes, achieves a delicate texture and natural aroma. This product reduces postprandial glycemic response by more than 40% compared to traditional refined cereal products, and extends satiety time by 2-3 hours, making it particularly suitable for individuals with high blood sugar and those managing their weight. This technological innovation overcomes the problem of excessively high glycemic index commonly found in traditional cereal products, providing a quantifiable solution for low-GI food development and offering a new option for low-GI ready-to-eat cereal products currently on the market.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the spirit and principle of the present invention without any creative effort should be included within the protection scope of the present invention.

Claims

1. A high fibre, low glycaemic index cereal food characterised in that, The raw material composition comprises: 15-40 parts of common corn flour, 15-40 parts of high amylose corn flour, 5-20 parts of iron stick yam powder, 5-20 parts of wheat paste powder layer powder, 5-15 parts of modified corn skin powder, 3-10 parts of red jujube powder, 3-10 parts of Chinese wolfberry powder, 3-10 parts of mulberry powder, 2-5 parts of erythritol, and 3-10 parts of skimmed milk powder.

2. The high fiber, low glycemic cereal food of claim 1, wherein, The high amylose corn flour has a straight-chain starch content of 50%-80%; the modified corn skin powder is obtained by crushing modified corn skin; and the modified corn skin is obtained by collecting the sieve upper material of corn skin passing through a 20-mesh sieve, treating the collected material under a steam pressure of 0.6-1.2 MPa for 40-120 s, and then collecting the material after pressure relief and drying at 50 ℃ with hot air for at least 12 h.

3. The process for the preparation of the high fibre, low glycaemic index cereal food product as claimed in claim 1, wherein, The method comprises the following steps: (1) Pretreatment: cleaning and removing impurities from common corn, high amylose corn, iron stick yam, wheat paste powder layer, modified corn skin, red dates, Chinese wolfberry, and mulberry, respectively, to obtain common corn flour, high amylose corn flour, iron stick yam powder, wheat paste powder layer powder, modified corn skin powder, red date powder, Chinese wolfberry powder, and mulberry powder; (2) Mixing: mixing the common corn flour, high amylose corn flour, iron stick yam powder, wheat paste powder layer powder, modified corn skin powder, red date powder, Chinese wolfberry powder, and mulberry powder obtained by crushing with erythritol and skimmed milk powder in a certain proportion to obtain a mixed powder; (3) Enzyme treatment: adding a certain amount of water and a certain proportion of a composite enzyme preparation to the mixed powder of step (2), and performing enzymolysis under suitable conditions; after the enzymolysis is completed, the material is dried at 50-60 ℃ to obtain an enzymolysis mixture; (4) Solid-state fermentation: adding a certain proportion of water to the enzymolysis mixture of step (3), mixing uniformly, sterilizing, and naturally cooling to room temperature to obtain a fermentation substrate; inoculating high-activity freeze-dried Lactobacillus plantarum powder on the fermentation substrate, and performing solid-state fermentation under suitable conditions; after the fermentation is completed, the fermentation substrate is dried at 50-60 ℃, crushed, and sieved through a 60-100-mesh sieve to obtain a raw material powder; (5) Extrusion and puffing: adjusting the water content of the raw material powder of step (4), and performing double-screw extrusion and puffing treatment, segmentation, and drying to obtain a high-fiber and low-glycemic-index cereal food.

4. The process for the preparation of a high fibre, low glycaemic index cereal food according to claim 3, characterised in that, In step (1), the common corn flour, high amylose corn flour, iron stick yam powder, wheat paste powder layer powder, modified corn skin powder, red date powder, Chinese wolfberry powder, and mulberry powder are crushed to a particle size of 60-100 mesh.

5. The method of making a high fiber, low glycemic cereal food of claim 3, wherein, In step (3), the composite enzyme preparation comprises xylanase and cellulase, and the mass ratio of the two is 1-3:0.5-1.5; the addition proportion of the composite enzyme preparation is 0.5%-1.5% of the dry weight of the mixed powder, and the water content is adjusted to 55-65 wt%.

6. The method of making a high fiber, low glycemic cereal food of claim 3, wherein, In step (3), the enzymolysis conditions are as follows: the temperature is 40-50 ℃, the pH is adjusted to 4.5-5.5 using a 0.1 M citric acid-sodium citrate buffer system, and the enzymolysis is performed for 2-6 h; during the enzymolysis, samples are taken every 30-60 min, and the reducing sugar content is determined by the DNS method; when the increment of the reducing sugar content between two consecutive detection intervals is less than 5%, the enzymolysis endpoint is determined.

7. The method of making a high fiber, low glycemic cereal food of claim 3, wherein, The solid fermentation process in step (4) is that the enzymatic mixture is mixed with deionized water at a weight ratio of 1:0.5-1, sterilized at 121-123℃ for 15-25 min, and naturally cooled to room temperature to obtain a fermentation substrate; the high-activity Lactobacillus plantarum freeze-dried bacterial powder is inoculated into the fermentation substrate without activation at an inoculation amount of 0.5-1.5% by mass fraction; the bacterial powder contains bacteria at a content of ≥1×10 11 CFU / g at the time of inoculation, and is fermented and cultured in a micro-aerobic environment with an oxygen concentration of 0.5-2%, at a temperature of 30-37℃, for 6-24 h.

8. The method of making a high fiber, low glycemic cereal food of claim 3, wherein, The moisture content of the raw material powder in step (5) is adjusted to 10%-25%; the extrusion puffing treatment is that the temperatures of I, II, III and IV zones of the extrusion puffing machine are set to 50-70℃, 60-80℃, 100-120℃ and 140-160℃ respectively, the screw rotation speed is 170-210 r / min, and the feeding speed is 150-190 r / min.

9. The method of making a high fiber, low glycemic cereal food of claim 3, wherein, The drying in step (5) is that the segmented cereal food is placed in a hot air circulating oven, the drying temperature is controlled to be 40-60℃, the drying time is 30-60 min, and the moisture content of the product is ≤10%.

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