Digestion-resistant multi-grain powder for preparing high-fiber medium-GI multi-grain biscuits as well as preparation and application of digestion-resistant multi-grain powder

Abstract

The invention discloses anti-digestion multi-grain powder for preparing high-fiber medium-GI multi-grain biscuits and application of the anti-digestion multi-grain powder, and belongs to the technical field of food processing. By innovatively utilizing an amylosucrase and pullulanase combined enzymolysis and retrogradation treatment technology, the mixed flour of the wheat flour, the whole oat flour and the whole buckwheat flour is converted into the multi-grain mixed flour rich in resistant starch, and the anti-digestion multi-grain flour has high resistant starch content, is favorable for maintaining the stability of blood sugar, is suitable for people with controlled sugar, and has the effects of improving the immunity of the human body and improving the immunity of the human body. Dietary fibers in the grains are reserved, so that the health of intestinal tracts is facilitated; when being used for preparing the biscuits, the nutritional and functional characteristics of the biscuits are remarkably improved, for example, the GI value is reduced, the dietary fiber content is increased, absorption and utilization of nutrient substances are promoted, and meanwhile the taste and flavor of food are improved; the multi-grain resistant starch can increase the crispness and expansibility of the food, improve the texture of the product and enable the taste to be richer and more diversified. Modern nutriology and food processing technologies are combined, and a new way is opened up for development of healthy food.

Description

Technical Field

[0001] The invention belongs to the field of food, and in particular relates to a digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits, and the preparation and application thereof. Background Art

[0002] With the accelerated pace of life and significant changes in dietary structure, modern people's eating habits are gradually leaning towards high-sugar and high-fat foods. This eating habit has not only led to the increasing health problems such as obesity, diabetes, and cardiovascular diseases, but also caused traditional high-sugar, high-GI (glycemic index) foods to gradually lose market favor. Therefore, the market demand for low-sugar, low-GI foods is increasing, and consumers are beginning to pay more attention to the health benefits of food. Traditional biscuits are mainly made from refined wheat flour, with a high sugar content and a large GI value. Long-term consumption of such biscuits is not only not conducive to controlling weight and blood sugar levels, but may also increase the risk of chronic diseases. Therefore, traditional biscuits can no longer meet the needs of modern people for a healthy diet.

[0003] Whole grain raw materials, such as oats and buckwheat, are characterized by high protein and high unsaturated fatty acid content, and are also rich in functional ingredients such as dietary fiber and polyphenols. These ingredients can effectively delay the increase in blood sugar after a meal and improve intestinal health, thus having a positive impact on human health. Studies have shown that in addition to allowing humans to ingest rich nutrients, eating whole grain products can also interact with starch during food processing and digestion, enhancing the starch's resistance to digestion and meeting people's demand for a low-calorie, high-nutrition diet.

[0004] In order to prepare food raw materials that meet health needs, starch modification technology is widely used. At present, the methods of starch modification mainly include chemical modification, physical modification (cooking, extrusion, wet heat, microwave, etc.) and biological modification. However, although chemical modification can change the gelatinization temperature of starch, increase the stability and taste of food, it has the advantages of poor consumer acceptance due to the use of chemical reagents in the production process, and may cause pollution to the environment. In contrast, physical treatment and biological treatment are more environmentally friendly and safe. Physical treatment does not involve chemical reagents and is easy to operate; biological treatment conditions are mild, the modification direction is controllable, and fewer by-products are produced. In order to take into account the advantages of different modified starches, composite modification technology came into being. Whether it is chemical modification, physical modification or biological modification, a single method is often difficult to simultaneously meet the requirements of taste, stability and health needs. In the process of composite modification, some nutrients such as dietary fiber and polyphenols are lost due to improper processing conditions, affecting the nutritional value of the final product, and the functionality and stability are insufficient, the resistance to digestion is not strong enough, and the stability is not high enough, which makes it difficult to meet specific health needs. Summary of the invention

[0005] In view of the health problems caused by the high-sugar and high-fat eating habits of modern people, the existing starch digestion-resistant modification technology mostly uses pure starch from a single grain as raw material to obtain digestion-resistant modified starch with a single crystal form, insufficient digestibility and stability, and low nutritional value, which is difficult to meet health needs. The present invention aims to provide a digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits and its application.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for preparing digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits, comprising the following steps: Wheat flour, whole oat flour and whole buckwheat flour are mixed in proportion to obtain mixed grain flour; the mixed grain flour is gelatinized, and a sucrose aqueous solution is added to obtain a multi-grain suspension; the multi-grain suspension is enzymatically hydrolyzed by amylosucrase and pullulanase in sequence to obtain a starch hydrolyzate; the starch hydrolyzate is sterilized, dried after regeneration, and crushed and sieved to obtain a digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits.

[0007] The mass ratio of the wheat flour, the whole oat flour and the whole buckwheat flour is 5:3:2.

[0008] The sucrose aqueous solution is added at 4-6 mL / g based on the mass of the mixed cereal flour.

[0009] Furthermore, the molar concentration of the sucrose aqueous solution is 1M.

[0010] The method adopts amylosucrase and pullulanase for enzymolysis in sequence. The amylosucrase is added in an amount of 1-3 U / g based on the mass of the mixed grain flour, and the enzymolysis conditions are: reaction at 34-36° C. for 5-7 hours; the pullulanase is added in an amount of 61-65 U / g based on the mass of the mixed grain flour, and the enzymolysis conditions are reaction at 50-60° C. for 5-7 hours.

[0011] Furthermore, the starch sucrase is added in an amount of 1 U / mL based on the mass of the mixed grain flour, and the enzymatic hydrolysis conditions are: reaction at 35°C for 6 hours; the pullulanase is added in an amount of 63 U / mL based on the mass of the mixed grain flour, and the enzymatic hydrolysis conditions are reaction at 55°C for 6 hours.

[0012] The regeneration temperature is 3°C to 5°C, the regeneration time is 22 h to 26 h, and the sieve mesh number is 60 to 80 meshes.

[0013] The present invention provides digestion-resistant multi-grain flour obtained by the preparation method for preparing high-fiber medium GI multi-grain biscuits, wherein the digestion-resistant multi-grain flour is rich in type III and type V resistant starch.

[0014] The present invention provides application of the digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits in preparing high-fiber medium GI multi-grain biscuits.

[0015] A high-fiber, medium-GI multi-grain biscuit is prepared from the above-mentioned digestion-resistant multi-grain flour for preparing high-fiber, medium-GI multi-grain biscuits.

[0016] The preparation method of the above-mentioned high-fiber medium GI multi-grain biscuits comprises: mixing the above-mentioned digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits with low-gluten flour, adding butter, eggs and erythritol zero-calorie sugar to knead the dough, baking the biscuits in an oven after making them, and cooling them to room temperature to obtain high-fiber medium GI multi-grain biscuits.

[0017] The mass ratio of the digestibility-resistant multi-grain flour to the low-gluten flour is 1:1, the amount of butter added is 40% to 60% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour, the amount of eggs added is 30% to 50% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour, and the amount of erythritol zero-calorie sugar added is 20% to 40% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour; the baking procedure is: baking at 140 to 160° C. for 5 to 15 minutes, and baking at 140 to 160° C. for 4 to 6 minutes after turning over.

[0018] Compared with the prior art, the present invention achieves the following technical effects: The preparation method of the digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits provided by the present invention uses a mixed flour of wheat flour and various whole grain flours as raw materials for the first time, integrates physical and biological modification technologies, and simultaneously prepares a digestion-resistant multi-grain flour rich in B+V type starch (i.e., containing both type III and type V resistant starch) and dietary fiber, polyphenols and other functional ingredients based on the recrystallization of starch in multiple grains, the interaction of starch-non-starch components (fat, polyphenols, protein) and particle size control. The mixed flour of wheat flour, oat flour and buckwheat flour can be treated by combined enzymatic hydrolysis and retrogradation of amylosucrase and pullulanase, and the nutritional and functional properties of the product can be significantly improved. These treatments not only help to reduce the GI value of the product, increase the content of functional substances such as dietary fiber, unsaturated fatty acids and polyphenols, and promote the absorption and utilization of nutrients, but also improve the taste and flavor of the food, providing consumers with a healthier and more delicious food choice; in the presence of sucrose and starch, amylosucrase hydrolyzes sucrose as a substrate to generate glucose, and then α-1, 4 Glycosidic bonds connect glucose molecules to synthesize glucan polymers on the side chains of amylopectin, extending the non-reducing ends of starch, creating conditions for subsequent debranching by pullulanase to form a large amount of long-chain starch; pullulanase is an enzyme that can specifically hydrolyze α-1,6-glycosidic bonds. On the basis of the initial enzymatic hydrolysis of amylosucrase, pullulanase can further debranch starch to form more long-chain starch molecules; through repeated wet heat treatment and retrogradation, long-chain starch molecules are more likely to recrystallize or rearrange through hydrogen bonds to form compact B-type crystals (type III resistant starch). At the same time, amylose can also interact with molecules such as fats, polyphenols, and proteins to generate a large amount of V-type crystals (type V resistant starch). Starch), eventually forming a highly ordered B+V type crystalline structure (containing both type III and type V resistant starch), which is not easily digested and absorbed in the human body, so it can reduce the GI value of food, which is very beneficial for people who need to control blood sugar; whole oat flour and whole buckwheat flour are rich in dietary fiber. Enzymatic hydrolysis and retrogradation will not destroy the dietary fiber components in the grains, but will help release more soluble dietary fiber, reduce the molecular weight of dietary fiber, change the physical and chemical properties of dietary fiber, help improve intestinal health, promote intestinal peristalsis, and thus be more easily absorbed and utilized by the human body; wet heat treatment can change the starch and protein structure of grains, thereby affecting the taste and flavor of food. Through reasonable processing conditions, the taste of food can be made crispier, delicate or softer, and the flavor of food can be enhanced, making it more delicious.

[0019] Furthermore, the enzymatic hydrolysis process of amylosucrase-pullulanase will cause the protein in wheat flour, whole oat flour and whole buckwheat flour to be destroyed, forming more small molecular proteins, peptides or amino acids, and significantly reducing the molecular weight of the protein. In addition to enhancing the protein-starch interaction and enhancing the digestibility of starch, it is also easier to be absorbed and utilized by the human body, thereby improving the utilization rate of protein; the starch enzymatic hydrolysis and its temperature change process will indirectly destroy anti-nutritional factors such as phytic acid in grains, thereby reducing their chelation effect on minerals (such as calcium, iron, zinc, etc.), which helps to increase the bioavailability of minerals and promote the absorption and utilization of these nutrients by the human body.

[0020] The digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits provided by the present invention has a high content of type III and type V resistant starch, which is not easily digested and absorbed in the small intestine, but can be fermented and utilized by probiotics in the large intestine, which helps to maintain intestinal health. The content of resistant starch in the multi-grain resistant starch is relatively high, and its molecular structure is optimized, so that the glycemic index (GI) of the starch is at a medium level, which means that after eating multi-grain biscuits containing the starch, the blood sugar level will not rise sharply, which helps to maintain blood sugar stability and is suitable for people who need to control blood sugar. In addition to containing resistant starch, the multi-grain resistant starch also retains dietary fiber, polyphenols, unsaturated fatty acids and other ingredients in grains, which helps to significantly reduce appetite and control weight by promoting intestinal peristalsis, increasing satiety of food, reducing amylase activity and other ways; it has processing characteristics such as low water holding capacity and can be used to improve food processing technology. When preparing multi-grain biscuits, multi-grain resistant starch can increase the crispness and swelling of food and improve the texture of the final product.

[0021] The application provided by the present invention combines modern nutrition and food processing technology, innovatively uses digestion-resistant multi-grain resistant starch rich in both type III and type V resistant starch (B+V type crystal) as a raw material, and provides a new idea for the development of healthy food. Due to the use of digestion-resistant multi-grain flour, the biscuits are rich in functional components such as water-soluble dietary fiber and polyphenols, which are helpful to promote intestinal health, prevent constipation, and improve antioxidant properties; the moderate glycemic index (GI) ensures that the biscuits will not cause a sharp increase in blood sugar after consumption, and are suitable for people who need to control blood sugar; the addition of digestion-resistant multi-grain flour improves the processing technology of the biscuits, promotes the improvement of the orderliness of the starch structure and the interaction between starch and other components, increases the crispness and expansion of the biscuits, and improves the texture of the final product; the biscuits incorporate the flavors of multiple grains, making the taste richer and more diverse. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The experimental results of in vitro digestion of starch in the digestion-resistant multi-grain flour used in Examples 1 and 2 of the present invention; Figure 2 This is a microstructure observation diagram of the digestion-resistant multi-grain flour of Example 1 of the present invention under a confocal laser microscope; Figure 3 The X-ray diffraction experimental results of the digestion-resistant multi-grain flour in Example 1 of the present invention; Figure 4 is a Fourier transform infrared spectrum of starch in the digestion-resistant multi-grain flour in Example 1 of the present invention; Figure 5 The digestion-resistant multi-grain flour in Example 1 of the present invention 13 C solid state NMR results.

[0023] Figure 6 These are the experimental results of in vitro digestion of starch in the multi-grain biscuits prepared in Examples 1 and 2 of the present invention.

[0024] Figure 7 The in vitro digestion curves of starch in the multi-grain biscuits prepared in Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] The present invention is described in further detail below: Example 1 This embodiment provides a high-fiber medium GI multi-grain biscuit, and the specific preparation steps are as follows: 1. Preparation of Digestive Resistant Multi-Grain Flour for High Fiber Medium GI Multi-Grain Biscuits 2.5 g wheat flour, 1.5 g oat flour and 1 g buckwheat flour were mixed to obtain mixed grain flour, 225 mL distilled water was added and boiled for 20 min, and 25 mL 1.0 M sucrose stock solution was added to obtain a 2% multi-grain suspension; 1U / mL amylosucrase (AS) was added to 250mL multi-grain suspension, and the suspension was enzymolyzed at 35℃ for 6h, inactivated in a boiling water bath at 100℃ for 10min, and aged at 4℃ for 24h. The suspension was then centrifuged, washed with distilled water for 3 times, dried in an oven at 45℃, crushed, ground, and passed through a 100-mesh sieve to obtain an AS hydrolyzed sample (AF). The AS hydrolyzed sample was mixed with distilled water to prepare a 10% AS hydrolyzed sample. The 10% AS hydrolyzed sample was gelatinized in boiling water for 20min, cooled to room temperature, adjusted to pH 5.5, and added with 63U / g pullulanase. The suspension was cultured in a constant temperature oscillating box at 55℃ for 6h to obtain an enzymolyzate. The starch hydrolyzate was sterilized in an autoclave at 121℃ for 21min, aged at 4℃ for 24h, dried in an oven at 45℃ for 48h, crushed and passed through a 60-80 mesh sieve to obtain an anti-digestive multi-grain flour for preparing high-fiber medium GI multi-grain biscuits.

[0027] 2. Preparation of high-fiber medium GI multi-grain biscuits Weigh 10g of butter, 6g of zero-calorie sugar, half an egg yolk (about 8g) and 20g of multi-grain resistant starch, mix well, knead the dough, roll it into 5 mm thin slices, carve out biscuits with a mold, bake in an oven at 150℃ for 10 min, turn it over and bake at 150℃ for another 5 min, cool to room temperature to obtain high-fiber medium GI multi-grain biscuits.

[0028] According to the Englyst method, 50 mg of sample was added to 20 mL of 0.2 M sodium acetate buffer, shaken, and incubated at 37°C for 30 min. Then 5 mL of mixed enzyme solution (290 U / mL porcine pancreatic enzyme, 50 U / mL amyloglucosidase) was added and the reaction was shaken in a shaker at 37°C and 200 r / min. 1 mL of supernatant was collected at 0 min, 10 min, 20 min, 30 min, 60 min, 90 min, 120 min, and 180 min, respectively, and placed in a boiling water bath for 5 min to terminate the enzyme reaction. The supernatant was centrifuged at 10,000 rpm for 5 min, and the glucose content (mg / mL) was determined using a biosensor. The RS content calculation formula is as follows: RDS(%) = (G20− FG) × 0.9 / TS SDS(%) = (G120-G20) × 0.9 / TS RS(%) = (TS − ​​RDS − SDS) / TS Among them, RDS represents rapidly digestible starch; SDS represents slowly digestible starch; FG represents the free glucose content in the system before adding digestive enzymes, mg; G20 and G120 represent the glucose content produced by hydrolysis at 20 min and 120 min of digestion, mg respectively; TS represents the total starch content, mg; and 0.9 is the conversion factor.

[0029] The content of multi-grain resistant starch in the high-fiber medium GI multi-grain biscuits prepared in this example is 31.56%.

[0030] Example 2 This embodiment provides a high-fiber, medium-GI, multi-grain biscuit, and the specific preparation steps are as follows: 5 g of multi-grain mixed flour was dispersed in 225 mL of distilled water, gelatinized in boiling water for 30 min, cooled to room temperature, and aged at 4°C for 24 h. The multi-grain flour precipitate containing long-chain amylopectin was obtained by centrifugation, washed with distilled water for 3 times, dried in an oven at 45°C for 48 h, crushed, ground, and sieved through a 100-mesh sieve. A certain amount of NMF was dispersed in distilled water to make a 10% suspension, gelatinized in boiling water for 20 min, cooled to room temperature, the pH was adjusted to 5.5, 63 U / g of pullulanase was added, and the mixture was reacted in a constant temperature shaking water bath at 55°C for 6 h to obtain an enzymatic solution. The enzymatic solution was placed in an autoclave for autoclaving at 121°C for 21 min, aged at 4°C for 24 h, and then dried in an oven at 45°C for 48 h. The powder was ground with a high-speed grinder and passed through a 100-mesh sieve to obtain a multi-grain resistant starch for preparing high-fiber medium-GI multi-grain biscuits.

[0031] Weigh 10g of butter, 6g of zero-calorie sugar, half an egg yolk and 20g of multi-grain resistant starch, mix well and knead into dough, roll into 5 mm thin slices, carve out biscuits with a mold, bake in an oven at 150°C for 10 min, turn over and bake at 150°C for another 5 min, cool to room temperature to obtain high-fiber medium GI multi-grain biscuits.

[0032] Calculated by the Englyst method, under the above parameters, the content of multi-grain resistant starch in the high-fiber medium GI multi-grain biscuits was 27.76%.

[0033] Example 3 Based on Examples 1 and 2, this Example performs performance tests on the digestion-resistant multi-grain flour and high-fiber medium GI multi-grain biscuits obtained in Examples 1 and 2 of the present invention.

[0034] The digestibility of multi-grain flour was determined according to the method reported by Englyst et al. 200 mg of the sample was placed in a 50 mL centrifuge tube, 15 mL of phosphate buffer (0.2 mol / L, pH 5.5) and 3 to 5 glass beads were added and mixed well. Then 5 mL of mixed enzyme solution (290 U / mL porcine pancreatic enzyme, 50 U / mL amyloglucosidase) was added and the reaction was shaken in a shaker at 37°C and 200 r / min. 1 mL of supernatant was collected at 0 min, 20 min, and 120 min, respectively, and placed in a boiling water bath for 5 min to terminate the enzyme reaction. The supernatant was centrifuged at 10,000 rpm for 5 min, and the glucose content (mg / mL) was determined using a biosensor.

[0035] The RS content calculation formula is as follows: RDS(%) = (G20− FG) × 0.9 / TS SDS(%) = (G120-G20) × 0.9 / TS RS(%) = (TS − ​​RDS − SDS) / TS Among them, RDS represents fast digestible starch; SDS represents slow digestible starch; FG represents the free glucose content in the system before adding digestive enzymes, mg; G20 and G120 represent the glucose content produced by hydrolysis at 20 min and 120 min of digestion, mg; TS represents the total starch content, mg; 0.9 is the conversion factor. Figure 1 The data shows that the resistant starch content of untreated natural multi-grain flour is 34.38%; the resistant starch content of multi-grain flour treated with amylosucrase-pullulanase is 73.07%.

[0036] The effect of enzymatic hydrolysis on the microscopic morphology of multi-grain flour during the preparation of multi-grain flour resistant starch in Example 1 of the present invention was investigated. Starch, protein, lipid and cell wall were stained with 0.25% fluorescein isothiocyanate (FITC, w / v, dissolved in water), 0.025% rhodamine B (RhB, w / v), 0.1% Nile red (w / v, dissolved in anhydrous ethanol) and Calcofluor fluorescent whitening agent (CWS), respectively. 50 mg of the sample was stained with 80 μL 0.25% FITC, 10 μL 0.025% RhB and 40 μL CWS at the same time to observe the structure of starch, protein and cell wall. Similarly, 80 μL 0.25% FITC, 40 μL 0.1% Nile red and 40 μL CWS were used to stain the starch, lipid and cell wall in the sample at the same time to observe the structure of starch, fat and cell wall. All samples were stained at room temperature in the dark for 12 h. The stained multi-grain flour was rinsed twice with distilled water and fixed on a slide. The cell wall (blue), starch (green), and protein / lipid (red) of the multi-grain flour were observed at excitation wavelengths of 405, 488, and 568 nm, respectively. The specific results are shown in the attached Figure 2 shown.

[0037] By the attached Figure 2 The data show that multi-grain flour has complete starch granules with proteins, lipids and other substances adhered to its surface. Multi-grain flour treated with amylosucrase-pullulanase forms dense irregular clumps, and some small fragments on the surface may come from denatured proteins, gelatinized starch or other ingredients.

[0038] Attached Figure 3 The X-ray diffraction (XRD) patterns of multi-grain flour at different processing stages can be used to analyze the dynamic changes in the starch crystal structure during the processing. During the measurement, the crystal structure of the sample was scanned and analyzed using an X-ray diffraction (XRD) instrument with a scanning range of 4-40°, a scanning speed of 2° / min, and a step length of 0.02°. The relative crystallinity (RC) was calculated using the Mihhalevski method, and the calculation formula is: RC%=100*Ac / (Ac+Aa), Where Ac is the area of ​​the crystalline region and Aa is the area of ​​the amorphous region.

[0039] By the attached Figure 3 The data show that natural multi-grain flour presents typical A-type crystals. After pullulanase treatment, a new peak appears at 20°, indicating that a large amount of amylose has been recrystallized. At the same time, starch combines with lipids, polyphenols or proteins to form a complex, and the starch crystal structure changes to B+V type.

[0040] Table 1: Changes in the long-range and short-range structure of starch in the digestion-resistant multi-grain flour in Example 1

[0041] Table 1 shows the changes in the long-range and short-range structures of the starch in the digestion-resistant multi-grain flour in Example 1. It can be seen from Table 1 that the RC value of NMF decreased from 23.79% to 11.26% after AS grafting, and the double helix directly participated in the crystallization, which significantly decreased the RC value of starch. Although the relative crystallinity decreased, the starch crystal form in AF had changed from type A to type B+V, and the digestion resistance was significantly enhanced; the increase in the RC value of starch in APF after pullulanase combined with high-pressure cooking and aging treatment was limited, which was related to the pregelatinization before pullulanase treatment and the destruction of the starch crystal structure caused by high-pressure cooking.

[0042] Table 2 shows the NMR spectrum of the digestion-resistant multi-grain flour in Example 1. The triple peak of NMF at C1 indicates the presence of type A crystals in starch. The signal peak at 105.4 ppm of C1 indicates that starch and polyphenols form a complex in NMF; the signal peak at 103.7 ppm indicates the presence of V 6III The majority of lipids are trapped in the helical cavities of starch. After AS treatment, the AF sample only showed a single peak at 105.00 ppm, indicating that starch and polyphenols combined to form a complex. At this time, the starch chains were unwound, branched and rearranged during the treatment process, and the extended branches were difficult to form starch-lipid complexes with lipids. After pullulanase-high pressure cooking treatment, the APF sample showed a double peak, and the double peak of the APHF sample after wet heat treatment was more obvious, proving that a B+V type crystalline structure was finally formed, which is consistent with the XRD results. The new signal peak of APF at 102.4 ppm indicates that starch interacted with lipids and formed a V 6Ⅰ In this type of resistant starch, almost all of the lipids enter the starch spiral cavity, further enhancing the starch's resistance to digestion.

[0043] Table 2: NMR spectra of digestion-resistant multi-grain flour in Example 1

[0044] Table 3 shows the molecular weight changes of digestion-resistant multi-grain flour in Example 1. It can be seen from the table that the internal structure of starch is opened after NMF pregelatinization, and its Mw and Mn are significantly reduced after AS grafting. The increase in Mw / Mn indicates that more branched starch is produced at this time, and starches of different molecular weights are widely distributed in the starch system, resulting in an increase in Mw / Mn. After the pullulan enzyme cuts the extended branched branches, the starch molecular weight drops significantly, and the large amount of amylose produced by the breakage of α-1, 6 bonds also causes a significant increase in Mw / Mn, and the starch components are more complex at this time.

[0045] Table 3: Changes in molecular weight of digestion-resistant multi-grain flour in Example 1

[0046] Table 4 Changes in protein molecular weight distribution of digestion-resistant multi-grain flour in Example 1. It can be seen from the table that the content of protein polymers (LPP, MPP, SPP) and macromolecular monomer protein (LMP) in AF samples is lower than that in NMF, and SMP increases significantly, indicating that high-temperature gelatinization destroys the structure of protein, and the protein is decomposed to a large extent, and most of it is converted into small molecular monomer protein. Compared with AF, the content of LPP, MPP, and SPP in APF increases, and the content of SMP does not change substantially. This may be because the probability of intermolecular collision increases during high-pressure cooking, and proteins polymerize to form protein aggregates; however, the content of small molecular monomer protein is still high, and these proteins can participate in the formation of protein-starch complexes and promote the improvement of starch resistance to digestion. From the perspective of UPP content, the addition of AS leads to a decrease in UPP content, but the addition of pullulanase increases UPP content, which is basically consistent with the change trend of protein polymer content, proving that UPP content is a key parameter for characterizing protein polymerization degree.

[0047] Table 4: Changes in the distribution of protein molecular weight before and after enzymatic hydrolysis of digestion-resistant multi-grain flour

[0048] Table 5 Digestible components of four kinds of starch in the medium-GI multi-grain biscuits with high fiber content in Example 1. As can be seen from the table, the order of resistant starch content from high to low is APF>PF>NMF>wheat flour. The digestion and hydrolysis rate curve of biscuits containing 50% APF is the lowest, and its eGI value is 64.87, which belongs to the medium GI range (GI<55 is low GI, 55≤GI≤75 is medium GI, and GI>75 is high GI). Biscuits prepared from wheat flour and NMF are both high GI, and biscuits containing PF and APF are both medium GI, which is consistent with the in vitro digestion results.

[0049] Table 5: Digestible components of four starches in high-fiber medium GI multi-grain biscuits in Example 1

[0050] Attached Figure 4To determine the formation of complexes between starch and other components by Fourier transform infrared spectroscopy (FTIR). About 3 times the volume of petroleum ether was added to 10 g of sample and stirred at room temperature for 3 h. The lower precipitate was centrifuged and 0.15% NaOH was added at a ratio of 1:10. After reacting for 2.5 h, it was washed with deionized water for 3 times and centrifuged, and the upper yellow material was scraped off. Then 0.08U / g neutral protease (5 KU / g) was added, and enzymatic hydrolysis was carried out at 45℃ for 1.5 h. After washing with 95% ethanol and centrifuging 3 times, the precipitate was dried and passed through a 100 mesh sieve to obtain a starch sample. Starch and KBr were dried in an oven at 40℃ overnight, mixed evenly in an agate mortar at a ratio of 1:100, and thin slices were made using a tablet press. Before testing the sample, KBr was scanned once as the background. The scanning wavenumber range was 400 to 4000 cm-1, the number of scans was 32, and the resolution was 4 cm-1. Data analyses were performed using Omnic (version 8.0, ThermoNicolet Inc, Waltham, MA, USA) and PeakFit (version 4.12, SPSS Inc, Chicago, IL, USA).

[0051] By the attached Figure 4 The data show that the multi-grain flour treated with amylosucrase-pullulanase has a -1 and 2854cm -1 The new peak at 1530 cm -1 The appearance of a new peak at indicates that starch-protein complex is formed between starch and protein through hydrogen bonds; the simultaneous appearance of these three peaks proves the existence of starch-lipid-protein ternary complex.

[0052] Attached Figure 5 For multi-grain flour 13 C solid state nuclear magnetic resonance (NMR) spectroscopy. NMR spectroscopy is performed by 13 C NMR (JNM-ECZ400R / S1, Japan Electron Optical Laboratory) was used for determination. The scanning frequency of multi-grain flour was 125.7 MHz, the number of scans was 2400, the spectral width was 40 kHz, and the contact time was 13 ms.

[0053] By the attached Figure 5 The data show that the peak at 105 ppm at C1 of multi-grain flour treated with amylosucrase-pullulanase indicates that free starch forms a single helical structure with lipids. The increase in the peak area at 175.92 ppm and 32.57 ppm indicates that starch interacts with protein. Attached Figure 6These are the experimental results of in vitro digestion of starch in the multi-grain biscuits prepared in Examples 1 and 2 of the present invention. During the determination, the total starch content of the multi-grain biscuits was determined with reference to the method of the total starch detection kit. After the biscuits were crushed, 100 mg of the test sample was weighed in duplicate. Add 0.2 mL of 80% v / v ethanol aqueous solution, vortex, add 2 mL of cold 1.7 M sodium hydroxide solution, and vortex. Use a magnetic stirrer to stir the ice water bath for 15 minutes, vortexing 2-3 times in between. Add 8 mL of sodium acetate buffer (600 mM, pH 3.8) containing 5 mM calcium chloride, vortex, and adjust the pH to about 5.0. Immediately add 0.1mL of undiluted thermostable α-amylase and 0.1mL of amyloglucosidase (AMG, 3,300U / mL) to one of the test tubes (sample tube), add 0.2mL of sodium acetate buffer (100mM, pH5.0) containing 5mM calcium chloride to the second test tube (sample blank), vortex, incubate in a 50°C water bath for 30min, and cool to room temperature. Take 2.0mL of each solution and centrifuge at 13,000rpm for 5min, take 1.0mL of the supernatant, transfer to a test tube containing 4mL of sodium acetate buffer (100mM, pH5.0) containing 5mM calcium chloride, and mix well. For the sample in duplicate, accurately pipette 0.1mL to the bottom of the test tube. At the same time, for the sample blank in duplicate, pipette 0.1mL to the bottom of the test tube. Add 3.0mL of GOPOD reagent to each test tube and mix well. Incubate in a 50°C water bath for 20 min, incubate the glucose standard control and reagent blank control at the same time, and measure the absorbance of the solution at 510 nm within 1 h after cooling. The total starch content of the four biscuit powders was calculated from this.

[0054] The digestibility of multi-grain biscuits was determined according to the method reported by Englyst et al. 50 mg of sample was added to 20 mL of 0.2 M sodium acetate buffer, shaken, and incubated at 37 °C for 30 min. Then 5 mL of mixed enzyme solution (290 U / mL porcine pancreatic enzyme, 50 U / mL amyloglucosidase) was added and the reaction was shaken in a shaker at 37 °C and 200 r / min. 1 mL of supernatant was collected at 0 min, 10 min, 20 min, 30 min, 60 min, 90 min, 120 min, and 180 min, respectively, and placed in a boiling water bath for 5 min to terminate the enzyme reaction. The supernatant was centrifuged at 10,000 rpm for 5 min, and the glucose content (mg / mL) was determined using a biosensor.

[0055] The RS content calculation formula is as follows: RDS(%) = (G20− FG) × 0.9 / TS SDS(%) = (G120-G20) × 0.9 / TS RS(%) = (TS − ​​RDS − SDS) / TS Among them, RDS represents rapidly digestible starch; SDS represents slowly digestible starch; FG represents the free glucose content in the system before adding digestive enzymes, mg; G20 and G120 represent the glucose content produced by hydrolysis at 20 min and 120 min of digestion, mg respectively; TS represents the total starch content, mg; and 0.9 is the conversion factor.

[0056] By the attached Figure 6 The data show that the content of SDS in PF decreased, the content of RDS and SDS in APF decreased, and the content of RS increased, indicating that the high-content long-chain starch recrystallization and RS content increased after pullulanase debranching combined with high-pressure cooking and starch retrogradation. AS uses sucrose as a substrate to synthesize α-1, 4-glucan polymers. When starch is present, sucrose acts as a glucose receptor to extend the branch chain at the non-reducing end of the external chain. Compared with the NMF sample, the content of RS in the APF and PF samples increased significantly.

[0057] Attached Figure 7 The digestion curve of multi-grain biscuits is shown in Figure 2. Figure 6 Based on the test results, a digestion and hydrolysis rate curve was drawn, the eGI value of each biscuit was calculated based on the digestion and hydrolysis rate of white bread, and the digestible components of starch were calculated.

[0058] By the attached Figure 7 The data show that the digestion characteristics of white bread and the four biscuit flours are different. APF has the lowest digestion and hydrolysis rate, followed by PF. Wheat flour and NMF have higher digestibility, which is related to the content of amylose and amylopectin. Starch with high amylose content is not easy to digest, while starch with high amylopectin content is easy to digest.

[0059] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits, characterized in that: The steps include: Mixing wheat flour, whole oat flour and whole buckwheat flour in proportion to obtain mixed grain flour; gelatinizing the mixed grain flour, adding a sucrose aqueous solution to obtain a multi-grain suspension; and sequentially enzymolyzing the multi-grain suspension with amylosucrase and pullulanase to obtain a starch hydrolyzate; The starch enzymatic hydrolysate is sterilized, dried after regeneration, and crushed and sieved to obtain digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits.

2. The method for preparing a digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits according to claim 1, characterized in that: The mass ratio of the wheat flour, the whole oat flour and the whole buckwheat flour is 5:3:

2.

3. The method for preparing the digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits according to claim 1, characterized in that: The added sucrose aqueous solution is added at 4-6 mL / g based on the mass of the mixed cereal flour.

4. The method for preparing a digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits according to claim 1, characterized in that: The method adopts amylosucrase and pullulanase for enzymolysis in sequence. The amylosucrase is added in an amount of 1-3 U / g based on the mass of the mixed grain flour, and the enzymolysis conditions are: reaction at 34-36° C. for 5-7 hours; the pullulanase is added in an amount of 61-65 U / g based on the mass of the mixed grain flour, and the enzymolysis conditions are reaction at 50-60° C. for 5-7 hours.

5. The method for preparing the digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits according to claim 1, characterized in that: The regeneration temperature is 3°C to 5°C, the regeneration time is 22 h to 26 h, and the sieve mesh number is 60 to 80 meshes.

6. The digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits obtained by the preparation method according to any one of claims 1 to 5, characterized in that: The digestion resistant multi-grain flour is rich in type III and type V resistant starch.

7. Use of the digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits according to claim 6 in preparing high-fiber medium GI multi-grain biscuits.

8. A high-fiber, medium-GI, multi-grain biscuit, characterized in that: The high-fiber, medium-GI, multi-grain biscuits are prepared from the digestion-resistant multi-grain flour for preparing high-fiber, medium-GI, multi-grain biscuits according to claim 6.

9. The method for preparing a high-fiber, medium-GI, multi-grain biscuit according to claim 8, characterized in that: include: The digestion-resistant multi-grain flour for preparing high-fiber medium GI multi-grain biscuits as described in claim 6 is mixed with low-gluten flour, and butter, eggs and erythritol zero-calorie sugar are added. After making the biscuits, they are baked in an oven and cooled to room temperature to obtain high-fiber medium GI multi-grain biscuits.

10. The method for preparing high-fiber medium GI multi-grain biscuits according to claim 9, characterized in that: The mass ratio of the digestibility-resistant multi-grain flour to the low-gluten flour is 1:1, the amount of butter added is 40% to 60% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour, the amount of eggs added is 30% to 50% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour, and the amount of erythritol zero-calorie sugar added is 20% to 40% of the total mass of the digestibility-resistant multi-grain flour and the low-gluten flour; the baking procedure is: baking at 140 to 160° C. for 5 to 15 minutes, and baking at 140 to 160° C. for 4 to 6 minutes after turning over.

Images