Insoluble dietary fiber containing bound phenols, preparation method thereof and application thereof in low GI food

Abstract

The present invention provides an insoluble dietary fiber containing bound phenols, its preparation and application in low GI foods. The insoluble dietary fiber containing bound phenols is obtained by sequentially subjecting white kidney bean skin to ultrasound, enzymatic hydrolysis, freeze-drying and dry vibration ultrafine grinding, wherein the enzymatic hydrolysis is: enzymatic hydrolysis is performed sequentially using pepsin, pancreatin and medium-temperature α-amylase. This method effectively improves the taste and physicochemical properties of the insoluble dietary fiber, retains the bound phenols in the insoluble dietary fiber to a great extent, and has the advantages of low average particle size, high water holding capacity, high oil holding capacity, high swelling property and high thermal stability, and is suitable for preparing functional foods.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization, and more specifically, relates to an insoluble dietary fiber containing bound phenols, and the preparation method thereof and the application thereof in low GI food. Background Art

[0002] White kidney bean (Phaseolus vulgaris L.var.Beldia) belongs to the Fabaceae, Fabaceae subfamily, Phaseolus genus. It is grown in all provinces and regions of my country. It is rich in nutrition, with higher protein and B vitamin content than chicken, more than 7 times the calcium content of chicken, and 4 times the iron content of chicken. It is also a rare high-potassium, high-magnesium, low-sodium food. White kidney bean has the functions of improving the body's own immune ability, enhancing disease resistance, activating lymphocytes, promoting deoxyribonucleic acid synthesis, and inhibiting the proliferation of tumor cells. It has received great attention from the medical community. At present, white kidney bean products are widely used, mainly in the fields of weight loss health products, candies, instant beverages, and medical hemagglutinin. However, in the process of white kidney bean production and utilization, certain by-products will be generated, such as bean skins and bean dregs, and since the mass of bean skins accounts for 7.5% to 8.0% of the particle mass, which is much higher than the mass of soybean skins, directly discarding it will be a serious waste of resources. In addition, the cell wall of white kidney bean skins also contains insoluble carbohydrates of 50% hemicellulose, 30% pectin and 20% cellulose. These macromolecules are usually combined with some insoluble phenolic compounds, called dietary fiber-bound phenols. Therefore, the considerable consumption yield and rich fiber composition make white kidney bean skins an ideal source of high-quality dietary fiber and bound phenols.

[0003] Dietary fiber is a non-starch polysaccharide carbohydrate that is resistant to endogenous digestive enzymes. It mainly comes from plant cell walls. It cannot be digested by human intestinal digestive enzymes and can only be fermented and absorbed by large intestinal microorganisms. According to its solubility in water, it is divided into soluble dietary fiber (water-soluble dietary fiber, SDF) and insoluble dietary fiber (water-insoluble dietary fiber, IDF). Both have certain functions and effects on human health and have been supplemented and recognized by the nutrition community as the seventh category of nutrients. Among them, soluble dietary fiber has certain functions of regulating blood sugar and blood lipid levels, can reduce human cholesterol, prevent cardiovascular diseases, promote intestinal health, etc., mainly including pectin, plant gum, mucilage, galactomannan, glucan, some hemicellulose and other components; insoluble dietary fiber can promote intestinal peristalsis, increase defecation, prevent and treat constipation, etc., mainly including cellulose, some hemicellulose, plant wax and lignin and other components. Due to its rough texture, poor taste and poor palatability, dietary fiber is difficult to be favored by people, especially insoluble dietary fiber, which is often difficult to be liked by consumers.

[0004] At present, studies have also shown that 90% to 95% of polyphenols in nature are bound to structural proteins, cellulose, hemicellulose and other plant matrices through covalent bonds, hydrogen bonds and other interactions, which are called bound polyphenols. When dietary fiber is used as a carrier for antioxidants such as phenols, the bound phenolic compounds formed by the connection reach the colon and are released through fermentation by intestinal flora. They can play important physiological activities, such as anti-oxidation, anti-inflammatory, and anti-tumor effects. They can also be used to prevent and treat cardiovascular diseases, Alzheimer's disease and many other modern chronic diseases.

[0005] The prior art provides a method for extracting insoluble dietary fiber from kidney beans, but the method requires high-pressure and high-temperature cooking at 0.1-0.2 MPa and 120-133° C., which has harsh process conditions, potential safety hazards, and is not conducive to mass production. In addition, the method does not utilize the bound phenols in the kidney beans, nor does it improve the palatability of the insoluble dietary fiber. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for preparing insoluble dietary fiber containing bound phenols, aiming to efficiently extract the insoluble dietary fiber from white kidney bean peel, improve its palatability, and retain the bound phenols therein as much as possible. The method is simple to operate, has a high safety factor, and has a low production cost, and is conducive to mass production.

[0007] The second object of the present invention is to provide insoluble dietary fiber containing bound phenols prepared by the method.

[0008] The third object of the present invention is to provide the use of the insoluble dietary fiber containing bound phenols in preparing low GI food.

[0009] The fourth object of the present invention is to provide a low GI mooncake crust.

[0010] The fifth object of the present invention is to provide a method for preparing a low GI mooncake crust.

[0011] A sixth object of the present invention is to provide the use of the low GI mooncake crust in the preparation of low GI mooncakes.

[0012] The seventh object of the present invention is to provide a low GI moon cake.

[0013] The eighth object of the present invention is to provide a method for preparing low GI moon cakes.

[0014] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0015] The present invention provides a method for preparing insoluble dietary fiber containing bound phenols, which comprises sequentially subjecting white kidney bean peel to ultrasonic treatment, enzymolysis, freeze drying, and dry vibration ultrafine grinding to obtain the insoluble dietary fiber containing bound phenols;

[0016] The enzymatic hydrolysis is: enzymatic hydrolysis is performed by using pepsin, pancreatin and medium-temperature α-amylase in sequence.

[0017] The method of the invention uses white kidney bean hull as a raw material, adopts a continuous enzyme method to extract insoluble dietary fiber therein, combines ultrafine grinding technology to reduce the average particle size, increase the specific surface area, expose more water binding points and oil binding points, can effectively improve the taste and physical and chemical properties of the insoluble dietary fiber, and retains the bound phenol in the insoluble dietary fiber to a great extent (the content is as high as 2.8-3.5 mg / 100 g). The obtained insoluble dietary fiber containing bound phenol is a light yellow powder with an average particle size as low as 20-35 μm and a specific surface area as high as 300-450 m 2 / kg, and has the characteristics of high water holding capacity, high oil holding capacity, high expansion and high thermal stability, and is suitable for the preparation of functional foods.

[0018] Preferably, the white kidney bean husk is pretreated before the ultrasonic treatment.

[0019] Further preferably, the pretreatment comprises: washing, drying, crushing and sieving the white kidney bean husk.

[0020] More preferably, the drying is forced air drying; the drying temperature is 35-45°C, most preferably 40°C.

[0021] More preferably, the sieving is through a 50-150 mesh sieve, most preferably through a 100 mesh sieve.

[0022] Preferably, the ultrasound is: mixing the white kidney bean hulls with the ethanol solution, and performing ultrasound for 25 to 35 minutes at a power of 200 to 450 W, a frequency of 35 to 45 KHz, and a temperature of ≤40° C. Most preferably, ultrasound is performed for 30 minutes at a power of 300 W, a frequency of 40 KHz, and a temperature of 40° C., in order to clean and remove impurities.

[0023] Further preferably, the mass volume ratio of the white kidney bean peel to the ethanol solution is 1 g: 5-10 mL.

[0024] More preferably, the concentration of the ethanol solution is 80% to 85% (v / v).

[0025] Further preferably, filtering, pre-freezing and freeze-drying are performed after the ultrasound.

[0026] More preferably, the sonication and filtration are repeated 2 to 5 times.

[0027] More preferably, the pre-freezing is pre-freezing at -25 to -15°C for 10 to 14 hours, and most preferably, pre-freezing at -20°C for 12 hours.

[0028] More preferably, the freeze-drying is performed at -50 to -10°C for 24 to 48 hours, and most preferably at -50°C for 48 hours.

[0029] Preferably, before the enzymatic hydrolysis, the ultrasonicated white kidney bean husk is added into water (ie, the enzymatic hydrolysis reaction system), so that the mass volume ratio of the ultrasonicated white kidney bean husk to water is 1 g: 10-20 mL.

[0030] Preferably, the amount of pepsin added is 0.15% to 0.3% (w / v) of the enzymatic reaction system, and the pH value of the enzymatic reaction system is 1.4 to 1.5.

[0031] More preferably, the enzymatic hydrolysis temperature of the pepsin is 38-42° C., and the time is 0.9-1.1 h.

[0032] Preferably, the amount of pancreatin added is 0.1% to 0.2% (w / v) of the enzymatic reaction system, and the pH value of the enzymatic reaction system is 7.5 to 8.0.

[0033] More preferably, the enzymatic hydrolysis temperature of the pancreatic enzyme is 36-38° C., and the time is 3.7-4.3 h.

[0034] Preferably, the addition amount of the medium-temperature α-amylase is 1.5% to 3.0% (w / v) of the enzymatic reaction system, and the pH value of the enzymatic reaction system is 6.8 to 6.9.

[0035] More preferably, the enzymatic hydrolysis temperature of the mesophilic α-amylase is 36-38° C., and the enzymatic hydrolysis time is 15-17 h.

[0036] Preferably, before adding the medium-temperature α-amylase for enzymolysis, the enzymolysis reaction system is heated.

[0037] More preferably, the heating is heating at ≤65°C for 30-40 min.

[0038] Preferably, the enzymatic hydrolysis is followed by centrifugation, washing and filtration.

[0039] More preferably, the centrifugation is performed at 3000-4000×g for 18-22 min, and most preferably at 3500×g for 20 min.

[0040] More preferably, the cleaning is: cleaning with water for 1 to 3 times, and then cleaning with 68% to 88% (v / v) ethanol solution.

[0041] Further preferably, the filtration is performed under vacuum conditions.

[0042] Preferably, pre-freezing is performed before freeze-drying.

[0043] More preferably, the pre-freezing is performed at -25 to -15°C for 10 to 14 hours, and most preferably at -20°C for 12 hours.

[0044] More preferably, the freeze-drying is performed at -50 to -10°C for 24 to 48 hours, and most preferably at -50°C for 48 hours.

[0045] Preferably, the dry vibration ultrafine grinding treatment is carried out at an amplitude of 3.5 to 5.5 mm and a temperature of -25 to 10°C for 10 to 20 minutes. The dry vibration ultrafine grinding treatment is carried out using a vibration ultrafine grinding machine with a low-temperature cooling cycle function, which can ensure that the entire grinding process is carried out at a low temperature, reducing the impact of high temperature on the biological activity of dietary fiber and bound phenols.

[0046] The above-mentioned insoluble dietary fiber containing bound phenol has the characteristics of low average particle size, high water holding capacity, high oil holding capacity, high swelling property and high thermal stability, and is suitable for preparing low GI foods, such as low GI mooncake crusts, etc. Therefore, the insoluble dietary fiber containing bound phenol prepared by the above-mentioned method, the use of the above-mentioned insoluble dietary fiber containing bound phenol in the preparation of low GI foods, and the use of the above-mentioned insoluble dietary fiber containing bound phenol in the preparation of low GI mooncake crusts should all be within the scope of protection of the present invention.

[0047] The present invention also provides a low GI mooncake crust, comprising the following components in parts by weight: 30 to 55 parts of flour, 35 to 60 parts of oligosaccharide syrup, 10 to 25 parts of edible oil, 2 to 4 parts of leavening agent, 1 to 6 parts of insoluble dietary fiber containing bound phenol, and 0.5 to 2 parts of acidity regulator.

[0048] Preferably, the low GI mooncake crust comprises the following components in parts by weight: 40-45 parts of flour, 35-45 parts of oligosaccharide syrup, 15-20 parts of edible oil, 2-3 parts of leavening agent, 2-5 parts of insoluble dietary fiber containing bound phenols, and 1-1.5 parts of acidity regulator.

[0049] Most preferably, the low GI mooncake crust comprises the following components in parts by weight: 45 parts of flour, 40 parts of oligosaccharide syrup, 15 parts of edible oil, 3 parts of leavening agent, 5 parts of insoluble dietary fiber containing bound phenols, and 1 part of acidity regulator.

[0050] Preferably, the oligosaccharide syrup is one or more of fructooligosaccharide syrup, glucose oligosaccharide syrup, xylooligosaccharide syrup and maltose oligosaccharide syrup.

[0051] Preferably, the edible oil is a vegetable oil, including but not limited to peanut oil, corn oil or soybean oil.

[0052] Preferably, the loosening agent is baking soda.

[0053] Preferably, the acidity regulator is one or more of potassium bicarbonate, sodium citrate and potassium citrate.

[0054] The preparation method of the low GI mooncake crust is as follows: uniformly mix the raw materials in the formula amount.

[0055] As a traditional specialty food in my country, mooncakes are purchased and eaten by consumers around the Mid-Autumn Festival. However, most traditional mooncakes are high in sugar, oil, and calories, which can easily cause drastic changes in blood sugar and constipation after consumption, and are not suitable for consumers with diabetes or constipation. Therefore, low-GI mooncakes are gradually loved by consumers, but most of the low-GI mooncakes on the market currently have a poor taste. The low-GI mooncakes prepared by the present invention using the low-GI mooncake crust as a raw material are delicious and healthy, not only making the taste more layered and chewy, but also regulating intestinal function, controlling the increase in postprandial blood sugar, and preventing constipation and obesity. Therefore, the use of the low-GI mooncake crust in the preparation of low-GI mooncakes and the low-GI mooncakes containing the low-GI mooncake crust should also be within the scope of protection of the present invention.

[0056] The present invention also provides a method for preparing a low GI mooncake, which specifically comprises wrapping the filling in the low GI mooncake crust and baking the mooncake.

[0057] The present invention has the following beneficial effects:

[0058] 1. The method of the present invention uses white kidney bean hull as a raw material, adopts a continuous enzymatic method to extract insoluble dietary fiber therein, and combines ultrafine grinding technology to effectively improve the taste and physicochemical properties of the insoluble dietary fiber without affecting the structure of the insoluble dietary fiber, and retains the bound phenols in the insoluble dietary fiber to a great extent (the content is as high as 2.8-3.5 mg / 100 g) without affecting the activity of the bound phenols. It has certain antioxidant activity and starch digestion enzyme inhibitory activity, and has the advantages of low average particle size, high water holding capacity, high oil holding capacity, high swelling property and high thermal stability, and is suitable for preparing functional foods.

[0059] 2. The method of the present invention is safe and non-toxic, has low requirements on equipment conditions, low production cost, high yield, realizes waste recycling, is more green and environmentally friendly, and is conducive to industrial production. DETAILED DESCRIPTION

[0060] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0061] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0062] Test method:

[0063] (1) Determination of insoluble dietary fiber content in white kidney bean peel

[0064] The insoluble dietary fiber content in white kidney bean peel was analyzed and tested in accordance with the National Food Safety Standard of the People's Republic of China - Determination of Dietary Fiber in Food (GB5009.88-2014).

[0065] (2) Determination of the content of bound phenols in insoluble dietary fiber from white kidney bean skin

[0066] The insoluble dietary fiber containing bound phenol was placed in a round-bottom flask, and a 5 mol / L NaOH solution (solid-liquid ratio 1 g: 20 mL) was added. The flask was sealed with nitrogen and then hydrolyzed. The flask was extracted in a water bath at 75°C for 2 h, and the pH was adjusted to 1.5-2.0 with hydrochloric acid. Ethyl acetate was then added for extraction. The extraction was performed 3 times. The extract phases were combined and rotary evaporated to dryness at 45°C. The residue was eluted with 10 mL of methanol to obtain a bound phenol extract. 0.5 mL of the 10-fold diluted bound phenol extract was added to a test tube, and 2.5 mL of Folin phenol reagent was added respectively. The mixture was mixed and allowed to stand for 3 min, and then 2.5 mL of 10% sodium carbonate solution was added. After mixing, distilled water was added to make the volume 10 mL and the mixture was colorized at 25°C in the dark for 2 h. The absorbance was measured at 760 nm, and the total bound phenol content (mg GAE / g DW) was calculated using a gallic acid standard solution as a control.

[0067] (3) Test of the inhibitory ability of phenol on α-glucosidase activity

[0068] The insoluble dietary fiber containing bound phenol was placed in a round-bottom flask, and a 5 mol / L NaOH solution (solid-liquid ratio 1 g: 20 mL) was added. The flask was sealed with nitrogen and then hydrolyzed. The flask was shaken and extracted in a water bath at 75°C for 2 h. The pH was adjusted to 1.5-2.0 with hydrochloric acid, and then ethyl acetate was added for extraction. The extraction was performed 3 times in total. The extract phases were combined and rotary evaporated to dryness at 45°C. The residue was eluted with 10 mL of methanol to obtain a bound phenol extract. The methanol was evaporated by rotary evaporation at 45°C, and the bound phenol was taken out and freeze-dried to obtain bound phenol. The bound phenol was added to PBS buffer (pH = 6.9) at a ratio of 1 g: 5 mL, and stirred and extracted at 45°C and 150 rpm for 2.5 h. The supernatant and residue were obtained by centrifugation at 4°C and 4000×g for 20 min. The residue was centrifuged again at 4°C and 4000×g for 20 min. The two supernatants were combined and filtered with a 0.22 μm filter membrane to obtain a crude extract. Through preliminary experimental concentration exploration, sample solutions with concentrations of 0.5, 1, 10, 25 and 50 mg / mL were prepared. 40 μL of sample solution was added to the 96-well plate (the blank group added the same volume of PBS), 20 μL of 0.4U / mL α-glucosidase solution was added and incubated at a constant temperature of 37°C incubator for 10 minutes, and then 40 μL of 0.5mmol / L PNPG solution was quickly added to the 96-well plate and reacted in a 37°C incubator for 20 minutes, and then 50 μL of 0.1mol / L Na2CO3 solution was added to the plate and incubated at 37°C for 5 minutes to terminate the reaction. After the reaction was completed, the absorbance was measured at 405nm absorbance (three parallels). The inhibition rate was calculated according to the formula.

[0069] Inhibition rate (%) = ([(A0-A b )-(A i -A j )]) / ((A0-A b ))×100%

[0070] Among them, A0 is the absorbance of the blank group, A b is the background absorbance of the blank group, A i is the absorbance of the sample group, A j is the background absorbance of the sample group.

[0071] (4) Test of the inhibitory ability of phenol on α-amylase activity

[0072] The insoluble dietary fiber containing bound phenol was placed in a round-bottom flask, and a 5 mol / L NaOH solution (solid-liquid ratio 1 g: 20 mL) was added. The flask was sealed with nitrogen and then hydrolyzed. The flask was shaken and extracted in a water bath at 75°C for 2 h. The pH was adjusted to 1.5-2.0 with hydrochloric acid, and then ethyl acetate was added for extraction. The extraction was performed 3 times in total. The extract phases were combined and rotary evaporated to dryness at 45°C. The residue was eluted with 10 mL of methanol to obtain a bound phenol extract. The methanol was evaporated by rotary evaporation at 45°C, and the bound phenol was taken out and freeze-dried to obtain bound phenol. The bound phenol was added to PBS buffer (pH = 6.9) at a ratio of 1 g: 5 mL, and stirred and extracted at 45°C and 150 rpm for 2.5 h. The supernatant and residue were obtained by centrifugation at 4°C and 4000×g for 20 min. The residue was centrifuged again at 4°C and 4000×g for 20 min. The two supernatants were combined and filtered with a 0.22 μm filter membrane to obtain a crude extract. Through preliminary experimental concentration exploration, sample solutions with concentrations of 0.5, 1, 10, 25, 50, 75 and 100 mg / mL were prepared. 0.25 mL of α-amylase solution (1.5 U / mL) and 0.25 mL of sample solution (the blank group added the same volume of PBS) were added to 0.5 mL of PBS solution, and 0.5 mL of soluble starch solution (AR pure for laboratory use) was added after 10 minutes of water bath at 37°C. After accurate reaction at 37°C for 5 minutes, 1 mL of DNS reagent was added, and then heated in a boiling water bath for 10 minutes, and then quickly placed in an ice water bath to cool to 25°C, and then 5 mL of deionized water was added, mixed evenly, and then allowed to stand for 10 minutes, and the absorbance was measured at 540 nm. The inhibition rate was calculated according to the formula.

[0073] Inhibition rate (%) = ([(A0-A b )-(A i -A j )]) / ((A0-A b ))×100%

[0074] Among them, A0 is the absorbance of the blank group, A b is the background absorbance of the blank group, A i is the absorbance of the sample group, A j is the background absorbance of the sample group.

[0075] (5) Average particle size of insoluble dietary fiber containing bound phenols

[0076] A small amount of insoluble dietary fiber containing bound phenol was taken and its particle size distribution was measured using a Malvern laser particle size analyzer (Mastersizer 3000, Malvern, UK).

[0077] (6) Specific surface area of ​​insoluble dietary fiber containing bound phenols

[0078] A small amount of dry powder of insoluble dietary fiber containing bound phenol was taken and the specific surface area of ​​the sample was measured using a BEST specific surface area tester (3H-2000A, BEST Instrument Technology, Beijing).

[0079] (7) Water-holding capacity of insoluble dietary fiber containing bound phenols

[0080] Weigh 0.5g of insoluble dietary fiber powder containing bound phenol accurately and mix thoroughly with 20mL of distilled water. Stir at 25℃ for 18h, centrifuge at 4000×g for 15min, remove the supernatant, absorb the water with filter paper, and then dry the precipitate in the tube at 105℃ to constant weight and weigh it. The calculation formula is:

[0081]

[0082] (8) Oil-holding capacity of insoluble dietary fiber containing bound phenols

[0083] Accurately weigh 0.5g of insoluble dietary fiber powder containing bound phenol and 20mL of soybean blended oil respectively, add them into a centrifuge tube and stir evenly. After mixing at 25°C for 18h, centrifuge the mixture at 4000×g for 15min, discard the supernatant, absorb the remaining blended oil with filter paper, and weigh it. The calculation formula is:

[0084]

[0085] (9) Swelling properties of insoluble dietary fiber containing bound phenols

[0086] Weigh 0.5g of insoluble dietary fiber powder containing bound phenol accurately into a 10mL colorimetric tube, add 5.00mL of distilled water accurately with a pipette, shake evenly, place in a 25℃ water bath and let stand for 24h, and read the volume of dietary fiber in the liquid. The expansion force calculation formula is as follows:

[0087]

[0088] Example 1 Preparation of an insoluble dietary fiber containing bound phenols

[0089] S1. Recover the waste bean skin in the process of white kidney bean utilization, clean it, dry it in a 40℃ blast drying oven for 72h, crush it, pass it through a 100-mesh sieve, mix it with 80% (v / v) ethanol solution at a mass volume ratio of 1g:8mL, perform ultrasonic cleaning for 30min at a power of 300W, a frequency of 40KHz, and a temperature of 40℃ to remove impurities, filter it, repeat the ultrasonic and filtering three times, and then place it in a -20℃ refrigerator for pre-freezing for 12h, and then freeze-dry it at -50℃ for 48h;

[0090] S2. The product obtained in S1 was added with a phosphate buffer solution (0.1 mol / L) of pH=7.5 at a material-liquid ratio of 1 g:8 mL, dispersed by a digital dispersing instrument, and then the pH was adjusted to 1.5 and a pepsin solution (the amount added was 0.2% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 40°C for 1 hour. The pH was then adjusted to 7.5 and a pancreatic enzyme solution (the amount added was 0.15% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 37°C for 4 hours, and then boiled at 65°C for 30 minutes, and then an equal volume of maleate buffer solution (0.1 mol / L) of pH=6.9 was added to adjust the pH to 6.9 and a medium-temperature α-amylase solution (the amount added was 2.5% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 37°C for 16 hours, and centrifuged at 3500×g for 20 minutes;

[0091] S3. The product obtained in S2 was washed with water three times, then washed with 78% (v / v) ethanol solution, filtered under vacuum conditions, and the residue was collected, pre-frozen in a -20°C refrigerator for 12 hours, and then freeze-dried at -50°C for 48 hours;

[0092] S4. The product obtained in S3 is subjected to dry vibration ultrafine grinding treatment at an amplitude of 5.5 mm and a temperature of 0° C. for 10 minutes to obtain the insoluble dietary fiber containing bound phenols.

[0093] Example 2 Preparation of an insoluble dietary fiber containing bound phenols

[0094] The method is the same as that of Example 1, except that in S4, the dry vibration ultrafine grinding treatment time is 20 minutes.

[0095] Example 3 Preparation of an insoluble dietary fiber containing bound phenols

[0096] The method is the same as that in Example 1, except that in S2, the amount of pepsin solution added is 0.3% (w / v) of the enzymatic reaction system, the amount of pancreatic enzyme solution added is 0.2% (w / v) of the enzymatic reaction system, and the amount of medium-temperature α-amylase solution added is 3.0% (w / v) of the enzymatic reaction system.

[0097] Example 4 Preparation of an insoluble dietary fiber containing bound phenols

[0098] The method is the same as that in Example 3, except that in S4, the dry vibration ultrafine grinding treatment time is 20 minutes.

[0099] Example 5 Preparation of an insoluble dietary fiber containing bound phenols

[0100] S1. Recover the waste bean skin in the process of utilizing white kidney beans, clean it, dry it in a 35°C air drying oven for 72 hours, crush it, pass it through a 50-mesh sieve, mix it with 80% (v / v) ethanol solution at a mass volume ratio of 1g:10mL, perform ultrasonic cleaning for 35 minutes at a power of 200W, a frequency of 45KHz, and a temperature of 40°C to remove impurities, filter it, repeat the ultrasonic and filtering twice, and then place it in a -25°C refrigerator for pre-freezing for 10 hours, and then freeze-dry it at -50°C for 24 hours;

[0101] S2. The product obtained in S1 was added with a phosphate buffer solution (0.1 mol / L) with a solid-liquid ratio of 1 g:8 mL, dispersed by a digital dispersing instrument, and then the pH was adjusted to 1.4 and a pepsin solution (the amount added was 0.15% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 38°C for 1.1 h. The pH was then adjusted to 7.5 and a pancreatic enzyme solution (the amount added was 0.1% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 36°C for 3.7 h, and then boiled at 60°C for 40 min, and then an equal volume of maleate buffer solution (0.1 mol / L) with a pH of 6.9 was added to adjust the pH to 6.9 and a medium-temperature α-amylase solution (the amount added was 1.5% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 36°C for 15 h, and centrifuged at 3000×g for 22 min;

[0102] S3. The product obtained in S2 was washed with water three times, then washed with 88% (v / v) ethanol solution, filtered under vacuum conditions, and the residue was collected, pre-frozen in a -25°C refrigerator for 10 h, and then freeze-dried at -50°C for 24 h;

[0103] S4. The product obtained in S3 is subjected to dry vibration ultrafine grinding treatment at an amplitude of 3.5 mm and a temperature of -25°C for 10 minutes to obtain the insoluble dietary fiber containing bound phenols.

[0104] Example 6 Preparation of an insoluble dietary fiber containing bound phenols

[0105] S1. Recover the waste bean skin in the process of white kidney bean utilization, clean it, dry it in a 45℃ blast drying oven for 72h, crush it, pass it through a 150-mesh sieve, mix it with 85% (v / v) ethanol solution at a mass volume ratio of 1g:5mL, perform ultrasonic cleaning for 25min at a power of 450W, a frequency of 35KHz, and a temperature of 35℃ to remove impurities, filter it, repeat the ultrasonic and filtering 5 times, and then place it in a -15℃ refrigerator for pre-freezing for 14h, and then freeze-dry it at -10℃ for 48h;

[0106] S2. The product obtained in S1 was added with a phosphate buffer solution (0.1 mol / L) of pH=7.5 at a material-liquid ratio of 1 g:8 mL, dispersed by a digital dispersing instrument, and then the pH was adjusted to 1.5 and a pepsin solution (the amount added was 0.3% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 42°C for 0.9 h. The pH was then adjusted to 8.0 and a pancreatic enzyme solution (the amount added was 0.2% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 38°C for 4.3 h, and then boiled at 65°C for 30 min, and then an equal volume of maleate buffer solution (0.1 mol / L) of pH=6.9 was added to adjust the pH to 6.9 and a medium-temperature α-amylase solution (the amount added was 3.0% (w / v) of the enzymatic reaction system) was added, and enzymatic hydrolysis was performed at 38°C for 17 h, and centrifuged at 4000×g for 18 min;

[0107] S3. The product obtained in S2 was washed once with water, then washed with 68% (v / v) ethanol solution, filtered under vacuum conditions, and the residue was collected, pre-frozen in a -15°C refrigerator for 14 h, and then freeze-dried at -10°C for 48 h;

[0108] S4. The product obtained in S3 is subjected to dry vibration ultrafine grinding treatment at an amplitude of 5.5 mm and a temperature of 10° C. for 20 minutes to obtain the insoluble dietary fiber containing bound phenols.

[0109] Comparative Example 1

[0110] The method is the same as that of Example 1, except that step S2 of Example 1 is replaced by: adding the product obtained in S1 into distilled water to make a material-liquid ratio of 1 g:30 mL, and extracting in a water bath at 80° C. for 2 h.

[0111] Comparative Example 2

[0112] The method is the same as that in Example 1, except that the step of "boiling at 65°C for 30 min, adding an equal volume of maleate buffer (0.1 mol / L) with a pH value of pH=6.9 to adjust the pH to 6.9, adding a medium-temperature α-amylase solution (the amount added is 2.5% (w / v) of the enzymatic reaction system), enzymolyzing at 37°C for 16 h, and centrifuging at 3500×g for 20 min" in S2 of Example 1 is not performed, but the step of "adjusting the pH to 6.0 with 0.1 mol / L NaOH solution, adding a thermostable α-amylase solution (the amount added is 2.5% (w / v) of the enzymatic reaction system), reacting at 95°C for 1 h, and centrifuging at 3500×g for 20 min" is performed.

[0113] That is, S2 of this comparative example is: the product obtained from S1 is added to a phosphate buffer solution (0.1 mol / L) with a pH of 7.5 at a solid-liquid ratio of 1 g:8 mL, dispersed by a digital dispersion instrument, and then the pH is adjusted to 1.5 and a pepsin solution is added (the amount added is 0.2% (w / v) of the enzymatic reaction system), and enzymolysis is carried out at 40°C for 1 hour, and then the pH is adjusted to 7.5 and a pancreatic enzyme solution is added (the amount added is 0.15% (w / v) of the enzymatic reaction system), and enzymolysis is carried out at 37°C for 4 hours, and then the pH is adjusted to 6.0 with a 0.1 mol / L NaOH solution, and a heat-stable α-amylase solution is added (the amount added is 2.5% (w / v) of the enzymatic reaction system), and the reaction is carried out at 95°C for 1 hour, and centrifuged at 3500×g for 20 minutes.

[0114] Comparative Example 3

[0115] The method is the same as that of Example 1, except that the dry vibration ultrafine grinding treatment described in S4 is not performed.

[0116] Comparative Example 4

[0117] The method is the same as that of Example 1, except that the ultrasonic cleaning in S1 is replaced by a constant temperature water bath.

[0118] That is, S1 of this comparative example is: recycling the waste bean skin in the process of utilizing white kidney beans, washing it clean, drying it in a 40°C blast drying oven for 72 hours, crushing it, passing it through a 100-mesh sieve, and then mixing it with 80% (v / v) ethanol solution at a mass volume ratio of 1g:8mL, stirring it in a constant temperature water bath at 40°C for 30min, filtering it, repeating the water bath and filtering 3 times, and then placing it in a -20°C refrigerator for pre-freezing for 12h, and then freeze-drying it at -50°C for 48h;

[0119] Test Example 1: Physical and Chemical Properties of Insoluble Dietary Fiber and Bound Phenols

[0120] The products of Examples 1 to 6 and Comparative Examples 1 to 4 were tested respectively, and their physicochemical properties (insoluble dietary fiber content, bound phenol content, inhibitory ability of bound phenol on α-glucosidase and α-amylase activity, average particle size, specific surface area, water holding capacity, oil holding capacity, and swelling capacity) were obtained as shown in Table 1.

[0121] Table 1 Physical and chemical properties of the products of Examples 1 to 6 and Comparative Examples 1 to 4

[0122]

[0123]

[0124] visible:

[0125] (1) Compared with the comparative example 1 which only used the hot water extraction method, the extraction rates of insoluble dietary fiber and bound phenols in Examples 1 to 6 which used the continuous enzymatic extraction method were significantly improved, indicating that the continuous enzymatic method can effectively remove impurities such as starch and protein in white kidney bean skin, and can also significantly improve the extraction efficiency of insoluble dietary fiber and bound phenols.

[0126] (2) By comparing Example 1 and Example 3, and Example 2 and Example 4, it can be seen that when the enzyme concentration used is increased, the extraction rate of insoluble dietary fiber and bound phenols by the method of the present invention is more significantly improved.

[0127] (3) Compared with Example 1 in which the extraction was carried out in a water bath at 80°C for 2 h and Example 2 in which the hydrolysis was carried out using a thermostable α-amylase at 95°C for 1 h, Examples 1 to 6 avoided the use of high temperatures for a long time during the extraction process and combined with the low-temperature cooling cycle function of ultrafine grinding, the high-speed grinding process can be maintained at 0°C, which can largely retain the original physiological activity of the bound phenols without affecting them, and effectively ensure the inhibitory activity of the bound phenols on α-glucosidase and α-amylase, indicating that continuous high-temperature reaction will cause a certain degree of damage to the structure and function of polyphenols and reduce their activity.

[0128] (4) Compared with the comparative example 3 which was not subjected to the dry vibration type ultrafine grinding treatment, the average particle size of the insoluble dietary fiber containing bound phenol in Examples 1 to 6 was significantly reduced, and its specific surface area, water holding capacity, oil holding capacity, swelling capacity, etc. were significantly improved. This shows that the physicochemical properties of the insoluble dietary fiber containing bound phenol obtained by combining the continuous enzymatic method and the ultrafine grinding technology of the present invention are significantly better than those of the insoluble dietary fiber containing bound phenol obtained without the ultrafine grinding technology.

[0129] (5) Comparing Example 1 and Example 2, as well as Example 3 and Example 4, it can be seen that as the pulverization time increases, the powder of insoluble dietary fiber containing bound phenol becomes finer, and its water holding capacity, oil holding capacity and swelling capacity are also better. When insoluble dietary fiber with high water holding capacity and swelling rate is added to foods such as moon cakes, it can continuously absorb water and swell in the intestine after being eaten. It can absorb water more than 10 times its own weight at most, making the texture of feces soft and easier to discharge. At the same time, it can also directly stimulate intestinal peristalsis. Under multiple effects, it can help the human body to defecate efficiently, reduce the pressure in the rectum and urinary system, and improve constipation; and as the pulverization time increases and the powder becomes finer, more bound phenol is exposed, and the inhibitory ability to α-glucosidase and α-amylase is naturally stronger. It can be seen that if the insoluble dietary fiber containing bound phenol of the present invention is added to moon cakes, its physiological activity can be better exerted, and while improving constipation, it can also control the increase of blood sugar after meal and prevent obesity.

[0130] (6) Compared with the comparative example 4 of constant temperature water bath cleaning, the extraction rates of insoluble dietary fiber and bound phenols in the examples 1 to 6 of ultrasonic cleaning were improved, indicating that ultrasonic cleaning can promote the extraction and release of insoluble dietary fiber and bound phenols, and improve the yields of both.

[0131] Test Example 2 Structure of combined phenol

[0132] Take 20g of the insoluble dietary fiber containing bound phenols in Example 2 and put it in a glass bottle with a cover, according to the material-liquid ratio of 1g:

[0133] 20mL of 4mol / L NaOH solution was added, the mixture was sealed with N2 and stirred at 25°C for 4h for hydrolysis, and then HCl was added to adjust the pH to 1.5-2.0, and then extracted with ethyl acetate for 3 times, and the organic phase was collected.

[0134] The organic phase was poured into a rotary evaporation flask in portions and subjected to rotary evaporation at 40°C until the ethyl acetate liquid was completely evaporated and the bound phenol remained in the rotary evaporation flask. It was redissolved with 10 mL of methanol to obtain a methanol solution of the bound phenol.

[0135] LC-MS / MS was used to identify the structure of the bound phenol, flow rate: 0.6 mL / min; injection volume: 10 μL; 20 column temperature: 35 °C; mass spectrometry detection conditions: ① Multiple reaction monitoring (MRM) detection conditions: spray voltage 4.5~

[0136] 5.5kv; desolvation temperature 500℃; desolvation gas (N2) 1000L / h; ②Mass spectrometry scanning conditions: ESI+

[0137] Mode: spray voltage 5.5 kv; desolvation temperature 500 °C; desolvation gas (N2) 1000 L / h; scanning range 100-1000 m / Z; ESI-mode: spray voltage 4.5 kv; desolvation temperature 500 °C; desolvation gas (N2) 1000 L / h; scanning range: 100-1000 m / Z. The main results are shown in Table 2: 20 Table 2 The dominant components and their contents of combined phenol

[0138]

[0139]

[0140] It can be seen that combined phenols contain rich active phenolic compounds such as anhydrous phloroglucinol, p-coumaric acid, punicalagin, ursolic acid, etc., which have analgesic, anti-inflammatory, antioxidant and other biological activities, which are beneficial to human health. Among them, punicalagin and ursolic acid are active ingredients with hypoglycemic and anti-diabetic functions. Therefore, applying insoluble dietary fiber containing combined phenols to the production of moon cakes can more effectively control the glycemic index, which is beneficial to the production of low GI moon cakes.

[0141] Test Example 3 Preparation and Properties of Low GI Mooncakes

[0142] 1. Preparation of a low GI mooncake

[0143] 10 According to the types and amounts of the raw materials in Table 3, low GI mooncakes (filling 48 g / piece, crust 16 g / piece) of Application Examples 1 to 5 and Application Comparative Examples 1 to 4 were prepared according to the following steps:

[0144] S1. Take the formula amount of maltooligosaccharide syrup, then add potassium bicarbonate, peanut oil, baking soda and the insoluble dietary fiber containing bound phenol obtained in Example 2, mix well, and finally add flour, mix well, and let stand for 2h, that is, 15 to obtain a low GI mooncake crust;

[0145] 15S2. Use S1 low GI mooncake skin to completely wrap the traditional lotus seed paste mooncake filling, then place it in a mold, compact it to form it, and bake it at a bottom heat of 130°C and a surface heat of 210°C for 15 minutes after demoulding. After baking, the low GI mooncake is obtained.

[0146] Table 3 Recipe for low GI mooncake crust

[0147]

[0148] 2. Sensory Evaluation Method

[0149] An evaluation team was formed by 10 volunteers (5 females and 5 males, aged 20-35 years old) who had undergone food sensory evaluation training. According to the sensory evaluation criteria in Table 4, the low GI mooncakes of Example 1-5 and Comparative Example 1-4 were evaluated.

[0150] Table 4 Sensory evaluation standards for moon cakes

[0151]

[0152]

[0153] 3. GI value testing method

[0154] Referring to WS / T 652-2019 "Method for Determination of Glycemic Index of Food", 12 healthy adult volunteers (6 females and 6 males, light manual laborers, no history of diabetes, no other metabolic diseases, digestive system diseases, endocrine system diseases and mental diseases, etc.) were selected for glycemic index testing. The volunteers were aged 22 to 30 years old, with an average age of 24.50±3.23 years old, and an average body mass index (BMI): 21.37±1.78kg / m 2 .

[0155] The volunteers began to fast at 8 pm on the day before the test. After measuring their fasting blood sugar by fingertip capillary method the next morning, they ate the low GI mooncakes (50 g carbohydrate equivalent) obtained by Application Examples 1 to 5 and Comparative Examples 1 to 4, respectively. Then, their blood sugar was measured by fingertip capillary method at 15 min, 30 min, 45 min, 60 min, 90 min and 120 min after eating, respectively. The blood sugar level after eating 50 g glucose was used as a reference. The test interval between different foods was greater than 72 h.

[0156] The area under the blood glucose response curve of each volunteer to moon cakes and glucose was calculated respectively, and the glycemic index GI was calculated according to the following formula:

[0157]

[0158] 4. Test Results

[0159] The sensory evaluation results and glycemic index determination results are shown in Table 5.

[0160] Table 5 Sensory evaluation results and glycemic index GI measurement results

[0161]

[0162]

[0163] visible:

[0164] (1) Compared with the application examples 1 and 4 without adding the insoluble dietary fiber containing bound phenols, the moon cakes of application examples 1 to 5 with the addition of the insoluble dietary fiber containing bound phenols were significantly improved in color (light yellow), hardness, texture and palatability, showing a richer texture and layered texture.

[0165] (2) The mooncakes of Application Examples 1 to 5 all have lower GI values ​​(42.38 to 50.47, lower than 55), which are significantly better than Application Comparative Examples 1 to 4 (58.24 to 79.49); and compared with Application Example 1, the GI values ​​of the mooncakes of Application Comparative Examples 2 to 4, in which the insoluble dietary fiber containing bound phenol in the crust is replaced with flour, white kidney bean powder and white kidney bean skin powder, are also significantly too high. This shows that the insoluble dietary fiber of the present invention can effectively inhibit the activity of α-glucosidase and α-amylase because it retains relatively rich bound phenols, so it can more effectively play a role in controlling postprandial blood sugar, and is more suitable and efficient for producing low GI mooncake crusts. In addition, the present invention can prepare healthy mooncakes with hypoglycemic effects by specifically controlling the type and amount of raw materials of the mooncake crust.

[0166] (3) Although the sensory scores of comparative examples 2 and 4 are close to those of some application examples, their GI values ​​are significantly higher than those of the application examples. Therefore, it is precisely because the present invention adds the insoluble dietary fiber containing bound phenols extracted by a specific method to the mooncakes that it is possible to simultaneously achieve both the excellent sensory score and the low GI value of the mooncakes.

[0167] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing insoluble dietary fiber containing bound phenols, characterized in that: The white kidney bean husk is subjected to ultrasound, enzymatic hydrolysis, freeze drying, and dry vibration ultrafine grinding treatment in sequence to obtain the insoluble dietary fiber containing bound phenols; The ultrasonic treatment comprises: mixing white kidney bean peel with an ethanol solution, and performing ultrasonic treatment for 25 to 35 minutes at a power of 200 to 450 W, a frequency of 35 to 45 KHz, and a temperature of ≤40° C. The mass volume ratio of the white kidney bean peel to the ethanol solution is 1 g: 5 to 10 mL, and the concentration of the ethanol solution is 80% to 85% v / v; The enzymolysis comprises: firstly adding pepsin to the enzymolysis reaction system in an amount of 0.15% to 0.3% w / v, performing enzymolysis at a temperature of 38 to 42°C and a pH value of 1.4 to 1.5 for 0.9 to 1.1 h; then adding pancreatin to the enzymolysis reaction system in an amount of 0.1% to 0.2% w / v, performing enzymolysis at a temperature of 36 to 38°C and a pH value of 7.5 to 8.0 for 3.7 to 4.3 h; then heating the enzymolysis reaction system at ≤ 65°C for 30 to 40 min; finally adding medium-temperature α-amylase to the enzymolysis reaction system in an amount of 1.5% to 3.0% w / v, performing enzymolysis at a temperature of 36 to 38°C and a pH value of 6.8 to 6.9 for 15 to 17 h; The dry vibration ultrafine grinding treatment is carried out at an amplitude of 3.5 to 5.5 mm and a temperature of -25 to 10° C. for 10 to 20 minutes.

2. The insoluble dietary fiber containing bound phenols prepared by the method of claim 1.

3. Use of the insoluble dietary fiber containing bound phenols according to claim 2 in preparing low GI food.

4. The use according to claim 3, characterized in that: The low GI food is a low GI mooncake crust.

5. A low GI mooncake crust, characterized in that: The invention comprises the following components in parts by weight: 30-55 parts of flour, 35-60 parts of oligosaccharide syrup, 10-25 parts of edible oil, 2-4 parts of bulking agent, 1-6 parts of insoluble dietary fiber containing bound phenol according to claim 2, and 0.5-2 parts of acidity regulator.

6. The method for preparing the low GI mooncake crust according to claim 5, characterized in that: Mix all the components by weight.

7. Use of the low GI mooncake crust according to claim 5 in preparing low GI mooncakes.

8. A low GI mooncake, characterized in that: Contains the low GI mooncake crust as claimed in claim 5.

9. A method for preparing low GI moon cakes, characterized in that: Wrap the filling in the low GI mooncake crust of claim 5 and bake.

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