Modification method and application of insoluble dietary fiber

Abstract

The invention belongs to the technical field of by-product deep processing, and particularly relates to a modification method and application of insoluble dietary fibers. The preparation method comprises the following steps: mixing insoluble dietary fibers and a solvent, and performing ultrasonic treatment to obtain a treated solution; the treated solution contains modified insoluble dietary fibers; the solvent comprises 25-28% v / v of choline chloride, 50-57% v / v of lactic acid and the balance of water; the power of the ultrasonic treatment is 250 to 350W, and the time of the ultrasonic treatment is 10 to 20 minutes. According to the invention, choline chloride, lactic acid and the balance of water are utilized, and ultrasonic assistance is adopted to modify the insoluble dietary fibers, so that the physical and functional characteristics of the insoluble dietary fibers can be optimized, and the modified insoluble dietary fibers are reduced in particle size, enhanced in water-holding capacity and enhanced in cholesterol and glucose adsorption capacity. The method is simple, convenient and efficient, and the prepared modified morinda citrifolia dietary fiber has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of deep processing of by-products, and specifically relates to a modification method of insoluble dietary fiber and application thereof. Background Art

[0002] Dietary fiber (DF) is an indigestible nutrient derived from plant cell walls and is known as the "seventh macronutrient". It has many benefits for human health. For example, cellulose and hemicellulose can directly promote intestinal motility, while inulin can prevent a variety of intestinal diseases by producing short-chain fatty acids through fermentation by intestinal microbiota. Studies have shown that a higher intake of dietary fiber can effectively reduce the risk of diseases such as diabetes, hypertension, hypercholesterolemia and obesity.

[0003] Dietary fiber can be divided into two categories: soluble and insoluble. Among them, insoluble dietary fiber (IDF) is the main component of dietary fiber. The structure of IDF is relatively compact, and the active groups such as hydroxyl, carboxyl, and amide groups cannot be fully exposed, resulting in weaker physical and physiological activities than soluble dietary fiber. Therefore, it is necessary to adjust the physicochemical properties of insoluble dietary fiber through modification to improve its functionality.

[0004] However, the prior art usually adopts alkaline hydrolysis and alcohol precipitation to prepare soluble dietary fiber and insoluble dietary fiber, which changes the structure and characteristics of insoluble dietary fiber by promoting the hydrolysis and release of soluble dietary fiber, but the modification effect is not obvious, the functionality of insoluble dietary fiber needs to be further improved, and there are risks such as residual alkali solution and side reactions during the application process, and a large amount of waste liquid will be generated, thus causing environmental pressure. Therefore, it is of great significance to develop an efficient and environmentally friendly insoluble dietary fiber modification method to enhance the functionality of insoluble dietary fiber. Summary of the invention

[0005] The purpose of the present invention is to provide a modification method of insoluble dietary fiber and application thereof, so as to enhance the functionality of the insoluble dietary fiber and improve the extraction efficiency and purity of the insoluble dietary fiber.

[0006] The present invention provides a method for modifying insoluble dietary fiber, comprising the following steps:

[0007] The insoluble dietary fiber and the solvent are mixed and then subjected to ultrasonic treatment to obtain a treated solution; the treated solution contains the modified insoluble dietary fiber;

[0008] The solvent comprises 25-28% v / v choline chloride, 50-57% v / v lactic acid and the balance water;

[0009] The power of the ultrasonic treatment is 250-350W, and the time is 10-20 minutes.

[0010] Preferably, the molar ratio of choline chloride to lactic acid in the solvent is 1:2;

[0011] The mass volume ratio of the insoluble dietary fiber to the solvent is 1g: (150-250)mL.

[0012] Preferably, after obtaining the treated solution, the method further comprises: performing solid-liquid separation on the treated solution, collecting the precipitate and drying it to obtain the modified insoluble dietary fiber.

[0013] Preferably, the drying temperature is 45-55°C.

[0014] Preferably, the method for preparing the insoluble dietary fiber comprises the following steps:

[0015] mixing the byproduct containing insoluble dietary fiber and a buffer to obtain a premix;

[0016] Performing a first enzymatic hydrolysis on the premix by using α-amylase to obtain a first enzymatic hydrolysis product;

[0017] Performing a second enzymolysis on the first enzymolysis product using papain to obtain a second enzymolysis product;

[0018] Performing a third enzymolysis on the second enzymolysis product using glucoamylase to obtain a third enzymolysis product;

[0019] Performing enzyme inactivation treatment on the third enzymatic hydrolysis product, performing solid-liquid separation, collecting the precipitate, and obtaining a crude extract;

[0020] The crude extract is purified to obtain insoluble dietary fiber.

[0021] Preferably, the temperature of the first enzymatic hydrolysis is 80-95°C and the time is 1-2h;

[0022] The pH value of the second enzymatic hydrolysis is 7.0, the temperature is 45-55°C, and the time is 1-2h;

[0023] The third enzymatic hydrolysis has a pH value of 2.0, a temperature of 55-65° C., and a time of 2 h;

[0024] The temperature of the enzyme inactivation treatment is 85-100°C and the time is 8-12 minutes;

[0025] The purification method includes drying; the drying temperature is 45-55°C.

[0026] Preferably, the mass ratio of the α-amylase to the by-product containing insoluble dietary fiber is 0.5-2:100; the enzyme activity of the α-amylase is 2000-3000U;

[0027] The mass ratio of the papain to the byproduct containing insoluble dietary fiber is 0.5-1:100; the enzymatic activity of the papain is 400-600 U;

[0028] The mass ratio of the glucoamylase to the by-product containing insoluble dietary fiber is 0.5-1:100; the enzyme activity of the glucoamylase is 100-300U.

[0029] Preferably, the by-product containing insoluble dietary fiber includes Noni pomace; the Noni pomace has a water content of ≤15% and a particle size of ≤0.85 mm;

[0030] The mass volume ratio of the byproduct containing insoluble dietary fiber to the buffer is 1g: (8-12)mL; the buffer comprises a phosphate buffer.

[0031] The present invention also provides modified insoluble dietary fiber obtained by the modification method described in the above technical solution.

[0032] The present invention also provides the application of the modified insoluble dietary fiber described in the above technical solution in food or medicine.

[0033] Beneficial effects:

[0034] The present invention mixes insoluble dietary fiber and solvent and then performs ultrasonic treatment to obtain a treated solution; the treated solution contains modified insoluble dietary fiber; the solvent includes 25-28% v / v choline chloride, 50-57% v / v lactic acid and the remainder of water; the power of the ultrasonic treatment is 250-350W, and the time is 10-20min. The present invention uses choline chloride, lactic acid and the remainder of water to modify the insoluble dietary fiber with the assistance of ultrasound, which can optimize the physical and functional properties of the insoluble dietary fiber, and the modified insoluble dietary fiber has a reduced particle size, enhanced water holding capacity, and enhanced cholesterol and glucose adsorption capacity. The method is simple and efficient, and the prepared modified noni dietary fiber has a wide range of application prospects. The results of the embodiment show that the modified insoluble dietary fiber obtained by the modification method of the present invention has a particle size reduction of 20-30%, a water holding capacity enhancement of 130-150%, a cholesterol adsorption capacity enhancement range of 60-70%, and a glucose adsorption capacity enhancement range of 250-290% compared with before modification.

[0035] Furthermore, the existing methods for preparing insoluble dietary fiber generally have the problems of low extraction efficiency and low purity. The present invention sequentially utilizes α-amylase, papain and glucoamylase to enzymolyze the byproduct containing insoluble dietary fiber, which can improve the extraction efficiency and purity of the insoluble dietary fiber. The results of the embodiment show that the extraction rate and purity of the insoluble dietary fiber reach 72.1-78.5% and 62.3-67.5% respectively. DETAILED DESCRIPTION

[0036] The present invention provides a method for modifying insoluble dietary fiber, comprising the following steps:

[0037] The insoluble dietary fiber and the solvent are mixed and then subjected to ultrasonic treatment to obtain a treated solution; the treated solution contains the modified insoluble dietary fiber;

[0038] The solvent comprises 25-28% v / v choline chloride, 50-57% v / v lactic acid and the balance water;

[0039] The power of the ultrasonic treatment is 250-350W, and the time is 10-20 minutes.

[0040] The invention mixes insoluble dietary fiber and a solvent and then performs ultrasonic treatment to obtain a treated solution.

[0041] In the present invention, the concentration of choline chloride in the solvent is 25-28% v / v; as an embodiment, the concentration of choline chloride in the solvent is 26% (v / v). The concentration of lactic acid in the solvent of the present invention is 50-57% v / v; as an embodiment, the concentration of lactic acid in the solvent is 52-56% v / v; as another embodiment, the concentration of lactic acid in the solvent is 54%. As an embodiment, the molar ratio of choline chloride to lactic acid in the solvent is 1:2.

[0042] In the present invention, as an embodiment, the preparation method of the solvent comprises: stirring a mixture of choline chloride and lactic acid at 55-65°C until a uniform and transparent liquid is formed, and then mixing with water after cooling to room temperature to obtain the solvent; as another embodiment, the stirring temperature is 60°C.

[0043] In the present invention, as an embodiment, the mass volume ratio of the insoluble dietary fiber and the solvent is 1g: (150-250) mL; as an embodiment, the mass volume ratio of the insoluble dietary fiber and the solvent is 1g: 200 mL.

[0044] In the present invention, as an embodiment, the power of the ultrasonic treatment is 250-350W; as another embodiment, the power of the ultrasonic treatment is 300W. As an embodiment, the time of the ultrasonic treatment is 10-20min; as another embodiment, the time of the ultrasonic treatment is 15min. The present invention limits the conditions of the ultrasonic treatment to avoid the destruction of insoluble dietary fiber while ensuring the modification effect.

[0045] After obtaining the treated solution, the present invention preferably performs solid-liquid separation on the treated solution, collects the precipitate and then dries it to obtain the modified insoluble dietary fiber.

[0046] In the present invention, as an embodiment, the solid-liquid separation method is filtration. The present invention has no strict requirements on the filtration method, and the conventional method in the art can be used for processing.

[0047] In the present invention, as an embodiment, the drying temperature is 45-55° C.; as another embodiment, the drying temperature is 50° C. The present invention performs drying treatment to remove excess water in the modified insoluble dietary fiber, making the water content less than 5%.

[0048] In the present invention, as an embodiment, the preparation method of the insoluble dietary fiber comprises the following steps: mixing a by-product containing insoluble dietary fiber and a buffer to obtain a premix; performing a first enzymatic hydrolysis on the premix using α-amylase to obtain a first enzymatic hydrolysis product; performing a second enzymatic hydrolysis on the first enzymatic hydrolysis product using papain to obtain a second enzymatic hydrolysis product; performing a third enzymatic hydrolysis on the second enzymatic hydrolysis product using glucoamylase to obtain a third enzymatic hydrolysis product; performing an enzyme inactivation treatment on the third enzymatic hydrolysis product, performing solid-liquid separation, collecting a precipitate, and obtaining a crude extract; purifying the crude extract to obtain insoluble dietary fiber.

[0049] The present invention mixes a byproduct containing insoluble dietary fiber and a buffer to obtain a premix. In the present invention, as an embodiment, the mass volume ratio of the byproduct containing insoluble dietary fiber and the buffer is 1g: (8-12)mL; as an embodiment, the mass volume ratio of the byproduct containing insoluble dietary fiber and the buffer is 1g: 10-mL. As an embodiment, the buffer includes a phosphate buffer.

[0050] In the present invention, as an embodiment, the by-product containing insoluble dietary fiber includes Noni pomace. As an embodiment, the moisture content of the Noni pomace is ≤15%; as another embodiment, the moisture content of the Noni pomace is ≤12%. As an embodiment, the particle size of the Noni pomace is ≤0.85 mm.

[0051] After obtaining the premix, the present invention preferably uses α-amylase to perform a first enzymolysis on the premix to obtain a first enzymolysis product. In the present invention, as an embodiment, the temperature of the first enzymolysis is 80-95°C; as another embodiment, the temperature of the first enzymolysis is 88-92°C; as another embodiment, the temperature of the first enzymolysis is 90°C. As an embodiment, the time of the first enzymolysis is 1-2h; as another embodiment, the time of the first enzymolysis is 1.5h. As an embodiment, the mass ratio of the α-amylase to the by-product containing insoluble dietary fiber is 0.5-2:100; as another embodiment, the mass ratio of the α-amylase to the by-product containing insoluble dietary fiber is 1:100. As an embodiment, the enzyme activity of the α-amylase is 2000-3000U; as another embodiment, the enzyme activity of the α-amylase is 2200-2800U; as another embodiment, the enzyme activity of the α-amylase is 2500U.

[0052] After obtaining the first enzymatic hydrolysis product, the present invention preferably uses papain to perform a second enzymatic hydrolysis on the first enzymatic hydrolysis product to obtain a second enzymatic hydrolysis product. In the present invention, as an embodiment, the pH value of the second enzymatic hydrolysis is 7.0. As an embodiment, the temperature of the second enzymatic hydrolysis is 45-55°C; as another embodiment, the temperature of the second enzymatic hydrolysis is 48-52°C; as another embodiment, the temperature of the second enzymatic hydrolysis is 50°C. As an embodiment, the time of the second enzymatic hydrolysis is 1-2h; as another embodiment, the time of the second enzymatic hydrolysis is 1.5h. As an embodiment, the mass ratio of the papain to the by-product containing insoluble dietary fiber is 0.5-1:100; as another embodiment, the mass ratio of the papain to the by-product containing insoluble dietary fiber is 0.8:100. As an embodiment, the enzymatic activity of the papain is 400-600U; as another embodiment, the enzymatic activity of the papain is 500U.

[0053] After obtaining the second enzymatic hydrolysis product, the present invention preferably uses glucoamylase to perform a third enzymatic hydrolysis on the second enzymatic hydrolysis product to obtain a third enzymatic hydrolysis product. In the present invention, as an embodiment, the pH value of the third enzymatic hydrolysis is 2.0. As an embodiment, the temperature of the third enzymatic hydrolysis is 55-65°C; as another embodiment, the temperature of the third enzymatic hydrolysis is 60°C. As an embodiment, the time of the third enzymatic hydrolysis is 2h. As an embodiment, the mass ratio of the glucoamylase to the by-product containing insoluble dietary fiber is 0.5-1:100; as another embodiment, the mass ratio of the glucoamylase to the by-product containing insoluble dietary fiber is 0.8:100. As an embodiment, the enzymatic activity of the glucoamylase is 100-300U; as another embodiment, the enzymatic activity of the glucoamylase is 200U.

[0054] After obtaining the third enzymatic hydrolysis product, the present invention preferably inactivates the enzyme in the third enzymatic hydrolysis product, separates the solid and the liquid, collects the precipitate, and obtains a crude extract. In the present invention, as an embodiment, the temperature of the enzyme inactivation treatment is 85 to 100°C; as another embodiment, the temperature of the enzyme inactivation treatment is 90 to 100°C; as another embodiment, the temperature of the enzyme inactivation treatment is 100°C. As an embodiment, the time of the enzyme inactivation treatment is 8 to 12 minutes; as another embodiment, the time of the enzyme inactivation treatment is 10 minutes. As an embodiment, the solid-liquid separation method is filtration.

[0055] After obtaining the crude extract, the present invention preferably purifies the crude extract to obtain insoluble dietary fiber. As an embodiment, the purification method includes drying. As an embodiment, the drying temperature is 45 to 55° C.; as another embodiment, the drying temperature is 50° C.

[0056] The invention utilizes alpha-amylase, papain and glucoamylase in sequence to enzymolyze the byproduct containing insoluble dietary fiber, and the extraction rate and purity of the insoluble dietary fiber reach 72.1-78.5% and 62.3-67.5% respectively.

[0057] The present invention also provides a modified insoluble dietary fiber obtained by the modification method described in the above technical solution. Compared with the modified insoluble dietary fiber before modification, the particle size of the modified insoluble dietary fiber is reduced by 20-30%, the water holding capacity is increased by 130-150%, the cholesterol adsorption capacity is increased by 60-70%, and the glucose adsorption capacity is increased by 250-290%. Fourier near-infrared spectroscopy shows that compared with the untreated dietary fiber, the modified insoluble dietary fiber obtained by the modification method of the present invention has a higher carbon dioxide content at 3420 cm -1 、2920cm-1 and 1750cm -1 The absorption peak intensity at becomes lower, which is caused by the stretching vibration of CH and carbonyl CO of OH, methyl or methylene chemical groups of cellulose and hemicellulose, indicating that the modification treatment may destroy the hydrogen bonds, ester and ether group structures between celluloses, prompting the redistribution of cellulose components in dietary fiber, and its structure, porosity and surface area change, thereby improving physical and chemical properties such as water holding capacity, cholesterol adsorption capacity and glucose adsorption capacity. The functionality of dietary fiber is closely related to its physical and chemical properties, such as particle size, water holding capacity, and ability to adsorb cholesterol and glucose. The present invention modifies insoluble dietary fiber, and the particle size, water holding capacity, and ability to adsorb cholesterol and glucose of the modified insoluble dietary fiber obtained are significantly changed. In view of this, the application of the modified insoluble dietary fiber obtained by the modification method of the present invention in food or medicine also belongs to the protection scope of the present invention.

[0058] In order to further illustrate the present invention, a modification method of an insoluble dietary fiber provided by the present invention and its application are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] A method for preparing noni pomace dietary fiber comprises the following steps:

[0061] (1) Select fresh, disease-free and insect-free Noni fruit as raw material, wash and drain it;

[0062] (2) squeezing the treated Noni fruit to obtain Noni juice and Noni pomace after filtering;

[0063] (3) drying the noni pomace to reduce the water content to less than 10%, then crushing it with a grinder and passing it through a 20-mesh sieve to obtain noni pomace powder (i.e., a byproduct containing insoluble dietary fiber);

[0064] (4) extracting dietary fiber from Noni pomace powder by using α-amylase, papain and glucoamylase, and removing impurities by filtering, washing and other steps to obtain purified Noni dietary fiber, specifically:

[0065] The noni pomace powder and phosphate buffer (pH 7.4, 0.1M) were mixed in a mass volume ratio of 1g:10mL, α-amylase was added at a mass ratio of 1% relative to the noni pomace powder, and stirred at 90℃ for 1.5h; the mixture was cooled and the pH was adjusted to 7.0, and then papain was added at a mass ratio of 1% relative to the noni pomace powder, and reacted at 50℃ for 2h; the pH of the reaction solution was adjusted to 2.0, mixed with 1% glucoamylase relative to the mass ratio of the noni pomace powder, and reacted at 60℃ for 2h. After the reaction was completed, the enzyme was heated at 100℃ for 10min to inactivate the enzyme, cooled to room temperature, filtered, and the noni pomace fiber crude extract was obtained. The obtained crude extract was washed with deionized water and dried at 50℃ to obtain the purified noni pomace dietary fiber (insoluble dietary fiber), and the extraction rate and purity were 78.1% and 67.2%, respectively.

[0066] Example 2

[0067] A method for preparing dietary fiber from noni pomace is similar to that of Example 1, except that, in step (4), noni pomace powder and phosphate buffer (pH 7.4, 0.1M) are mixed at a mass volume ratio of 1 g:10 mL, α-amylase is added at a mass ratio of 1% relative to the noni pomace powder, and stirred at 90° C. for 1.5 h; the mixture is cooled and the pH is adjusted to 7.0, and then papain is added at a mass ratio of 0.5% relative to the noni pomace powder, and reacted at 60° C. for 2 h; the pH of the reaction solution is adjusted to 2.0, and the mixture is mixed with glucoamylase at a mass ratio of 1% relative to the noni pomace powder, and reacted at 60° C. for 1.5 h. After the reaction is completed, the mixture is heated at 80° C. for 10 min to inactivate the enzyme, cooled to room temperature, and filtered to obtain a crude extract of noni pomace fiber. The crude extract was washed with deionized water and dried at 50° C. to obtain purified Noni pomace dietary fiber (insoluble dietary fiber), with an extraction rate and purity of 75.8% and 63.6% respectively.

[0068] Example 3

[0069] An ultrasound-assisted low eutectic solvent modification method for noni pomace dietary fiber comprises the following steps:

[0070] (1) choline chloride and lactic acid are mixed in a molar ratio of 1:2, the mixture is stirred at 60° C. until a uniform and transparent liquid is formed, the mixture is taken out and cooled to room temperature, and deionized water is added at a ratio of 20% (v / v) to make the volume concentration of choline chloride 28% and the volume concentration of lactic acid 56%, thereby obtaining a deep eutectic solvent;

[0071] (2) The purified noni pomace dietary fiber purified in Example 1 and the deep eutectic solvent were mixed in a mass volume ratio of 1 g: 200 mL, and subjected to ultrasound-assisted modification treatment at an ultrasound power of 300 W for 15 min;

[0072] (3) separating the modified Noni dietary fiber from the low eutectic solvent by filtering, and drying at 50° C. until the water content is less than 5%, thereby obtaining modified Noni dietary fiber.

[0073] Example 4

[0074] An ultrasound-assisted low eutectic solvent modification method for noni pomace dietary fiber is similar to Example 3, with the only difference being that the purified noni pomace dietary fiber purified in Example 1 is replaced by the purified noni pomace dietary fiber purified in Example 2, and other steps and parameters remain unchanged, and modified noni dietary fiber is finally obtained.

[0075] Example 5

[0076] An ultrasound-assisted low eutectic solvent modification method for noni pomace dietary fiber is similar to Example 3, with the only difference being that the ultrasonic power is 350 W, the time is 10 min, and the other steps and parameters remain unchanged, and finally the modified noni dietary fiber is obtained.

[0077] Comparative Example 1

[0078] An ultrasound-assisted low eutectic solvent modification method for noni pomace dietary fiber is similar to Example 3, with the only difference being that the purified noni pomace dietary fiber purified in Example 1 and the low eutectic solvent are mixed at a mass volume ratio of 1 g: 200 mL, and soaked for 50 minutes for modification treatment, and other steps and parameters remain unchanged, and finally modified noni dietary fiber is obtained.

[0079] Comparative Example 2

[0080] A method for modifying noni pomace dietary fiber by ultrasound-assisted low eutectic solvent is similar to Example 3, except that: (1) lactic acid is replaced by acetic acid to prepare the low eutectic solvent; (2) the ultrasonic power is 350 W and the time is 10 min; other steps and parameters remain unchanged, and modified noni dietary fiber is finally obtained.

[0081] Comparative Example 3

[0082] A method for modifying dietary fiber with cellulase comprising the following steps:

[0083] The purified noni pomace dietary fiber and water after purification in Example 1 were mixed in a mass volume ratio of 1 g: 40 mL, the pH was adjusted to 4.5, 3% relative to the mass ratio of noni pomace powder cellulase was added, and the mixture was stirred in a 50°C water bath for 1 hour. Then, the enzyme was inactivated by heating at 100°C for 15 minutes to terminate the hydrolysis reaction. Then, it was cooled to room temperature and centrifuged. The residue was dried at 50°C to obtain modified noni dietary fiber.

[0084] Test Example 1

[0085] The purified Noni pomace dietary fiber of Example 1, and the modified Noni dietary fiber obtained in Examples 3 to 5 and Comparative Examples 1 to 3 were used as test samples to measure the following physiological and biochemical indices:

[0086] (1) Dissolved in ultrapure water and measured by laser particle size analyzer;

[0087] (2) Determination of swelling capacity and water holding capacity: 0.5 g of the sample to be tested (m0) was diluted to 10 mL (V0) in ultrapure water, and the sample was hydrated in a measuring cylinder for 24 h. The suspended volume of the sample to be tested was recorded as V1 (mL). The suspension of the sample to be tested was then centrifuged at 6000 r / min for 20 min, the supernatant was discarded, and the weight of the wet sample to be tested was recorded as m1 (g). The swelling capacity (SC) and water holding capacity (WHC) were determined according to the following formulas.

[0088] SC (mL / g) = (V1-V0) / m0;

[0089] WHC(g / g)=(m1-m0) / m0.

[0090] (3) Determination of cholesterol adsorption capacity: dilute fresh egg yolk with 9 volumes of ultrapure water, add 0.5 g of the sample to be tested to 25 mL of the diluted egg yolk solution, and stir at 220 r / min for 2 min. Adjust the mixture to pH 2.0. React the mixture in an oscillator at 37°C for 150 min with a stirring rate of 150 r / min. Then centrifuge the mixture at 7000 r / min for 10 min to collect the supernatant, dilute the supernatant with 10 volumes of ultrapure water, and determine its cholesterol concentration using the o-phthalaldehyde method. Calculate the cholesterol adsorption capacity (CAC) according to the following formula.

[0091] CAC(mg / g)=(Cyolk-Cs)×V×F / W;

[0092] Where F is the dilution factor, which is 0.1 in this experiment;

[0093] W is the dry weight of the sample to be tested (g);

[0094] V is the volume of the adsorption solution, which is 25 mL in this experiment;

[0095] Cyolk is the cholesterol concentration of the diluted egg yolk solution;

[0096] Cs represents the residual cholesterol concentration of the mixture of the sample to be tested and the diluted egg yolk solution;

[0097] (4) Determination of glucose adsorption: 0.5 g of the sample to be tested was added to 25 mL of a 200 mmol / L glucose solution and reacted at 37°C for 6 h. The solution was then centrifuged at 5000 r / min for 10 min, and the glucose concentration of the supernatant was determined by the dinitrosalicylic acid method (DNS). The glucose adsorption capacity (GAC) was calculated according to the following formula.

[0098] GAC (mmoL / g) = (Ci-Cf) × V / W;

[0099] Wherein, Ci is the glucose level before adsorption (mmoL / L);

[0100] Cf is the glucose level after adsorption (mmoL / L);

[0101] W is the sample weight (g);

[0102] V is the volume of glucose solution (L).

[0103] The results of physiological and biochemical indices are shown in Table 1.

[0104] Table 1 Physiological and biochemical index test results of different samples

[0105]

[0106]

[0107] Note: Different lowercase letters in the table indicate statistically significant differences, p<0.05.

[0108] It can be seen from Table 1 that, compared with other modification methods, the technical solution provided in the present application significantly improves the swelling capacity, water holding capacity, cholesterol adsorption capacity and glucose adsorption capacity of dietary fiber.

[0109] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for modifying insoluble dietary fiber, characterized in that: The steps include: The insoluble dietary fiber and the solvent are mixed and then subjected to ultrasonic treatment to obtain a treated solution; the treated solution contains the modified insoluble dietary fiber; The solvent comprises 25-28% v / v choline chloride, 50-57% v / v lactic acid and the balance water; The power of the ultrasonic treatment is 250-350W, and the time is 10-20 minutes.

2. The modification method according to claim 1, characterized in that: The molar ratio of choline chloride to lactic acid in the solvent is 1:2; The mass volume ratio of the insoluble dietary fiber to the solvent is 1g: (150-250)mL.

3. The modification method according to claim 1, characterized in that: After obtaining the treated solution, the method further comprises: performing solid-liquid separation on the treated solution, collecting the precipitate and drying it to obtain the modified insoluble dietary fiber.

4. The modification method according to claim 3, characterized in that: The drying temperature is 45-55°C.

5. The modification method according to any one of claims 1 to 4, characterized in that: The preparation method of the insoluble dietary fiber comprises the following steps: mixing the byproduct containing insoluble dietary fiber and a buffer to obtain a premix; Performing a first enzymatic hydrolysis on the premix by using α-amylase to obtain a first enzymatic hydrolysis product; Performing a second enzymolysis on the first enzymolysis product using papain to obtain a second enzymolysis product; Performing a third enzymolysis on the second enzymolysis product using glucoamylase to obtain a third enzymolysis product; Performing enzyme inactivation treatment on the third enzymatic hydrolysis product, performing solid-liquid separation, collecting the precipitate, and obtaining a crude extract; The crude extract is purified to obtain insoluble dietary fiber.

6. The modification method according to claim 5, characterized in that: The temperature of the first enzymatic hydrolysis is 80-95°C and the time is 1-2h; The pH value of the second enzymatic hydrolysis is 7.0, the temperature is 45-55°C, and the time is 1-2h; The third enzymatic hydrolysis has a pH value of 2.0, a temperature of 55-65° C., and a time of 2 h; The temperature of the enzyme inactivation treatment is 85-100°C and the time is 8-12 minutes; The purification method includes drying; the drying temperature is 45-55°C.

7. The modification method according to claim 5, characterized in that: The mass ratio of the α-amylase to the by-product containing insoluble dietary fiber is 0.5-2:100; the enzyme activity of the α-amylase is 2000-3000U; The mass ratio of the papain to the byproduct containing insoluble dietary fiber is 0.5-1:100; the enzymatic activity of the papain is 400-600 U; The mass ratio of the glucoamylase to the by-product containing insoluble dietary fiber is 0.5-1:100; the enzyme activity of the glucoamylase is 100-300U.

8. The modification method according to claim 5, characterized in that: The by-product containing insoluble dietary fiber includes Noni pomace; the Noni pomace has a water content of ≤15% and a particle size of ≤0.85 mm; The mass volume ratio of the byproduct containing insoluble dietary fiber to the buffer is 1g: (8-12)mL; the buffer comprises a phosphate buffer.

9. The modified insoluble dietary fiber obtained by the modification method according to any one of claims 1 to 8.

10. Use of the modified insoluble dietary fiber according to claim 9 in food or medicine.

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