Preparation method of soybean dietary fiber powder rich in peptides and soluble dietary fibers

Abstract

The invention belongs to the technical field of comprehensive utilization of bean dregs, and discloses a preparation method of soybean dietary fiber powder rich in peptides and soluble dietary fibers, which comprises the following steps: drying bean dregs at 40-60 DEG C for 10-14 hours, crushing, and sieving with 40-60 meshes for later use; stirring the treated bean dregs and water according to a material-liquid ratio of 1: (10-20) for 180-360 seconds; adjusting the pH value of the bean dreg solution to 4-6, adding composite plant hydrolase, and after enzymolysis is finished, performing boiling water bath enzyme deactivation; adjusting the pH value of the enzymatic hydrolysate to be 1-3, adding pepsase, and after enzymolysis is finished, performing boiling water bath enzyme deactivation; and carrying out spray drying or freeze drying on a product obtained after enzyme deactivation to obtain the soybean dietary fiber powder. The soybean dregs are subjected to enzymolysis by utilizing the composite plant hydrolase and the pepsase, the peptide content in the obtained soybean dietary fiber powder is greater than or equal to 5g / 100g, the ratio of soluble dietary fibers to insoluble dietary fibers reaches 1: (2-5), and the soybean dietary fiber powder has the effects of reducing blood fat and reducing blood pressure.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of soybean dregs, and relates to a preparation method of a soybean dietary fiber powder rich in peptides and soluble dietary fiber. Background Art

[0002] Soybean dregs are the residues in the production processes of tofu, yuba, etc. In China, the tofu production industry generates approximately 2.8 million tons of soybean dregs every year. In recent years, soybean dregs have been widely studied due to the health effects of their main nutritional components, protein and dietary fiber. However, the insoluble dietary fiber (IDF) in soybean dregs is as high as 95%. IDF forms a highly ordered fiber structure through hydrogen bonds and van der Waals forces between molecular chains, and adding it to food will increase the hardness and roughness of the food. The protein components in soybean dregs are mainly basic 7S globulin and 11S protein. Among them, basic 7S globulin is a glycoprotein rich in cysteine, and the subunits are connected by disulfide bonds, resulting in poor solubility of soybean dregs. In addition, soybean dregs have a high water content and are not easy to preserve, and most of them are treated as livestock feed or waste, with relatively low added value.

[0003] The physiological properties of dietary fiber in soybean dregs largely depend on the relative amounts of soluble (SDF) and IDF fiber components. Research shows that the hypoglycemic ability of dietary fiber is related to its physicochemical properties and sources. In particular, the viscosity of the fiber is considered an important factor affecting glucose absorption. SDF has good viscosity and plays a major role in postprandial blood glucose and insulin responses. It can inhibit the rise of postprandial blood glucose values by delaying the digestion and absorption of carbohydrates, and improve the sensitivity of nerve ending tissues to insulin, reducing the requirement for insulin. The basic 7S protein contained in soybean dregs has relatively high insulin and insulin-like growth factor binding activities, and also has a certain positive intervention effect on the prevention and treatment of type II diabetes. However, the HI and II subunits of the basic 7S protein in soybean dregs are tightly combined with non-starch polysaccharides such as soybean cellulose, hemicellulose, and lignin to form a mixture, which is a difficult problem faced by the modification of proteins and dietary fiber in soybean dregs.

[0004] At the present stage, the in-depth development of soybean dregs in China is relatively weak. For example, CN 119366648 A discloses a method for multi-stage extraction of dietary fiber from soybean dregs, which only conducts research on insoluble dietary fiber and does not explore the extraction process of water-soluble dietary fiber. For example, CN 118947916 A discloses a method for preparing water-soluble dietary fiber from soybean dregs based on microbial fermentation, but its process removes proteins through enzymatic hydrolysis. Therefore, there is an urgent need to invent a method for preparing a soybean dietary fiber powder rich in peptides and soluble dietary fiber from soybean dregs, which can efficiently improve the comprehensive utilization value of soybean dregs. Summary of the Invention

[0005] In view of the technical problem that the soluble dietary fiber and protein in soybean dregs cannot be utilized simultaneously, the present invention provides a method for preparing a soybean dietary fiber powder rich in peptides and soluble dietary fiber. The soybean dregs are enzymatically hydrolyzed using a composite plant hydrolase and pepsin. In the obtained soybean dietary fiber powder, the peptide content is ≥5 g / 100 g of soybean dietary fiber powder, and the ratio of soluble dietary fiber to insoluble dietary fiber reaches 1:2 - 5, realizing the comprehensive utilization of soybean dregs.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a soybean dietary fiber powder rich in peptides and soluble dietary fiber, comprising the following steps:

[0008] 1) Dry the soybean dregs at 40 - 60 °C for 10 - 14 h, pulverize them, and sieve through a 40 - 60 mesh sieve for standby;

[0009] 2) Stir the soybean dregs processed in step 1) with water according to a solid - liquid ratio of 1:10 - 20 for 180 - 360 s;

[0010] 3) Adjust the pH of the soybean dregs solution to 4 - 6, add the composite plant hydrolase, and after the enzymatic hydrolysis ends, inactivate the enzyme by boiling water bath;

[0011] 4) Adjust the pH of the enzymatic hydrolysate in step 3) to 1 - 3, add pepsin, and after the enzymatic hydrolysis ends, inactivate the enzyme by boiling water bath;

[0012] 5) Spray - dry or freeze - dry the product obtained after enzyme inactivation to obtain the soybean dietary fiber powder.

[0013] Preferably, the composite plant hydrolase in step 3) is a mixture of arabinase, cellulase, β - glucanase, hemicellulase, and xylanase, and the enzyme activity is 100 FBG / g.

[0014] Preferably, the addition amount of the composite plant hydrolase in step 3) is 0.25 - 1.5% of the mass of the soybean dregs.

[0015] Preferably, the enzymatic hydrolysis conditions in step 3) are as follows: the enzymatic hydrolysis temperature is 40 - 60 °C, and the enzymatic hydrolysis time is 2.0 - 6.0 h.

[0016] Preferably, the addition amount of the pepsin in step 4) is 0.25 - 1% of the mass of the soybean dregs, and the enzyme activity is 250000 U / g.

[0017] Preferably, the enzymatic hydrolysis conditions in step 4) are as follows: the enzymatic hydrolysis temperature is 27 - 47 °C, and the enzymatic hydrolysis time is 1 - 3 h.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The present invention uses a composite plant hydrolase and pepsin to enzymatically hydrolyze soybean dregs. The resulting soybean dietary fiber powder has a peptide content of ≥ 5 g / 100 g of soybean dietary fiber powder, and the ratio of soluble dietary fiber to insoluble dietary fiber reaches 1:2 - 5, which has the effects of reducing blood lipid and blood pressure.

[0020] 2. The process conditions of the present invention are mild, and the processing cost is low, which significantly improves the technical level and added value of the deep processing of soybean dregs, providing an efficient and green solution for the comprehensive utilization of soybean dregs. Specific embodiments

[0021] The following examples are used to illustrate the present invention, but do not limit the protection scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are all conventional methods unless otherwise specified.

[0022] In the following examples, the composite plant hydrolase was purchased from Novozymes and is a mixture of arabinase, cellulase, β - glucanase, hemicellulase and xylanase, with an enzyme activity of 100 FBG / g; the pepsin was purchased from Solarbo, with an enzyme activity of 250000 U / g.

[0023] Comparative Example 1

[0024] 1) Take 50 g of soybean dregs, pre - treat them by drying at 50 °C for 12 h, crush them and pass through a 60 - mesh sieve, and set aside; stir 5 g of the sieved soybean dregs with distilled water at a solid - liquid ratio of 1:10 for 270 s to obtain a soybean dregs suspension;

[0025] 2) Adjust the pH of the soybean dregs suspension to 5.0 with 0.01 mol / L HCl, add 0% of the composite plant hydrolase (v / w), heat in a water bath at 50 °C for 4.0 h, and then carry out a boiling water bath for 5 min after completion;

[0026] 3) Adjust the pH of the sample after enzyme inactivation to 2 with 1 mol / L HCl, control the water bath temperature at 37 °C, add 0.5 g of pepsin, enzymatically hydrolyze for 2.0 h, and then carry out a boiling water bath for enzyme inactivation for 5 min; freeze - dry the sample after enzyme inactivation to obtain soybean dietary fiber powder.

[0027] Example 1

[0028] 1) Take 50 g of soybean dregs, pre - treat them by drying at 50 °C for 12 h, crush them and pass through a 60 - mesh sieve, and set aside; stir 5 g of the sieved soybean dregs with distilled water at a solid - liquid ratio of 1:10 for 270 s to obtain a soybean dregs suspension;

[0029] 2) Adjust the pH of the soybean dregs suspension to 5.0 with 0.01 mol / L HCl, add 0.125 g of the composite plant hydrolase, heat in a water bath at 50 °C for 4.0 h, and then carry out a boiling water bath for 5 min after completion;

[0030] 3) Adjust the pH of the sample after enzyme inactivation to 2 with 1 mol / L HCl, control the water bath temperature at 37 °C, add 0.5 g of pepsin, after enzymatic hydrolysis for 2.0 h, inactivate the enzyme in a boiling water bath for 5 min; freeze-dry the sample after enzyme inactivation to obtain soybean dietary fiber powder.

[0031] Example 2

[0032] This example is basically the same as Example 1, the difference is that: in step 2), 0.25 g of compound plant hydrolase is added.

[0033] Example 3

[0034] This example is basically the same as Example 1, the difference is that: in step 2), 0.75 g of compound plant hydrolase is added.

[0035] Example 4

[0036] This example is basically the same as Example 2, the difference is that: in step 2), the pH of the soybean residue suspension is adjusted to 4.0 with 0.01 mol / L HCl.

[0037] Example 5

[0038] This example is basically the same as Example 2, the difference is that: in step 2), the pH of the soybean residue suspension is adjusted to 6.0 with 0.01 mol / L NaOH.

[0039] Example 6

[0040] This example is basically the same as Example 2, the difference is that: in step 2), it is heated in a water bath at 40 °C.

[0041] Example 7

[0042] This example is basically the same as Example 2, the difference is that: in step 2), it is heated in a water bath at 60 °C.

[0043] Example 8

[0044] This example is basically the same as Example 2, the difference is that: in step 2), it is heated in a water bath for 2.0 h.

[0045] Example 9

[0046] This example is basically the same as Example 2, the difference is that: in step 2), it is heated in a water bath for 6.0 h.

[0047] Example 10

[0048] This example is basically the same as Example 2, the difference is that: in step 3), 0.125 g of pepsin is added.

[0049] Example 11

[0050] This example is basically the same as Example 2, except that: in step 3), 0.375 g of pepsin is added.

[0051] Example 12

[0052] This example is basically the same as Example 2, except that: in step 3), 0.75 g of pepsin is added.

[0053] Example 13

[0054] This example is basically the same as Example 11, except that: in step 3), the pH of the soybean residue suspension is adjusted to 1.0 with 1 mol / L HCl.

[0055] Example 14

[0056] This example is basically the same as Example 11, except that: in step 3), the pH of the soybean residue suspension is adjusted to 1.5 with 1 mol / L HCl.

[0057] Example 15

[0058] This example is basically the same as Example 11, except that: in step 3), the pH of the soybean residue suspension is adjusted to 3.0 with 1 mol / L HCl.

[0059] Example 16

[0060] This example is basically the same as Example 14, except that: in step 3), enzymatic hydrolysis is carried out by water bath heating for 1.0 h.

[0061] Example 17

[0062] This example is basically the same as Example 14, except that: in step 3), enzymatic hydrolysis is carried out by water bath heating for 3.0 h.

[0063] Example 18

[0064] This example is basically the same as Example 14, except that: in step 3), water bath heating is carried out at 27 °C.

[0065] Example 19

[0066] This example is basically the same as Example 14, except that: in step 3), water bath heating is carried out at 47 °C.

[0067] Soybean dietary fiber powder property test

[0068] (1) Protein peptide content

[0069] Take the freeze-dried soybean dietary fiber powder, dissolve it and centrifuge. Take 3 mL of the supernatant, then add 3 mL of 15% (w / v) trichloroacetic acid aqueous solution, mix on a vortex mixer for 1 min, let it stand for 30 min, then centrifuge at 5000 r / min for 10 min. Take 1 mL of the solution and place it in a test tube, add 4 mL of biuret reagent, mix evenly on a vortex mixer, let it stand for 30 min, and take the supernatant to measure the absorbance at a wavelength of 540 nm. Calculation formula: Polypeptide content (%) = polypeptide mass / soybean dietary fiber powder mass × 100%.

[0070] (2) Dietary fiber content

[0071] Determination of insoluble dietary fiber: Take the freeze-dried soybean dietary fiber powder (m2), dissolve it and centrifuge. The centrifuged residue phase is freeze-dried, and the mass of the residue phase minus the protein mass is the IDF mass (m1).

[0072]

[0073] In the formula: m2 is the mass of the soybean dietary fiber powder (g); m1 is the mass of the IDF (g).

[0074] Determination of soluble dietary fiber: Take the freeze-dried soybean dietary fiber powder (m2), dissolve it and centrifuge. The centrifuged supernatant is freeze-dried. Take 0.2 g of the supernatant, add 5 mL of distilled water, and add 95% ethanol (4 times the volume of the solution). After precipitation overnight, centrifuge (5000 r / min, 20 min). The precipitate is dried in a ventilated place for a certain time and then freeze-dried. The mass of the freeze-dried sample minus the protein mass is the SDF mass (m3) in the soybean dietary fiber powder

[0075]

[0076] In the formula: m2 is the mass of the soybean dietary fiber powder (g); m3 is the mass of the SDF (g).

[0077] Table 1 Contents of polypeptide, SDF and IDF (g / 100 g soybean dietary fiber powder) and SDF / IDF ratio in soybean dietary fiber powder

[0078]

[0079]

[0080] As can be seen from Table 1, with the increase in the addition amount of the compound plant hydrolase, the peptide content in the soybean dietary fiber powder shows an increasing trend, the SDF content and SDF / IDF show a trend of first increasing and then decreasing, and the IDF content shows a decreasing trend; with the increase in the enzymatic hydrolysis pH and temperature, the peptide content, SDF content and SDF / IDF in the soybean dietary fiber powder show a trend of first increasing and then decreasing, and the IDF content shows a trend of first decreasing and then increasing; with the extension of the enzymatic hydrolysis time, the peptide content in the soybean dietary fiber powder shows an increasing trend, the SDF content and SDF / IDF show a trend of first increasing and then decreasing, and the IDF content shows a decreasing trend. When the addition amount of the compound plant hydrolase is 0.5%, the pH is 5.0, the enzymatic hydrolysis temperature is 50 °C and the enzymatic hydrolysis time is 4 h, the enzymatic hydrolysis efficiency is the best (Example 2). The peptide, SDF and IDF contents in the soybean dietary fiber powder are 7.30 g / 100 g of soybean dietary fiber powder, 15.03 g / 100 g of soybean dietary fiber powder and 58.61 g / 100 g of soybean dietary fiber powder respectively, and SDF / IDF is 0.26.

[0081] With the increase in the addition amount of pepsin, the peptide content, SDF content and SDF / IDF in the soybean dietary fiber powder show an increasing trend, and the IDF content shows a decreasing trend; with the increase in the enzymatic hydrolysis pH and temperature of pepsin, both the peptide and SDF contents show a trend of first increasing and then decreasing, and the IDF content first increases and then tends to be balanced. With the increase in the pepsin enzymatic hydrolysis time, the peptide content shows an increasing trend, the SDF content and SDF / IDF both show a trend of first increasing and then decreasing, and the IDF shows a trend of first decreasing and then increasing. When the enzymatic hydrolysis pH of pepsin is 1.5, the addition amount is 0.75%, the temperature is 37 °C and the time is 2 h, the enzymatic hydrolysis efficiency is the best (Example 14). The peptide, SDF and IDF contents in the soybean dietary fiber powder are 7.08 g / 100 g of soybean dietary fiber powder, 23.35 g / 100 g of soybean dietary fiber powder and 48.52 g / 100 g of soybean dietary fiber powder respectively, and SDF / IDF is 0.48.

[0082] The above-mentioned embodiments are only the preferred embodiments of the present invention, which are only used to explain the present invention and do not limit the scope of implementation of the present invention. For those skilled in the art of this technology, of course, other implementation methods can be easily made by means of substitution or change according to the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A preparation method of soy dietary fiber powder rich in peptides and soluble dietary fiber, characterized in that, It includes the following steps: 1) Dry the okara at 40 - 60 °C for 10 - 14 h, pulverize it, and sieve it through 40 - 60 meshes for standby; 2) Stir the okara processed in step 1) and water at a solid - liquid ratio of 1:10 - 20 for 180 - 360 s; 3) Adjust the pH of the okara solution to 4 - 6, add a composite plant hydrolase, and after the enzymatic hydrolysis ends, inactivate the enzyme by boiling water bath; 4) Adjust the pH of the enzymatic hydrolysate in step 3) to 1 - 3, add pepsin, and after the enzymatic hydrolysis ends, inactivate the enzyme by boiling water bath; 5) Spray - dry or freeze - dry the product obtained after enzyme inactivation to obtain soybean dietary fiber powder.

2. The preparation method of the soybean dietary fiber powder according to claim 1, characterized in that, The composite plant hydrolase described in step 3) is a mixture of arabinase, cellulase, β - glucanase, hemicellulase, and xylanase, and the enzyme activity is 100 FBG / g.

3. The preparation method of the soybean dietary fiber powder according to claim 1 or 2, characterized in that The addition amount of the composite plant hydrolase described in step 3) is 0.25 - 1.5% of the mass of the okara.

4. The preparation method of the soybean dietary fiber powder according to claim 1, wherein The enzymatic hydrolysis conditions in step 3) are as follows: the enzymatic hydrolysis temperature is 40 - 60 °C, and the enzymatic hydrolysis time is 2.0 - 6.0 h.

5. The preparation method of the soybean dietary fiber powder according to claim 1, characterized in that, The addition amount of the pepsin described in step 4) is 0.25 - 1.5% of the mass of the okara, and the enzyme activity is 250000 U / g.

6. The method for preparing soybean dietary fiber powder according to claim 1 or 5, characterized in that, The enzymatic hydrolysis conditions in step 4) are as follows: the enzymatic hydrolysis temperature is 27 - 47 °C, and the enzymatic hydrolysis time is 1 - 3 h.

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