Preparation method of peanut meal soluble dietary fiber and application of peanut meal soluble dietary fiber in preparation of edible composite preservative film

Abstract

The invention discloses a preparation method of peanut meal soluble dietary fibers and application of the peanut meal soluble dietary fibers in preparation of an edible composite preservative film in the field of biological materials. The preparation method of the peanut meal soluble dietary fibers comprises the following steps: preparing peanut meal powder by taking peanut kernels as raw materials; performing ultrasonic-assisted enzymolysis treatment on the degreased peanut meal powder by using cellulase, and performing purification, centrifugation, washing, freeze drying and crushing treatment to obtain the peanut meal soluble dietary fiber. The efficient and mild peanut meal soluble dietary fiber preparation method is established on the basis of an ultrasonic-assisted enzyme method, the peanut meal soluble dietary fibers are creatively used for preparing the preservative film, and the edible composite preservative film with good mechanical performance, low-temperature viscosity and high-humidity preservation effect is obtained. A new direction and a theoretical basis are provided for high-value resource utilization of the peanut meal and improvement of the fresh-keeping function of the fresh-keeping film.

Description

Technical Field

[0001] This invention relates to the field of biomaterials, specifically to a method for preparing soluble dietary fiber from peanut meal and its application in the preparation of edible composite preservation films. Background Technology

[0002] Peanuts are an important oilseed and economic crop in my country, and the peanut meal byproduct produced after oil extraction reaches millions of tons annually, making it an extremely abundant resource. Peanut meal is rich in dietary fiber, protein, polysaccharides, minerals, vitamins, and phenolic compounds, among other bioactive components. It possesses various physiological functions, including antioxidant properties, blood sugar and lipid-lowering effects, and improved gut health, making it highly valuable. However, currently, peanut meal is mostly used as feed or fertilizer, resulting in low utilization rates and a lack of high-value resource utilization methods, leading to the waste of this potential resource.

[0003] To address the problems of traditional plastic wrap being difficult to degrade and detrimental to environmental protection, the development of environmentally friendly plastic wrap based on natural materials has become a hot topic in the industry. Plastic wrap based on natural biomolecular raw materials has advantages such as being biodegradable, safe and non-toxic, and reducing food contamination. However, compared to traditional plastic wrap, existing plastic wrap based on natural materials generally suffers from poor environmental adaptability. Specifically, on the one hand, these plastic wraps are prone to becoming brittle and losing their adhesiveness at low temperatures, making it difficult to adhere tightly to fruits and vegetables; on the other hand, these plastic wraps have poor air permeability and moisture barrier balance, resulting in poor anti-corrosion effects in high-humidity environments.

[0004] In view of the above-mentioned problems of lack of high-value resource utilization methods for peanut meal and poor environmental adaptability of existing food preservation films based on natural materials, the present invention provides a method for preparing soluble dietary fiber from peanut meal and its application in the preparation of edible composite food preservation films. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing soluble dietary fiber from peanut meal and its application in the preparation of edible composite preservation film in order to solve the above problems.

[0006] The present invention achieves the above objectives through the following technical solutions: This invention provides a method for preparing soluble dietary fiber from peanut meal, comprising the following steps: (1) Peanut kernels are dried, pressed for oil, crushed and sieved in sequence to obtain peanut meal powder; (2) Peanut meal powder was degreased using petroleum ether as an extractant to obtain degreased peanut meal powder; (3) Using cellulase, defatted peanut meal powder was subjected to ultrasonic-assisted enzymatic hydrolysis to obtain the enzymatic hydrolysis product; (4) After centrifuging the enzymatic hydrolysis product, take the supernatant, add 4 times the volume of ethanol to the concentrated supernatant, precipitate at 4°C and then centrifuge. The obtained precipitate is washed, freeze-dried and pulverized in sequence to obtain peanut meal soluble dietary fiber.

[0007] As a further optimization of the present invention, in step (2), the specific operation of the defatting treatment is as follows: extracting at a material-to-liquid ratio of 1:(4-6) (g / mL), collecting the solid after filtering the extract, drying and sieving.

[0008] As a further optimization of the present invention, in step (3), the conditions for ultrasonic-assisted enzymatic hydrolysis are as follows: enzyme dosage is 1.8-2.2% of the dry weight of peanut meal, material-liquid ratio is 1:(25-33) (g / mL), ultrasonic time is 28-32 min, ultrasonic power is 200-300W, 45-55℃, and pH is 4-6.

[0009] This invention also provides an application of peanut meal soluble dietary fiber obtained by the above preparation method in the preparation of edible composite preservation film. As a further optimization of the present invention, the preparation method of the edible composite preservation film includes the following steps: (1) Dissolve peanut meal soluble dietary fiber in distilled water to obtain peanut meal soluble dietary fiber solution, dissolve chitosan in glacial acetic acid solution to obtain chitosan solution, mix peanut meal soluble dietary fiber solution and chitosan solution in equal proportion to obtain premixed solution; (2) After adding glycerol and Tween-80 to the premixed solution and stirring evenly, vacuum degassing is performed to obtain the membrane solution; (3) The film liquid is drawn onto the mold for casting, dried and then peeled off to obtain an edible composite preservation film.

[0010] As a further optimization of the present invention, in step (1), the concentration of peanut meal soluble dietary fiber solution is 3.75-11.25 g / L, the concentration of glacial acetic acid solution is 10-14 g / L, and the concentration of chitosan solution is 20-25 g / L; in step (2), the concentration of glycerol is 6-8.5 g / L.

[0011] As a further optimization of the present invention, in step (2), the mass ratio of glycerol, Tween-80 and premix is ​​1:1:(15-18).

[0012] As a further optimization of the present invention, in step (2), the conditions for vacuum degassing are as follows: the obtained mixture is placed in a vacuum dryer, degassed under the conditions of -0.09 to -0.08 MPa, and then left to stand. This process is repeated several times until all bubbles in the membrane liquid are removed.

[0013] As a further optimization of the present invention, in step (3), the drying conditions are: drying at 35-45℃ for 5-6 hours, and then storing at 20-25℃ and 55-60%RH for 24-48 hours.

[0014] The beneficial effects of this invention are as follows: (1) This invention establishes an efficient and mild method for preparing soluble dietary fiber from peanut meal based on ultrasound-assisted enzymatic method. By optimizing the enzymatic hydrolysis conditions and ultrasound parameters, a high extraction rate was achieved. The antioxidant and enzyme-inhibiting effects of soluble dietary fiber from peanut meal were also verified, providing a direction and theoretical basis for the high-value resource utilization of peanut meal.

[0015] (2) This invention innovatively uses soluble dietary fiber from peanut meal to prepare a food preservation film, resulting in an edible composite food preservation film with good mechanical properties, low-temperature adhesion, and high-humidity preservation effect. This food preservation film not only has a good preservation effect in normal temperature and humidity environments, but also maintains good adhesion in low-temperature environments. Furthermore, it can alleviate the damage of moisture to fruits and vegetables in high-humidity environments to reduce the probability of spoilage. It comprehensively achieves the effect of maintaining preservation stability in different scenarios, has a wider range of applications, and has a reliable preservation effect, thus possessing high practical value. Attached Figure Description

[0016] Figure 1 The in vitro antioxidant activity of peanut meal SDF; Figure 2 The inhibition rate of peanut meal SDF against α-glucosidase; Figure 3 The inhibition rate of peanut meal SDF against α-amylase; Figure 4 Optimize the extraction process of SDF from peanut meal; Figure 5 The effect of peanut meal SDF concentration on the mechanical properties of edible composite preservation film; Figure 6 The effect of glacial acetic acid concentration on the mechanical properties of edible composite food preservation film; Figure 7 The effect of chitosan mass concentration on the mechanical properties of edible composite food preservation film; Figure 8 The effect of glycerol concentration on the mechanical properties of edible composite preservation film. Detailed Implementation

[0017] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0018] 1. Experimental Materials Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products.

[0019] 2. Preparation and testing of edible composite food preservation film 2.1 Preparation of soluble dietary fiber from peanut meal (1) Preparation method A soluble dietary fiber from peanut meal, the preparation method of which includes the following steps; ① Using whole Dali white peanut kernels as raw material, after drying with hot air at 60℃, the oil is extracted by pressing at 140℃ to obtain peanut meal. The peanut meal is then crushed and passed through a 60-mesh sieve to obtain peanut meal powder. ② Weigh out peanut meal powder quantitatively, use petroleum ether as extractant, and defatt it at a material-to-liquid ratio of 1:5 (g / mL). After filtration, collect the solids, dry them, and pass them through a 60-mesh sieve to obtain defatted peanut meal powder. ③ Weigh defatted peanut meal powder and perform ultrasonic-assisted extraction with cellulase. The extraction conditions are: enzyme dosage 1.9% (based on the dry weight of peanut meal), material-liquid ratio 1:30 (g / mL), ultrasonic time 28 min, ultrasonic power 250 W, extraction temperature 50℃, pH 5, to obtain soluble dietary fiber extract. ④ After centrifuging the soluble dietary fiber extract, the supernatant was collected, concentrated, and then 4 times the volume of 95% ethanol solution was added. After alcohol precipitation at 4°C, the mixture was centrifuged again and the precipitate was collected. The precipitate was washed with 78% ethanol solution and then freeze-dried and pulverized to obtain peanut meal soluble dietary fiber, abbreviated as peanut meal SDF.

[0020] (2) Extraction rate detection The extraction rate of peanut meal SDF obtained under the cellulase-assisted ultrasonic extraction conditions used in the above preparation method was tested. The extraction rate was tested by weighing the dry weight of the peanut meal powder obtained in step ①, denoted as M1, and weighing the dry weight of the peanut meal SDF obtained in step ④, denoted as M2. The extraction rate was calculated using the following formula: .

[0021] The results showed that the extraction rate was 13.87% under the following extraction conditions (enzyme dosage 1.9%, solid-liquid ratio 1:30 (g / mL), ultrasonic time 28 min, ultrasonic power 250 W).

[0022] 2.2. Preparation of composite preservation film using peanut meal soluble dietary fiber ① Take the peanut meal SDF prepared in 2.1, dissolve the peanut meal SDF in distilled water to obtain an 8.7 g / L peanut meal SDF solution, dissolve the chitosan in an 11 g / L glacial acetic acid solution to obtain a 20 g / L chitosan solution, mix the peanut meal SDF solution and the chitosan solution in equal proportions to obtain a premixed solution; ② Add 6.9 g / L of glycerol and Tween-80 to the premixed solution at a mass ratio of (15-18):1:1, stir well to obtain a mixed solution. Place the obtained mixed solution in a vacuum dryer, degas it under conditions of -0.09 to -0.08 MPa and let it stand. Repeat this process several times until all air bubbles in the membrane solution are removed to obtain the membrane solution. ③ Accurately pipette 10 mL of the membrane solution and cast it onto a polytetrafluoroethylene plate (10 cm × 5 cm × 0.2 cm). Dry the plate at 40°C for 5-6 hours. After drying the membrane sample in a desiccator at 23°C and 56% relative humidity, peel off the membrane to obtain an edible composite preservation film.

[0023] 2.3. Preparation of composite preservation film using naturally derived soluble dietary fiber (1) A composite preservation film using soybean soluble dietary fiber Based on the preparation method used in 2.2, the peanut meal SDF used in step ① was replaced with soybean soluble dietary fiber (purchased from Pingdingshan Jinjing Biotechnology Co., Ltd.) to prepare an edible composite preservation film.

[0024] (2) A composite preservation film using rapeseed soluble dietary fiber Based on the preparation method used in 2.2, the peanut meal SDF used in step ① was replaced with rapeseed soluble dietary fiber (purchased from Shaanxi Sinote Biotechnology Co., Ltd.) to prepare an edible composite preservation film.

[0025] (3) Composite preservation film using inulin Based on the preparation method used in 2.2, the peanut meal SDF used in step ① was replaced with inulin (purchased from Jiangsu Huace Biotechnology Co., Ltd.) to prepare an edible composite preservation film.

[0026] 2.4 Performance Testing of Composite Food Preservation Film The testing items and methods include: ① The testing methods for tensile strength and elongation at break are as follows: Tensile strength is measured using an XWL(PC) intelligent electronic tensile testing machine from Jinan Langguang Company according to the GB / T 1040.3-2006 standard. During the test, the maximum tensile force and the elongation of the gauge length at which the sample breaks are recorded. The tensile strength and elongation at break are then calculated using the following formulas: Tensile strength = Maximum tensile force / Initial cross-sectional area of ​​the sample; Elongation at break = (Gazelle length at break - Initial gauge length) / Initial gauge length × 100% ④ Self-adhesion: Self-adhesion was tested according to GB / T 10457-2021 under conditions of 25℃ and 40% humidity and 4℃ and 40% humidity. The specific procedure was as follows: Several 50mm×150mm pieces of cling film were cut, with two pieces forming a group, and five parallel groups were set up. The adhesive surfaces of each group of samples were placed together, and the bonding area S was measured and recorded. A rubber roller was used to roll back and forth three times at a speed of 300mm / min to remove air and ensure uniform bonding. After bonding, the samples were left to stand under the experimental conditions for 30 minutes. Then, the tensile testing machine speed was adjusted to 250mm / min, and the maximum force value during the separation of the two samples was measured and recorded. The average of the maximum force values ​​in the five parallel groups was taken as P, and the self-adhesion strength of the cling film was calculated using the formula T (N / cm²). 2 = P / S.

[0027] ⑤ Preservation effect test: The preservation effect of plastic wrap was tested under normal temperature and humidity (25℃, 40%RH) and normal temperature and high humidity (25℃, 90%RH) conditions. The specific operation was as follows: 30 blueberries of uniform size were spread evenly in a stainless steel container, the container was sealed with plastic wrap, and then placed under the experimental conditions for 3 days. After 3 days, the number of blueberries with intact skin was counted and recorded as N. The preservation rate = N / 30 × 100%; 2.5 Test Results The test results are shown in the table below. The table shows that, comparing the tensile strength and elongation at break, self-adhesive strength at room temperature, and preservation effect under normal humidity conditions, the peanut meal group is only slightly better than the soybean and rapeseed groups, and similar to the inulin group. However, the peanut meal group's self-adhesive strength under low temperature conditions is significantly better than the soybean, rapeseed, and inulin groups, and its preservation effect under high humidity conditions is also significantly better, specifically manifested in a lower spoilage rate during the preservation process. These results indicate that, based on the preservation film provided by this invention, compared to using soluble dietary fiber from other plant sources, the application of soluble dietary fiber from peanut meal can give the preservation film better low-temperature self-adhesive effect and better high-humidity preservation effect, making the preservation effect of the preservation film more stable in different environments, thus helping to broaden the application range of the preservation film.

[0028] 3. Efficacy testing of peanut meal SDF To further investigate the performance of peanut meal SDF, the peanut meal SDF prepared in section 2.1 was used as the test sample for analysis. The specific test items and methods are as follows: 3.1 In vitro antioxidant activity detection (1) DPPH free radical scavenging ability test The method for determining DPPH free radical scavenging activity involved accurately weighing peanut meal SDF samples and quantitatively diluting them with distilled water to prepare test solutions with concentrations of 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 mg / mL. 2 mL of each concentration of test solution was accurately measured and mixed with 2 mL of DPPH-ethanol solution in a test tube. After shaking, the solution was allowed to stand at room temperature in the dark for 30 min. The absorbance of the test group (A1) was measured at 540 nm. Anhydrous ethanol was used instead of the DPPH-ethanol solution to measure the absorbance of the control group (A2) at 540 nm. Anhydrous ethanol was used instead of the test solution to measure the absorbance of the blank group (A0) at 540 nm. The same method was used, with the same concentration of vitamin C as a positive control. Each sample was evaluated three times. The formula for calculating the scavenging activity is as follows: ; In the formula: A1 is the DPPH solution containing the sample, A2 is the sample containing ethanol but not DPPH, and A0 is the DPPH solution without the sample.

[0029] (2) ABTS+ free radical capacity test Add 0.3 mL of different concentrations of the test sample solution and 3 mL of ABTS⁺ working solution to test tubes, respectively. After reacting at room temperature for 6 min, quickly measure the absorbance of the control group (A1) at a wavelength of 734 nm. Replace the working solution and sample solution with distilled water and measure the absorbance of the control group (A2) and the blank group (A0) at a wavelength of 734 nm. Use the same method, with Vc as a control, evaluate each sample three times, and calculate the ABTS free radical scavenging activity according to the following formula: ; In the formula: A0 is the absorbance value of the blank control group, A2 is the absorbance value of the control group, and A1 is the absorbance value of the test sample group.

[0030] (3) Detection of hydroxyl radical free radical capacity Take 2.0 mL of sample solutions of different concentrations, and add 0.2 mL each of FeSO4 solution, salicylic acid-ethanol solution, and H2O2 solution sequentially. After mixing, let stand for 60 min. Measure the absorbance of the experimental group at 510 nm (A1). Measure the absorbance of the control group at 510 nm using an equal volume of distilled water instead of salicylic acid solution, following the same method (A2). Measure the absorbance of the blank group at 510 nm using an equal volume of distilled water instead of the sample solution (A0). Use the same method, with vitamin C as a control. Each sample was evaluated three times. The hydroxyl radical scavenging activity was calculated as follows: ; In the formula: A0 is distilled water without the test sample or H2O2, A2 is H2O2 without the test sample, and A1 is a mixture of H2O2 and the test sample.

[0031] 3.2 Detection of the ability to inhibit α-glucosidase in vitro Peanut meal SDF extract was prepared into sample solutions with a mass concentration of 0.05-0.50 mg / mL. Then, 2 U / mL α-glucosidase solution, 0.1 mol / L phosphate buffer, 2.5 mmol / L p-nitrophenyl-α-D-glucopyranoside solution and 0.2 mol / L sodium carbonate solution were prepared. 30 µL of the sample solution, 25 µL of α-glucosidase solution and 120 µL of phosphate buffer were taken and thoroughly mixed, and reacted in a water bath at 37 °C for 10 min. Then, another 25 µL of p-nitrophenyl-α-D-glucopyranoside solution was added, and the mixture was reacted in a water bath at 37 °C for another 25 min. Finally, 100 µL of sodium carbonate solution was added, and the absorbance was measured at 540 nm. Simultaneously, a blank control (using PBS buffer instead of the α-glucosidase working solution) and a negative control (using PBS buffer instead of the peanut meal polyphenol sample solution) were set up. The absorbance (A2, A0) of the two groups was measured respectively, and the inhibition rate of α-glucosidase was calculated according to the following formula.

[0032] ; In the formula: A0 is the absorbance value of the negative control group, A2 is the absorbance value of the blank control group, and A1 is the absorbance value of the sample group.

[0033] 3.3 Detection of the ability to inhibit α-amylase activity in vitro The inhibitory activity of peanut meal SDF and the positive control acarbose on α-amylase was determined. First, a 12.5 U / mL α-amylase solution was prepared using 0.1 mol / L PBS buffer (pH 6.8), and sample solutions of concentrations of 0.5, 1.0, 1.5, 2.0, and 2.5 mg / mL were prepared. 500 μL of each concentration of sample solution was mixed with 500 μL of α-amylase solution and reacted at 37°C for 5 min. Then, 500 μL of 1% soluble starch solution was added, and the reaction was continued at 37°C for another 5 min. Subsequently, 500 μL of DNS reagent was added to terminate the reaction. The mixture was then heated in a 100°C water bath for 5 min, cooled, and brought to a final volume of 10 mL with PBS. The absorbance of the experimental group was measured at a wavelength of 540 nm (A1). Under the same conditions, PBS was used to replace the enzyme solution and peanut meal SDF solution as blank control and background control, respectively. The corresponding absorbance was measured at 54 nm (denoted as A2 and A0), and the inhibition rate of α-amylase was calculated according to the following formula.

[0034] ; In the formula: A0 is the absorbance value of the negative control group, A2 is the absorbance value of the blank control group, and A1 is the absorbance value of the sample group.

[0035] 3.4 Test Results like Figure 1 As shown in Figure A, peanut meal SDF exhibits significant scavenging ability against DPPH free radicals, and the scavenging rate increases with increasing concentration, showing a good dose-response relationship. Figure 1 As shown in Figure B, within the concentration range of 0.5-3.0 mg / mL, peanut meal SDF exhibited a scavenging effect on ABTS⁺ free radicals, with the scavenging effect increasing in a concentration-dependent manner, and the half-maximal concentration (IC50) of the target group being significantly higher than that of the target group. 50 A concentration less than 3 mg / mL indicates that the substance possesses good ABTS⁺ free radical scavenging ability. Figure 1 As shown in C, peanut meal SDF has a strong scavenging ability even at low concentrations. Its scavenging effect on hydroxyl radicals is concentration-dependent. Its scavenging rate shows a non-linear increase with increasing peanut meal SDF concentration, with a slow increase in the low concentration range and a rapid increase in the high concentration range.

[0036] like Figure 2 As shown, within the mass concentration range of 0.1-0.5 mg / mL, the inhibition rate of both acarbose and peanut meal SDF against α-glucosidase gradually increased with increasing concentration. At the same mass concentration, the inhibitory effect of acarbose was always higher than that of peanut meal SDF, but the difference in inhibition rate between the two showed a convergent trend as the concentration increased.

[0037] like Figure 3As shown, peanut meal SDF has a strong inhibitory effect at low concentrations. Its inhibition rate against α-amylase gradually increases with increasing concentration, showing a clear concentration dependence. Under the same concentration conditions, although the inhibitory effect of acarbose (positive control) is always higher than that of peanut meal SDF, the difference between the two inhibition rates gradually decreases with increasing concentration.

[0038] 4. Optimization of peanut meal SDF extraction process A single-factor comparative experiment was designed with four factors: enzyme dosage, material-liquid ratio, ultrasonic time, and ultrasonic power. The effects of each factor on the extraction rate were analyzed based on the differences in extraction rates among the comparative groups.

[0039] The specific setup for a single-factor comparison experiment is as follows: ① In each control group, the enzyme dosage was set as follows: 1%, 2%, 3%, 4%, 5%; ② In each comparison group, the material-to-liquid ratio was set as follows: 1:15, 1:20, 1:25, 1:30, and 1:35, respectively. ③ In each control group, the ultrasound time was set as follows: 10 min, 20 min, 30 min, 40 min, and 50 min. ④ In each control group, the ultrasound power was set to 150W, 200W, 250W, 300W, and 350W respectively.

[0040] Experimental results are as follows Figure 4 As shown in the figure, the extraction of soluble dietary fiber from peanut meal initially increases and then decreases with increasing enzyme dosage, reaching a peak at an enzyme dosage of 2%. Similarly, the extraction of soluble dietary fiber from peanut meal initially increases and then decreases with decreasing material-to-liquid ratio, reaching a peak at a material-to-liquid ratio of 1:30. Furthermore, the extraction of soluble dietary fiber from peanut meal initially increases and then decreases with increasing ultrasonic time, reaching a peak at an ultrasonic time of 30 minutes. Finally, the extraction of soluble dietary fiber from peanut meal initially increases and then decreases with increasing ultrasonic power, reaching a peak at an ultrasonic power of 250W.

[0041] According to the experimental results, based on the preparation method used in 2.1, the optimal extraction conditions for ultrasonic-assisted extraction of cellulase are: enzyme dosage 2%, material-liquid ratio 1:30, ultrasonic time 30 min, and ultrasonic power 250 W.

[0042] 5. Process optimization for preparing composite preservation film using peanut meal soluble dietary fiber A single-factor comparative experiment was designed using four factors: the mass concentration of peanut meal SDF solution, glycerol, glacial acetic acid solution, and chitosan. The mechanical properties of the edible composite preservation films obtained in each comparative group were detected, and the influence of each factor on the mechanical properties of the edible composite preservation films was analyzed.

[0043] The specific setup for a single-factor comparison experiment is as follows: ① In each control group, the SDF concentration of peanut meal was set as follows: 0, 3.75 g / L, 7.5 g / L, 11.25 g / L, and 15 g / L. ② In each control group, the mass concentration of glycerol was set as follows: 0, 3.75 g / L, 7.5 g / L, 11.25 g / L, and 15 g / L, respectively; ③ In each control group, the mass concentration of glacial acetic acid was set as follows: 6 g / L, 8 g / L, 10 g / L, 12 g / L, and 14 g / L, respectively. ④ In each control group, the mass concentration of chitosan was set as follows: 5 g / L, 10 g / L, 15 g / L, 20 g / L, and 25 g / L.

[0044] Experimental results are as follows Figure 5-8 As shown in the figure, it can be seen that: with the increase of the mass concentration of peanut meal SDF and glycerol, the tensile strength of the edible composite preservation film first increases and then decreases, while the elongation at break continues to decrease; with the increase of the mass concentration of glacial acetic acid, both the tensile strength and elongation at break of the edible composite preservation film continue to increase; with the increase of the mass concentration of chitosan, the tensile strength of the edible composite preservation film first increases and then decreases, while the elongation at break continues to increase.

[0045] According to the experimental results, when preparing edible composite preservative film based on the preparation method in section 2.2, the optimal mass concentrations of peanut meal SDF are 5.61 g / L, glycerol is 7.96 g / L, glacial acetic acid is 12 g / L, and chitosan is 25 g / L.

[0046] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing soluble dietary fiber from peanut meal, characterized in that: Includes the following steps: (1) Peanut kernels are dried, pressed for oil, crushed and sieved in sequence to obtain peanut meal powder; (2) Peanut meal powder was degreased using petroleum ether as an extractant to obtain degreased peanut meal powder; (3) Using cellulase, defatted peanut meal powder was subjected to ultrasonic-assisted enzymatic hydrolysis to obtain the enzymatic hydrolysis product; (4) After centrifuging the enzymatic hydrolysis product, take the supernatant, add 4 times the volume of ethanol to the concentrated supernatant, precipitate at 4°C and then centrifuge. The obtained precipitate is washed, freeze-dried and pulverized in sequence to obtain peanut meal soluble dietary fiber.

2. The preparation method according to claim 1, characterized in that: In step (2), the specific operation of the defatting treatment is as follows: extracting at a material-to-liquid ratio of 1:(4-6) (g / mL), filtering the extract, collecting the solid, drying and sieving.

3. The preparation method according to claim 2, characterized in that: In step (3), the conditions for ultrasound-assisted enzymatic hydrolysis are as follows: enzyme dosage is 1.8-2.2% of the dry weight of peanut meal, material-liquid ratio is 1:(25-33) (g / mL), ultrasound time is 28-32 min, ultrasound power is 200-300 W, temperature is 45-55℃, and pH is 4-6.

4. The application of peanut meal soluble dietary fiber obtained by the preparation method described in claim 1 in the preparation of edible composite preservation film.

5. The application according to claim 4, characterized in that: The method for preparing the edible composite preservation film includes the following steps: (1) Dissolve peanut meal soluble dietary fiber in distilled water to obtain peanut meal soluble dietary fiber solution, dissolve chitosan in glacial acetic acid solution to obtain chitosan solution, mix peanut meal soluble dietary fiber solution and chitosan solution in equal proportion to obtain premixed solution; (2) After adding glycerol and Tween-80 to the premixed solution and stirring evenly, vacuum degassing is performed to obtain the membrane solution; (3) The film liquid is drawn onto the mold for casting, dried and then peeled off to obtain an edible composite preservation film.

6. The application according to claim 5, characterized in that: In step (1), the concentration of peanut meal soluble dietary fiber solution is 3.75-11.25 g / L, the concentration of glacial acetic acid solution is 10-14 g / L, and the concentration of chitosan solution is 20-25 g / L. In step (2), the concentration of glycerol is 6-8.5 g / L.

7. The application according to claim 5, characterized in that: In step (2), the mass ratio of glycerol, Tween-80 and the premix is ​​1:1:(15-18).

8. The application according to claim 5, characterized in that: In step (2), the conditions for vacuum degassing are as follows: the obtained mixture is placed in a vacuum dryer, degassed under the conditions of -0.09 to -0.08 MPa, and then left to stand. This process is repeated several times until all bubbles in the membrane liquid are removed.

9. The application according to claim 5, characterized in that: In step (3), the drying conditions are: drying at 35-45℃ for 5-6 hours, and then storing at 20-25℃ and 55-60%RH for 24-48 hours.

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