Peanut oil pressing and peanut protein production process

Abstract

The application belongs to the technical field of peanut oil preparation method, and particularly relates to a high-quality peanut oil pressing and peanut protein production process. Through accurate control of process parameters and innovation of key technologies, the method realizes efficient synchronous extraction of oil and protein and maintains high-quality characteristics of the two. The process not only breaks through the technical limitations of mutual restriction of the quality of the two in traditional extraction, but also significantly improves the whole-component utilization efficiency of peanut resources, and promotes the upgrading of peanut industry to whole-component high-value and green.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of peanut oil preparation methods, and particularly relates to a high-quality peanut oil pressing and peanut protein production process. BACKGROUND

[0002] Peanut is one of the important oil crops in the world, and the efficient extraction and high-value comprehensive utilization of oil and protein have always been the research focus in the field of grain and oil processing technology and engineering, which is of great significance to improve the overall added value of the peanut industry chain and promote the sustainable use of resources. Peanut kernel is rich in protein and is a high-quality plant protein resource, which has the characteristics of large yield, rich nutrition, easy absorption, wide raw material sources and strong processing adaptability.

[0003] At present, the methods commonly used in industry for extracting peanut oil mainly include pressing method (hot pressing and cold pressing), organic solvent extraction method and aqueous enzymatic method. Among them, the hot pressing method has become one of the mainstream processing methods due to its simple process equipment and low cost, but the high pressing temperature easily leads to the serious denaturation of protein in peanut cake, which greatly reduces its edible and feed value. The cold pressing method is often used to produce high-quality peanut oil, which can better retain the natural nutritional ingredients in oil, but has the limitations of low oil yield and low production efficiency. Although the organic solvent extraction method has high extraction efficiency and high oil yield, it has the hidden danger of solvent residue, and needs to be matched with perfect solvent removal equipment to ensure food safety, which has high overall process cost and environmental pressure. The aqueous enzymatic method as an environmentally friendly new oil extraction technology has an oil extraction rate between hot pressing and cold pressing, but has the problems of long processing time, cost increase due to the addition of exogenous enzyme preparation, and easy introduction of odor.

[0004] The core problem of current peanut processing technology is that there is a difficult to coordinate contradiction between the process temperature required for oil extraction and the threshold of protein thermal denaturation, and high oil extraction rate and high protein quality retention cannot be achieved simultaneously. In addition, the traditional heating method has the problems of low thermal efficiency and uneven temperature field distribution, which easily leads to local overheating or insufficient heating of the material, affecting the quality stability of the product. The cake after pressing is rich in protein, but the subsequent extraction process is complex, the functional properties of protein are seriously damaged, and it is difficult to meet the demand for high-functional protein raw materials in the food field, which restricts the high-value application of peanut protein.

[0005] Therefore, it is urgent to develop a new preparation process which can realize the efficient extraction of peanut oil and protein and maintain high quality of both, so as to break through the bottleneck that the oil yield and protein functionality cannot be considered in the prior art, and promote the upgrading of peanut industry to high value and green. SUMMARY

[0006] In view of the bottleneck that the peanut oil and protein extraction in the prior art cannot simultaneously achieve high oil yield and high protein functionality, the present application aims to provide a novel peanut oil and protein extraction process. The method realizes efficient and simultaneous extraction of oil and protein by precise control of process parameters and innovation of key technologies, while maintaining the high quality characteristics of both. The process not only breaks through the technical limitations of the mutual restriction of the quality of the two in traditional extraction, but also significantly improves the whole component utilization efficiency of peanut resources, and promotes the upgrading of peanut industry to whole component high value and green.

[0007] The technical solution of the present application is: a high-quality peanut oil pressing and peanut protein production process, comprising the following steps:

[0008] A. Pretreatment and pressing: take the shelled, peeled and red-coated peanuts, crush them with a super micro grinder, add purified water, treat them with high-pressure microjet, and then place them in the press chamber of a hydraulic oil press, control the temperature and pressure, and press to obtain defatted peanut meal and crude peanut oil;

[0009] B. Refining of crude peanut oil: filter the crude peanut oil obtained in step A with a hollow fiber ultrafiltration membrane to obtain peanut oil;

[0010] C. Preparation of peanut protein powder: disperse the porous ceramic in a buffer solution, add enzyme solution containing alkaline protease and neutral protease, stir at room temperature, filter to obtain immobilized enzyme, vacuum dry to obtain porous ceramic immobilized enzyme; take the defatted peanut meal obtained in step A, then add the prepared immobilized enzyme, use infrared-assisted enzymolysis, filter with an ultrafiltration membrane, and freeze-dry to obtain peanut protein powder.

[0011] Preferably, in the process, in step A, the volume of purified water added is 0.08-0.1 times the weight of the shelled, peeled and red-coated peanuts, wherein the volume is measured in liters and the weight is measured in kilograms.

[0012] Preferably, in the process, in step A, the pressure of the high-pressure microjet treatment is 100-110 MPa.

[0013] Preferably, in the process, in step A, the high-pressure microjet treatment is performed 2-3 times.

[0014] Preferably, in the process, in step A, the temperature control for pressing is 35-40℃.

[0015] Preferably, in the process, in step A, the pressure control for pressing is gradient pressure increase: the initial pressure is 0 MPa, first increase the pressure to 20 MPa at a rate of 2 MPa / 10 min, wherein the holding time at each pressure gradient is not less than 10 min to ensure stable pressure; then increase the pressure to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and continue pressing for 20-30 min.

[0016] Preferably, in the process, in step B, the hollow fiber ultrafiltration membrane is polyvinylidene fluoride or polyether sulfone, and the pore size is 0.01-0.03 μm.

[0017] Preferably, in the process, in step C, the buffer is 30-50 mM Tris-hydrochloric acid buffer.

[0018] Preferably, in the process, in step C, the ratio of the weight of the porous ceramic to the protein amount of the enzyme is 1:50-65, wherein the weight of the porous ceramic is in g and the protein amount is in mg.

[0019] Preferably, in the process, in step C, the alkaline protease is Alcalase alkaline protease.

[0020] Preferably, in the process, in step C, the neutral protease is papain.

[0021] Preferably, in the process, in step C, the ratio of the protein amount of the alkaline protease to the neutral protease is 2-2.5:1.

[0022] In the present application, in one preferred embodiment, the enzyme activity of the Alcalase alkaline protease is 6.0 x 10 5 U / g, and the enzyme activity of the papain is 6.2 x 10 5 U / g.

[0023] Preferably, in the process, in step C, the time of infrared-assisted enzymolysis is 30-40 min, and the infrared radiation physical field parameters are set as follows: the long-wave infrared wavelength range is 4-8 μm, and the heating temperature is set to 30-40℃.

[0024] Preferably, in the process, in step C, when the ultrafiltration membrane is filtered, the control pressure is 0.3-0.7 MPa.

[0025] The enzyme used in the present application is not limited in its specific source, and can be self-made or purchased commercially using the method in the prior art.

[0026] Compared with the prior art, the present application has the following outstanding advantages:

[0027] 1. The production process of the present application realizes the synchronous and efficient extraction process of peanut oil and peanut protein by combining high-pressure micro-jet with hydraulic oil press, solves the problem of mutual restriction of the yield of the two in the traditional process through precise parameter control, and significantly improves the extraction efficiency.

[0028] 2. The production process of the present application improves the utilization rate of the enzyme by combining immobilized enzyme with infrared-assisted enzymolysis, and the prepared immobilized enzyme can be recycled more than 20 times, greatly reducing the production cost.

[0029] 3. The peanut oil and peanut protein prepared by using the production process of the present application, the peanut oil has high oil yield, VE content, polyphenol and squalene content, low acid value and peroxide value, the peanut protein has high solubility, strong emulsifying activity and complete nutrition, and the quality indexes of the peanut oil and peanut protein are better than those of conventional process.

[0030] 4. The production process of the present application promotes the peanut industry to develop in the direction of high value, low carbon and low pollution. DETAILED DESCRIPTION

[0031] The specific embodiments are listed below to further illustrate the present application, but do not limit the scope of the present application in any way, and those skilled in the art can make various modifications or improvements according to the basic idea of the present application, as long as they do not deviate from the basic idea of the present application, and are within the scope of the present application.

[0032] Example 1

[0033] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min by using a super micro pulverizer, 0.8 L of purified water was added, and after being treated by high pressure microjet twice at 100 Mpa, the peanuts were placed in the pressing chamber of a hydraulic oil press, the pressing temperature was controlled at 35-37℃, and the pressure was increased by gradient: the initial pressure was 0 MPa, the pressure was increased to 20 MPa at 2 MPa / 10 min, and the holding time at each pressure gradient was not less than 10 min to ensure the stability of the pressure; then the pressure was increased to the final pressure of 40 MPa at 5 MPa / 10 min, and the continuous pressing time was 20 min, and defatted peanut meal and peanut crude oil were obtained, respectively;

[0034] B. Refining of peanut crude oil: the peanut crude oil obtained in step A was filtered by using a polyvinylidene fluoride hollow fiber ultrafiltration membrane with a pore size of 0.01 m to obtain peanut oil;

[0035] C. Preparation of peanut protein powder: 500 g of porous ceramic was dispersed in 30 mM Tris-hydrochloric acid buffer, and enzyme solution containing Alcalase alkaline protease (protein content 16.7 g) and papain (protein content 8.3 g) was added, wherein the enzyme activity of Alcalase alkaline protease was 6.0×10 5 U / g, and the enzyme activity of papain was 6.2×10 5U / g, after stirring for 40 min at room temperature, the immobilized enzyme was obtained by filtration, and the immobilized enzyme was dried in vacuum for 2 h; the defatted peanut meal obtained in step A was taken, and the prepared immobilized enzyme (200 U of the complex protease of the alkaline protease and the neutral protease per gram of the defatted peanut meal) was added, hydrochloric acid was used to adjust the pH to 6.5, and infrared-assisted enzymolysis was performed for 30 min, the infrared radiation physical field parameters were set as follows: the long-wave infrared wavelength range was 4-5 μm, and the heating temperature was set to 30-35 °C; after the enzymolysis, the enzymolysis liquid was subjected to ultrafiltration membrane filtration, the control pressure was 0.3-0.4 MPa, and the obtained liquid was subjected to freeze-drying to obtain peanut protein powder.

[0036] Example 2

[0037] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min by using a supermicro grinder, 1 L of purified water was added, and the peanuts were treated by high-pressure microjet for 3 times at 100 MPa, and then the peanuts were placed in the press chamber of a hydraulic oil press, the pressing temperature was controlled to be 38-40 °C, and the pressure was increased in stages: the initial pressure was 0 MPa, the pressure was increased to 20 MPa at a rate of 2 MPa / 10 min, and the pressure was kept at each pressure stage for no less than 10 min to ensure the stability of the pressure; then the pressure was increased to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and the pressing was continued for 30 min to obtain defatted peanut meal and crude peanut oil;

[0038] B. Refining of crude peanut oil: the crude peanut oil obtained in step A was filtered by using a polyether sulfone hollow fiber ultrafiltration membrane with a pore size of 0.03 m to obtain peanut oil;

[0039] C. Preparation of peanut protein powder: 500 g of porous ceramic was dispersed in 50 mM Tris-hydrochloric acid buffer, and enzyme liquid containing Alcalase alkaline protease (protein content: 23.2 g) and papain (protein content: 9.3 g) was added, wherein the enzyme activity of the Alcalase alkaline protease was 6.0×10 5 U / g, and the enzyme activity of the papain was 6.2×10 5 U / g, and the immobilized enzyme was obtained by filtration after stirring for 40 min at room temperature, and the immobilized enzyme was dried in vacuum for 2 h; the defatted peanut meal obtained in step A was taken, and the prepared immobilized enzyme (200 U of the complex protease of the alkaline protease and the neutral protease per gram of the defatted peanut meal) was added, hydrochloric acid was used to adjust the pH to 6.5, and infrared-assisted enzymolysis was performed for 40 min, the infrared radiation physical field parameters were set as follows: the long-wave infrared wavelength range was 7-8 μm, and the heating temperature was set to 36-40 °C; after the enzymolysis, the enzymolysis liquid was subjected to ultrafiltration membrane filtration, the control pressure was 0.6-0.7 MPa, and the obtained liquid was subjected to freeze-drying to obtain peanut protein powder.

[0040] Comparative Example 1

[0041] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 3 h using a super micro grinder, 0.8 L of purified water was added, and the mixture was placed in the pressing chamber of a hydraulic oil press. The pressing temperature was controlled at 35-37 °C, and the pressure was increased in stages: the initial pressure was 0 MPa, and the pressure was increased to 20 MPa at a rate of 2 MPa / 10 min. Each pressure stage was maintained for at least 10 min to ensure stable pressure. Then, the pressure was increased to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and the pressing was continued for 20 min to obtain defatted peanut meal and crude peanut oil, respectively;

[0042] B. Refining of crude peanut oil: The crude peanut oil obtained in step A was filtered through a polyvinylidene fluoride hollow fiber ultrafiltration membrane with a pore size of 0.01 m to obtain peanut oil;

[0043] C. Preparation of peanut protein powder: 500 g of porous ceramic was dispersed in 30 mM Tris-hydrochloric acid buffer, and an enzyme solution containing Alcalase alkaline protease (protein content 16.7 g) and papain (protein content 8.3 g) was added. The enzyme activity of the Alcalase alkaline protease was 6.0 x 10 5 U / g, and the enzyme activity of the papain was 6.2 x 10 5 U / g. After stirring at room temperature for 40 min, the immobilized enzyme was filtered and vacuum dried for 2 h to obtain porous ceramic immobilized enzyme. The defatted peanut meal obtained in step A was then added to the prepared immobilized enzyme (200 U of alkaline protease and neutral protease complex protease per gram of defatted peanut meal), the pH was adjusted to 6.5 with hydrochloric acid, and infrared-assisted enzymolysis was performed for 30 min. The infrared radiation physical field parameters were set as follows: long-wave infrared wavelength range 4-5 μm, and heating temperature 30-35 °C. After enzymolysis, the enzyme solution was filtered through an ultrafiltration membrane with a pressure of 0.3-0.4 MPa, and the obtained liquid was freeze-dried to obtain peanut protein powder.

[0044] Comparative Example 2

[0045] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min using a super micro grinder, 0.8 L of purified water was added, and the mixture was heated at 120-130 °C for 20 min. The mixture was then fed into a single-screw oil press, and the inlet temperature was controlled at 80 °C. The single-screw oil press was operated at a rotation speed of 30 r / min to obtain first-pressed peanut meal and crude peanut oil;

[0046] B. Refining of crude peanut oil: The crude peanut oil obtained in step A was filtered through a polyvinylidene fluoride hollow fiber ultrafiltration membrane with a pore size of 0.01 m to obtain peanut oil;

[0047] C. Preparation of peanut protein powder: 500 g porous ceramic was dispersed in 30 mM Tris-hydrochloric acid buffer, and enzyme solution containing Alcalase alkaline protease (protein amount 16.7 g) and papain (protein amount 8.3 g) was added, wherein the enzyme activity of Alcalase alkaline protease was 6.0×10 5 U / g, and the enzyme activity of papain was 6.2×10 5 U / g, after stirring at room temperature for 40 min, the immobilized enzyme was filtered, vacuum dried for 2 h, and the porous ceramic immobilized enzyme was obtained; the first pressing peanut meal obtained in step A was taken, then the prepared immobilized enzyme (200 U of alkaline protease and neutral protease complex protease per gram of defatted peanut meal) was added, hydrochloric acid was used to adjust the pH to 6.5, infrared assisted enzymolysis was used for 30 min, and the infrared radiation physical field parameters were set as follows: long wave infrared wavelength range was 4-5 μm, and heating temperature was set to 30-35℃; after enzymolysis, the enzyme solution was subjected to ultrafiltration membrane filtration, the control pressure was 0.3-0.4 MPa, and the obtained liquid was subjected to freeze-drying to obtain peanut protein powder.

[0048] Comparative Example 3

[0049] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min with a supermicro grinder, 0.8 L of purified water was added, and after being treated twice by high pressure microjet at 100 MPa, it was placed in the pressing chamber of a hydraulic oil press, and the pressing temperature was controlled at 70℃. The pressure was increased by gradient: the initial pressure was 0 MPa, and then it was increased to 20 MPa at a rate of 2 MPa / 10 min, and each pressure gradient was maintained for no less than 10 min to ensure stable pressure; then it was increased to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and the continuous pressing time was 20 min, and defatted peanut meal and crude peanut oil were obtained, respectively;

[0050] B. Refining of crude peanut oil: the crude peanut oil obtained in step A was filtered through a polyvinylidene hollow fiber ultrafiltration membrane with a pore size of 0.01 m to obtain peanut oil;

[0051] C. Preparation of peanut protein powder: 500 g porous ceramic was dispersed in 30 mM Tris-hydrochloric acid buffer, and enzyme solution containing Alcalase alkaline protease (protein amount 16.7 g) and papain (protein amount 8.3 g) was added, wherein the enzyme activity of Alcalase alkaline protease was 6.0×10 5 U / g, and the enzyme activity of papain was 6.2×10 5U / g, after stirring for 40 min at room temperature, the immobilized enzyme was obtained by filtration, and the immobilized enzyme was dried in vacuum for 2 h; the defatted peanut meal obtained in step A was taken, and the prepared immobilized enzyme (200 U of the complex protease of the alkaline protease and the neutral protease per gram of the defatted peanut meal) was added, hydrochloric acid was used to adjust the pH to 6.5, and infrared-assisted enzymolysis was performed for 30 min, the parameters of the infrared radiation physical field were set as follows: the long-wave infrared wavelength range was 4-5 μm, and the heating temperature was set to 30-35 °C; after the enzymolysis, the enzymolysis liquid was subjected to ultrafiltration membrane filtration, the control pressure was 0.3-0.4 MPa, and the obtained liquid was subjected to freeze-drying to obtain peanut protein powder.

[0052] Comparative Example 4

[0053] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min by using a supermicro grinder, 0.8 L of purified water was added, and the peanuts were treated by high-pressure microjet for 2 times at 100 MPa, and then were placed in the press chamber of a hydraulic oil press, the pressing temperature was controlled to be 35-37 °C, and the pressure was increased in stages: the initial pressure was 0 MPa, the pressure was increased to 20 MPa at a rate of 2 MPa / 10 min, and the time for each pressure stage was not less than 10 min to ensure the stability of the pressure; then the pressure was increased to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and the continuous pressing time was 20 min, and defatted peanut meal and crude peanut oil were obtained, respectively;

[0054] B. Refining of crude peanut oil: the crude peanut oil obtained in step A was filtered through filter cloth for 3 times to obtain peanut oil;

[0055] C. Preparation of peanut protein powder: 500 g of porous ceramic was dispersed in 30 mM Tris-hydrochloric acid buffer, and enzyme liquid containing Alcalase alkaline protease (protein amount: 16.7 g) and papain (protein amount: 8.3 g) was added, wherein the enzyme activity of the Alcalase alkaline protease was 6.0 x 10 5 U / g, and the enzyme activity of the papain was 6.2 x 10 5 U / g, after stirring for 40 min at room temperature, the immobilized enzyme was obtained by filtration, and the immobilized enzyme was dried in vacuum for 2 h; the defatted peanut meal obtained in step A was taken, and the prepared immobilized enzyme (200 U of the complex protease of the alkaline protease and the neutral protease per gram of the defatted peanut meal) was added, hydrochloric acid was used to adjust the pH to 6.5, and infrared-assisted enzymolysis was performed for 30 min, the parameters of the infrared radiation physical field were set as follows: the long-wave infrared wavelength range was 4-5 μm, and the heating temperature was set to 30-35 °C; after the enzymolysis, the enzymolysis liquid was subjected to ultrafiltration membrane filtration, the control pressure was 0.3-0.4 MPa, and the obtained liquid was subjected to freeze-drying to obtain peanut protein powder.

[0056] Comparative Example 5

[0057] A. Pretreatment and pressing: 10 kg of shelled, peeled and red-coated peanuts were pulverized for 30 min using a super micro grinder, 0.8 L of purified water was added, and the mixture was treated twice by high-pressure micro-jet at 100 MPa, and then placed in the press chamber of a hydraulic oil press, the pressing temperature was controlled at 35-37℃, and the pressure was increased in stages: the initial pressure was 0 MPa, first increased to 20 MPa at a rate of 2 MPa / 10 min, and each pressure gradient was maintained for no less than 10 min to ensure stable pressure; then increased to the final pressure of 40 MPa at a rate of 5 MPa / 10 min, and the continuous pressing time was 20 min, to obtain defatted peanut meal and crude peanut oil, respectively;

[0058] B. Refining of crude peanut oil: the crude peanut oil obtained in step A was filtered through a polyvinylidene fluoride hollow fiber ultrafiltration membrane with a pore size of 0.01 m to obtain peanut oil;

[0059] C. Preparation of peanut protein powder: the defatted peanut meal obtained in step A was super-micro ground to 100-200 mesh peanut protein powder, microwave sterilization was performed at a temperature of 50℃ and a wave frequency of 2500 MHz for 3 min to obtain peanut protein powder.

[0060] I. Determination of the basic properties of peanut oil

[0061] The peanut oil obtained in the examples and comparative examples was detected according to the following method, and the results are shown in Table 1.

[0062] (1) Flavor evaluation: 10 people sensitive to the flavor of peanut oil were randomly selected, 10 mL of oil sample was taken, and the overall flavor of the oil sample was evaluated by smelling the odor while stirring, the flavor sensory score was: 1-weak; 2-obvious; 3-moderate, 4-strong; 5-intense; the evaluation result was the average value of the scores of 10 volunteers.

[0063] (2) Oil yield of peanut oil: the freshly pressed peanut oil was placed in a constant temperature storage room at 2℃ for 48 h, then filtered, and the mass of the residue after filtration was recorded, the peanut kernel cake produced during oil pressing was collected and weighed, and the mass ratio of the peanut oil obtained in each batch to the peanut kernel was the oil yield, which was calculated according to the following formula: Y=(m1-m2-m3) / m1x100%, wherein m1 was the mass of peanut kernel, m2 was the mass of peanut protein powder, and m3 was the mass of the residue after filtration.

[0064] (3) Vitamin E detection: HPLC method (C18 chromatographic column, mobile phase methanol: water=95:5, detection wavelength 294 nm).

[0065] (4) Determination of polyphenol content: according to LS / T6119-2017 "Determination of polyphenols in vegetable oil by spectrophotometry".

[0066] (5) Squalene content determination: according to "Determination of Squalene Content in Plant Oil" (NY / T 3673-2020).

[0067] Table 1. Results of basic performance determination of peanut oil

[0068]

[0069] II. Determination of key indicators of peanut oil

[0070] The peanut oil obtained from the examples and comparative examples was detected according to the following method, and the results are shown in Table 2.

[0071] Acid value and peroxide value: The acid value of the peanut oil was detected according to GB / T 5009.229 "Determination of Acid Value in Food Safety National Standard Food", and the peroxide value of the peanut oil was detected according to GB / T 5009.227 "Determination of Peroxide Value in Food Safety National Standard Food", then the peanut oil was filled into ground brown glass bottles, and the bottle stopper was covered, 3 bottles of peanut oil of each example or comparative example were placed in a 70°C oven for constant temperature preservation for 30 days, then the accelerated stability was investigated, the acid value and peroxide value of the product were determined, and the average value was calculated.

[0072] Table 2. Results of key indicators determination of peanut oil

[0073]

[0074] III. Determination of performance of peanut protein powder

[0075] The peanut protein powder obtained from the examples and comparative examples was detected according to the following method, and the results are shown in Table 3.

[0076] 1. Soluble nitrogen index determination: determined by reference to Kjeldahl method (GB 5009.5).

[0077] 2. Oil content: determined by reference to GB 5009.6.2016 for oil content in protein powder.

[0078] 3. Protein content and solubility determination:

[0079] (1) Sample pretreatment: the peanut protein powder sample was passed through a 60-mesh sieve (particle size ≤0.25 mm) to ensure uniformity; if the oil content of the sample is >5%, the sample needs to be Soxhlet extracted with petroleum ether (boiling range 30-60°C) for 6 hours, and then dried at 60°C for standby;

[0080] (2) Dissolution and centrifugation: 1.5 g of sample was accurately weighed in a 250 mL beaker, 75 mL of 0.03% KOH solution (pH≈12.5) was added, and it was placed in a 25°C constant temperature magnetic stirrer for stirring for 20 minutes, the solution was transferred to a centrifuge tube, and centrifuged at 3000 r / min for 10 minutes, and the supernatant was filtered through a 0.45 μm filter membrane;

[0081] (3) Protein content determination: The total protein content of the original sample was determined according to the Kjeldahl method GB5009.5-2016 “National Food Safety Standard Determination of Protein in Food”; the supernatant after centrifugation was taken, and the soluble protein content was determined by the same method;

[0082] (4) The solubility calculation formula is as follows:

[0083]

[0084] Table 3 Performance determination results of peanut protein powder

[0085]

Claims

1. A process for pressing peanut oil and producing peanut protein, characterized in that, The production process includes the following steps: A. Pre-treatment and pressing: Peanuts that have been shelled, peeled and deskinned are crushed using an ultra-fine pulverizer, purified water is added, and after being treated by high-pressure micro-jet, they are placed in the pressing chamber of a hydraulic oil press and pressed under controlled temperature and pressure to obtain defatted peanut meal and crude peanut oil. B. Refining of crude peanut oil: The crude peanut oil obtained in step A is filtered through a hollow fiber ultrafiltration membrane to obtain peanut oil; C. Preparation of peanut protein powder: Porous ceramics were dispersed in a buffer solution, and an enzyme solution containing alkaline protease and neutral protease was added. After stirring at room temperature, the immobilized enzyme was obtained by filtration and vacuum drying to obtain porous ceramic immobilized enzyme. The defatted peanut meal obtained in step A was taken, and the prepared immobilized enzyme was added. Infrared-assisted enzymatic hydrolysis was performed, and after filtration through an ultrafiltration membrane, the peanut protein powder was obtained by freeze drying. In the process described, in step A, the pressure of the high-pressure microjet treatment is 100~110 MPa, the pressing temperature is controlled at 35~40℃, and the pressing pressure is controlled by a gradient increase: the initial pressure is 0 MPa, first increasing the pressure to 20 MPa at 2 MPa / 10min, wherein each pressure gradient is maintained for no less than 10min to ensure pressure stability; then increasing to the final pressure of 40 MPa at 5 MPa / 10min, and continuing the pressing time for 20~30min; in step B, the hollow fiber ultrafiltration membrane is polyvinylidene fluoride or polyethersulfone, with a pore size of 0.01~0.03μm; in step C, the ratio of the weight of porous ceramic to the protein content of the enzyme is 1:50~65, wherein the weight of the porous ceramic is in g and the protein content is in mg, the infrared-assisted enzymatic hydrolysis time is 30~40min, the infrared radiation physical field parameters are set to a long-wave infrared wavelength range of 4~8μm, and the heating temperature is set to 30~40℃.

2. The process as described in claim 1, characterized in that, In the process described, in step C, the alkaline protease is Alcalase.

3. The process as described in claim 1, characterized in that, In the process described, in step C, the neutral protease is papain.

4. The process as described in claim 1, characterized in that, In the process described, in step C, the protein ratio of alkaline protease to neutral protease is 2~2.5:1.

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