CN1290422C - Technology of extracting oil and hydrolyzed protein from peanut using hydroenzyme method - Google Patents

Abstract

The invention discloses a process for extracting oil and hydrolyzed protein from peanuts by an aqueous enzymatic method, which belongs to the technical field of application of biotechnology in food industry. In the present invention, peanuts are used as raw materials, a single alkaline protease is used for aqueous enzymatic oil extraction, the obtained emulsifiable oil is demulsified by freezing and thawing to obtain free oil, and at the same time, the hydrolyzed liquid and the alkaline lotion are recovered in the form of small peptides. protein. By adopting the invention, free oil can be directly extracted from peanuts, and the yield of oil is high; the hydrolyzed protein powder in the form of recovered small peptide can make up for the nutritional deficiency of peanut protein itself, and has high nutritional value.

Description

A process for extracting oil and hydrolyzing protein from peanuts by aqueous enzymatic method

technical field

The invention discloses a process for extracting oil and hydrolyzed protein from peanuts by an aqueous enzymatic method, which belongs to the technical field of application of biotechnology in food industry.

Background technique

At present, the main oil-making processes in the world include mechanical method, leaching method and aqueous method. At present, there are two main processing methods in China, one is the organic solvent leaching method, and the other is the physical pressing method using mechanical external force. The above-mentioned method is also a traditional method for separating oil and protein in oil plants, that is, a two-step process route of first extracting oil from oil plants and then extracting protein from the resulting cake. Although these methods have high oil extraction rates, the oil extraction process will cause protein denaturation to varying degrees, thereby affecting its nutritional value and functional properties. It can only be used as fertilizer and feed, resulting in a waste of oil-seed protein resources; while solvent leaching requires a desolventization process, which requires a lot of equipment, large investment, and heavy pollution.

As early as the 1950s, it was observed that enzyme pretreatment had a significant effect on the oil yield of oil plants. In foreign countries, aqueous enzymatic oil extraction has been widely used in laboratories to extract oil from various oilseeds, including sunflower seeds, soybeans, cottonseeds, shea nuts, coconuts, and corn. Enzymatic treatment of olives, avocados, and coconuts to increase oil yield has achieved good results in industrial trials.

Peanut is an important oil crop in my country, accounting for about 42% of the country's annual output of oil crops. In 2003, the annual output was 15.2 million tons, and its total output and total output value ranked first in the world. At the same time, my country is a large agricultural country with a large population. The annual consumption of edible oil reaches 13 million tons, but some edible oil has long been dependent on imports. In recent years, the annual amount of imported oil has reached as high as 4-7 million tons. In terms of oil production, my country's soybean international competitiveness is insufficient, so vigorously developing the peanut industry is the fundamental way out to solve my country's oil problem.

Peanut is also the third plant protein source in the world, which can provide about 11% of the world's protein requirement. Modern nutritional studies have found that most of the protein ingested by humans is digested and absorbed in the form of low-peptides after the action of enzymes in the digestive tract, and the proportion absorbed in the form of free amino acids is very small. Further experiments revealed that peptides are digested faster and absorbed more than free amino acids, indicating that peptides have higher biological potency and nutritional value than free amino acids. Although peanut protein has excellent properties, the composition of essential amino acids in peanut protein is unbalanced, and lysine, threonine, and methionine are the limiting amino acids; in addition, the net utilization rate (NPU) of protein is 48. Generally speaking, the NPU of high-quality protein is above 70, and the NPU value of peanut protein is low, which becomes the second deficiency of peanut protein nutrition. Therefore, it is of great significance and value to eliminate the nutritional deficiency of peanut protein and obtain hydrolyzed short peptides with high nutritional value and easy digestion and absorption to more effectively utilize peanut protein resources. At present, there are researches in the world on obtaining hydrolyzed peptides from crops such as soybeans, peas, and corns. Japan uses food protein as raw material, enzymatically deodorizes and decolorizes polypeptide food. The market size of mobile food alone has reached nearly 13 billion yen, and there is still a strong momentum of development. But so far there are no systematic research reports on peanut peptides at home and abroad.

There are only two research reports abroad on extracting oil from peanuts by aqueous enzymatic method, [Lanzani, A. et al. LaRiv. Ital. Sostanze grass, 1975, 52, 226-229; 79):215-218] The free oil yields were 78% and 86%, respectively. But none of them investigated the recycling of another component of peanut protein. At present, the domestic CN1419837A reports: Compared with the traditional water preparation method without enzyme treatment, after the three enzymes of cellulase, pectinase and neutral protease are used to enzymatically treat peanuts, the oil yield of peanuts and peanut protein Yields increased from 86% and 67% to 94-96% and 73-75%, respectively. However, the author did not indicate in the article whether the oil yield refers to the total oil extraction rate or the free oil (free oil) extraction rate, did not specify whether the oil is recovered in the form of emulsifiable concentrate or in the form of free oil, and did not specify the properties and recovery methods of peanut protein. Research.

Contents of the invention

The purpose of the present invention is to provide a process for extracting oil and hydrolyzing protein from peanuts by aqueous enzymatic method. Peanut seeds were treated with enzymes to increase the yield of free oil and simultaneously recover high-quality, high-nutrient hydrolyzed peanut protein.

The technical scheme of the present invention: Peanut kernels are dried to remove the red coat, dry crushed and alkaline extracted, and then enzymolyzed with a single alkaline protease. After the enzymolysis is completed, the enzymolysis system is centrifuged. The slag is combined with the obtained emulsifiable oils obtained by alkali elution, and the combined emulsifiable oils are demulsified by freezing-thawing method to obtain free oil; , spray or freeze-dry to obtain hydrolyzed protein powder in the form of small peptides.

In vegetable oils, oil exists inside the oil plant cells and is usually combined with other macromolecules (proteins and carbohydrates) to form complexes such as lipoproteins and lipopolysaccharides. Only by destroying the cell structure and oil complexes of oil plant tissues can the Remove the fat from it. Treat oil plants with enzymes (such as protease, cellulase, hemicellulase, pectinase, amylase, glucanase, etc.) that can degrade oil plant tissues and complexes such as lipoproteins and lipopolysaccharides, and can achieve The purpose of oil pretreatment. On the basis of mechanical crushing, the further destruction of cell structure by enzymes and the decomposition of complexes such as lipoproteins and lipopolysaccharides by enzymes can increase the fluidity of oil in oil plant tissues, thereby increasing the oil yield. In addition, during the oil extraction process, part of the phospholipids is transferred to the oil, combined with protein and adsorbed on the surface of oil droplets to form a stable emulsion, which is not conducive to the separation and extraction of oil, and the action of enzymes can reduce the stability of the emulsion and improve oil yield.

1. Process route, as shown in Figure 1.

2. Analysis method

Protein: semi-micro Kjeldahl method

Fat: Soxhlet Extraction

Starch: the sample is hydrolyzed by acid first, and then titrated by reducing sugar

Total oil yield: (oil content in raw material - oil content in residue II) × 100%/oil content in raw material

Total protein yield: (protein content in raw material-protein content in slag II)×100%/protein content in raw material

Free oil yield: (free oil I + free oil II) × 100% / oil content in raw materials

Hydrolyzed protein yield: the amount of amino nitrogen in the hydrolyzed solution and alkaline washing solution after deactivating the enzyme × 100% / the amount of amino nitrogen in the raw material

Material particle size distribution: Mastersizer2000 laser particle size analyzer

Hydrolysis degree: pH-stat method and TNBS method

Relative Molecular Mass Distribution of Hydrolyzed Peanut Protein: Gel Filtration Chromatography and HPLC

3. Process conditions

1) Screening and peeling

Fresh and mildew-free peanuts are dried by a far-infrared dryer to a moisture content of less than 5%, and the temperature during the drying process is not higher than 60°C. Use a peanut peeling machine to remove more than 98% of the red coat, so as to avoid the red coat from affecting the color and flavor of the hydrolyzed protein product.

2) Dry crushing and alkaline extraction

Dry crushing is to destroy the tissue cells of raw materials. Dry pulverization can use ultrafine mill (CWM type) or portable traditional Chinese medicine pulverizer, dry pulverization does not add water to avoid the formation of stable emulsion during the pulverization process. The temperature during the crushing process should not exceed 80°C, and the particle size of the crushed material should be controlled below 20 μm.

The alkaline extraction process is to release protein and oil from the broken cell tissue. Peanut protein contains 10% albumin and 90% globulin, which have high solubility in dilute NaOH solution. Disperse the dry pulverized material in NaOH solution with 4-6 times the amount of water, so that the pH range of the system is 8.0-8.5, the temperature is 60°C, and the alkali extraction time is 20-60min. After alkali extraction, most of the protein in the raw material exists in the NaOH solution in a dissolved state, which is conducive to the full action of the enzyme.

3) Enzymatic hydrolysis process

The protein content in peanuts is relatively high. In a system containing oil, water, and amphipathic proteins, emulsions will inevitably be formed during stirring. Selecting appropriate enzymes to act on the emulsification system can not only destroy the cell wall to facilitate oil penetration, but also destroy the lipoprotein membrane to a certain extent and improve the oil yield of oilseeds.

Due to the nutritional deficiencies of peanut protein, the selected enzyme and its mode of action should make the obtained product really make up for the deficiency of peanut protein, improve the nutritional value and expand the application range. In the process, food-grade alkaline protease Alcalase is selected. Alcalase is purchased from NOVO company and is a high-efficiency bacterial protease specially developed for hydrolyzing various proteins. The main active ingredient of the enzyme, subtilisin A (subtilisin Carlsberg) is an endoprotease with a wide range of substrates.

Add 0.5-2.5ml/100g protein enzyme amount to the system, the action temperature is 55-65°C, and the action time is 5-8hr. During the reaction process, the degree of hydrolysis can be measured by pH-stat method, and the pH value of the control system is kept at about 8.00; Alternatively, the pH of the enzymatic hydrolysis system can not be controlled, and the enzymatic hydrolysis method is allowed to degrade naturally, and the degree of hydrolysis can be determined by the TNBS method.

4) Elution and demulsification

After enzymatic hydrolysis, the system is centrifuged, and the obtained slag is extracted with NaOH solution with a pH of about twice that of the raw material at 60° C. for 30 minutes. Combine the cream obtained after centrifugation and the cream obtained from the residue after centrifugation by alkali elution, and the combined cream is demulsified by freezing (-8-4°C) and thawing (25-35°C).

5) Recovery of peanut hydrolyzed protein

After combining the hydrolyzed solution and the alkaline washing solution, the enzyme is inactivated at 85° C. for 10 minutes, and the centrifuged supernatant is spray-dried or freeze-dried to obtain peanut hydrolyzed protein powder in the form of small peptides.

Beneficial effects of the present invention: simple equipment, safe operation, less pollution; oil and hydrolyzed protein can be separated at the same time, shortening the process route; operating conditions are mild, and the quality of the obtained oil and hydrolyzed protein is high; the hydrolyzed protein obtained by enzymatic separation is The highly processed oil-seed protein product has high solubility, good taste, easy digestion and absorption, and good dispersibility. It can be widely used in a variety of food systems, which is beyond the reach of natural proteins.

Compared with the background technology CN1419837A, the present invention uses a single alkaline protease Alcalase to carry out enzymolysis reaction on peanut raw materials, while the background technology uses three enzymes of cellulase, pectinase and neutral protease to jointly carry out enzymolysis reaction on peanut raw materials The reaction, obviously, is far superior to be performed with a single enzyme. First of all, the selection of a single enzyme avoids the restriction of multiple enzymes on the popularization and application of the technology; secondly, the alkaline protease Alcalase is a high-efficiency bacterial protease specially developed for hydrolyzing various proteins. Protease Carlsberg) is a kind of endoprotease, and the scope of action to substrate is much wider than the neutral protease of B.subtilis source, can improve the recovery rate of peanut hydrolyzed protein more substantially.

Compared with the background technology CN1419837A, the present invention specifically proposes to demulsify the emulsifiable oil by freezing-thawing method, so as to obtain free oil. The demulsification method is simple to operate and easy to realize industrial production. However, the background technology only mentions "treatment with emulsified oil" in general, and does not further mention specific treatment schemes. Obviously, the background technology only obtains emulsified oil.

Compared with the background technology CN1419837A, the present invention adopts alkaline protease Alcalase to carry out enzymolysis reaction, and the recovered hydrolyzed peanut protein is detected to be in the form of small peptides. This small peptide has the characteristics of high nutritional value and high absorption and utilization rate of human body, which can make up for the nutritional deficiencies of peanut protein, which is limited by many amino acids and low net utilization rate (NPU).

Description of drawings

Fig. 1 Schematic diagram of the technological process of extracting oil and hydrolyzing protein from peanuts by aqueous enzymatic method.

Detailed ways

Example 1

The raw material is stripped of the red coat, and the peeled peanut kernels are dry crushed with a portable traditional Chinese medicine grinder. The crushed peanuts are extracted with 4 times the lye, the initial pH of the extraction is 8.25, and the temperature is 60°C. After 20 minutes, the pH of the system was adjusted to 8.00 (within the optimum pH range of Alcalase2.4L), the amount of enzyme added was 2.5ml/100g protein, and the pH of the system was controlled at about 8.00 by pH-stat. After 7 hours, the degree of hydrolysis of the system was Reached 22.7%.

The total oil yield was 97.3%, and the total protein yield was 95.6%.

The total free oil yield was 92.4%, and the recovery rate of peanut hydrolyzed protein reached 90%.

Example 2

The raw material is stripped of the red coat, and the peeled peanut kernels are dry crushed with a portable traditional Chinese medicine grinder. The crushed peanuts are extracted with 5 times the alkali solution, the initial pH of the extraction is 8.50, and the temperature is 60°C. After 40 minutes, the pH of the system was adjusted to 8.50, the amount of enzyme added was 1.5mL/100g protein, and the natural enzymatic hydrolysis was carried out for 8 hours.

The total oil yield was 97%, and the total protein yield was 94.1%.

The total free oil yield was 91.6%, and the recovery rate of peanut hydrolyzed protein reached 84%.

Claims (1)

1. the technology of aqueous enzymatic extracting of peanut oil and protein hydrolysate, it is characterized in that the shelled peanut drying takes off scarlet, dry grinding and alkali are carried, carry out enzyme digestion reaction with single alkali protease then, it is centrifugal to enzymatic hydrolysis system that enzymolysis finishes the back, directly isolates a part of free oil after enzymatic hydrolysis system is centrifugal, also isolates another part missible oil, gained missible oil and centrifugal after slag carry gained missible oil with alkali cleaning and merge, the missible oil after being combined also obtains free oil with the method breakdown of emulsion of freeze-thaw; Hydrolyzate that enzymatic hydrolysis system is obtained after centrifugal and the alkali wash water after the alkali cleaning merge, the enzyme that goes out, and spraying or freeze drying obtain the protein hydrolysate powder of little peptide form;

Scarlet is taken off in the shelled peanut oven dry: bake out temperature is not higher than 60 ℃, and being dried to shelled peanut moisture is below 5%;

Pulverize: pulverize temperature and be no more than 80 ℃, the crushing rear material particle diameter is controlled at below the 20 μ m;

Alkali is carried: the material after the dry grinding is dispersed in the NaOH solution that 4-6 doubly measures, and the pH that alkali is carried is 8.0-8.5, and temperature is 60 ℃, and alkali is carried time 20-60min;

Enzymolysis: enzyme digestion reaction carries out enzymolysis with single alkali protease Alcalase, and every 100g protein adds the enzyme amount of 0.5-2.5mL, hydrolysis temperature 55-65 ℃, enzymolysis time 5-8hr in the system;

Alkali cleaning is carried: the NaOH solution of 2 times of amounts of the centrifugal slag usefulness raw material that obtains stirs and extracts 30min at 60 ℃, pH7.5, and layering obtains missible oil;

Breakdown of emulsion: missible oil that obtains after the merging enzymatic hydrolysis system is centrifugal and the slag after centrifugal are carried gained missible oil with alkali cleaning, the method breakdown of emulsion of freeze-thaw of the missible oil after being combined, and-8～-4 ℃ are freezing, 25～35 ℃ of acquisition free oils that thaw;

Reclaim the hydrolysis albumen powder: hydrolyzate and the alkali wash water after the alkali cleaning that enzymatic hydrolysis system is obtained after centrifugal merge, 85 ℃ of enzyme 10min that go out, and the supernatant after centrifugal obtains the protein hydrolysate powder of little peptide form through spraying or freeze drying.