Application value of peanut protein

Peanuts contain more than 50% of the oil, but also rich in 22% to 26% of the protein, which contains about 90% of the peanut globulin and companion peanut protein, each accounting for 63% and 33%, and the remaining about 10% for water-soluble proteins, called whey protein. The isoelectric point of peanut protein is about pH=4.5, under this pH condition, the solubility of peanut protein is the smallest, when the pH of the aqueous solution of peanut protein rises, its viscosity increases, and during the stirring test, the foaming viscosity of pH=6.6 is 5 times that of pH=4.0.

The protein in peanut has high nutritional value, with little difference from animal protein, higher than the protein content of milk, pork and eggs, and low cholesterol content, second only to soy protein among plant proteins. Compared with soy protein, peanut protein has a high digestibility, up to 90%, very easy to be absorbed by the body, the amount of trypsin inhibiting factor contained in only 20% of the soybean, but also no soy flavor, is an ideal basic raw material for the food industry. Peanut protein as a patient food, to help diabetes, hypertension, atherosclerosis and gastrointestinal disease patients to restore health have a certain effect.

Peanut protein extraction technology

There are many types of peanut protein products, which can be divided into peanut flour, peanut protein concentrate, peanut isolate protein, etc., of which peanut flour includes full-fat peanut flour, partially defatted peanut flour, defatted peanut flour and so on. The following introduces several methods of extracting peanut protein: pressing method, leaching method, water enzyme method, reverse micelle extraction technology, alkaline dissolution and acid precipitation method.

1) Pressing method

Pressing method is through the extraction of some of the oil in the peanut, to achieve the effect of peanut cake meal at the same time, can be divided into hot pressing method and cold pressing method. Hot pressing method can remove up to 80% ~ 90% of the oil, but due to the preparation process using high temperature treatment, most of the proteins in the peanut meal has been denatured, the water-soluble protein content is reduced, the functional properties have also decreased significantly. The general cold pressing method is below 60 ℃ environment for processing, nutrient retention of the most complete, but its lower oil yield, degreasing is not too thorough, so often used in conjunction with the leaching method.

2) Leaching method

Leaching process includes direct leaching process and first pressing and then leaching process, the former is suitable for some low oil content of oilseeds, for peanuts, oil content is higher, suitable for first pressing and then leaching process. However, the production process of the leaching method is more complicated and costly, and the addition of volatile and flammable organic solvents also adds safety hazards.

3) Water enzyme method

With the development of bioengineering technology and enzyme preparation, people began to study the enzyme treatment to extract oil and grease to obtain better nutritional value. The biggest advantage of the water enzyme method is that it can effectively recover the protein (or its hydrolysis products) in the plant material while extracting the oil. Compared with the traditional process, water enzyme technology equipment is simple, safe operation, not only can improve efficiency, but also the technology processing conditions are mild, can produce low denaturation of protein products, hydrolyzed protein solution is easier to digest; the production process is relatively low energy consumption, the BOD and COD value of wastewater greatly reduced, less pollution, easy to deal with.

4）Anti-micellar extraction technology

Anti-micellar extraction technology is a new type of extraction technology, surfactants dissolved in non-polar organic solvents, soluble part of the water to form a “pool” to achieve the extraction of proteins, and at the same time to achieve the separation of the role of fats and oils. Because the “pool” has a certain protective effect on the protein, so you can get better functional properties of peanut protein. Due to the existence of surfactant residues and the lack of production equipment and other problems, the technology is still in the preliminary study.

(5) Alkali acid precipitation method

Alkali acid precipitation method is usually used to prepare isolated protein, not only to remove water-soluble sugars, but also to remove starch, cellulose and other components, the protein content of the resulting product up to 90%, but the use of a large number of acids and alkalis in the industrial production process, which will cause a certain degree of environmental pollution.

Peanut protein in food applications

Adding some peanut protein in food in moderation can not only improve the nutritional value of food, but also improve the quality of food through the functional properties of peanut protein.

1）Application of peanut protein in meat products

In meat products, especially in the processing of minced meat products, vegetable protein is not only a substitute, but also an essential raw material. Peanut protein powder is a good binder for meat products, filler, will be added to the sausage, fish sausage, ham, can effectively maintain the moisture of the meat juice is not lost, the processing of flavor substances are not lost, can promote fat absorption, its products do not produce the phenomenon of walking oil. Through the addition of peanut protein powder, so that the products to achieve fine tissue, good texture, the use of 5% to 10%.

(2) Peanut protein in the application of noodle products

Adding peanut protein in noodle products can not only improve the nutritional value of food, but also make the product structure puffy, soft and elastic. Peanut protein powder as a nutrient added to the production of steamed bread, improve the quality of steamed bread, adding peanut protein powder steamed bread elasticity and recovery are higher than those not added.

(3) Peanut protein in beverage applications

Add peanut protein powder in beverage, because it does not contain cholesterol, and rich protein, essential amino acids, vitamins and unsaturated fatty acids, easy to be absorbed by the human body, is a kind of beverage with health care functions. The low-temperature defatted peanut protein is processed through ultra-micro crushing and matched with soybean meal, milk powder and other high-quality protein, which can produce peanut protein milk powder with good brewing performance of solid beverages, and improve the nutritional value of the products. Add peanut protein powder in milk to make yogurt, can effectively improve the texture characteristics and sensory quality of the product, peanut protein yogurt tissue structure is fine, uniform texture, sweet and sour taste, with peanut protein and milk double flavor and nutritional effects, improve the bioavailability and nutritional value of food.