China is the country with the largest rice production in the world. With the vigorous development of rice planting industry, the deep processing and comprehensive utilization of rice provide a new growth point for China's agricultural economy. Rice processing often only use starch, broken rice, rice embryo, rice bran, rice husk and other processing by-products contain a large number of high-quality rice protein can not be effectively developed and utilized, resulting in a great waste of protein resources.
With the continuous progress of food science and technology, the high nutritional and hypoallergenic properties of rice protein have gradually been recognized by people, and the development of processed base materials for food or nutritional health products has become a major trend. In this paper, the comprehensive benefit of rice protein was summarized.
The research on rice protein at home and abroad mainly includes food additives to improve the physical and chemical functions of food. Natural thickeners and foaming agents as washing and protection products; High protein nutrition powder needed by special groups; Bioactive peptides to meet specific functions; Active ingredients to promote body health care; Protein feed for livestock and poultry production; Green edible film, etc. These technologies are closely related to the hydrolysis and modification of rice protein isolate (RPI).
01 Food Additives
Food additives are a kind of additives that can improve the quality, color, aroma and taste of food. The appropriate molecular size and amino acid composition will give the protein certain physical and chemical properties, such as solubility, foaming, emulsifying and so on.
Rice protein is more easily soluble in water and concentrated in the gas-liquid interface under the hydrophobic, flexible and disordered structure, showing foaming emulsification. Wu Yujing used rice residue as raw material to obtain protein foaming powder with high protein content and good foaming performance through a series of technological processes such as sugar removal, neutral protease enzymatic modification, decolorization and drying.
Anderson treated rice protein isolate with protease, the apparent viscosity of 10% protein solution decreased significantly, and the foaming ability and foam stability were greatly enhanced.
In addition to enzymatic hydrolysis, chemical modification methods can also be used to improve the properties of rice protein, such as the addition of Na2SO3 or SDS, which can relieve the aggregation state of protein molecules and show colloidal properties.
The rice protein hydrolyzed or modified by the above enzymatic method has a wide range of uses in food production, such as stabilizing and thickening in liquid or semi-solid foods, foaming in baked foods and candies, etc.
02 Protein supplements
Rice protein has become the preferred plant protein for nutritional supplements for special populations because of its low allergenicity and high nutritional properties. Rice protein formula rice flour can be used for sensitive diarrhea of infants and young children. Gluten-free rice protein is more suitable for people with wheat intolerance, allergy or celiac disease. Rice protein concentrate can better supplement the body's ability and maintain nitrogen balance when normal protein intake is reduced or the digestive function is damaged. And can assist in the treatment of digestive ulcer, trauma, etc.
03 Functional peptide development
Modern studies have shown that amino acid residues in small peptides are more easily digested and absorbed by the human body than free amino acids. Amino acids in the form of small molecule peptides can not only avoid transport competition, but also reduce the toxic and side effects of high concentrations of amino acids. The peptide transport system has low energy consumption and is not easy to saturate, making the study of hydrolyzed protein products to obtain active peptides welcomed by people.
Li Huoyun and others used Alcalase alkaline protease to enzymatically hydrolyze rice protein to obtain rice polypeptides that can eliminate hydroxyl radical, superoxide anion radical and DPPH radical, which provided a guarantee for inhibiting and delaying the aging of the body and opened up the application prospect of anti-aging cosmetics.
The active peptides in rice protein isolate can affect the expression of cyp4a and cyp2c, thereby improving the metabolism of arachidonic acid as an antihypertensive component. In addition, it can also inhibit the genetic high cholesterol mouse model of atherosclerosis, reduce the incidence of disease.
Rice protein hydrolysates have a wide range of small molecular peptides with diverse functions. Such as antibacterial active peptides, cholesterol-lowering active peptides, antihypertensive active peptides, antitumor active peptides, antioxidant active peptides, etc.
04 Protein Feed
Rice protein powder, the by-product of rice starch sugar preparation, is an excellent feed raw material with high protein content, fast energy conversion, high digestibility, good palatability, good disease resistance, low antigenicity and amino acid balance. Adding rice gluten concentrate to aquatic feed can not only improve the digestive performance of fish, but also control its excretion, thereby keeping water quality clear and controlling water pollution.
Rice protein hydrolysis can produce flavor peptides instead of sodium glutamate (MSG), which can effectively mask the bitter taste, enhance the viscosity of feed and improve the palatability of feed, and can chelate trace elements and minerals, which can improve the feed intake of animals and ensure the safety and harmlessness at the same time.
Liu Weidong and others added 1.5 ~ 2% rice protein as chicken feed significantly improved the egg production rate, feed intake, total protein in blood and survival rate of chickens.
05 edible film
Rice edible protein film is a green packaging film with good freshness, gas barrier, oil barrier and moisture resistance, which promotes the development of edible packaging film materials and opens up a new way for renewable agriculture.
Wu Yinghua and others studied the forming conditions of rice protein film, which showed that the edible film with certain strength could be formed on smooth stainless steel plate by dissolving rice protein with 80% ethanol at constant temperature of 4O ℃, and the transparency and tensile strength of the film could be improved by adding oleic acid and glycerin. The Southern Louisiana Research Center has developed an edible film that is resistant to tension and water vapor. Its raw material is rice protein concentrate and pullulan conjugate. The edible film can be used as a flavor substance, a nutrient additive carrier or as a separator for separation, protection and preservation.