Views: 0 Author: Site Editor Publish Time: 2022-10-28 Origin: Site
Rice protein is mainly composed of four types of proteins, including clear protein, globulin, alcohol-soluble protein and glutenin. The rice residue is mainly endosperm protein, which consists of albumin (4%-9%), salt-soluble globulin (10%-11%), alcohol-soluble glutenin (3%) and alkali-soluble glutenin (66%-78%). The quality of rice protein is better than wheat protein and corn protein, and it is hypoallergenic, while the amino acid composition pattern of rice protein is better than that of casein and soybean isolate, and it can meet the amino acid requirements of children aged 2 to 5 years, which makes it ideal for developing foods for infants and young children.
Among cereal proteins, the biological value (B.V.) and protein value (P.V.) of rice protein are higher than other proteins. The amino acid composition of rice protein is balanced and reasonable, and the amino acid content is high, which is unmatched by other vegetable proteins. Rice protein is recognized as a high-quality food protein, in line with the ideal pattern recommended by WHO/FAO. The biological value of rice protein is very high, and its nutritional value is high, which is comparable to that of eggs, milk and beef. In addition, rice protein is a low antigenic protein and does not cause allergic reactions, which is very beneficial to the production of infant food. Rice protein not only has unique nutritional functions, but also some other health-care functions. Recent studies have shown that rice protein can lower serum cholesterol levels.
Rice, rice grains, rice bran and other raw materials can be used to prepare rice protein. Focusing on the development and utilization of rice protein, researchers have proposed various preparation methods, mainly including: solvent extraction, enzymatic extraction, alkaline extraction, acid extraction, physical Extraction and compound extraction methods.
Rice protein quality is recognized as the leader among cereal proteins. It is rich in essential amino acids, the first limiting amino acid lysine content is higher than other cereal proteins, and the amino acid composition pattern is close to the WTO/FAO recommended pattern, which is easy to be digested and absorbed by the human body. . Compared with other cereal proteins, rice protein has higher biological value (BV) and protein utilization rate (PER), the biological value can be as high as 77, and the protein utilization rate is 1.36%~2.56%, ranking first among all kinds of grains. . Rice protein is superior in quality to wheat protein and corn protein, contains high-quality lysine, and has low allergy, making rice protein very suitable for the development of infant food. The amino acid composition pattern of rice protein is better than that of casein and soybean protein isolate, which can meet the amino acid needs of children aged 2 to 5 years. In addition, rice protein can be processed into soy sauce, high protein powder, protein drink, peptone and protein foaming powder, etc. If it is degraded into short peptides or amino acids, it can be made into amino acid nutrient solution with extremely high nutritional value, which can be used in health drinks , condiments, food additives, etc.
The effect of rice protein isolate on the expression of cyp4a and cyp2c in the kidney of young mice can improve the metabolism of arachidonic acid and can be used as an antihypertensive component. Studies have found that rice protein isolate can increase the amount of messenger ribonucleic acid (mRNAs), which are responsible for the synthesis of two important proteins cyp2c11 and cyp2c23 in the kidneys, which play an important role in the metabolism of arachidonic acid and hydroxyeicosatetraenoic acid. important role, and hydroxyeicosatetraenoic acid is important in regulating blood pressure. Clinical studies have found that rice protein isolate can lower cholesterol. Rice contains many chemicals related to its protein composition, including tocopherol derivatives, tocotrienols, and oryzanol, which have been shown to lower cholesterol.
A nutritious diet can prevent some diseases, such as heart disease and cancer. Asians are less likely to suffer from heart disease than Europeans, which may be related to the fact that Asians eat rice as their staple food. Relevant studies have found that rice protein isolate has a certain inhibitory effect on atherosclerosis in a mouse model of genetic high cholesterol, and can reduce the damage caused by atherosclerosis to arteries heart disease rate.
The solubility of rice protein is low, mainly because rice protein contains 75%~90% alkali-soluble glutenin. These glutenins are formed by many macromolecular fragments through disulfide bonds, cross-linked and aggregated with each other, while water-soluble albumin is only It accounts for 2% to 5% of rice protein. Samson Agboola et al. found that at pH 4~7, the solubility of rice protein gluten increased slowly, and when it was close to pH 9, the protein solubility increased rapidly; at the same time, the modification would have a certain impact on the solubility of rice protein.
Emulsification includes emulsifying activity and emulsifying stability. Emulsification is one of the important functions of protein. Each protein has a certain molecular composition and specific spatial structure, and its emulsifying properties are closely related to the hydrophobicity of the molecular surface. Acid-base can change the charged properties and charge distribution of proteins, and change the spatial conformation of molecules, which may improve the physicochemical functions such as protein emulsification and foaming while improving solubility. For example, the emulsification of the rice protein hydrolyzate after being hydrolyzed by pronase is greatly improved.
Under the optimal enzymatic hydrolysis reaction conditions, at the beginning of the reaction, as the hydrolysis degree of the enzymatic hydrolyzate increases, the foaming property of the enzymatic hydrolysate increases. When the hydrolysis degree reaches 10.4%, the foaming property is the highest (37.5%); When the degree of hydrolysis increases, the foaming property decreases rapidly. When the degree of hydrolysis reaches 11.5%, the foaming property begins to decrease slowly, and the foaming stability also has a similar trend. It was found that with increasing protein concentration, its foamability and foaming stability were enhanced. In order to obtain the best foaming characteristics, both solubility and hydrophobicity should be taken into account, and a good balance of hydrophilicity and hydrophobicity should be achieved. Some researchers believe that insoluble protein particles will improve the foaming stability. The study found that at pH 4~7, the solubility and emulsifying properties of gluten in rice protein increased slowly, and when it was close to pH 9, it increased rapidly. At the same time, the foaming property of the rice protein hydrolyzate after hydrolysis by pronase increases greatly with the increase of its nitrogen solubility.
The water-holding capacity of white matter is closely related to the "preservation" and "shape preservation" of food during storage, and it is also related to the viscosity of the food; while the oil absorption is related to the type of protein, source, processing method, temperature and oil used. Due to the poor solubility of rice protein, its water and oil holding capacity is limited. However, after deamidation modification, the water and oil holding properties of rice protein were improved. When the degree of deamidation was 35.7%, the water holding capacity was the lowest at 2.4 g/g, and the oil holding capacity was the highest at 3.4%. When it is 42.4%, the water holding capacity and oil holding capacity are equivalent, both are 2.6g/g.