Do You Know What The Characteristics Of Rice Protein Are ?
Among cereal proteins, rice protein is a plant protein with high nutritional Value. It not only has high Biological Value (BV), but is rich in essential amino acids and lysine content is higher than that of other cereals. In addition, rice protein has the characteristics of hypoallergenicity, no pigment interference and soft taste that soy and milk cannot match. Therefore, rice protein has attracted more and more attention from the food industry.
1. Solubility of rice protein
Solubility is one of the important factors determining the functional properties of food protein, because the solubility of protein directly affects its emulsification, foaming and gelation properties, and thus plays a decisive role in its application in food.
The solubility of rice protein changed with pH, and the new rice protein (LTRPC) had better solubility than the traditional rice protein (HTRPC). In acidic and alkaline solution under the condition of the solubility of LPRTC than in neutral solution under the condition of much higher, this is mainly because of the rice protein gluten dominate, and fragments of gluten is made up of many large molecules through disulfide bond formation, crosslinking and cohesion, to each other about 80% of the gluten can not soluble in neutral salt solution, can only be dissolved in dilute acid, dilute alkali. The solubility index of 60% indicated that the denaturation of rice protein was well avoided during the whole process. However, for HTRPC, its solubility change is not as obvious as that of LTRPC, which may be due to the denaturation of rice protein after high temperature treatment, which changes its structure and leads to the change of its solubility.
2. The Blister of rice protein
Foam usually refers to a dispersed system of bubbles in a continuous liquid or semisolid phase containing soluble surfactants. Because rice protein contains hydrophobic groups and hydrophilic groups, it has surface activity and can form foam when fully stirred. Good foaming ability and foam stability is a prerequisite for protein with high solubility, because dissolved protein can quickly spread to the air/water interface, and quickly, enrichment and spread, around the sparkling form adsorption film, so as to reduce the surface tension, at the same time, insoluble protein particles can improve the surface viscosity and plays a useful role in the stability of foam. LTRPC not only has good foaming ability, but also excellent foam stability. For HTRPC, low solubility leads to low foaming ability and even worse foam stability. After 30 minutes, the foam height is almost zero.
3. The Emulsification of rice protein
Emulsification refers to the ability of protein to combine oil and water to form an emulsion. Because soluble protein can diffuse and adsorb at the oil/water interface is one of the important characteristics determining the emulsification property of protein, the high solubility of protein is very beneficial to its emulsification. Emulsifying stability refers to the ability of oil-water solution to maintain stability, which is related to interfacial tension, protein surface charge number, solution PH, concentration, etc. Through the comparison of LTRPC and HTRPC, although the emulsification of LTRPC is close to that of HTRPC, there is an obvious gap in the stability of the two. These results indicate that LTRPC can be used as a good functional protein additive in emulsified food.
4. Water Holding Capacity of rice protein
The water holding capacity of protein refers to the residual water content of protein after centrifugation in a certain concentration of protein aqueous solution. There are three conditions for protein to have good water retention: (1) protein particles can fully swell but not dissolve after rehydration; (2) protein particles have good viscosity after rehydration; (3) protein can form gel network. In the comparison between LTRPC and HTRPC, the water holding capacity of LTRPC is much higher than that of HTRPC, which may be due to the difference in production process. LTRPC maintains the original biological activity of protein without high temperature treatment, while in the production process of HTRPC, the high temperature of more than 100 degrees Celsius far exceeds the temperature of denaturation of rice protein. This may change the structure of protein, resulting in poor cross-linking ability of protein particles after swelling.