Relationship Between Degree Of Hydrosis And Functionality Of Soybean Protein Isolate And Development Of Dispersed Protein

Soybean protein isolate, mainly used in meat products, beverages, frozen food, is a kind of high-protein functional foods or food ingredients, which is obtained by removing the soybean oil and water-soluble non-protein ingredients at low temperature. The soybean protein isolate is viewed as a good source of vegetable protein with high nutritional value and good functional properties.Nowadays, there are fewer types of soy protein isolate in China, and most of them are gel-bases soybean protein isolate. Therefore, the study of functional properties of modified soy protein isolate is particularly important. The enzyme aqueous process is the common modification method in addition to physical and chemical modification method. The condition of enzyme aqueous modification method is mild, which will not damage the original function of protein. Furthermore, enzyme aqueous modification method is easy to operate with a wide practical application. In recent years, there are many studies of soy protein solution in China, while the researches about the functional properties of soy protein isolate hydrolysates are single, poor uniformity and largely meaningless to industrial application. Therefore, the research of the properties of soybean protein isolate hydrolysates plays an important role in the production and promotion.In this study, the solubility, water holding capacity, emulsification, oil absorption, foaming, gelation, viscosity and film-forming properties of eight kinds of processing functions of four different proteases (alkaline protease, neutral protease, papain and flavourzyme) hydrolysates were studied and then valued the bitterness of protein after hydrolysis. According to the results, a highly dispersed soybean protein isolate was developed, and then determine the optimal conditions of different approaches to debitter in order to choose a suitable way for debitter. Finally, the optimum conditions of high dispersion soybean protein isolate were determined and analyzed the prepared product.1) The functional processing and bitterness of hydrolysis of soybean protein isolate were studied under the determined hydrolysis degree. The result shows as follows: the solubility and emulsifying activity of neutral protease is best, the water holding capacity, oil absorption, emulsion stability, foaming capacity, gelation and viscosity of papain is best, the hydrolysis solution of flavourzyme is no bitterness and the bitterness of alkaline protease hydrolysates is maximum. 2) The solubility of neutral protease is best by processing functional determining. The neutral protease was chosen for the development of high dispersed soybean protein isolate. Optimum the hydrolysis condition of neutral protease bases on the NSI value, the result shows as follows: reaction temperature 45°C, substrate concentration 5%, enzyme dosage 7000U/g, reaction time 6h and reaction pH 7.5.3) Based on the cost and optimum conditions of neutral protease, the production conditions of high dispersed soybean protein isolate are as follows: hydrolysis 2h under the neutral protease,the hydrolysates of neutral protease were bitter and reached its highest bitterness value at 20 min. The comparison of enzyme debitter and active carbon debitter of flavourzyme technology was studied. The optimum debitter condition of flavourzyme was: temperature 50℃, enzyme dosage 280U/g, pH 7 and reaction time 3h; active carbon content 2%, pH 5, temperature 65°C and reaction time 15 min. By comparing the two methods in terms of safety, cost and protease loss, the optimum debitter method of flavourzyme was finally determined.4) Based on the cost and optimum conditions of neutral protease, the production conditions of high dispersed soybean protein isolate are as follows: hydrolysis 2h under the neutral protease, debitter 3h by flavourzyme and the NSI of final production is 92.63%.