Study On The Extraction Of Protein From Amaranthus And Its Functional Properties

In this paper, with the utilization of amaranthus as the main raw material, the alkaline-solution and acid-precipitation process to extract the amaranthus protein isolate from the amaranthus was optimized.Further studies were conducted to investigate the functional properties of amaranthus protein and the process of alcalase modification of amaranthus protein.The results were as followings:1、The composition of amaranthus was analyzed. The components were moisture10.8%, fat6.75%, ash2.85%, protein15.57%and starch63.5%.2、To obtain higher rate of protein extraction by the means of alkali-extracting and acid-precipitating, the extraction conditions were optimized mono-factor test and response surface methodology. The results shows that the optimized extracting conditions of total protein are as follow:alkaline extraction temperature40℃, alkaline extraction time107min, alkaline extraction pH10, liquid ratio of1:16. Under the conditions, the extraction rate of protein is71.91%。3、Amaranthus protein solubility, emulsifying and emulsion stability, foaming capacity and foam stability properties of functions, were measured at different protein concentration, pH value, ionic strength and temperature. The results showed:(1)The protein isolate solubility with the rise of pH. down then up, up in the isoelectric point of minimum, Amaranthus protein isolate solubility with NaCl concentration and temperature rise high and then decreased.(2)with the increase of temperature, the WHC and oil-binding capability of amaranthus decreased. When the temperature is above60℃,WHC of the protein decreased faster. The oil-binding capability of amaranthus decreased slowly.(3)With the increase of protein concentration, the protein of foaming ability and of foaming stability increased. Foam capacity (FC) as a function of pH showed a maximum value (136%) at pH2and it became lower at higher pH values. It remained marginally same at pH4-12. However, values of FS were highest at pH6. The foam stability increased with increasing NaCl concentration. Foam stability (FS) was improved significantly at all the concentrations of NaCl. But the increase of NaCl concentration had a little effect on the Protein of foaming stability.(4)With the increase of the Protein concentration, the Protein emulsifying Property and Emulsifying stability increased. Emulsifying activity (EA) of amaranth meal was highest (60%) at pH10and lowest at pH4(47.11%), while emulsion stability (ES) was maximum at pH6(62.07%) and minimum at pH12(48.95%).Emulsion stability (ES) was better in the presence of salts, but NaCl concentration has weak effect on the protein of emulsifying stability. At the temperature50℃, the Protein showed the highest emulsifying and emulsifying stability.4、Enzymatic hydrolysis modification treatment to amaranthus protein was adopted, and to determine its optimal technology condition by single factor experiment and orthogonal experiment. The results showed that the modified protein had improved greatly in the functional properties than the unmodified, especially in the solubility and foaming capacity. Under the optimized enzymatic hydrolysis conditions, the solubility was28.46%, foam capacity was131.2%, and emulsifying capacity was72.8%, that had been raised169%,148%and48%respectively as compared with the amaranthus protein which before modification. The changes of the components were observed by the SDS-PAGE electrophoresis on the amaranthus protein before and after enzymatic hydrolysis modification...