Study On Protein Characteristic And Polypeptide’s Functional Activity Of Almond

Almond protein is of higher quality among the plant proteins. The research object is Jiayi Almond produced in MaiJi district, TianShui city in Gansu Province. To optimize the extraction process of almond protein, alkali-extraction and acid-precipitation method was carried out. Then the functional properties of almond protein including solubility, water-holding capacity, oil-holding capacity, foaming property and emulsifying property were analyzed. The SDS-PAGE was used to analyze the protein subunits and the technology of hydrolyzing almond protein is optimized. Finally, the cleaning nitrite and blocking synthesis of nitrosamine by almond polypeptide were studied. The results of experiment were as follows:Research on extracting almond protein:firstly, the experiment is carried out in the condition of single factor that is pH, liquid-to-solid ratio, reaction time and temperature. Then by using orthogonal test the optimum condition of extracting protein were as follows:pH10, liquid-to-solid ratio1:30, reaction time50min and temperature45℃. Under the optimum condition, the yield of almond protein could amount to58.98%, with purity of79.3%, and the isoelectric point (pI) of almond protein was4.4with the isolation rate of98.26%.The functional properties of almond protein:the solubility, water-holding capacity, oil-holding capacity foaming property and emulsifying property were studied. pH had significant effects on the functional properties of almond protein, and the solubility, foaming capacity and emulsifying capacity reached the minimum near the pI, but emulsifying stability reached the maximum.SDS-PAGE analysis suggested that the distribution range of almond protein molecular weight is between14.4and45KDa and the number of subunits is9. According to the relative mobility, the molecular weight of nine stripe are mainly44.8,42.4,35.9,31,24.5,22.8,19.6,17.2,14.9KDa.Research the optimum hydrolysis technology for almond protein:firstly, the compound protease is filtrated to hydrolyze effectively the almond protein. In the condition of single factor that is pH, substrate concentration, enzyme quantity and temperature, the test is carried out. Finally, by using orthogonal test the optimum condition were as follows:pH8.5, substrate concentration7%, enzyme quantity5%and temperature50℃. Under the optimum condition, the degree of hydrolyzing almond protein is29.71%.The cleaning nitrite and blocking synthesis of nitrosamine by almond polypeptide:In the condition of simulated gastric juice, the experiment result showed that the cleaning rate of nitrite and the blocking rate of synthesis of nitrosamine increased following with the increase of polypeptide’s concentration and reaction time. The maximum rate for cleaning nitrite reached86.0%, and the maximum rate for blocking synthesis of nitrosamine reached61.0%. Compared with Vc, it has weak capability of cleaning nitrite and blocking synthesis of nitrosamine.