Studies On Camellia Seeds-Cake Protein And Peptides From Cold Pressing Camellia Seeds

In this paper, the extraction technology and the functional properties of cold pressing camellia seeds-cake protein were studied. The preparation techniques & the optimal extraction process of camellia seeds-cake peptides and ACE inhibitory peptide through hydrolyzing camellia seeds-cake protein by neutrase were studied, molecular weight distribution and amino acids composition of polypeptides were determined and analyzed by high performance liquid chromatography. The simulation experiments in vitro were used to determine the effects of camellia seeds-cake peptides on scavenging active oxygen free radicals. The main findings are as follows:Through orthogonal and optimization experiments, the optimal conditions for protein extraction were:The leaching solution pH value,10.0; extraction temperature, 45℃; grinding degree of teacake,80 mesh; feed-liquid ratio,1 :25; leaching,80 min and pH value of extracting solution,4.5.At this condition, protein extraction rate was 57.8%.Through four-factor quadratic regression orthogonal rotation experiments, a mathmatical model was set up as follow:Y=-205.520625-0.000581*X1+2.240417*X2+46.334167*X3+0.261667*X4-0.00 0000177*X1*X1+0.000012692*X1*X2-0.026592*X2*X2+0.000233*X1*X3+0.004500 *X2*X3-3.434167*X3*X3+0.000265*X1*X4+0.027000*X2*X4+0.275000*X3*X4-0.6 49167*X4*X4Based on this model, the optimal conditions for neutrase enzymolysis were: enzymolysis temperature 46.8℃, enzymolysis time 4.3 hours, enzymolysis pH value 7.2, substrate concentration 3.0%,and the amout of enzyme 8028.2 u/g substrate, the degree of hydrolysis was up to 12.4%.The total amino acids of camellia seeds-cake protein was 43.38 g/100g protein, and the glutamic acid was up to 9.67 g/100g protein. To the camellia seeds-cake protein, most of them was insoluble in water, but soluble in dilut alkali, and the isoelectric ponit was around pH5.The results indicated that MW of the most of camellia seeds-cake peptides were below 3000 Da, the oligopeptide(MW below 1000 Da) were predominated (83.73%). The MW of those components was 942.3; the average length of peptide chain(PCL) was 8.4. The oligopeptide was up to 97.54%, the MW changed into 905.1 and PCL to 8.06 after ultrafiltration.Through three-factor quadratic regression orthogonal rotation experiments, a mathmatical model was set up as follow: Y=-700.499176+30.442000*X1+5.646534*X2-2.555909*X3-0.323605*X1*X1+0.002 000*X1*X2-0.698722*X2*X2+0.236841*X1*X3+0.112727*X2*X3-1.124574*X3*X3Based on this model, the optimal conditions for ACE inhibitory peptides were: enzymolysis temperature 48.6℃, substrate concentration 4.4%,the ratio of enzyme and substrate concentration 4.2%, pH value7.2,and enzymolysis time 3 hours, ACE inhibitory rate was 46.24%.The simulation experiments in vitro were used to determine the effects of camellia seeds-cake peptides on scavenging active oxygen free radicals. The results indicated that camellia seeds-cake peptides can scaveng hydroxyl radical, superoxide anion radiacl and DPPH·radical.