Antioxidative Activity of Tobacco Leaf Protein Hydrolysates

Discarded tobacco leaf protein hydrolysate (DTLPH) was prepared by enzymatic hydrolysis using papain and then separated using ultrafiltration (UF) membranes with molecular mass cut-off (MMCO) of 10, 5, 3 and 1 kDa. Four permeate fractions including 10-K, 5-K, 3-K and 1-K (the permeate fractions from 10, 5, 3 and 1 kDa) hydrolysate fractions were obtained. The 5-K hydrolysate fraction had high oxidation inhibilitory ratio (42.62 %), which was about twofold higher than the original hydrolysate and as high as that of vitamin E (a-tocopherol). The fractionated hydrolysates were superior to the original hydrolysate in the antioxidative activity tested. Moreover, these separated hydrolysates showed the enhanced functional property. The amino acid composition of 5-K hydrolysate was analyzed and the results show that the high antioxidative activity of 5-K hydrolysate was derived from high content of histidine, methionine, cystine and tryptophan.