Chemical composition, molecular mass distribution and antioxidant capacity of rohu (Labeo rohita) roe (egg) protein hydrolysates prepared by gastrointestinal proteases

Underutilized Labeo rohita roes, a by-product from fish processing units, were subjected to proteolytic hydrolysis using digestive proteases namely, pepsin and trypsin to prepare bioactive roe protein hydrolysates. The degree of hydrolysis was found to be 34% and 21%, respectively, for pepsin and trypsin enzymes after 180min of hydrolysis at 37°C. Evaluation of chemical composition of pepsin and trypsin hydrolysates revealed the presence of high protein content (69.3% for pepsin & 73.5% for trypsin) with all essential amino acids, good proportion of ω-3 fatty acids, especially docosahexaenoic acid (DHA) and substantial amounts of K, Na, P, Fe, Mg and Zn. Molecular mass analysis of hydrolysates demonstrated the presence of highest level of low molecular mass peptides below 10kDa. Both the hydrolysates showed excellent antioxidant activities in a dose dependent manner in various in vitro models such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-azino-bis(3-ethylbenzthiazoline-6)-sulfonic acid (ABTS+) radical cation scavenging activity, ferric reducing antioxidant power (FRAP), and ferrous ion (Fe2+) chelating ability. In conclusion, these results suggest that bioactive roe protein hydrolysates could be useful in food industry for various applications. •Bioactive rohu roe protein hydrolysates were prepared by pepsin and trypsin enzymes.•Protein hydrolysates contained high quality protein, ω-3 fatty acids and minerals.•Molecular mass analysis indicated the presence of peptides below 10kDa.•Hydrolysates showed excellent antioxidant activities in various in vitro methods.•These protein hydrolysates could be useful in the food or pharmaceutical industries.