Kamal Alahmad^{1, 2}, Wenshui Xia^1,, Qixing Jiang¹, Yanshun Xu¹

In our study, fish protein hydrolystes (FPH) were produced from bighead carp using ficin and flavourzyme enzymes with fresh and dried substrates. Under optimum conditions for two proteases, the hydrolysates obtained from fresh substrate showed a significant variation in different characteristics compared with hydrolysates obtained using microwave-dried substrate. The best E/S ratio was 3% with DH 16.85% and 4% with DH 22.51% (fresh substrate) for ficin and flavourzyme respectively, whereas, the best ratio of (dried substrate) was 4% with DH 13.92% and 4% with 17.31% for ficin and flavourzyme enzymes respectively. The yield of FPH was recorded 16.11% and 17.39% (fresh substrate) using ficin and flavourzyme respectively. Moreover, more peptides with low molecular weight were formed during hydrolysis which could enhance the functional properties of FPH in particular solubility property which ranged from 84% to 95%. However, FTIR demonstrated that enzymatic hydrolysis with type of substrate had an influence on the secondary structure of the protein by observing a slight change in wavelength of amide band. Furthermore, DDPH radical scavenging and hydroxyl radical scavenging were determined and showed high activity values of the hydrolysates products. The present study revealed that the physicochemical, structural and antioxidants properties of protein hydrolysates under hydrolysis of two proteases could be a great source of protein and possess a potential applications in food factory.

ficin, flavourzyme bighead carp, enzymolysis, amino acids, FTIR, solubility, SEM, antioxidants properties