Subcritical water hydrolysis for the production of bioactive peptides from tuna skin collagen

Subcritical water hydrolysis was applied to obtain antioxidant and antimicrobial hydrolysates from tuna skin and isolated collagen. Different temperatures (150-300 degrees C) with a pressure (50-100 bar) and reaction time (5 min) were employed to find the optimum condition. Degree of hydrolysis was highest at 250 degrees C for both skin hydrolysate (SH) and collagen hydrolysate (CH). Antioxidant activities evaluated by four different assays increased with increasing temperature and were found to be highest at 280 degrees C. Both hydrolysates showed antimicrobial activity with the highest activity at 280 degrees C in CH. The structural and free amino acids in CH were found to be highest at 220 degrees C and 250 degrees C, respectively. Molecular weight profile of selected hydrolysate showed that low molecular weight peptides ( < 600 Da) and/or free amino acids are associated with functional activity. Therefore, hydrolysates produced have immense potential to be used as functional elements in food industries.