Stability of antioxidant properties and essential amino acids in squid viscera hydrolysate produced using subcritical water

Abstract

Subcritical water hydrolysis was carried out in a batch reactor to produce valuable materials, such as low-molecular weight (MW) peptides and essential amino acids with antioxidant properties, from heat-dried squid viscera. Hydrolysis of squid viscera was performed at 160 to 280°C for 3 min. The yield was increased by increasing the temperature and pressure, while the protein content of squid viscera hydrolysate decreased with increasing temperature. Low-MW peptides were detected in all hydrolysates by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The highest yields of free and structural amino acids in heat-dried squid viscera hydrolysate were at 160°C and were 411.95 ± 1.15 and 346.62 ± 1.25 mg/100 g, respectively. All essential amino acids were detected in viscera hydrolysates; leucine was the most abundant. Antioxidant activities of hydrolysates were highest at 220°C. Greater than 98 ± 0.26% of the ABTS antioxidant activity was retained in hydrolysates after long-term heat treatment. © The Korean Society of Fisheries and Aquatic Science.