Static hydrothermal processing and fractionation for production of a collagen peptide with anti-oxidative and anti-aging properties

[Display omitted] •Hydrothermal process showed efficacy for collagen hydrolysis.•Elevated temperature and pressure are synergistic in hydrothermal hydrolysis.•Hydrothermal process is an environmentally friendly and effective technology.•An ultrafiltration membrane is useful for separation of bioactive peptides.•Collagen peptides exhibited superior antioxidant and anti-aging abilities. Collagen, in a form suitable for human consumption, can be obtained from the large amounts of fish skin via protein hydrolysis to produce low-molecular-weight substances with enhanced bioavailability and function. To optimize this method, we investigated the synergistic effect of elevated temperature (150–250 °C) and pressure (350–3900 kPa) of a hydrothermal process on the hydrolytic ability and characteristics of collagen hydrolysates. Elevated temperature and pressure of the hydrothermal process increased the levels of free amino groups and lower-molecular-weight collagen hydrolysates, particularly at 210 °C and 2100 kPa. The resulting hydrolysates were fractionated by ultrafiltration membranes of different molecular weight cutoff and evaluated for their antioxidant (ABTS radical scavenging activity and reducing power) and anti-aging (tyrosinase and collagenase inhibition) activities. The