Temperature-dependent extraction kinetics of hydrolyzed collagen from scales of croaker fish using thermal extraction

This study investigates the kinetics of hydrolyzed collagen extraction from the scales of the croaker fish (Pseudotolitus elongatus) at temperature ranging from 60°C to 90°C. Extraction was carried out using hydrothermal treatment over a period of 8 hr, during which the mass of hydrolyzed collagen extracted was obtained every hour. The rate order of extraction was temperature-dependent within the times investigated. At 60°C no measurable extraction was achieved, between 70°C and 80°C the extraction was a zero order while at 90°C and 100°C the extraction was a first order process. The rate constants for 70, 80, 90 and 100°C were 0.56 g s^-1, 1.03 g s^-1, 0.019 s^-1 and 0.04 s^-1, respectively. The overall yield increased as temperature is increased with the highest increase in yield occurring between 90 and 100°C. The yield increased from 6% at 70°C to 30% at 100°C, thus indicating that temperature has significant effect on the yield as well as kinetics. These findings are relevant in the predictive assessment as well as design and optimization of processes for extraction of hydrolyzed collagen from fish scales.