Comparative dynamics of fish by-catch hydrolysis through chemical and microbial methods

Abstract

Fish protein hydrolysates were prepared through microbial-assisted fermentation (using Lactobacillus plantarum and Pediococcus acidilactici), and compared to the conventional chemical-assisted hydrolysis (using formic acid). The effects of processing method (chemical and microbial), temperature (30 °C and 37 °C), lactose concentration (5% and 10%, w/w) and duration (1–9 days) on dynamics of proteolysis and kinetics of fermentation were investigated. For all the treatments, the residual dry matter reached a constant level after 3 days of processing indicating a rapid liquefaction of fish biomass. Regardless of the processing method, the degree of hydrolysis rapidly increased in the first 3 days and stabilized thereafter reaching more than 40%. The bioprocessing of fish by-catch for 6 days at 37 °C using 1% (w/w) lactic acid bacteria (LAB) and 5% (w/w) lactose as a substrate were the optimum conditions for maximizing the release of peptides through the microbial-assisted fermentation. The optimum conditions for the chemical-assisted hydrolysis were 6 days at 30 °C using 2% (w/w) formic acid.