Optimisation of the marination process for frozen-thawed squid rings using response surface methodology.

The frozen-thawed squid rings were marinated by using different formulations of the mineral water and lemon juice at different times at 4°C. Analyses of microbe counts (total mesophilic bacteria (TMB), total psychrotrophic bacteria, lactic acid bacteria, yeast-mould, Enterobactericeae, coliform, fecal coliform, E.coli, S.aureus, Vibrio spp.), pH and sensory factors were conducted during the marination process. Increasing the fraction of lemon juice in the marinade solution resulted in a decrease in the number of TMB and a lower squid ring pH. Increasing the fraction of lemon juice in the marinade solution increased the growth of lactic acid bacteria. Faecal coliform, E.coli, S.aureus and Vibrio spp. were not observed in any of the marinated or non-marinated samples. Response Surface Methodology (RSM) was used to optimise the marination conditions, including the content of the marination liquid (lemon juice+mineral water), the marination time (1,3,6,12,24,48,72 h) and the pH. The recommended optimal conditions for marinating frozen-thawed squid rings at 4°C are as follows: 41.2 ml lemon juice+61.7 ml mineral water/100 g squid rings, pH 4.4, 1 h marination time. Additionally, Good agreement was found between the experimental values and those estimated from the RSM model for the pH (r² =0.89), total mesophilic bacteria count (R² =0.93) and lactic acid bacteria count (r² =0.84). Given the desirable sensory qualities of the resulting squid rings, these optimal marination conditions can be evaluated in the seafood-processing industry. [ABSTRACT FROM AUTHOR]