A predictive model for assessment of decontamination effects of lactic acid and chitosan used in combination on Vibrio parahaemolyticus in shrimps

Abstract

Vibrio parahaemolyticus is a major causative agent of human gastroenteritis in seafood products including shrimps. Lactic acid and chitosan are natural antimicrobials for food decontamination in the washing process of seafood. In this research, a 4-factor response surface model based on the Box–Behnken experimental design was developed to evaluate the effects of lactic acid (1%, 2%, and 3%, v/v), chitosan (0.4%, 1%, and 1.6%, w/v), rotational rate (90, 110, and 130rpm) and washing time (10, 20, and 30min) on reduction of V. parahaemolyticus inoculated in raw shrimps. These treatments achieved 2.2 to 4.3log10CFU/g reduction of V. parahaemolyticus in shrimps. Stepwise stratification led to a simplified model that has a satisfactory performance as evidenced by statistical indices (R2=0.92; p<0.0001; RMSE=0.196) and external validation parameters [bias factor (Bf)=1.01; accuracy factor (Af)=1.05]. The model generated an optimum treatment combination (3% lactic acid, 1.6% chitosan, and rotational rate at 110rpm) that could achieve greatest bacterial reduction of 4.5log10CFU/g. Among the four factors, lactic acid and chitosan were the major contributors for bacterial decontamination. Analysis of variances showed a significant interactive inactivation effect (p<0.05) from combined use of lactic acid and chitosan. The treatments did not have adverse effects on the quality attributes such as color and pH of the shrimps.