Effect of Lactate Treatments on Survival of Food-Borne Pathogens in Frozen Shrimp (Penaeus merguiensis)

Abstract

Problem statement: Sodium lactate treatments were evaluated for reducing population of pathogenic bacteria such as Salmonella enteritidis, E. coli O157:H7, Vibrio parahaemolyticus and Vibrio cholerae, inoculated on frozen shrimp (Penaeus merguiensis). Approach: Fresh shrimp were inoculated with the above pathogens, separately, at level of 10⁵ CFU g^-1 and appliedin sodium lactate solutions (NaL: 0.5% and 2.5% v/v) and 1% Lactic Acid (LA) plus 1.5% sodium lactate (as buffered lactic acid) followed by freezing. The samples were stored at -18°C and antimicrobial and organoleptical effects of the treatments were evaluated after 90 days. Results: Results indicated that there was synergistic effect between frozen storage combined with 2.5% (v/v) buffered LA which resulted in a great significant reductions (p≤0.05) approximately 5.11, 5.39, 2.86 and 2.66 log CFU g^-1 in the number of colonies of V. cholerae, V. parahaemolyticus, S. enteritidis and E. coli O157:H7, respectively. On the other hand, although the effectiveness of sodium lactate increase with increased concentrations, however, there are sensory problems associated with increasing concentrations of sodium lactate. Conclusion/Recommendations: Therefore, 1.5% (v/v) sodium lactate plus 1.0% (v/v) Lactic Acid (buffered LA) was recommended to be used for frozen shrimps without adversely interfering with sensory quality.