Statistical Optimization of Salmonella Survival in Different Protein Hydrolysates

Abstract

Protein hydrolysates are composed of peptones and peptides, and their type depends on the biological source and manufacturing process. We studied the survival response of Salmonella enterica in the presence of casein, soy protein, and fish protein hydrolysates at refrigeration and freezing temperatures. Fish protein hydrolysate (FPH) was identified as the only capable hydrolysate of sustaining the viability of S. enterica for 60 days at refrigeration temperatures. None of the three hydrolysates were able to impart cryoprotection to S. enterica under freezing conditions. The survival rate of S. enterica in FPH was further enhanced by growing the inoculum on agar instead of broth. An optimization study using response surface methodology was also conducted to identify suitable concentrations of protein hydrolysates capable of maximizing the survival of S. enterica. The results of this study can be used to manage Salmonella-related food safety incidents by replacing animal-sourced with plant-sourced protein hydrolysates at the recipe development stage, as well as the use of FPH in microbiological growth media and the formulation of secondary reference materials. These results indicate that FPH produced by enzymatic hydrolysis of Stolephorus indicus at lower concentrations (5%) can serve as nutritive agents in culture media, contribute to long-term preservation, and can be used in the formulation of quantitative reference materials for Salmonella.