Bactericidal Efficacy of Food Additive-Grade Calcium Hydroxide Against Salmonella Infantis on Eggshells

The bactericidal efficacy of food additive-grade calcium hydroxide [FdCa(OH)₂] was evaluated for inactivation of Salmonella Infantis and Salmonella Enteritidis in liquid and Salmonella Infantis on contaminated eggshells. The activity of FdCa(OH)₂ was also compared with that of sodium hypochlorite (NaOCl) containing 150 ppm chlorine (150 ppm NaOCl). FdCa(OH)₂ solutions (0.1% and 0.2%) in the presence or absence of organic materials (5% calf serum [CS]) at pH 12.6 were used to inactivate Salmonella Infantis and Salmonella Enteritidis in a reaction tube or on eggshells artificially contaminated with Salmonella Infantis. Both 0.1% and 0.2% FdCa(OH)₂ were capable of inactivating Salmonella Infantis and Salmonella Enteritidis in liquid at >3 log₁₀ colony-forming units (CFU)/ml within 3 and 1 min of contact time, respectively, even in the presence of 5% CS. Additionally, 0.1% and 0.2% FdCa(OH)₂ reduced bacterial levels on contaminated eggshells to >3 log₁₀ CFU/ml, within 3 and 1 min, respectively, in the presence of 5% CS. Without CS, 0.1% and 0.2% FdCa(OH)₂ could reduce bacteria on eggshells to >3 log₁₀ CFU/ml within 1 min and 30 sec, respectively. In contrast, 150 ppm NaOCl solution could not inactivate bacteria on eggshells down to >3 log₁₀ CFU/ml within 3 min contact time, either with or without CS, and no bacterial reduction was observed in redistilled water. The findings of the present study indicate that FdCa(OH)₂ solution has high efficacy against foodborne bacteria and may be a good candidate for enhancement of biosecurity at farms and egg processing plants.