Incorporation of probiotics in post-harvest wash treatments reduces Salmonella contamination and improves egg safety

Salmonella Enteritidis (SE) is a prevalent foodborne pathogen that is commonly transmitted through contaminated shell eggs. Therefore, decontamination of eggs is critical to food safety. Hence, this study determined the efficacy of incorporating probiotics in wash water to promote egg safety. Fresh eggs inoculated with a five-strain mix of SE (∼9 log CFU/egg) were washed using either a dip or spray method with one of the following treatments: Lactobacillus rhamnosus NRRL-B-442 (LR; ∼10 log CFU/ml), L. paracasei DUP 13076 (LP; ∼10 log CFU/ml), Hafnia alvei (HA; ∼10 log CFU/ml), chlorine (200 ppm), or tap water (Control). Eggs were sampled for surviving SE and probiotic populations immediately following wash and during refrigerated storage for 21 days. Three independent trials were conducted in a completely randomized design, and data were analyzed using GraphPad (Version 9.3.1) with significance set at P ≤ 0.05. Both dip and spray application of probiotics significantly reduced SE populations on eggshells and within internal contents throughout refrigerated storage (p ≤ 0.05). On the external surface SE populations in LP and LR groups were reduced to ∼4 log CFU/egg and ∼2 log CFU/egg on days 7 and 14 respectively, while ∼5.6 log CFU/egg and ∼4.8 log CFU/egg were still recovered from control and chlorine-treated samples. Similarly, only 10 % of probiotic-treated samples tested positive for SE in internal contents as opposed to 30-40 % positivity in the control and chlorine-treated samples. Overall, probiotic application by spraying or dipping significantly reduced SE populations on eggs (P ≤ 0.05) without impacting egg quality parameters including Haugh units and egg grade (P > 0.05). Although both washing modalities were effective, reduced water usage makes the spray method more environmentally friendly. Overall, incorporation of probiotics in wash water can be a safe, effective, and organic-friendly antimicrobial strategy to promote egg safety.