Title: Effects of antimicrobial coatings and cryogenic freezing on survival and growth of Listeria innocua on frozen ready-to-eat shrimp during thawing Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2013
Publication Date: August 1, 2013
Citation: Guo, M., Scullen, O.J., Sommers, C.H., Jin, Z.T. 2013. Effects of antimicrobial coatings and cryogenic freezing on survival and growth of Listeria innocua on frozen ready-to-eat shrimp during thawing. Journal of Food Science. 78(8):1195-1200. Interpretive Summary: Frozen ready-to-eat (RTE) shrimp are precooked. They are thawed and consumed typically without further heat treatment; therefore, would pose a higher health risk if they are contaminated with foodborne pathogens such as Listeria monocytogenes, as compared with raw shrimp. In this study, edible antimicrobial coatings alone, or in combination with cryogenic freezing, were evaluated for their ability to inhibit the growth of Listeria innocua on RTE shrimp during thawing period. The coating treatments significantly reduced or inhibited Listeria growth on shrimp thawed at 4, 10 or 22 degree C for either 24 or 48 h. The combination of edible antimicrobial coatings with temperature controls would be an effective approach to enhance the safety of RTE shrimp.
Technical Abstract: Foodborne pathogens such as Listeria monocytogenes could pose a health risk for frozen ready-to-eat (RTE) shrimp as the pathogen can grow following thawing. In this study, antimicrobial coating treatments alone, or in combination with cryogenic freezing, were evaluated for their ability to inhibit the growth of Listeria innocua, a surrogate for L. monocytogenes, on RTE shrimp during thawing. Cooked RTE shrimps were inoculated with L. innocua at three population levels and treated with coating solutions consisting of chitosan, allyl isothiocyanate (AIT), or lauric arginate ester (LAE). The treated shrimp were then stored at -18C for 6 days before being thawed at 4, 10, or 22C for either 24 or 48 h. Results revealed that antimicrobial coatings achieved ca. 5.5 to 1 log CFU/g reduction of L. innocua on RTE shrimp after the treatments, depending on inoculated population levels. The coating-treated shrimp samples had significantly (p less than0.05) less L. innocua than controls at each thawing temperature and time. Additional cryogenic freezing to coating treatments did not achieve synergistic effects against L. innocua. Antimicrobial coatings can help to improve product safety by reducing Listeria on RTE shrimp.