EFFECT OF COMPOSITION AND METHOD OF FREEZING ON MICROBIAL-FLORA OF GROUND BEEF PATTIES

This study was designed to evaluate effects of meat composition and freezing by conventional or cryogenic methods on microbial numbers and types in beef patties. Beef patties of different fat content or containing soy protein were frozen by liquid nitrogen, liquid carbon dioxide, or by mechanical freezing and stored at – 18°C for 5 months. Cryogenic freezing produced significantly greater reduction in total viable mesophiles and paychrotrophs than did mechanical freezing. Patties containing 30% fat provided greater survival than observed with 20% fat or added soy protein. After frozen storage, predominant flora consisted of species of Moraxella‐Acinetobacter (42%) and Pseudomonas (32%). The former group was favored by mechanical freezing, but a greater proportion of Pseudomonas app. survived cryogenic freezing than mechanical freezing. Copyright © 1979, Wiley Blackwell. All rights reserved