A survey of microbial levels for incoming raw beef, environmental sources, and ground beef in a red meat processing plant

Abstract

A microbial survey was performed for a midwestern red meat processing plant that produces retail cuts and ground beef. Samples were obtained from incoming ingredients, beef during processing, finished product, food contact and environmental surfaces, and the air. Aerobic plate count (APC), coliform count (CC), andEscherichia colicount (ECC) were determined for each sample. Product samples (25 g) were taken from beef carcasses, boxed beef, and ground beef. Swab samples (10 cm2) were obtained from food surfaces, food contact surfaces, floors, and walls. All samples were plated on aerobic plate count Petrifilm (for APC) andE. coliPetrifilm (for CC and ECC). Average log10APC for product samples ranged from 3 cfu g−1for retail cuts to nearly 7 cfu g−1for boxed beef and the brisket and flank areas of beef carcasses. Average log8APC for ground beef samples was 4.6 cfu g−1. Average log10CC for product samples ranged from 1.4–2.3 cfu g−1. Highest CC was usually obtained from the brisket area of the beef carcass. Average log10ECC ranged from <1–2 cfu g−1and ECC was usually highest in finished ground beef. Average surface counts for log10APC ranged from <1 cfu cm−2on sanitized processing equipment to 5 cfu cm−2on processing floors. Coliforms andE. coliwere rarely recovered from food contact surfaces or from food surfaces. Airborne log10APC was generally low (0.6 cfu m−3), except for the carcass receiving area where counts were 2.4 cfu m−3. The most important factor contributing to source and level of microbial contamination for ground beef and retail cuts was from incoming raw materials obtained from different suppliers of beef. Microbial testing for beef products and the environment is an important tool for identifying and monitoring potential hazards as part of HACCP and GMP program development.