Microbial shelf life of chub-packaged ground beef from four large U.S. processing plants (1998)

P.E Peters,S.D Gamage,J.B Luchansky,Randall K Phebus

doi:10.4148/2378-5977.1913

Abstract

Ten pound chubs of coarsely ground beef quality of ground beef becomes an important of two different lean:fat specifications (73:27 issue. The nutrients in meat that are essential and 81:19) were stored at three temperatures for humans also are essential for microorgan(34, 38 or 45EF) to monitor the effects of isms, resulting in an extremely perishable storage temperature on microbial condition of product. the product. Ground beef from four U.S. plants was tested (2 trials each), and microIncreased bacterial growth reduces shelf bial analyses were conducted on storage days life by initiating spoilage characteristics such 0, 6, 10, 14, and 18 using seven different as off odor, off color, and gas formation in media to estimate counts of total aerobic and vacuum bags. Contamination during processanaerobic, lactic acid bacteria (LAB), and ing limits shelf life of the already fragile Gram-negative bacteria. Bacterial counts for ground beef product. a given culture medium were similar among plants and meat types. At day 10, total miGroups of microorganisms interact to crobial counts from chubs stored at 38 or inhibit each other, depending especially on 45EF were approximately 8 log CFU/g, storage temperature. A small number of 10 whereas total counts from chubs stored at initial carcass microflora are psychrotropic 34EF were approximately 4.5 log CFU/g (4 (grow best in the cold). They increase as the 10 log=10,000, CFU is colony forming units). initial predominant mesophilic organisms Regardless of storage temperature and meat (grow best at body temperature) decrease type, LAB predominated. Growth of gramunder cold conditions. negative enteric bacteria was delayed in chubs stored at 34EF throughout the 18 day Organisms associated with meat spoilage study, whereas counts increased in chubs include Pseudomonas, Acinetobacter, Morstored at 38 or 45EF. axella, Serratia, Altermonas, Brochrothrix,

Highlights

In 1994, the average American consumed 64 pounds of ground beef
Ground beef from four U.S plants was tested (2 trials each), and microbial analyses were conducted on storage days 0, 6, 10, 14, and 18 using seven different media to estimate counts of total aerobic and anaerobic, lactic acid bacteria (LAB), and Gram-negative bacteria
Bacterial counts for a given culture medium were similar among plants and meat types

Summary

Ten pound chubs of coarsely ground beef of two different lean:fat specifications (73:27 and 81:19) were stored at three temperatures (34, 38 or 45EF) to monitor the effects of storage temperature on microbial condition of the product. Ground beef from four U.S plants was tested (2 trials each), and microbial analyses were conducted on storage days 0, 6, 10, 14, and 18 using seven different media to estimate counts of total aerobic and anaerobic, lactic acid bacteria (LAB), and Gram-negative bacteria. Bacterial counts for a given culture medium were similar among plants and meat types. At day 10, total microbial counts from chubs stored at 38 or 45EF were approximately 8 log CFU/g, whereas total counts from chubs stored at 34EF were approximately 4.5 log CFU/g (4 log=10,000, CFU is colony forming units). Regardless of storage temperature and meat type, LAB predominated. Growth of gramnegative enteric bacteria was delayed in chubs stored at 34EF throughout the 18 day study, whereas counts increased in chubs stored at 38 or 45EF

Introduction

Experimental Procedures

Results and Discussion