Sources of Escherichia coli deposited on beef during breaking of carcasses carrying few E. coli at two packing plants

Abstract

Microbiological samples were obtained from the hands of workers, personal equipment and conveyor belts, in the carcass breaking facility of a beef packing plant where chilled carcasses carry coliforms and Escherichia coli at numbers < 1 cfu/10,000 cm2. Before work started, steel mesh gloves carried coliform and E. coli at numbers of 4 and 3 log cfu/25 items, respectively, while their numbers on conveyor belts were >2 and <2 log cfu/2500 cm2, respectively. After a period of work the numbers of both coliforms and E. coli on steel mesh gloves and conveyor belts were reduced by about 1 log unit, but the numbers on cotton gloves worn under steel mesh gloves were 5 and >4 log cfu/25 items, respectively. The findings indicate that the proximate source of most coliforms and E. coli that contaminate cuts and trimmings are, respectively, cotton gloves and conveyors. Microbiological samples were similarly obtained at a second plant where drying of carcass surfaces during chilling gave carcasses with coliforms and E. coli at numbers about 1 cfu/1000 cm2. Before work started, steel mesh gloves were free of coliforms and E. coli; and the uniform wearing of rubber gloves over cotton ones precluded contamination of cotton gloves. The conveyor belt carried coliforms and E. coli at numbers about 1 cfu/cm2 and >1 cfu/100 cm2, respectively, before work started; and at numbers < 1 cfu/cm2 and about 1 cfu/100 cm2, respectively, after a period of work. The findings indicate that at the second plant both cuts and trimmings are contaminated with coliforms and E. coli from the conveyor.