Reduction of Aqueous Chlorine by Organic Material.

Aqueous chlorine, used to reduce surface bacteria populations on carcasses of slaughter animals after evisceration, during chilling, and after transport, dissipates in the presence of organic matter. This study characterized the amount of residual chlorine present when aqueous HOCI was exposed to bovine serum albumin, bovine lean muscle, porcine adipose tissue, or Trypticase soy agar (TSA) surfaces. Test chlorine solutions, made using Ca (OCl)2, contained 0, 50, 100, 200, 400, 800, 1,600, or 3,200 ppm chlorine, the latter two concentrations being used only in the case of albumin. Chlorine depletion by albumin was almost instantaneous, but was influenced by the amount of albumin present and the initial chlorine concentration. Chlorine exposed to organic surfaces was reduced most readily by lean muscle, then by TSA, and least by adipose tissue. Available chlorine was reduced by about 62% when the volume of aqueous chlorine was 22 ml/cm2 of lean muscle and by about 89% when the volume of aqueous chlorine was 0.69 ml/cm2. With increasing exposure time, the exposure to lean and fat decreased available chlorine by an average of about 10% in 4 min, 27% in 32 min, and 45% in 96 min. Thirteen pure bacterial cultures and two mixed cultures associated with meat were exposed to aqueous chlorine to characterize the effectiveness of the chlorine. All cultures except Bacillus cereus and Enterococcus faecalis were destroyed within 15 s by 3 ppm chlorine. Based on the data, the authors conclude that (a) available chlorine reduction is dependent on exposure time, chlorine concentration, and amount/source of organic material and (b) bacterial inactivation by aqueous chlorine is species specific. These data are of value for estimating chlorine dose for carcass decontamination during washing/chilling and for confirming that bacterial resistance to HOCI is species specific.

Bacterial Contamination of Broiler Chickens before Scalding.

The bacterial load on the feathers (breast, thigh, and drum), skin (breast, thigh, and drum), and feet of a total of 40 broiler chickens from four different production units was characterized after the chickens were exsanguinated but before the carcasses were scalded. Each broiler carcass contained a mean of aerobic bacteria at or near 8log10/g, a level at which the carcasses would be considered spoiled. Escherichia coli counts ranged from 6.3 to 8.0 log10/g, with the highest presence on the feathers and breast skin and lower levels on the thigh and drum skin, and feet. Contamination of the carcasses followed a similar pattern for Salmonella spp., which ranged between 5.8 and 7.2 log10/g, and Campylobacter jejuni/coli which ranged between 6.1 and 7.5 log10/g. The incidence of potential pathogens was higher on the feathers, breast skin, and feet than on the thigh and drum skin. The incidence of E. coli ranged from 42.5 to 100%, Salmonella spp. ranged from 27.5 to 75%, and C. jejuni/coli ranged from 45 to 82.5%. The mean counts of microorganisms on broilers from the four different grow-out farms were significantly different (P > 0.05) from one another immediately after killing, although the magnitude of the differences was small in most cases. The means ranged from 7.3 to 8.0 log10/g for total colony-forming units (CFU), 6.7 to 7.6 log10/g for E. coli , 5.4 to 6.9 for Salmonella spp., and 5.7 to 7.9 for C. jejuni/coli . All birds were contaminated with E. coli , 60 to 100% with Salmonella spp., and 80 to 100% with C. jejuni/coli , depending on grow-out farm. C. jejuni/coli counts and incidences were higher than those of Salmonella spp., and usually lower than those of E. coli . This research demonstrates that broilers entering the processing plant are highly contaminated. Although processing seems to decrease the number and incidence of microorganisms on the carcasses, additional modifications in production, transportation, and processing are warranted to reduce the microbial population on the birds before they are slaughtered.

Microbiological and Sensory Attributes of Retail Cuts of Beef Treated with Acetic and Lactic Acid Solutions.

This research characterized the effect of 0.6 and 1.2% acetic and lactic acids applied for 20 and 120 s at a temperature of 1 to 2°C on total colony forming units (CFU) and Escherichia coli counts, and sensory qualities including shear value, expressible moisture, color and sensory panel of retail cuts of beef rib steaks. Microbial inhibition was directly proportional to the concentration and times of treatment with a 1.2% acid treatment for 120 s being the most effective treatment for reducing microbial counts, for both acids. Although there were significant reductions (p <0.05) in bacterial populations, these reductions which had a maximum of 2.0 log, were of questionable practical significance. The inhibitory effect of the acids decreased with storage time, up to 9 days. Treatment with both the acids resulted in paler meat (p <0.05) than the non-treated control. There were no significant differences (p >0.05) in shear values or expressible moisture due to acid treatment. Sensory panels reported only small differences between the samples. These results indicate that an aqueous acetic or lactic acid treatment of retail beef reduced total CFU and E. coli numbers immediately after treatment, but the magnitude was less than 1 log. However, a residual influence was observed so that after 3 and 9 days both acid treatments inhibited total CPU and E. coli growth by up to 2 logs compared with the non-treated control samples.