No abstract

Numbers of bacteria on beef carcasses in EC abattoirs

Combined analysis of three experiments showed that when lamb carcases with initial bacterial numbers of between logi103.29 and 4.22/cm2 were spray washed, statistically significant reductions in bacterial numbers of log10O.5 were obtained when the spray wash water temperature was > 57°C, and reductions of log101.0 were obtained when the temperature was ≥ 80°C. Reductions at all temperatures were enhanced by log100.66 when the water contained 30 µg/ml chlorine, but increasing the concentration to 450 µg/ml reduced bacterial numbers only by a further log100–29. At highly contaminated sites increasing the duration of spraying from 30 to 120 s significantly increased the reductions obtained when water containing added chlorine was used. Reductions in bacterial numbers after spray washing with pressures of 3.5, 5.6. 7.7 kg/cm2 were not significantly different.

The bacteriological, chemical (FFA and peroxide value) and organoleptic quality of stored (3°C) radurized beefburgers were investigated. Treatment with gamma radiation at doses of 0.103 and 0.154 Mrad (1.03 and 1.54 kGy) resulted in an immediate reduction in total bacterial numbers of 82 and 92%, respectively. No 'pseudomonadlike' organism survived irradiation. Beefburger surface colour was influenced more than internal colour by irradiation; the larger dose (154 krad, 1.54 kGy) having the more pronounced effect. At the end of 15 days storage (3°C) 'spoilage' odours were not detected in the 1.54 kGy treated burgers but were detected in those irradiated at 103 krad (1.03 kGy). However 'irradiation' odours were detectable at both levels of treatment when burgers were exposed to the air. Irradiation had a larger effect on peroxide formation than on free fatty acid formation.

Forty-five samples of unsliced, cooked, ready-to-eat meats on sale in retail premises and supermarkets were examined. Thirty-six (80%) had Escherichia coli I and 21 (47%) had coagulase positive staphylococci in numbers ranging from 1 to > 1000/100 cm.(2). Twenty-one samples contained Clostridium spp. in numbers from 1 to > 100/100 cm.(2). Of the 45 samples tested, 11 (factory-produced) and 7 (home-produced) were examined after cooking but before being offered for sale. Cooked hams were contaminated after handling in a factory, as were samples of canned corned beef after sale and exposure for 24 hr. Some sources of contamination were: (a) raw beef, (b) factory and shop surfaces and equipment, and (c) workers' hands. Curing brines used in retail shops and supermarkets to produce corned beef were a potent source of contamination. The effect of holding cooked meats at ambient temperature on their spoilage (22 degrees C) and food-poisoning (37 degrees C) microflora was demonstrated.