Influence of different periods of pre-slaughter fasting on microbiological quality of bullfrog carcasses (Lithobates catesbeianus)

ABSTRACT The aim of this study was to evaluate the influence of different periods of pre-slaughter fasting (F1: 2 to 24 hours and F2: 48 to 72 hours) on the counts of hygiene indicator microorganisms and the presence of Salmonella spp. in carcasses of bullfrogs. Two different stages of the slaughter process were analyzed: after bleeding (A) and after the final carcasses cleaning (B). Samples from each fasting period were analyzed to count hygiene indicator microorganisms (n=30) and Salmonella spp. (n=140). For aerobic mesophilic microorganisms, the variation in fasting periods caused a reduction of 0.69 log10 CFU / g (P<0.05) in F2 when compared to F1 at point B of the slaughter. Coliforms at 35º C and Escherichia coli showed no differences (P >0.05) between the fasting analyzed periods. Considering the presence of E. coli, it was observed that F2 resulted in a reduction of 30% (P<0.05) positivity on point B. For Salmonella spp., the results showed that F2 contributed to an 11.5% reduction in the presence of this bacteria at point B. (P<0.05). Therefore, it is concluded that 48 to 72 hours of pre-slaughter fasting resulted in a positive impact on the microbiological quality of bullfrog carcasses.

摘要 本研究旨在评估不同时长的屠宰前禁食方案（F1：2~24小时，F2：48~72小时）对牛蛙胴体的卫生指示微生物计数及沙门氏菌（Salmonella spp.）检出情况的影响。本研究分析了屠宰流程的两个关键阶段：放血后（A阶段）与最终胴体清洗完成后（B阶段）。针对各禁食组的样本，分别开展卫生指示微生物计数（样本量n=30）与沙门氏菌检测（样本量n=140）。针对需氧嗜温微生物，在屠宰流程的B阶段，F2组的菌落数较F1组降低0.69 log₁₀ CFU/g（P<0.05）。35℃培养条件下的大肠菌群与大肠埃希氏菌（Escherichia coli）在不同禁食组间无显著统计学差异（P>0.05）。但就大肠埃希氏菌的检出阳性率而言，F2组在B阶段的阳性率较F1组降低30%（P<0.05）。对于沙门氏菌，结果显示F2组在B阶段的沙门氏菌检出率较F1组降低11.5%（P<0.05）。综上，本研究得出结论：48~72小时的屠宰前禁食可对牛蛙胴体的微生物学品质产生积极影响。