The microbial quality of ostrich carcases produced in a export-approved South African abattoir

Abstract

The aim of this study was to evaluate the microbial quality of ostrich carcases produced in a South African export-approved ostrich abattoir. Ninety surface samples were collected on 30 ostrich carcases at three processing points in the abattoir: post-flaying, post-evisceration and post-chilling. Carcase samples were evaluated for the Aerobic Plate Count (APC), Pseudomonas spp., Enterobacteriaceae, Staphylococcus aureus and for the presence of Escherichia coli and presumptive Salmonella spp. One hundred isolates obtained from the APC were identified. The mean log CFU/cm2 and standard deviations for surface counts at post-flaying, post-evisceration and post-chilling processing points respectively were: 4.32 ±0.62, 4.21 ±0.63 and 4.57 ±0.48 for the APC; 2.82 ±1.65, 2.86 ±1.53 and 3.75 ±0.94 for Pseudomonas spp.; 2.89 ±0.78, 2.90 ±0.53 and 2.38 ±0.67 for S. aureus and 2.55 ±1.53, 2.78 ±1.31 and 2.73 ±1.46 for Enterobacteriaceae. No significant differences were detected between the mean log counts of the post-flaying and post-evisceration processing points for the above-mentioned bacterial counts. However, statistically significant differences were detected between the mean log CFU/cm2 counts for post-flaying and post-chilling and between the counts for the post-evisceration and the post-chilling processing points for the APC, Pseudomonas spp. and S. aureus. The trend was towards a marginal increase for the APC, and a negligible decrease for S. aureus counts obtained on samples collected post-chilling. However, there was an increase of practical significance for Pseudomonas spp. counts obtained post-chilling. Seventeen out of 90 (18.8%) samples were positive for E. coli in terms of samples collected and 13 out of 30 (43%) in terms of carcases sampled. Log CFU/cm2 counts for E. coli positive samples ranged from 1.0 to 3.79, with a mean log count of 2.15. Most of the samples, which were positive for E. coli were collected post-evisceration. The prevalence rate for presumptive Salmonella spp. on both Brilliant Green Agar and Xylose Lysine Desoxycolate Agar was 15.5% in terms of samples collected and 23.3% in terms of carcases sampled. Most of the positive samples were collected post-evisceration. The proportional distribution of one hundred (100) bacterial isolates identified was Enterobacteriaceae: 57%, Acinetobacter spp.: 24 %, Pseudomonas spp.: 11%, Aeromonas spp.: 3%, Micrococcus spp.: 3%, Staphylococcus spp.: 1% and yeasts: 1%. Enterobacteriaceae were the predominant bacteria in terms of the total number of isolates identified per processing point and for the whole study.