APPLICATION OF MULTIVARIATE STATISTICAL ANALYSIS TO EVALUATE THE MICROBIOLOGICAL QUALITY AND HYGIENE OF MINCED PORK MEAT SAMPLED AT THE POINT OF SALE

摘要

The objective of the present work was to investigate and establish the microbial association of minced pork meat. Minced pork samples (n=150) obtained from butcher's shops (n=127) and supermarkets (n=23), during summer (May to September, n=75) and winter (November to March, n=75), were subjected to microbiological and physicochemical (pH) analysis. The microbiological parameters tested were: Total viable counts (TVC), Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria (LAB), yeasts and moulds, Enterobacteriaceae, total coliforms/EschericMa coli, hydrogen sulfide (H_2S)-producing bacteria, Staphylococcus spp./St. aureus and Listeria spp. Statistical analysis of data was performed using the @Risk 4.5 and SPSS V15.0 software programs. Distributions, principal component analysis (PCA), correlations and analysis of covariance (ANCOVA) were employed to associate meat quality and hygiene with microbiological parameters. The 87, 30, 79, 20 and 36% of samples were found positive to (mean and 95% confidence interval in log CFU/g): total coliforms (2.9, 0.8-0.5), E. coli (1.4,1.1-2.8), Staphylococcus spp. (4.3, 2.3-6.2), St. aureus (2.4, 0.6-4.2) and Listeria spp. (1.4, 0.3-2.6), respectively. The distribution of the rest microbial flora was also demonstrated: TVC (6.8, 4.9-8.7), Pseudomonas spp. (6.4, 4.1-8.8), Br. thermosphacta (5.9, 3.8-8.0), Enterobacteriaceae (3.6,1.4-5.9), yeasts and moulds (4.6, 3.3-5.9), LAB (5.3, 3.4-7.3) and H_2S-producing bacteria (4.3,1.6-6.9). Mean value for pH was 5.9 (5.5-6.3). The highest correlations existed between TVC and pseudomonads, Br. thermosphacta and H_2S-producing bacteria, whereas the lowest between total coliforms and all the microbiological parameters examined (except of enterobacteria). Three components, accounted for 80% of total variance, were selected during the application of PCA. The first component was related to potential spoilage flora (TVC, pseudomonads, Br. thermosphacta, yeasts and moulds, H_2S-producing bacteria and LAB), the second to microbiological indicators of hygienic conditions (enterobacteria and total coliforms) and the third component to an indicator of human contamination (Staphylococcus spp.). Based on PCA, meat quality was mapped on a graph. ANCOVA showed no significant (p>0.05) effects of the type of retail shop sampled and the season at which the samples were analyzed.