Coliforms Contamination in Raw Milk and Some Dairy Products with Special Reference to Comparative Identification of Enterobacter spp.

Document Type : Original Article

Authors

1 Directorate of Veterinary Medicine, Mansoura - General Organization for Veterinary Services, 35511, Egypt

2 Food Control Department, Faculty of Veterinary Medicine, Zagazig Univeristy, 44511, Zagazig Egypt

Abstract

The current study was undertaken to examine 200 sample of raw milk and some dairy products (Kariesh cheese, plain yoghurt, milk powder and infant formula) for contamination with Coliform group especially Enterobacter spp. Coliforms were detected in; 42/50 (84%) raw milk samples from farmers' houses, 25/30 (83.33%) kariesh cheese samples and 23/30 (76.67%) plain yoghurt samples, however, they could not be detected in any of raw milk samples from dairy shops, milk powder and infant formula samples. The mean values of coliforms in the examined samples were 2.80x106 ±0.73x105, 2.30×106 ±0.75×104 and 1.08×106 ± 1.50×104 cfu /ml or gm in raw milk from farmers' houses, kariesh cheese and plain yoghurt samples, respectively. The biochemically identified coliforms were E. aerogenes, E. agglomerans, E. cloacae, C. diversus, C. freundii, E.coli, K. oxytoca and K. pneumonia with respective percentages of; 1.19, 1.19, 2.38, 25, 15.48, 26.19, 13.09 and 15.48, in raw milk from farmers' houses, 6, 0, 2, 28, 10, 22, 0, and 32 in kariesh cheese, 0, 0, 2.12, 23.91, 0, 36.96, 26.09, 10.87 in plain yoghurt. Comparative identification of isolated Enterobacter spp.by standard biochemical methods and Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry revealed that the total conformity of identification of Enterobacter strains between standard biochemical technique and MALDI-TOF MS technique was 66.6%, where, it ranged from 50% to 100 for E. aerogenes and E. cloaca, respectively. However, the only identified E. agglomerans isolatesfrom raw milk could not be confirmed by MALDI-TOF MS technique. It has been shown through these results that the presence of coliform and Enterobacter bacteria is an evidence of the lack of health requirements and thermal treatments of raw milk and some of its products (kariesh cheese and yoghurt).

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