Enumeration of coliforms in fermented milk product (nono) sold in Samaru, Kaduna State, Nigeria

Abstract

The quality of cow milk is reduced by microbial contamination and this poses a health risk to humans. One hundred fermented milk products (nono) sold within Samaru, Zaria were collected to determine the bacterial quality of nono using total aerobic plate and coliform counts on Nutrient and MacConkey agar plates respectively, The isolation of Escherichia coli was with the use of Eosin Methylene Blue agar. The mean pH of the nono samples from ten retail outlets ranged from 3.2 in Samaru leather research to 3.8 each in Faculty of Veterinary Medicine and ICSA market. Other mean pH values were as follows: Suleiman Hall and Dogon Ichi 3.3 each, Community market, Faculties of Science and Arts, 3.5 each, Samaru market and Hayin Dogo, 3.6 each. The highest total aerobic plate count of 1.390 x 10¹³ CFU/mL was from site B while the least of 0.789 x 10¹³ CFU/mL was from site G. The mean coliform count ranged from 2.10×10¹⁰ to 5.12 ×10¹⁰ CFU/mL. Site F had the least of 2.10 × 10 ¹⁰ while site H had the highest count (5.12 ×10¹⁰) closely followed by site E (5.03 ×10¹⁰). Out of 100 samples obtained, 46 (46%) yielded colonies suspected to be E. coli. On confirmation, after biochemical characterization, only 27 (58.7%) out of the 46 presumptive samples were positive for E. coli. An E. coli isolation rate of 27% was recorded out of the 100 nono samples, with the highest prevalence of 50% in nono samples from site I and the least of 10% from site E. The prevalence of other coliforms in the 100 samples were Enterobacter (8%), Klebsiella (6%), Citrobacter (2%) and Proteus (3%) species. The study has shown that fermented milk, nono is contaminated and can pose a health hazard to consumers of this product.

Keywords: Coliforms, Escherichia coli, Milk, Nono, Samaru