Microbiological analysis of traditionally fermented milk sold in Kinigi Sector of Musanze District in Rwanda

Abstract

A research work entitled: “Microbiological analysis of traditionally fermented milk (Ikivuguto) sold in Kinigi Sector of Musanze District,” was carried out at Higher Learning Institution of Applied Sciences (INES-Ruhengeri) Laboratory of Microbiology located near Volcanoes in the Northern Province of Rwanda. The main objective of this work was to determine the microbiological quality of traditionally fermented milk, which is consumed by Kinigi Center local people. The hypothesis was to analyze if traditionally fermented milk commercialized in Kinigi restaurants contained pathogenic bacteria such as fecal coliforms and Escherichia coli, in addition to staphylococci and yeasts. Milk samples were collected from Kinigi sector and examined in the microbiology laboratory in order to assess the microbiological quality and safety of traditionally fermented milk in rural areas. The samples were analyzed qualitatively and quantitatively for the microbes found in fermented milk sold in Kinigi Center, and the results were as follows: 7.21x10⁷ CFU/ml for total counts; 3.89x10⁷ CFU/ml for Lactobacillus; 2.77x10⁷ CFU/ml for yeasts; 1.196x10⁵ CFU/ml for total coliforms; 9.63x10⁴ CFU/ml for fecal coliforms and 8.92x10³ CFU/ml for staphylococci. Biochemical tests were carried out and the results showed that identified pathogens were E. coli, Providencia alcalifaciens, and the staphylococci group. It was found that fermented milk contained genera and species of Staphylococcus haemolyticus, Staphylococcus aureus, Staphylococcus intermedius, Staphylococcus xylosus and Staphylococcus saprophyticus. Findings showed that the commercial milk samples were cross-contaminated by different pathogens from environment. These contaminations could have been due to improper handling, presence of flies, soil erosion, dust from atmosphere, as well as contaminated milk vessels or pots, stirrers and unpasteurized water. It was concluded that local farmers and milk retailers did not adhere to required hygienic conditions for milk safety. In this regard, the sold traditional fermented milk does not meet health and safety standards because people did not respect good manufacturing practices. The hypothesis and main objective were confirmed, because traditionally fermented milk of Kinigi was cross-contaminated before consumption. Thus, it would be better to train farmers in the areas of product hygiene, sanitation and safety during milking, processing and marketing.

Keywords: Cross-contamination, Escherichia coli traditionally fermented milk, Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Candida spp., milk spoilage