Hygienic quality of raw and fermented cow milk in the local milk sector of the Liptako-Gourma area in Niger

Abstract

Background and Aim: Milk is a food of high nutritional value, which occupies an undeniable place in the human food ration, but is an ideal medium for microbial growth. This study aims to assess the hygienic quality of local raw and fermented milk from the Liptako-Gourma region in Niger. Materials and Methods: We performed physical and bacteriological analyses on 330 samples of bovine milk from local breeds, including 110 individual milk samples (per cow), 110 fermented milk samples, and 110 blended milk samples. The microbiological parameters were determined using standard methods. Results: The physical analysis revealed temperatures during sample collection for all milk types between 35.2°C and 37.8°C. The average pH of fermented milk varied between 3.16 and 4.92 and those of individual and blended raw milks between 5.42 and 6.98. The titratable acidity varied from 15° to 18.1°D for raw milk and between 59° and 122°D for fermented milk. The average density of individual and blended milks ranged between 1.028 and 1.035. Regionally, milk samples from Tillaberi had a significantly higher aerobic mesophilic germ (GAM) load (7.42 ± 0.53 × 107 Colony-forming unit/mL; p = 0.0025) compared to the Dosso and Niamey regions. The prevalence of Staphylococcus aureus, Escherichia coli, and Salmonella spp. were 86.36%, 12.73%, and 20.91%, respectively, in fermented milk. Phenotypic identification pointed toward three genera: E. coli (30.76% ± 0.25%), S. aureus (20.58% ± 0.14%), and Salmonella spp. (2.74 ± 0.04%). Conclusion: The present data suggest that milk samples collected from three regions in Liptako-Gourma had low quality; further, some of the bacteria identified (E. coli, S. aureus, and Salmonella spp.) could be potential foodborne pathogens.