Evaluation of Microbiological Quality of Soy-based Products (Milk and Yogurt) Collected in Ouagadougou

Abstract

Soybean (Glycine max) is leguminous plant cultivated for their protein-rich seeds, which are used in human and animal nutrition. Their seeds are processed into yogurt, milk, and many other by-products. However, during the processing of these products (milk and yogurt), they can be contaminated with physical, chemical, and biological contaminants that negatively impact consumer health. The objective of this study was to evaluate the microbiological quality of soy milk and yogurt produced in Ouagadougou. A total of 10 soy samples were collected and analyzed, including five (05) samples for soy milk and five (05) samples for soy yogurt. The microbiological parameters analyzed were total mesophilic aerobic flora, yeasts and molds, total and thermotolerant coliforms, Salmonella, and Shigella. These analyses were performed according to standard microbiological methods. The results revealed a total mesophilic aerobic flora load ranging from 6±0.7 x102 CFU/mL to 1±0.8x103 CFU/mL for soy milk and 1.42±0.3 x 103 CFU/mL to 4.63 ± 0.49 x 104   CFU/mL for soy yogurt. Yeast and mold counts ranged from 1.54 ± 0.3 x 102 CFU/mL to 3.64 ± 0.48 x 102 CFU/mL for yogurt and less than 10 CFU/mL for milk. Total and thermotolerant coliform counts were less than 10 CFU/mL for milk and soy yogurt. All samples were free of Salmonella-Shigella. All soy milk samples analyzed were of satisfactory quality and acceptable for soy yogurt. Soy milk and yogurt produced in Ouagadougou could be consumed safely by consumers based on the bacteria studied.