Microbial Safety of Milk from Vending Machines in the Informal Settlements of Nairobi, Kenya

Abstract

The microbial quality of milk is an important parameter in determining its safety. Processes such as pasteurization are meant to ensure milk is safe for consumption; however, postpasteurization activities could lead to milk contamination, hence threatening the health of consumers. This study sought to determine the microbial safety of milk obtained from vending machines that were located in Nairobi’s informal settlements of Kibra and Dagoretti North. 37 milk samples were collected both from the storage tanks and vending machines located in the study area using a cross-sectional design and tested for microbial safety. Data were then recorded in datasheets and analyzed using frequencies and t-test with the aid of Statistical Package for Social Sciences software. Milk samples tested had acceptable levels of pH with a mean of 6.75; however, the pH of samples from the vending machines was lower than that of samples from the storage tanks. Milk samples from the vending machines had high levels of total viable count (Log 4.7028 cfu/mL) with 81% of the samples having counts beyond the acceptable standard. High levels of Staphylococcus aureus (Log 2.5485 cfu/mL) were also detected in 51% of the samples. Escherichia coli was detected in 27% of the milk samples from the vending machines, while Salmonella spp. was not detected. There was a significant increase in the number of total viable counts ( $P\le 0.001$ ), Staphylococcus aureus ( $P\le 0.007$ ), and Escherichia coli ( $P\le 0.015$ ) in milk samples from the vending machines compared to samples from the storage tanks. Study findings show that milk from the vending machines in the selected informal settlements of Nairobi is highly contaminated and can pose a health risk to consumers if taken without any further heat treatment. Milk vending machine handlers should be trained on practices that safeguard the quality and safety of milk. Public awareness should also be created on the general safety of milk from vending machines to protect consumers from potential health risks resulting from drinking contaminated milk.