Evaluation of Raw Milk Quality Using the Methylene Blue Reduction Test

Abstract

The microbiological quality of raw milk remains a significant public health concern, especially in regions where unpasteurized milk is commonly consumed. Although raw milk hygiene has been studied previously, detailed assessments of bacterial load using the Methylene Blue Reduction Test (MBRT) under the specific environmental and hygienic conditions of Kabul, Afghanistan, are lacking. This study aimed to evaluate bacterial contamination in raw milk from the 13th district of Kabul city. A total of 52 milk samples were randomly collected from four locations—Qala-e-Naw, Pul-e-Khesk, Tank-e-Tel, and Qala-e-Qazi—and transported under strict hygienic conditions to the Food Technology and Hygiene Laboratory at the Faculty of Veterinary Science. Bacterial load was determined by the time required for methylene blue decolourization, which reflects microbial metabolic activity. Descriptive statistics were used to calculate contamination percentages and compare mean decolourization times to classify milk quality. Results revealed contamination rates of 42.33%, 30.76%, 15.30%, and 11.53% in Qala-e-Naw, Pul-e-Kheshk, Tank-e-Tel, and Qala-e-Qazi, respectively, with Qala-e-Naw exhibiting the highest contamination. These findings indicate substantial microbial risks in raw milk and underscore the need for improved milking hygiene, proper handling practices, and public education to ensure food safety and protect consumer health in the region.