The Effect of Fermentation on the Physicochemical Quality and the Presence and Levels of Pesticide Residue in Cow Milk

The study investigated the effect of spontaneous fermentation time (0, 12, and 24 h) on the physicochemical properties (pH, titratable acidity, total soluble solid, and colour) and the levels of pesticide residue in cow milk using standard analytical procedures. Expectedly, the pH and titratable acidity were inversely related, where the pH significantly (p = 0.001) decreased from 5.7 to 3.8 and titratable acidity significantly (p = 0.001) increased from 2.7 to 7.5% after the 24 h fermentation period. Like pH, the total soluble solid significantly declined from 10.7 to 3.8 ᵒbrix after the 24 h fermentation. Generally, fermentation resulted in significant (p < 0.05) changes in all the quantitative parameters evaluated. Pesticides were not detected in about 85% of the milk samples. Only chlorpyrifos was detected in about 15% of raw milk samples in concentrations above the Maximum Residue Limit (MRL) (0.0670). Interestingly, chlorpyrifos was not detected in milk samples after 24 h of spontaneous fermentation.