The effect of the seasons on the chemical composition of raw cow’s milk collected from farmers and dairy factories in some areas of Western Libya

Abstract

This study was conducted in north west of Libya, in which five dairy farms of high yielding milk production were selected. Cow's raw milk samples were collected directly from milking fields every month. Samples were also collected from milk tanks trucks from three dairy factories. Results showed that the average temperature of the raw milk collected directly from dairy farms reached 20±0.23?C, pH 6.63±0.01 and titratable acidity 0.16±0.001% while the milk of tanks trucks have an average temperature of 11±0.09°C, pH 6.65±0.01 and titratable acidity 0.15±0.001%. The results of chemical analysis of the milk collected from dairy farms showed that the average of fat, protein, non-fat total solids, total solids content were 2.90±0.04%, 2.99 ±0.02%, 7.86±0.07% and 10.73±0.10% respectively, while the average fat, protein, non-fat total solids, total solids of the milk collected from tanks trucks were 3.07±0.05%, 3.06± 0.04%, 8.06±0.13% and 11.13±0.18% respectively. The alcohol coagulation test was negative for all samples from dairy farms and dairy factories. The statistical analysis showed there were significant differences at the level of the probability of 5% in the titratable acidity, fat content, non-fat total solids, total solids, while no significant differences were observed at the level of the probability of 5% in the protein content and pH between raw cow's milk from farms and raw cow's milk collected from dairy factories. The study concluded that the year's seasons had obvious impact on the chemical composition of raw milk, where the titratable acidity in the summer rose compared to other seasons of the year, as the fat, protein, non-fat total solids and total solids content rose in the winter.