Abstract
This study was planned to investigate the raw milk characteristics and quality aspects and to evaluate the impact of nongenetic factors on physicochemical composition and microbial quality of milk from local Maghrebi camels (Camelus dromedarius) kept under a traditional system in oasis areas, southern west, Tunisia. Forty-nine individual milk samples were collected from lactating Negga over two periods of the year (winter and summer). Animals belonging to private flocks were between 5 and 17.5 years of age, with parity numbers ranging from first to sixth. Samples were analyzed for physical parameters, chemical composition, mineral concentrations, and microbiological features according to standard methods. The overall means of physical characteristics were 6.63 ± 0.22, 1030.63 ± 2.54, and 19.11 ± 4.08 for pH, density, and acidity, respectively. No significant association (P > 0.05) between physical characteristics and nongenetic factors has been observed. The average results of chemical composition for dry matter, protein, fat, casein, lactose, ash, and casein/protein ratio were 115.24±15.67g/L, 30.98±6.40 g/L, 32.84±4.88 g/L, 22.77±4.27 g/L, 37.21±4.64 g/L, 6.87±1.59 g/L, and 0.74±0.06 g/L respectively. Season, parity, and age were confirmed to impinge significantly on chemical components, except for lactose. The maximum contents of total solids, protein, casein, and fat content were observed during winter. The third lactation was characterized with the highest content of total solids, protein, casein, and lactose; while the highest fat content was recorded in the second lactation. Lactose content was stable throughout all the studied age classes (P > 0.05), whereas the other chemical constituents, showed an obvious superiority in the age class of 7≤ age ≤ 9 years. Season, parity, and age of the animal exerted a significant effect on all minerals. The highest levels of Ca, P, and K were recorded in the winter (P<0.01) whereas Na showed an opposite pattern and was higher in the summer (P<0.01). All major minerals were higher in milk from multiparous than primiparous camels, with maximum concentrations at the fourth lactation. The uppermost levels of mineral concentrations were recorded in the age class of 7≤ age ≤ 9 years. The lowest ones were those of animals over 12 years old. The microbial analysis of raw milk which is affected by season, parity, and age showed higher overall contamination levels in all studied bacterial counts. The highest levels were observed in winter, among the multiparous and oldest Negga. The results highlighted the complete absence of the two dangerous pathogens Salmonella and CSR in all analyzed samples.
Incidence of fluid inclusions on the chemical quality of salt produced in Sfax Saline -E.S of Tunisia
