Résumé:
Due to the increasing consumption of milk and dairy products in the human diet, efforts have been made to improve its quality. This thesis was conducted to assess the physicochemical and bacteriological qualities and to determine the spatial variability of seven heavy metals (Pb, Cd, Cr, Zn, Fe, Cu and Ni) content in raw milk of local bovine breed collected at the level of various communes of the Northeast of Algeria. A theoretical hazard quotient (HQ) indicator was used to evaluate the possible risk of milk consumption to human health. Additionally, a survey was conducted to identify the potential of local cattle breeds to maintain their production ability under global warming. At the international level, the assessment of the potential risk of raw cow milk consumption for human health has been studied using mathematical approaches for two families of emerging contaminants (heavy metals and pesticides).
At the national level, the concentrations of Pb, Cd and Cu in all analysed samples (N=88, 100%) of the study area were higher than their corresponding Maximum Residue Levels (MRLs), while 82.95%, 42.04%, 15.90% and 5.68% of Zn, Fe, Cr and Ni samples exceeded their MRLs, respectively. The Task Hazard Quotient (THQ) values suggest that the levels of Ni, Zn, Cu and Fe in the raw cow milk samples were not causing a health risk for consumers. Moreover, the results indicated that there might be a potential risk of toxic metals, especially Pb, for infants via the consumption of raw cow milk.
Physicochemical analysis (N=122) revealed acceptable quality according to Codex Alimentarius but poorly bacteriological quality. The analysis of the milk yield history and the comparison with the collected data revealed a very stable milk yield per cow, suggesting that exploiting local cattle breeds is an interesting adaptation strategy for climate change effects. Conservation programs for these breeds can promote biodiversity and maintain a balanced ecosystem. The breeder can benefit from a genetic improvement program to increase productivity and profitability. However, eliminating any pollution source must be a priority to ensure a healthy product for the consumer.
At the international level, data extracted and then analysed revealed high levels of heavy metal and pesticide residues in raw cow milk, especially in developing countries (e.g. Pakistan, India and Turkey). Moreover, the evaluation of the potential risk for human health revealed a significant human risk, particularly in developing countries such as Pakistan, Colombia, Sudan and Egypt.
In conclusion, the local cattle breed seems to be an interesting strategy to fight against the effects of climate change; however, it is strongly recommended to monitor the contamination levels with pesticides and heavy metals to ensure healthy food free of any risk.
