Development of analytical methodologies for the monitoring of contaminants and residues in milk and dairy products

Abstract

Milk and dairy products are very rich in nutrients and thus provide an ideal growth environment for food-borne pathogens. Moreover, milk and dairy products can also contain chemical hazards and residues mainly introduced through the environment, animal feedstuffs, animal husbandry and industry practices. We focused in this Thesis on chemical hazards which include contaminants (such as mycotoxins) and residues of other chemicals (as pesticides or antibiotics) that are used or added during the animal production or manufacturing processes, such as veterinary drugs and pesticides. In addition, considering the increasingly consume of vegetable milks (most of them based on cereals), this commodity has been included in the study. Mycotoxins are highly toxic secondary metabolites produced by certain fungi that grow on agricultural products. Ingestion, inhalation or skin absorption of mycotoxins can cause illness or even death in both humans and animals. The presence of mycotoxins in milk is a topic of great interest, since milk is an important food for adults and children. Given the variety of mycotoxins that may occur in the diet of animals, the number of studies related to the transfer of these compounds to milk and especially to dairy products is very limited. It would also be possible to find mycotoxins in vegetable-derived milk. Studies on mycotoxins in these matrixes are scarce, although the products of origin (soy, oat, rice, etc.) may be contaminated. Milk production has an effect on the environment, and otherwise, the environment can have an effect on milk production through environmental contaminants such as pesticides, extensively used for agricultural activities, which may lead to residues in milk. Among the different families of pesticides, carbamates are commonly used as insecticides, and their presence in foods could have adverse health effects, as they have high acute toxicity. Thus, their presence on milk and dairy products as a consequence of feeding the animals with contaminated food or water is a matter of concern. With regard to veterinary antibiotics, the presence of residues in foods of animal origin and specially milk and dairy products, may have adverse health effects. The development of antibiotic resistance in bacteria has long been attributed to the overuse of antimicrobials in human medicine but the relationship between the agricultural use of antimicrobials and the antibacterial resistance in humans is also the subject of much concern. Referring to these problems and taking into account the last technical advances in terms of efficiency and miniaturization, different separation techniques, such as high performance liquid chromatography (HPLC), ultra-high performance liquid chromatography (UHPLC) and also capillary electrophoresis (CE) have been assessed, coupled to detection techniques such as fluorescent detection (FLD), tandem mass spectrometry (MS/MS) and high resolution mass spectrometry (Q-TOF). In addition, alternative sample treatments have been proposed, making possible an increased efficiency and sample throughput.