Critical review: Metabolomics in dairy science - Evaluation of milk and milk product quality.

Milk and milk products are nutritionally rich and consumed globally. Maintaining nutritional quality and ensuring safety of these products have become one of the major topics in dairy research. Dairy products contain metabolites including key nutritional elements, which are derived from dairy animals and elsewhere (e.g. milk processing, fermentation). Since the level and type of metabolites can vary by diverse factors from farm to table dairy, metabolites may represent the quality of milk and milk products in terms of nutritional value, authenticity, safety, and so on. In this review, we introduce metabolomics as a powerful tool to obtain a comprehensive snapshot of metabolite composition and dynamic changes, and focus on its recent progress and applications in dairy product quality. Factors (pre- and post-harvest effects, contamination, adulteration, etc.) affecting the quality and safety of products are dissected, and examples of related metabolomics works are provided. Potential metabolite indicators and metabolic mechanisms associated with the quality factors of dairy products are presented. With cases of single metabolomics approach, current trends in the integration of metabolomics with other omics techniques (so called multi-omics) in dairy science, as well as future perspectives of metabolomics in the field are also explored and discussed.