Food systems are complex from compositional, structural and chronicle points of view. Compositionally, each food product differs in the type and concentration of chemical elements it contains. The compositional variation in food products requires that we should analyze case by case for all possible reactions—formation of physical and chemical bonds between molecules, consumption of nutrients by microorganisms, enzymatic or microbial breakdown of molecules, among others. Structurally, molecules in food systems form nanoscopic, microscopic, and macroscopic domains, which may strain the type and rate of reaction. Chronically, reactions in food systems occur during processing and storage and hardly stop before being consumed. All the above aspects pose challenges to develop a comprehensive description of kinetics of biological reactions within real food products.