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Chapter 1 : Physiology, Growth, and Inhibition of Microbes in Foods
This chapter addresses three issues: (i) the ability of bacteria to use different biochemical pathways to generate the energy required to grow under adverse conditions in foods; (ii) the interaction of bacteria and foods in ecosystems in which the cells may exist in a variety of physical and physiological states and in which the roles of intrinsic and extrinsic factors and (iii) the kinetics of microbial growth. It talks about microbial physiology and metabolism, and glycolytic pathways such as Embden-Meyerhof-Parnas Pathway and Entner-Doudoroff Pathway. It also discusses the heterofermentative catabolism, homofermentative catabolism, tricarboxylic acid cycle, aerobes, anaerobes, the regeneration of NAD, and respiration, bioenergetics. The food ecosystem is composed of intrinsic factors, which are inherent to the food (i.e., pH, water activity [aw], and nutrients) and extrinsic factors, which are external to it (i.e., temperature, gaseous environment, and the presence of other bacteria). In addition, the chapter focuses on the physiological and genetic responses that bacteria utilize in osmoregulation. Bacteria are classified as psychrophiles, psychrotrophs, mesophiles, and thermophiles according to how temperature influences their growth. Microbial growth in foods is a complex process governed by genetic, biochemical, and environmental factors.