9/18/2016 Hurdle Technology Food as Ecosystems Interaction of intrinsic and The food environment consists of: extrinsic factors determines which intrinsic factors-inherent to the food microbes grow in an ·pH environment ·water activity Hurdle technology ·nutrients uses multiple extrinsic factors-external to the food environmental factors ·temperature to inhibit microbial ·gaseous environment growth ·other bacteria important preservation Both can be manipulated to preserve food strategy Microbial Ecology Heterogeneity of Food the study of the interactions between Heterogeneous on a scale of the chemical,physical,and structural micrometers aspects of a niche and the composition Gradients of pH,oxygen,and nutrients of its specific microbial population Example-food poisoning outbreak "interactions"emphasize the dynamic associated with aerobic foods caused by complexity of food ecosytems "strict anaerobe"Clostridium botulinum Oxygen is driven out by cooking and diffuses in slowly so that most of the product remains anaerobic 9/18/2016 2 Hurdle Technology Interaction of intrinsic and extrinsic factors d i hi h determines which microbes grow in an environment Hurdle technology - uses multiple environmental factors to inhibit microbial growth - important preservation strategy 5 Food as Ecosystems The food environment consists of: intrinsic factors - inherent to the food • pH • water activity • nutrients extrinsic factors - external to the food • temperature • gaseous environment • other bacteria Both can be manipulated to preserve food 6 Microbial Ecology • the study of the interactions between th h i l h i l d t t l th e c hemical, p hysical, and s truc tural aspects of a niche and the composition of its specific microbial population • ”interactions” emphasize the dynamic complex complex ty of food ecosytems ity of food ecosytems 7 Heterogeneity of Food • Heterogeneous on a scale of micrometers • Gradients of pH, oxygen, and nutrients • Example - food poisoning outbreak associated with aerobic foods caused by ”strict anaerobe” Clostridium botulinum • Oxygen is driven out by cooking and diffuses in slowly so that most of the product remains anaerobic 8