Micro of Fermented Foods2

Micro of Fermented Foods2 - Microbiology of Fermented Foods...

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Microbiology of Fermented Foods Harrison FDST 4030/6030 1 Harrison FDST 8090 Microbiology of Fermented Foods Microorganisms in Food and Factors Affecting Them Hungate (1962) What kinds of organisms occur? What activities do they perform and how are these activities interrelated? In what number does each kind of organism occur? What is the magnitude of its activity, and what factors influence this magnitude? Harrison FDST 8090 Homeostasis – e.g., pH Intracellular pH maintained within narrow range Done by pumping protons out Cell expends energy to maintain homeostasis Shift of energy from biosynthesis to maintenance of homeostasis inhibits growth If energy needs exceed energy production the cell dies Harrison FDST 8090 Microbial Physiology and Metabolism Glycolytic Pathways Embden-Meyerhof-Parnas Pathway Entner-Doudoroff Pathway Heterofermentative Catabolism Homofermentative Catabolism Tricarboxylic Acid (TCA) Cycle Electron Transport Chain Harrison FDST 8090 Microbial Physiology and Metabolism - Aerobes Use the electron transport system Use molecular O 2 as the terminal electron acceptor during oxidative phosphorylation Electrons travel down the chain and protons are pumped out forming a proton gradient – drives ATP production Aerobic bacteria Oxidizes glucose to CO 2 O 2 is reduced to water 36 ATP produced per glucose molecule Harrison FDST 8090 In Aerobes Only
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Microbiology of Fermented Foods Harrison FDST 4030/6030 2 Harrison FDST 8090 Microbial Physiology and Metabolism - Anaerobes Lack electron transport system Reduces internal compound through fermentation 1-2 ATP produced Use sulfur and nitrogen compounds as terminal electron acceptors in “anaerobic respiration” or Harrison FDST 8090 Microbial Physiology and Metabolism - Anaerobes Have fermentative metabolism Oxidizes carbohydrates in absence of an external electron acceptor Terminal electron acceptor is an organic product from the degradation of the carbohydrate e.g., pyruvic acid is reduced to lactic acid Harrison FDST 8090 Harrison FDST 8090 Fermentation Purpose Microbial standpoint Obtain energy for growth and reproduction Human standpoint Product preservation Create a variety of products Harrison FDST 8090 Chemical Alterations during Fermentation Production of desirable end-products Balance of different end-products and intermediate products Lactic, acetic, propionic acids, CO 2 , ethanol, flavor cpds What is produced – depends on: Which m/o are present Which enzymes are active Harrison FDST 8090
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Microbiology of Fermented Foods Harrison FDST 4030/6030 3 Harrison FDST 8090 Fermentation Practices Consider factors affecting growth of Desired m/o Undesired m/o Can influence: Rate of reactions Final products produced Harrison FDST 8090 Inoculation Types
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This note was uploaded on 09/30/2011 for the course FDST 4030 taught by Professor Harrison during the Fall '11 term at University of Georgia Athens.

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Micro of Fermented Foods2 - Microbiology of Fermented Foods...

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