micro_of_fermented_foods

micro_of_fermented_foods - Microorganisms in Food and...

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Harrison FDST 4030/6030 Microbiology of Fermented Foods 1 Harrison FDST 8090 Microbiology Microbiology of of Fermented Fermented Foods 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 ± 38 ATP produced per glucose molecule Harrison FDST 8090 In Aerobes Only
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Harrison FDST 4030/6030 Microbiology of Fermented Foods 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 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
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Harrison FDST 4030/6030 Microbiology of Fermented Foods 3 Harrison FDST 8090 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 04/08/2011 for the course FDST 4080 taught by Professor Pegg during the Winter '10 term at University of Georgia Athens.

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micro_of_fermented_foods - Microorganisms in Food and...

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