Microsoft PowerPoint - Microbiology & Food

Microsoft PowerPoint - Microbiology & Food -...

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MICROBIOLOGY & FOOD Microorganisms in Food Food Preservation Food-borne Illness Fermented Foods
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Microorganisms in Food Factors affecting microbial growth in food composition pH resence and availability of water presence and availability of water oxidation-reduction potential altered by cooking physical structure presence of antimicrobial substances
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Microorganisms in Food r Factors affecting microbial growth in food c temperature lower temperatures retard microbial growth c relative humidity higher levels promote microbial growth c atmosphere oxygen promotes growth c modified atmosphere packaging (MAP) use of shrink wrap and vacuum technologies to package food in controlled atmospheres
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Microorganisms in Food Composition and pH Putrefaction proteolysis and anaerobic breakdown of proteins, yielding foul- smelling amine compounds H impacts make up of microbial community and therefore pH impacts make up of microbial community and therefore types of chemical reactions that occur when microbes grow in food
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Microorganisms in Food Water availability in general, lower water activity inhibits microbial growth water activity lowered by: drying dition of salt or sugar addition of salt or sugar osmophilic microorganisms prefer high osmotic pressure xerophilic microorganisms prefer low water activity
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Microorganisms in Food Physical structure grinding and mixing increase surface area and distribute microbes romotes microbial growth promotes microbial growth outer skin of vegetables and fruits slows microbial growth
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Microorganisms in Food Antimicrobial substances coumarins – fruits and vegetables lysozyme – cow’s milk and eggs ldehydic and phenolic compounds erbs and aldehydic and phenolic compounds – herbs and spices allicin – garlic polyphenols – green and black teas
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Microorganisms in Food Food spoilage results from growth of microbes in food alters food visibly and in other ways, rendering it unsuitable for consumption volves predictable succession of microbes involves predictable succession of microbes different foods undergo different types of spoilage processes toxins are sometimes produced algal toxins may contaminate shellfish and finfish
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Microorganisms in Food Toxins ergotism toxic condition caused by growth of a fungus in grains aflatoxins carcinogens produced in fungus-infected grains and nut products fumonisins carcinogens produced in fungus-infected corn
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Food Preservation Removal of Microorganisms usually achieved by filtration commonly used for water, beer, wine, juices, soft rinks, and other liquids drinks, and other liquids
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Food Preservation Low Temperature refrigeration at 5 ° C retards but does not stop microbial growth icroorganisms can still cause spoilage with microorganisms can still cause spoilage with extended spoilage growth at temperatures below -10 ° C has been observed
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Microsoft PowerPoint - Microbiology & Food -...

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