Final Review - Food Processing Preservation Storage life at...

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Food Processing & Preservation * Storage life at 70˚F: - Meat/fish/poultry/leafy veggies: 1-2 days - Fruits: 1-7 days - Dried fruits/seeds, dried/salted/smoked meat & fish: 360+ * Deterioration: - Microorganisms: bacteria, yeasts, molds - Yeasts: unicellular; problems in acid products - Molds: multicellular, grows w/ O 2 ; grows at a variety of temps, for solid cheese cut off ½ - 1 inch - Natural food enzymes: every 10˚C rise in temp, rxn rate doubles - Insects/rodents: destroy 5-10% of US grain crop; 20-50% of food supply never reaches people - Excessive heat (& cold): ~ Accelerates deterioration process ~ Microorganisms double more quickly ~ Foods dry out; moisture removed - Moisture: req’d for chem. rxns, but too much accelerates - Dryness: food crumbles, loses structure/taste - Air (O 2 ): causes oxidation of food → modified atmosphere packaging: use N 2 & CO 2 to lower O 2 amt - Light: Destroys Vitamins A, C, Riboflavin ~ Milk in bl-mlded, polyethlne containers in lighted display for 24 hrs lose 90% of vit A & 8% Ribofla - Time: except wine & cheese, everything deteriorated with time * Process foods to increase availability and slow microorganism growth * Preservation techniques: freezing, canning, refrigeration, dehydration, irradiation, chem. preservatives… * Pasteurization: Method Params Approx Shelf Life - Batch 145˚F for 30min ~ 12 days - ↑ Tempt, Short Time 161˚F for 15sec ~ 14 days - Ultra Pasteurized 280˚F for 2sec; conv pack ~ 45-60 days - Ultra High Temp 280˚F for 2sec; aseptic pack ~ 6mo at room temp, 1 yr in fridge * Freezing: Quality of frozen foods is related to rate of freezing: faster is better * Food dehydration methods: air/spray/freeze drying * Food Irradiation: Application of ionizing radiation to food; “cold process” - Low Doses: inhibit sprouting, delay ripening, control insects/parasites - Medium: control pathogens, extend shelf-life - High: produce high-quality shelf-stable foods * Shelf life of food depends on: composition of the food, microbiological quality, processing method, packaging system, storage conditions
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Microorganisms & Their role in foods * Roles of microorganisms in food: - Beneficial: fermented dairy, meat, veggies and other - Food Spoilage: off flavors & physical defects - Harmful: food borne illness * Major food incidents result from: mishandling, incorrect ingredients, packaging problems, lack of attention to detail, malicious contamination * Food borne illnesses are a major cause of: personal distress, preventable death, economic burden * Factors affecting rise in food borne illnesses: - Changes in food processing technologies - Increase in food prepared outside the home - Changes in microorganisms (fewer cells needed to cause illness/some are more sever) …However, there are improved diagnostic techniques * Food borne pathogens: EColi, listeria monocytogenes (can grow in fridge), salmonella, hep A, norovirus * Factors increasing the risk of food borne infection/severity: - Age <5yrs: lack of developed immune system - Age >50-60yrs: immune system failing - Pregnancy: altered immune system during pregnancy - Hospitalized people: individuals already debilitated by illness
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