Lesson6ThermalPreservationofFoods - Lesson 6 Thermal...

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Understanding Nutrition
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Chapter 14 / Exercise 04
Understanding Nutrition
Rolfes/Whitney
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Lesson 6: Thermal Preservation of Foods1. Interpret the basis of thermal food processing
E.Considerations for selecting heata.What is the objective or purpose? (blanching or pasteurization or commercial sterilization)b.Are there additional preservation steps? (is it combined with other preservation method?)c.What are the physical, chemical properties of the food? (Type of food)d.What is the heat resistance of microorganisms in the food?F.Use combo of pasteurization + fridge storage if eat fast after process (i.e., pasteurized milk, pasteurized vacuum package, cured meats) G.Use commercial sterilization if store longer at ambient temp in evacuated sealed containers H.Time-temperature combo for pasteurization + commercial sterilization depends on the most heat-resistant disease-cause and spoilage-causing microorg in that foodI.Consider the food’s physical properties (solid vs. liquid) & chemical properties (pH, fat content etc.,) when choosing type of thermal process +rate of heat penetrationJ.Thermal preservation processes MUST be designed so that the slowest heating portion of the food commodity receives the specific time-temperature thermal treatment to minimize risks of illness/ post-process spoilageK.Choose thermal process based on the heat resistance of the microorg in the foodL.Low acid foods need thermally processed + vacuum sealed in gas-tight containers (anaerobic condition) → Clostridlum botullnum = microorg most concern (found in soil, water, mud) = all foods of agricultural and fisheries origin have this spore2. Compare and contrast thermal processing categories: blanching, pasteurization, and commercial sterilizationBlanchingMainly to veggies, some fruits by heat in boiling water or steam.Basis of blanching:1.Inactivate enzymesenzymatic degradation no occur in interval btwn packaging and thermal processing or during frozen storage or in early stages of food dehydration and after reconstitution of dehydrated plant foods2.Wilt vegetable products → enable packing of products into containers for proper fill weights 3.Drive off inter- and intracellular oxygen and other gasses from plant tissues so containers no deform by high internal pressure due to expanding gases within container + permit formation of vacuum in container after thermal processing. PasteurizationAt least 72C for 15 seconds. High temperature short time HTSTBasis of pasteurization:Inactivate pathogenic bacteria and viruses in low acid food (i.e., milk)Pasteurize acid food (pH <4.6) to inactivate spoilageSpoilage-causing microorg in low-acid/acid food can still survive typical pasteurization process conditions (milk→ proteolytic+lipolytic bacteria = heat
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Understanding Nutrition
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Chapter 14 / Exercise 04
Understanding Nutrition
Rolfes/Whitney
Expert Verified
resistant = survive pasteurization)

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