Extending Shelf Life

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What are the four methods of extending shelf life at low temperatures?
chilling, cook-chilling, freezing, AFD
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What is AFD?
accelerated freeze drying
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What is meant by quick frozen?
food is reduced from 0*c- -18*c in 12 minutes
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What does quick freezing reduce?
cell damage in the food
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What is AFD a combination of?
freezing and drying
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What happens during AFD?
the food is quick frozen then placed in a vacuum under reduced pressure, before being slightly heated to change ice to vapour and dry the food
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What is cook-chilling?
when food is cooked then cooled to between 0*c and 3*c in 90 minutes or less
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How long do cook-chill products have a shelf life of?
5 days
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How hot do cook-chill dishes have to be heated to at least?
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Why is the optimum temperature for chilling foods 4*c?
prevents growth of listeria monocytogenes
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Once cooked how long do you have to heat cook-chill products?
2 hours
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What does chilling cause?
enzyme activity to be reduced
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What are the five high-temperature methods of extending shelf-life?
pasteurisation, sterilisation, ultra-heat treatment, canning, irradiation
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What is pasteurisation?
liquid is heated and held at a temperature for a short time (HTST)
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What is sterilisation?
food is heated to high temperatures for a longer period than in pasteurisation
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What is ultra-heat treatment?
when liquid is heated to a very high temperature for a short time
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What do radicals do during irradiation?
destroy the bacteria
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Where does irradiation use ionising radiation from?
electron beams or gamma rays
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What is canning a form of?
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How do radicals form in irradiation?
the food absorbs the energy
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How long do baked beans have to be heated at 120*c for until being quickly cooled?
33 minutes
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What is irradiation NOT the same as?
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Other cards in this set

Card 2


What is AFD?


accelerated freeze drying

Card 3


What is meant by quick frozen?


Preview of the front of card 3

Card 4


What does quick freezing reduce?


Preview of the front of card 4

Card 5


What is AFD a combination of?


Preview of the front of card 5
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