1
are used to ensure safe food products for extended periods.
2
of milk, a heating process that eliminates bacteria.
3
or heat capacity is the heat required to increase the temperature of one unit of mass by one degree.
4
In steady state conduction through a solid-like material the important thermal property
5
is a measure of the ease with which heat flows through a material. Heat is conducted quickly through a metal like copper, hence its thermal conductivity value is high. Heat flows more slowly through materials like wood or fiberglass insulation; their thermal conductivity is low.
6
determines the speed of heat of three-dimensional propagation or diffusion through the material. It is represented by the rate at which temperature changes in a certain volume of food material, while transient heat is conducted through it in a certain direction in or out of the material (depending if the operation involves heating or cooling).
7
is a measure of the ability of a material to absorb radiation, equal to the internal absorptance of a
homogeneous layer of the materials under conditions in which the path of the radiation has unit length and the boundaries of layer has no influence.
8
is defined as the ratio of the energy radiated from a material's surface to that radiated from a perfect emitter, known as a blackbody, at the same temperature and wavelength and under the same viewing conditions.
9
is an optical property of a material, which describes how much light is transmitted through material in relation to an amount of light incident on the material.
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are sterilized with heat processes.
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(100-125oC,15 min-2 h) -
Steam
- Meat , fish, soup, vegetables, fruit
- Sterilization of solids and liquid
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(135–150 oC, 1-10s) – steam
- Milk, cream, custard, dessert, soup
- Aseptic Packaging
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(40-100 oC, 2 s–2 h) - Steam
- Milk, fruit juices, coffee, cheese, whey
- Removal of pathogenic microorganisms
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(150-250C) - Hot air, steam hot water
- Milk, potato, vegetables, fruit, meat, fish
- Removal of water
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(10–0 oC) - Cold air
- Milk, cream, custard, dessert, soup
- Aseptic Packaging
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Hot air, steam hot water,
electricity
- Milk, fruit juices, coffee, cheese, whey
- Cooking foods, baking cereal-based foods
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(100-150C) - using hot air steam hot water
- French fried, potatoes, doughnuts
- Immersion in hot water
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Cryogenic fluids (liquid nitrogen)
- Reducing temperature below freezing point
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It is the total heat content of a material per unit mass
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Homogenous material of slab form
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Powdered granular, material
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Simple, fast, popular for small sample
size food
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Low to high moisture food
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It is defined as the “rate of heat transfer per degree of
temp diff across the solid fluid interface per unit of the
solid’s surface area”.
26
Fruit and vegetable products are living organisms. To
maintain their life processes, they must consume
energy.
● They do this by a “combustion” process that “burns”
sugar to produce CO2 and heat.
● The heat produced by this process is commonly
27
can then be related to the
commodity’s heat generation rate from respiration
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When a material is heated, it leads to density
difference. Solids mostly expand in response to
heating and contract on cooling.
● This response to temperature change is expressed as
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is the ratio of total
emissive power of any body to the total emissive
power of a black body at the same temperature.
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Photosynthesis vs Cellular Respiration - Practice Quiz