Download Thermal Pres. Cold Notes

Thermal Preservation
Cold
Processing
Thermal PreservationCold Processing
Chemical reactions involving enzymes or
microbes are usually the cause of food
spoilage.
The speed at which chemical reactions
occur are directly related to the temperature
of the food.
The chemical reaction rates roughly double
for every 10* C. (18*F) increase in
temperature.
Types of Cold Processing:
 Refrigeration:
 Temperature
should be kept below 4*C
(40*F).
 Slows the growth of bacteria; it does not
stop it.
 Once food reaches room temperature,
bacteria will start to grow again, increasing
the rate of spoilage.
Freezing
 Temperature
should be 18*C (0*F) or
lower.
 Food will keep for several months in a
frozen state.
 Freezing may change the texture of
some foods. (When the water in the food
expands, the ice crystals may cause the
cells to rupture).
Freezer Burn
 Foods
should be stored in airtight
packaging to avoid freezer burn.
 If the packaging is not airtight, moisture
will evaporate from the food.
 Evaporated moisture will re-freeze on
the packaging or the walls of the
freezer.
 The food cannot regain the lost
moisture, thus becoming tough and dry.