Biomedical Engineering Reference
In-Depth Information
TABLE 10.7
Basic Preservation Principles of Main Food Processing Techniques
Process
Type/Product
Principle
Ref.
Drying
Air, drum, vacuum drum,
spray, puff, freeze,
fluidized bed, osmotic
Removal of water necessary for growth
of microorganisms.
125, 126
Thermal
processing
Still retorts, agitating
retorts, rotomats,
hydrostatic sterilization,
flame sterilization, flash
“18”, aseptic canning
Inactivation of all viable forms of
microbial life in the food; hermetic
packaging prevents recontamination.
126
Biological
preservation
Fermentation
Lowering of pH by acid-producing
microorganisms used as culture.
125, 126
Antibiotics (nisin)
Antimicrobial action.
127
Natural antioxidants
Avoiding free radicals formation.
Chemical
preservation
Controlled or modified
atmosphere
Lack of O
2
for microbial growth.
2, 126
Nitrites, NaCl, ethylene
oxide, benzoates,
methylene bromide,
sorbic acid
Different antimicrobial actions.
Pasteurization
Inactivation of many viable
microorganisms.
125, 126
Refrigeration
Meats, dairy, produce, fish,
miscellaneous
Microbial growth stopped or slowed
down (psychotrophs) by low
temperatures
125, 126
Freezing
Sharp, blast, plate,
fluidized bed, freon,
carbon dioxide, liquid
nitrogen
Solid water (ice) in food unavailable to
microorganisms; low temperature of
storage inhibits microbial growth and
many enzymatic reactions.
125, 126
Intermediate
moisture foods
Pickling, salting, sugaring
Lowering of pH and/or
a
w
below
microbial growth tolerance limits by
added acidulants, salts, or sugars
125, 126
Physical methods
Ionizing energy;
nonionizing radiations:
macrowave dielectric
heating, microwave
heating
Killing of some microorganisms present
in foods and inactivation of many
viable microorganisms
125, 126
Other heating
process
Baking, smoking, frying
Inactivation of many viable
microorganisms.
125, 126
functionally identical in all living organisms. Thus, it can be transferred between
related and unrelated living organisms, and specific vectors and gene transfer systems
have been developed for microbial, plant, and animal applications. Genetic engi-
neering has the potential to be more predictable, controllable, and precise than
classical breeding and selection. In addition, genetic improvements can proceed at
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