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The components of food product quality include:
- Safety
- Healthfulness
- Flavor
- Texture
- Color
- Shelf Life
A seventh component of quality in the minds of
many consumers is that of convenience
These components are dependent upon the
composition of the food, processing methods, packaging and storage. In many cases the
shelf life and convenience built into the product by the manufacturer dictates the safety,
healthfulness, flavor, texture and color attributes of the product.
In many cases compromises are made to achieve
desired shelf life or convenience. This is illustrated for milk in the following table,
where product attributes are changed to achieve increased shelf life.
| PRODUCT |
SHELF LIFE |
PROCESS |
COMMENTS |
| Fluid milk |
2 weeks under
refrigeration |
HTST
pasteurization |
Retains most
of the characteristics of unprocessed milk |
| UHT fluid
milk |
3-6 months at
room temperature |
UHT
pasteurization and aseptic filling in plastic packages |
Higher heat
produces changes in flavor; off flavors generally develop after 90 days due to chemical
changes |
| Evaporated
milk |
1-2 years at
room temperature |
Concentration
and retort sterilization, canned |
Higher heat
that UHT pasteurization causes brown color and caramelized flavor; often thickens on aging |
| Spray dried
whole milk |
1-3 years at
room temperature |
HTST
pasteurization, concentration and spray drying |
Must be
reconstituted for use; process changes flavor; shelf life depends on degree of oxidation
during storage - which depends on Aw, packaging materials and temperature of
storage |
The extension of storage life of products
generally involves heat treatments, refrigeration or freezing or reduction of water
activity by either addition of water binding agents (sugars, etc) or drying. Such
processes, while improving shelf life almost always have some effect on the components of
the food:
The factors which influence changes for various
ingredients in foods include the following:
Proteins:
- heat denaturation which changes solubility and
texture of foods
- light oxidation causes off flavors
- enzymatic degradation can cause changes in body
and texture and also bitter flavors
- freezing can alter protein conformation and
solubility in some cases
Lipids:
- enzymatic hydrolysis can cause off flavors - such
as soapy or goaty, depending on type of oil;
- also makes frying oils unsuitable for use; can
change functionality and crystallization properties
- oxidation of unsaturated fatty acids causes off
flavors
Carbohydrates:
- high heat treatments cause interactions between
reducing sugars and amino groups to give Maillard browning and changes in flavor
- hydrolysis of starch and gums can change texture
of food systems; some starches can be degraded by enzymes or under acidic conditions
Vitamins:
-depending upon the vitamin, losses can occur
when the food is heated, exposed to light or to oxygen
A summary of effects of some processing on food
products is shown in the following table:
| Process |
Effects |
| High Heat treatment |
Inactivation of
enzymes, destruction of microorganisms; browning; flavor changes; texture changes |
| Freezing |
Minimize of microbial
growth; slowing the rate of chemical reactions; disruption of cellular material
(softening); precipitation of
proteins on thawing |
| Packaging |
Improper packaging or
packaging materials can permit the transfer of oxygen into the product and cause off
flavors; moisture transfer into packaged foods can cause caking, increase in the rate of
chemical reactions and permit enzymes to action of food constituents |
| High shear pumping |
Can cause size
reductions; production of foams (either desired on undesired); disruption of protein
structure; activation of enzymes in some cases. |
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