2.6. Contamination during food storage
Food storage conditions are key parameters in food quality and
safety. Proper storage extends the shelf life of food, which depends
on the food type, packaging and storage conditions, particularly
temperature and humidity. During storage conditions (e.g., high
temperature and humidity), packaging material properties can be
affected. Migration and sorption of external/internal substances
phenomena (which at the end can be released again from the
packaging to the food) can occur anytime. Organoleptic changes
should not occur during food storage (European-Commission,
2011) and therefore packaging materials used for long term storage
should exhibit very good barrier properties. These barrier
properties not only affect the permanent gases such as O2, CO2 or
even water vapor, but also aromas and volatile organic compounds,
as was above mentioned. These physico-chemical processes heavily
depend on temperature and in a lesser extent on humidity, which
controls the diffusion of these contaminants into the foodstuff. To
minimize these unwanted phenomena, humidity in the storage
environment should be low. Moisture can lead to the breakdown of
some packaging materials (e.g., paper degradation and metal
rusting). The optimal range of temperature is the cool to moderate
range, between 4 and 21 C. Direct sunlight can speed deterioration
both on the food and on the packaging. Adsorption of unwanted offodors
is also a common phenomena in food storage. High fatty
foods are prone to odor contamination. In addition, food contamination
depends on the food type under consideration. Dry food and
canned foods have a long shelf-life, but color, flavor, and nutritive
value deteriorate over time. Freezer storage and refrigerator is
necessary for meat, fish, eggs, dairy products, etc. Under these
conditions food contamination by chemical or physical interactions
is minimized, as at low temperature the kinetics of processes is
slow and the reaction constants are also lower.
When using flexible plastic materials it is also important to
evaluate its permeability, since depending on the barrier properties
the transference of compounds through the packaging material will
be different as was demonstrated by Nerinetal. (Nerínetal., 2007).