Factors Causing Degradation of Food Products and How to extend their Shelf life
Foods
constitute are essential for sustenance of human and
animal life. The present article covers some of the physico-chemical changes
that take place in foods resu
lting in their deterioration.
Expiry date and Best before date
Today
superstores are flooded with large variety of synthetic foods to cater to the
choice and taste of consumers. Such foods bear labels which mention date of
manufacture, use by date or best before date. Use by date and best before date
are not well understood and often confuse the consumer.
Best before
date is
mentioned on food articles which deteriorate outwardly affecting consumer
acceptance but without affecting consumer health and safety. Foods with a shelf
life of a minimum of two years are not required to display a best before date.
Expiry date is a time
limit set by the manufacturer for consumption of the food items for reasons of
consumer health and safety.
Physical,
chemical and microbiological studies are required to be conducted on several
batches of finished products and contamination factors established also in
relation to packaging and storage condition variations before deciding on the
above described dates.
Factors
responsible for processed food deterioration
The main
factors which lead to deterioration of processed foods are:
- Moisture gain or loss producing
changes in texture, hardness, microbial growth and colouration
- Chemical and enzymatic activity
resulting in colour, odour and texture changes
- Microbiological spoilage
Role of
water activity
Water
activity refers to the amount of free water present in a product that
is available for microbial growth. The gain or loss of moisture depends on
factors such as hygroscopicity of the product, temperature and relative
humidity. In packaged foods the changes are relatively lower.
Microbiological
growth
Microbiological
deterioration and possibility of growth of pathogens is dependent on the
availability of moisture, pH of media, temperature and presence of required
nutrients. Shelf life can be extended by exercising control on these
conditions. Inoculation with various spoilage organisms and observing growth of
pathogens can help control such harmful bacterial growth.
Chemical
deterioration
Oxidation of
lipids results in product before deterioration and can be prevented by
conducting accelerated stability tests.
Degree of
unsaturation in fats leads to higher degradation due to increased reactivity.
Lipase
enzymes cleave fatty acids from triglycerides and the free fatty acids add to
the odour and bitter taste thereby making the food unacceptable.
Photo- oxidation
reactions during storage can result in the formation of hydroperoxides which
break down to peroxides. The peroxide value can be estimated in a fat or oil by
quantitating the aldehydes which helps estimate the extent of fat or oil
degradation. The aldehyde n-hexanal can be estimated at low concentration
levels using GC – Headspace technique.
Stability of
cosmetic products for safety of use and factors governing their degradation
will be discussed in subsequent article.
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