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| Microbial Spoilage of Foods By Sadia Akhtar |
Microbial Spoilage of Foods
Food spoilage is the result of enzymatic,
bacterial and mechanical action on food, causing undesirable changes such as in
texture, flavour, colour, consistency, appearance and nutritive value.
For example, lactic acid formation by Lactobacillus,
Leuconostoc.
Lipolysis by Pseudomonas, Alcaligenes, Serratia, Micrococcus.
The spoiled food is
then harmful for human consumption and if consumed may cause diseases, called
food-borne diseases. And also causes economical loss.
Reasons
Behind Food Spoilage:
a.
Action of the enzymes:
Food may be spoiled by the action of the enzymes present on the food or by the
enzymes synthesized from the microbes.
Microbial metabolism results in production of
various metabolic compounds pH change and formation of toxic compounds, gas.
And these enzymatic reactions change the appearance of food.
Enzymes present in the foods containing fat
cause oxidation of lipids.
b.
Growth and metabolic activity of microorganisms:
Food contamination may be occurred by a wide range of microorganisms during
harvesting, processing, handling and cooking and then in storage.
The growth of microorganisms is mainly
influenced by the components present in the food, how the food is processed and
cooked and finally the environmental conditions of the storage such as
temperature, moisture etc.
c.
Chemical reactions:
Chemical reactions within the compounds present in food.
d.
Physical or mechanical actions:
Physical or mechanical actions such as freezing, drying,
burning, pressure, bite of insects.
The
components in the food are degraded mainly by these reactions:
1.
Fermentation
Carbohydrate + enzyme = acid, alcohol and gas
2.
Putrefaction
Protein + proteolytic
enzymes = Amino acids, ammonia, amines.
3.
Rancidity
Fatty acids +
lipolytic enzymes = Glycerol and fatty acids.
Foods are classified into three groups
based on spoilage:
1.
Stable or non-perishable foods:
Stable or non-perishable foods do not spoil easily unless they are handled
improperly.
For example, flour, sugar, powdered foods, spices, canned foods.
2.
Semi perishable foods:
These foods will not be spoiled for a long time ( for six months to about one
year) if they are handled and stored properly.
For example, Apples, potatoes, cake, pastry.
3.
Perishable foods:
These foods spoil
easily. Perishable foods should be refrigerated at 4.4℃ or below.
For example, fish, meats, fruits, vegetables, poultry, dairy products.
Sources
of Microorganisms in Foods Causing Food Spoilage:
Soil, water, air, plant products, intestinal tract of animals and humans,
improper handling, utensils.
Prevention
of Microbial Spoilage of Foods:
a) proper harvesting, handling and
processing.
b) refrigeration, which slows enzymatic reactions of microorganisms.
c) Drying
d) Salting and increased sugar concentration.
e) pasteurization, which reduces the number of pathogenic microbes.
f) Canning.
g) UV radiation.
h) heating.
The Daily Youth- tdy24.com Present
" Microbial Spoilage of Foods"
Written By
Sadia Akhtar
Student of Department of Microbiology
Jagannath University.
Email- sadiabd810@yahoo.com
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