With the beginning of civilisations and human settlements, the
consumption of food by the human population increased and thus,
the need to preserve excess foods became essential for survival.
Since then, many traditional and household methods of food
preservation have evolved to limit food spoilage. Such as cooking,
the addition of spices and fermentation.

In modern commercial food production, spoilage and contamination
are preserved by a variety of methods.

1. Filtration:

Microorganisms can be removed from the water, wine, beer, juices,
soft drinks and other liquids by filtration. Several major brands
of beers are filtered rather than pasteurised to preserve the
flavour and aroma of the original product.

2. Dehydration and freeze drying:

Dehydration, such as Lyophilisation to produce freezing dried foods,
is a common method of eliminating microbial growth. It is especially
effective for vegetables and pasta.

3. Refrigeration:

Refrigeration temperatures (typically -2°c to 16°c) slows microbial
growth but can’t eliminate microbes completely. Thus, it is only
used to preserve food for shorter periods and generally used for
household purposes.

4. Vacuum Packing:

Food can be packed under vacuum or under atmosphere with decreased
oxygen or increased carbon dioxide level. For example, carbon dioxide
storage is particularly effective for extending the shelf life of

5. Pasteurisation:

Pasteurisation involves heating food to a temperature that kills
disease-causing microorganisms and substantially reduces the levels
of spoilage organisms with minimal effect on food value and texture.
For example, milk is commonly pasteurised at 63°c for 30 minutes
followed by quick cooling to 4°c.

6. Canning:

Canning is most widespread and effective means of long-term food
storage. In canning, food is cooked under pressure to attain a
temperature high enough to destroy endospores (around 121°c).
After heat treatment, the cans are cooled as rapidly as possible,
usually with cold water. The main drawback of canning is that the
quality of food is sometimes compromised, particularly that of
liable biochemicals such as vitamins.

7. Microbial Product Based Inhibition:

Bacteriocins are bactericidal proteins active against closely related
bacteria, which bind to specific sites on the cell, and affect cell
membrane integrity and function. The only currently approved product
is Nisin. It is nontoxic to humans and affects mainly gram-positive
bacteria, especially Enterococcus faecalis. Nisin can be used
particularly in low-acid foods to improve inactivation of Clostridium
botulinum during the canning process or to inhibit germination of any
surviving spores.

What Is Bacteria

8. Irradiation:

Exposure to ionising radiation, known as food irradiation, effectively
sterilises many kinds of food for long-term storage. The main concerns
about food irradiation are its potential for unknown effects on food
chemistry and the hazards of irradiation during human involvement in
the process.

9. Organic Acids as Preservatives:

Organic acids commonly used to preserve food include benzoic acid, sorbic
acid, and propionic acid. The acids are generally added as salts such as
sodium benzoate, potassium sorbate, sodium propionate. They work best in
foods that already have moderate acidities (pH 5-6), such as dried fruits
and processed cheeses.

10. Inorganic Compounds as Preservatives:

Inorganic food preservatives include salts, such as phosphates, nitrites,
and sulphites. Nitrites and sulphites in inhibit aerobic respiration of
bacteria, and their effectiveness is enhanced at low pH. Current concern
about nitrite arises from the observation that it can react with amines
to form carcinogenic nitrosamines.

What Is Bacteria

11. Other organic compounds:

Numerous organic compounds, both traditional and synthetic, have antimicrobial
properties. For examples, Cinnamon and Cloves contain the benzene derivative
eugenol, a potent antimicrobial agent.

11 Methods of Food Preservation used by Food Industry


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