What are Food Preservatives?

A food preservative is any substance that is added to retard spoilage whether from microbial growth, or undesirable chemical changes. Food preservatives helps to maintain the freshness and shelf life of food products because without them, they would spoil quickly due to exposure to air, moisture, bacteria or mold.

Types of Food Preservatives –

There are 2 types of Food Preservatives – 

1. Class I Preservatives
2. Class II preservatives

Class I Preservatives –

Class I Preservatives Includes such as salt, sugar, alcohol, vinegar, oil, etc. Class I Preservatives are also known as natural preservatives.

Salt as a Food Preservatives –

• Salt is used in brine or may be directly applied to the food. Salt at a concentration of 15-25% is sufficient to preserve most food products

It exerts its preservative action by:

• Increases the osmotic pressure at a level in which plasmolysis of microbial cells takes place.
• Salt causes dehydration by drawing out and tying out water from the tissue of food.
• Salt also ionizes to yield chlorine ions, which is harmful to microorganisms.
• Salt also interferes with the action of proteolytic enzymes.

Sugar as a Food Preservatives – 

• Sugar act as a food preservative in those food products in which it is used at a concentration of 66% or more alone acts as a preservative.

It exerts its preservative action by:

• Absorbing most of the available water in food products results in less water available for the growth of microorganisms.  Hence, their multiplication is inhibited and even those already present die out gradually.
• Causing high osmotic pressure that creates a condition that is unfavorable for growth for microorganisms.

Class II preservatives:

Class II Preservatives are also known as chemical preservatives which are synthesized from the chemicals. Class II Preservatives are added to the food after they are processed.

Sodium benzoates as Food Preservatives –

• Preserves food by having antifungal properties. It works by entering the individual cells in the food and balancing its pH level, increasing the overall acidity of the food. By lowering the pH of food, it creates an environment in which fungi cannot grow. It is primarily added to acidic foods to enhance their flavors such as in pickles, jam, and fruit juices.

Sorbates as Food Preservatives – 

• Sodium sorbates and potassium sorbates inhibit mold and yeast in foods such as cheese, baked products; fruit juices, wines, pickles, etc. The antimycotic action of sorbates is due to the instability of mold to metabolize its conjugated unsaturated structure.

Nitrites as Food Preservatives – 

• Sodium nitrites are commonly used as preservatives for ham, bacon, and sausages. It inhibits the growth of clostridium botulinum spores in refrigerated meats.

Propionic acid and its sodium and calcium salts:

• Exerts its antimicrobial activity against mold and some bacteria. The acid finds extensively used in bakeries where it not only limits the mold growth but is also highly active against the bacillus mesentericus that cause ropiness of bread.

Parabens as Food Preservatives – 

• These are esters of para – hydroxybenzoicacid, which are used as antimicrobial compounds .mainly methyl, ethyl, propyl, heptyl, and benzyl esters are used. Mainly used for preservation of beer, sauces, desserts, soft drinks, processed fish, jams, pickles, and flavoring syrups

Sulphur dioxide as Food Preservatives – 

• Used for the preservation of juices, pulp, beverages, and other products. It is highly active against bacteria, mold and also prevents enzymatic browning. Being gas it is more convenient to handle it, generally used in the form of its salts such as sulphites, bisulphites, and metabisulphites.

Epoxides as Food Preservatives – 

• Ethylene oxides and Propylene oxide. These are cyclic ether that destroys all forms of microorganisms even including spores and viruses. These oxides are used in gaseous form and after adequate exposure, residual oxides are removed by flushing and evacuation. Their use is limited to dry items such as nuts and spices.