Food is one of the 3 most basic needs of life. Its importance can be gauged by understanding that throughout history, entire civilizations have been based on the availability of food. More plentiful food supply could support denser populations, and farming was a way for people to stay connected to their land. Small villages became towns, and towns became cities. Due to such importance of food, even in ancient times the production and preservation of food have been considered paramount among other things.
Food preservation can be defined as the process of treating and handling food in such a way as to stop or greatly slow down spoilage and prevent food-borne illness while maintaining nutritional value, texture, and flavor. Food preservation strategies include those that limit the growth of germs and slow the oxidation of fats that produce rancidity. Ancient preservation techniques include fermentation, oil packing, pickling, salting, and smoking. Refrigeration in caverns or under chilly water was another well-known ancient food preservation technique. As early as 6000 BC, people in different parts of the world discovered techniques for drying and smoking foods.
Food preservatives can be classified by quite a few parameters. A classification based on the type of action they perform has been explained ahead. On this basis, they can be classified into antibacterial and anti-oxidants.
Anti-oxidant:
Anti-oxidants follow a chain-breaking mechanism by which the primary antioxidants donate electrons to the free radicals present in the system, for example, lipid radicals. Chain breaking antioxidants act by scavenging free radicals and donating hydrogen atoms. An antioxidant is a molecule that is stable enough to give an electron to a rogue free radical and neutralize it, decreasing the free radical's ability to harm. Because of their ability to scavenge free radicals, these antioxidants can postpone or prevent cellular damage. These low-molecular-weight antioxidants can safely interact with free radicals and stop the chain reaction from causing harm to essential components.
The principal mechanism of action considered is the chain-breaking mechanism by which the primary antioxidants donate electrons to the free radicals present in the system. The mechanism of chain reactions can be divided into three stages:
- Initiation
- Propagation
- Termination
On the first stage of oxidation reaction from biological systems, RH is formed radicals R- as a result of abstraction of a hydrogen atom H-
Initiation Stage:
(1) RH → R˙+H˙
(2) R˙ → R˙+O2 → ROO˙
(3) 2ROOH → ROO˙+RO˙+H2 O
After initiation, propagation of the free radical chain occurs, in which molecules of oxygen from the environment react with reactive radical species, resulting in the formation of peroxides and peroxyl radical ROO-. These intermediates may further propagate free radical reactions.
Propagation Stage:
(1) R˙+O2 → ROO˙
(2) ROO˙+RH → ROOH+R˙
(3) RO˙+RH → ROH+R˙
In the last stages, the interaction of two radicals may lead to the formation of non-radical adduct and termination of the free radical chain.
Termination Stage:
(1) R˙+R˙ → R–R
(2) R˙+ROO˙ → ROOR
(3) ROO˙+ROO˙ → ROOR+O2
(4) Antioxidants+O2 → Oxidized antioxidants.
Antioxidants can slow lipid oxidation by inactivating or scavenging free radicals, thus inhibiting initiation and propagation reactions. The antioxidants function by the very simple and effective method of donating a hydrogen atom to free radicals and thus terminating their life. factors such as the bond dissociation energy between oxygen and phenolic hydrogen, pH related to the acid dissociation constant, and reduction potential and delocalization of the antioxidant radicals determine how efficient the antioxidants are at scavenging free radicals in foods.
Anti-bacterial:
Bacterial deterioration is prevented by antimicrobial preservatives. Lactic acid is the most widely used antimicrobial preservative. Nitrates and nitrites are also antibacterial, and the detailed mechanisms of these chemical substances range from bacterial growth suppression to enzyme inhibition. Most anti-bacterial preservatives have the same mechanism of action. They interfere with the cell membrane of the target microorganism and disrupt cellular activities. These can be Pore development in the cytoplasmic membrane of target bacteria is part of the antimicrobial process, they can cause the loss of intracellular molecules and the collapse of the proton motive force cause cell death.
A few methods of action of certain antimicrobial agents are as follows:
Nitriles:
They are commonly used in meat, poultry, etc. They are used to prevent the microbial activity of staphylococcus aureus, Escherichia, Pseudomonas, and Enterobacter. The mode of action of nitriles is through reaction with the enzymes in vegetative cells and germinating spores. they also restrict the use of iron by the bacteria and interfere with the membrane permeability hence limiting transport.
Butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT), and t-Butyl hydroxyquinone (TBHQ):
These are considered indirect microbial. They inhibit the growth of many Gram-positive and Gram-negative bacteria and also effectively prevent growth and toxin production by molds and the growth of yeasts. The antimicrobial action is produced by their adverse effect on the cell membrane and enzymes.
Benzoic acids:
Used in acidified food. It inhibits the function of enzymes and membrane protein, destroys membrane potential.
Propionic acid:
Used in bread, bakery products, etc. It causes acidification of cytoplasm, destabilization of membrane protein
Sorbic acid:
Effective against molds and yeasts. It interferes with the synthesis of the cell wall, protein, RNA, DNA. Inhibit spore germination.
Food preservation, coupled with agriculture, allowed civilizations to form once food supplies could be safely kept in quantity, reducing the need to hunt and gather for food on the move. Rather than having to eat the kill or harvest immediately, preservation allowed for planning for times. Food preservation aids in extending the shelf life of food products. As food production has risen rapidly, the need for improved preservation and storage has become critical. Preservation allows for foods to be sent over longer distances, stored for longer periods in shops, and enjoyed for a longer period with more nutrients intact, all adding to building a healthier society.
Marvellous
Work!!!
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