BlogIIT-JEEImportant Topic of Chemistry:Preservatives

Important Topic of Chemistry:Preservatives

Preservatives come in a variety of forms that are tailored to specific products and are effective against specific chemical changes. Mold growth is inhibited by antimycotics in products such as fruit juice, cheese, bread, and dried fruit; sodium and calcium propionate, as well as sorbic acid, are examples. Antioxidants (for example, butylated hydroxytoluene, or BHT) slow the development of rancidity caused by oxidation in margarine, shortening, and a variety of fat and oil-containing foods. Tetracyclines, for example, are antibiotics used to prevent the growth of harmful bacteria in poultry, fish, and canned foods. Humectants, or moisture-absorbing substances, aid in the retention of moisture in products like shredded coconut. Several preservatives have an aesthetic role in addition to retarding spoilage—that is, they improve the appearance of the product. One such preservative is sodium nitrate (or its nitrite form), which is controversial due to its link to the formation of an alleged carcinogen. Nitrate and nitrite are being used in the curing of meats to prevent the growth of botulism-causing bacteria; they also give ham, bacon, and luncheon meats their reddish colour. Adversaries argue that modern sanitation and refrigeration eliminate the need for chemical preservatives. Representatives from the meat industry defend their use for cosmetic reasons, claiming that the natural brownish colour of these meats would be unappealing. Antistaling agents are preservatives used in baked goods to keep moisture and softness (e.g., glyceryl monostearate). Such substances are thought to work by preventing starches from losing water.

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    A preservative is really a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to avoid or prevent decomposition by microbial growth or by undesirable chemical changes. Overall, preservation is implemented in two modes, chemical and physical. Chemical preservation is the process of adding chemical compounds to a product. Refrigeration and drying are examples of physical preservation processes. Food additives with preservatives reduce the risk of foodborne infections, reduce microbial spoilage, and preserve freshness and nutritional quality. Dehydration, UV-C radiation, freeze-drying, and refrigeration are some physical techniques for food preservation. Techniques for chemical and physical preservation are sometimes combined.

    Since prehistoric times, preservatives have been used. Smoked meat, for example, contains phenols and other chemicals that help it last longer. Food preservation has evolved significantly over the centuries and has played an important role in increasing food security. Use of such preservatives other than traditional oils, salts, paints, and so on in food began in the late 1800s but did not become widespread until the twentieth century.

    Any use of food preservatives varies greatly between countries. Countless developing countries that lack strong governments to regulate food additives face either harmful levels of preservatives in foods or a complete avoidance of foods deemed unnatural or foreign. Because chemical preservatives were only recently introduced in these countries, they have also proven useful in case studies. Despite the consumption of these imported foods, knowledge about the contents of food is extremely low in urban slums of densely populated countries.

    Antimicrobial preservatives

    Antimicrobial preservatives keep bacteria at bay. This is the most traditional and ancient method of preserving—ancient methods like pickling and adding honey prevent microorganism growth by altering the pH level. Lactic acid is the most commonly used antimicrobial preservative. Nitrates and nitrites seem to be antimicrobial as well. Such chemical compounds’ detailed mechanisms range from inhibiting bacterial growth to inhibiting specific enzymes. Broad-spectrum preservatives, such as isothiazolinones and formaldehyde releasers, are used in water-based home and personal care products, which can cause sensitization and allergic skin.


    Most foods are ruined by the oxidation process, especially those with a high fat content. When fats are exposed to oxygen, they quickly become rancid. Antioxidants either prevent or inhibit oxidation. Ascorbic acid (vitamin C) and ascorbates are the most common antioxidant additives. As a result, antioxidants are frequently added to oils, cheese, and chips. BHA, BHT, TBHQ, and propyl gallate are phenol derivatives that act as antioxidants. These substances prevent the formation of hydroperoxides. Ethanol and methylchloroisothiazolinone are two other preservatives. A number of agents are used to sequester (deactivate) metal ions that would otherwise catalyse fat oxidation. Disodium EDTA, citric acid (and citrates), tartaric acid, and lecithin are common sequestering agents.

    Preservatives in Food

    Food preservatives are being used to prevent spoilage caused by bacteria, moulds, fungus, and yeast. Preservatives can keep food fresher for longer periods of time, thereby increasing its shelf life. Food preservatives are often used to slow or prevent changes in colour, flavour, or texture, as well as to postpone rancidity.

    Preservatives in Medicine and Pharmaceuticals

    To prevent future microbial contamination, preservatives are commonly used in medications such as acetaminophen, insulin, and cough syrup. Simply define, preservatives aid in the prevention of the growth of microorganisms, specifically bacteria and fungi, which can cause disease or infection.

    Preservatives in Cosmetics and Personal Care Products

    Preservatives in beauty products help prevent contamination and the growth of harmful bacteria in a wide range of products, including sunscreens, lotions, and shampoos, as well as cleansers, toothpaste, and makeup.

    Antimicrobial preservatives in skincare helps to prevent mould, yeast, and bacteria growth, protecting against contamination that can cause irritation or infections. Antioxidant preservatives could also help prevent the spoilage of personal care products by suppressing reactions that can occur when certain ingredients in a cosmetic or personal care product and oxygen will merge in the presence of light, heat, and some metals.

    Preservatives in Wood

    Preservative-treated wood could be used to construct telephone poles, road signs, and marine pilings, as well as decks, play structures, and raised garden beds.


    What are the preservatives in food?

    For hundreds of years, salt, sodium nitrite, spices, vinegar, and alcohol have been used to preserve foods. In order to prevent microbial growth that causes spoilage and to slow changes in colour, texture, and flavour, sodium benzoate, calcium propionate, and potassium sorbate are used.

    What are the most common preservatives used?

    All across history, salt is being used as a preservative. Despite multiple advances in chemical and food science over the years, plain NaCl table salt remains the world's most commonly used preservative.

    How do preservatives work?

    Preservatives have been classified into three types: antimicrobials, which inhibit the growth of bacteria, moulds, or yeasts; antioxidants, which slow the oxidation of fats and lipids, which causes rancidity; and a third type, which inhibits enzymes that promote natural ripening after fruits or vegetables are picked.

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