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Food Preservatives are chemical substances that are used in food products in order to prevent the process of decomposition caused by the growth of microbial or other chemical changes. Chemical preservatives are also used in products such as chemical drugs/ pharmaceuticals, bottled beverages, beauty products, paints, and many other different products. Chemical food preservatives are extensively used in the food industry and are customarily cheap components that are efficient against a huge range of decomposed organisms.
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Key Terms: Food Preservative, Pharmaceutical, Chemicals, Chemical Reactions, Benzoates, Sulphites, Nitrites, Nitrates, Microbes, Enzymes
Food Preservatives
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Food preservatives are engaged to ensure quality and safety from microbial, enzymatic or any other physical/ chemical reactions. There are various types of antioxidant and antimicrobial agents, each one with different modes of action.
- Chemical food preservatives are added to extend the time of degeneration in food products by discouraging the growth of antioxidants, fungi or bacteria.
- Unlike the traditional way of preservation like drying food or exposing to sun, many chemical preservatives don't require desiccation.
- Some of the natural ways to prevent microbial growth are by adding sugar, salt or vinegar.
Principles of Food Preservation
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Chemicals Used in Food Preservation
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There are 3 categories of chemical preservatives mainly used in foods, they are:
- Benzoates (Such as sodium benzoate)
- Sulphites (Such as sulphur dioxide)
- Nitrites (Such as sodium nitrite)
Types of Food Preservation
Some of the preservatives used in food are calcium sorbate, sodium benzoate, benzoic acid, erythorbic acid, potassium nitrate, etc. Before going through chemical preservation, the food product goes through other steps such as irradiation, pasteurization, and cooking in which huge energy, heat or ionizing radiations are applied. The food irradiation process consists of applying gamma rays from cesium-137 radioisotopes. Irradiation is also used in food packaging to assure sterility.
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Benzoates as Food Preservatives
Sodium benzoate is a salt of the conjugate base and its chemical formula is C6H5COONa. When sodium benzoate dissolves with water, it separates into its ions. Benzoate ion acts as base, forming hydroxide ion and conjugate acid. Sodium benzoate is created using the chemical reaction between benzoic acid and sodium hydroxide.
Structural Formula
Sodium benzoate can inhibit fungal and bacterial growth, hence it is used as a food preservative. Sodium benzoate solution is acidic which makes it efficient at killing microorganisms.
Read More: Rancidity
Sulphites in Food Preservation
Chemically, the sulphites are used as food preservatives for dried potato, radish, dried fruits, etc. Sulphites make food look fresh by resisting the oxidation process which makes fruits and vegetables turn brown. Sulphites also help in extending the shelf value of food by eliminating fungi and bacteria.
Nitrites and Nitrates in Food Preservation
Nitrites and nitrates are mainly used as preservatives for meat products. Like other food preservatives, these chemicals also inhibit the growth of fungi and bacteria. Nitrites and nitrates particularly prevent the growth of clostridium botulinum which causes botulism. Nitrates are used in the production of cheese to resist them from bloating while being fermented.
Nitrates in Food
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Examples of Food Preservatives
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The food we eat today consists of lots of food preservatives added in them. Let us look at some of the widely used food preservatives:
- Potassium Nitrate- used predominantly in red color meats to delay rancidity, prevent odor and an off flavor.
- Erythorbic Acid- used as an antioxidant
- Benzoic Acid- antimicrobial preservative used in carbonated foods and beverages.
- Sodium Benzoate- Prevents spoilage from bacteria, molds and yeast.
- Calcium Sorbate- prevents the growth of mibcrobes.
- Antioxidats- these slow down the tendency to spoil the food. Examples: Butylated Hydroxyanisole (BHA), Butylated Hydroxytoluene, and Ascorbyl Palmitate.
Sodium Food Preservatives
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Sodium benzoate is the most commonly added form of sodium in food. This is added in foods and beverages to extend the shell-life. Another commonly added form of sodium is sodium nitrate. This is used very commonly in foods like bacon and luncheon meats. However, consumption of this causes a risk to the functioning of the heart as it damages the heart vessels.
Role of Salt as Food Preservative
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Salts plays an important role as a fermenting agent. In fermentation, fresh foods get converted to foods which can be stored for greater duration without being affected by the action of microbes. Some of the benefits of salt addition include:
- Killing of bacteria
- Carrying out Osmosis
- Developing physical attributes to the food
- Imparting adhesive properties to doughs and baked food items
Natural Vs Artificial Food Preservative
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Preservatives are added to food before their consumption. Food preservatives are used for the following:
- Extending shell-life of the food
- Flavoring of foods
- Coloring of foods
- Nutritional supplements like vitamins and minerals
Apart from this, contaminants from manufacturing, storing or packaging can alse indirectly get added int he food we eat. Microbes that rot food are inhibited by the addition of preservatives. This helps prevent them from poisoning, giving them a fresh look and taste. Some of the artificial preservatives added are:
- Chelating agents
- Antimicrobial Agents
- Antioxidants
These preservatives delay the growth of food spoiling bacteria and avoid discolouration.
Side Effects of Food Preservatives
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There are some food preservatives that are harmful if consumed above the prescribed limits. Some of the harmful or unhealthy food preservatives are caramel, butyrates, and benzoates. Studies show that nitrites and nitrates are carcinogenic and very harmful for the health.
Things to Remember
- Preservatives are substances that are used in food products to resist the process of decomposition caused by the growth of microbial and other chemical/ physical changes.
- Some of the traditional ways of preservation are fermentation, cooling, and freezing. Some are natural.
- The natural ways to prevent microbial growth are by adding salt, sugar, or vinegar.
- The three categories of chemical preservatives are sulphites (Like sulphur dioxide), benzoates (Like sodium benzoate), and nitrites (Like sodium nitrite).
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Previous Year Questions
- Gammexane is ? [NEET 1999]
- Artificial sweetener which is stable in cold conditions only is? [NEET 2014]
- Which of these is narrow spectrum antibiotic? [NEET 2019]
- Mixture of choloxylenol and terpeneol acts as? [NEET 2017]
- Aspirin is an acetylation product of? [NEET 1998]
- Chloropicrin is bbtained by the reaction of? [NEET 2004]
- Dettol is a mixture of? [NEET 2013]
- Diazo coupling is used to prepare? [NEET 1994]
- Which is employed as a tranquilizer drug? [NEET 2010]
- Which forms cationic miscelles above a certain concentration? [NEET 2004]
- Which is an antihistamine? [NEET 2011]
- Which is a cationic detergent. [NEET 2020]
- Which is an analgesic. [NEET 2016]
- An ester used as medicine is? [KCET 2002]
- Which is a bactericidal antibiotic? [KCET 2017]
- Butylated hydroxy toluene acts as a? [KCET 2014]
- Antipyretic and analgesic is? [KCET 2000]
- Which cleansing agent gets precipitated in water? [KCET 2019]
- Which is the artificial weetener containing chlorine? [KEAM]
- Cetyltrimethylammonium bromide is a popular? [KEAM]
Sample Questions
Ques: How to prevent food from decomposition? (2 marks)
Ans: A preservative is a chemical or natural substance added to products such as food, beverages, biological samples, etc in order to prevent microbial growth.
Ques: Explain the functioning of preservatives? (2 marks)
Ans: Preservatives help in preventing the bacterial growth in various compounds including food products. They are acidic in nature which helps in resisting the growth of unwanted organisms such as bacteria, yeast, molds, etc in food. Generally, preservatives are classified into three types as follows:
- Antioxidants which slows the oxidation process of lipids and fats that leads to rancidity.
- Antimicrobials which block the growth of bacteria, yeast, and molds.
- It fights enzymes which help in the natural ripening that occurs after fruits and vegetables are picked.
Ques: State some of the benefits of preserving food? (2 marks)
Ans: The chemical preservatives acts as antioxidants which makes food more acidic. It reduces the speed of ripening and resists the growth of microorganisms. It also decreases the moisture level of food. All these help the food last longer.
Ques: Why does salt act as a preservative? (2 marks)
Ans: Some of the natural preservatives are sugar, salt, and vinegar. Salt engages in a process called osmosis. Here, the salt extracts water out of the cells. This makes the growth of bacteria too difficult in the food product. High concentrated salt can kill the organisms that decay food. Salt is also used in the fermentation process of some food products.
Ques: What are some of the harmful food preservatives? (2 marks)
Ans: There are some food preservatives that are harmful if consumed more than the prescribed limit. Some of them are caramel, butyrates, and benzoates. Also, nitrites and nitrates are carcinogenic and very harmful for our health.
Ques: How does sugar help in the preservation of jams and jellies? (2 marks)
Ans: Jams contain more sugar than any other sweet products. Sugar engages in the osmosis process. This helps sugar extract water content from the food. This way sugar helps in the preservation of jams, jellies and other high sweet contain products.
Ques: List down different types of microbes? (2 marks)
Ans: The major groups of microorganisms are fungi (Yeast and molds), bacteria, archaea, protozoa, algae and viruses.
Ques: How do pathogens enter the body? (2 marks)
Ans: The microorganisms are capable of causing serious diseases. Pathogens enter the body of a human or any living creature through eyes, mouth, nose, urogenital openings or through wounds and bites.
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