Chemicals Use Food Preservatives
1.0What are Food Preservatives?
Food preservatives are substances added to food products to prevent spoilage caused by microbial growth and chemical changes. They help in extending the shelf life of food items, maintaining their nutritional value, and ensuring safety for consumption. Preservatives can be natural or synthetic and are used in various food products, including beverages, baked goods, dairy products, and processed meats.
2.0Types of Food Preservatives
Natural Preservatives
Natural preservatives are substances derived from natural sources that help in preserving food. Common natural preservatives include:
- Salt: Dehydrates food by drawing out moisture, inhibiting microbial growth.
- Sugar: Similar to salt, it reduces water activity, preventing microbial proliferation.
- Vinegar: Contains acetic acid, which lowers the pH and creates an environment unfavorable for microbial growth.
- Lemon Juice: Rich in citric acid and vitamin C, it acts as an antioxidant and antimicrobial agent.
Artificial Preservatives
Artificial preservatives are chemically synthesized substances added to food to prevent spoilage. Common artificial preservatives include:
- Sodium Benzoate: Effective against bacteria and fungi, commonly used in acidic foods.
- Potassium Sorbate: Inhibits molds and yeasts, used in dairy products and baked goods.
- Calcium Propionate: Prevents mold growth in bread and other baked items.
- BHA and BHT: Antioxidants that prevent oxidation of fats and oils, extending shelf life.
3.0Food Additives
Food additives are substances intentionally added to food to enhance its shelf life, appearance, flavor, or texture. They play a crucial role in the modern food industry, ensuring the safety, palatability, and appeal of processed foods. While some additives are naturally occurring, many are synthesized or extracted through chemical processes. Understanding food additives, their types, chemical properties, and safety profiles is fundamental for students preparing for JEE and other competitive exams.
Classification of Food Additives
Food additives can be broadly classified into the following categories:
- Food Colours and Colouring Agents
- Preservatives
- Enzymes
- Artificial Flavours and Sweeteners
Food Colours and Colouring Agents
Food colours are chemicals used to enhance or restore the appearance of food. They can be natural (derived from plant or animal sources) or synthetic (artificially produced). Adding colour to food makes it more attractive and can also signal freshness.
- Natural Colouring Agents: Examples include carotenoids (from carrots), chlorophyll (from leafy greens), and caramel (from heated sugar).
- Artificial Colouring Agents: Examples are tartrazine (yellow), sunset yellow, and carmoisine (red), which are commonly used in confectionery and beverages.
Caramel is one of the oldest and most widely used food colours, produced by controlled heating of carbohydrates such as glucose or sucrose. Caramel colouring is prevalent in soft drinks, sauces, and baked goods.
Preservatives
Preservatives are chemicals added to food to inhibit the growth of microorganisms, thereby extending shelf life and preventing spoilage. They can be classified as:
- Class I Preservatives: Natural substances such as salt, sugar, and vinegar. These are generally regarded as safe and have been used traditionally.
- Class II Preservatives: Synthetic chemicals like sodium benzoate and potassium metabisulphite. These are more effective but must be used within regulated limits.
Key Examples:
- Sodium Benzoate: Widely used in acidic foods and beverages such as soft drinks, fruit juices, and pickles. It prevents the growth of bacteria, yeast, and fungi.
- Sodium Metabisulphite: Used in canned fruits, jams, and juices to prevent browning and spoilage.
- Sorbic Acid and Its Salts: Employed in cheese, baked goods, and meats to inhibit the growth of molds and yeasts.
Enzymes
Enzymes are biological catalysts that speed up chemical reactions during food processing, improving efficiency and product quality. They are crucial in the production of dairy products, baking, brewing, and fruit juice clarification.
- Examples:
- Amylase: Breaks down starch into sugars during bread-making.
- Protease: Used in cheese-making to curdle milk.
- Pectinase: Clarifies fruit juices by breaking down pectin.
Enzymes are preferred over harsh chemical treatments as they operate under mild conditions and are highly specific.
Artificial Flavours and Sweeteners
Artificial flavours are chemically synthesized compounds added to mimic natural flavours, while artificial sweeteners provide sweetness without the caloric value of sugar.
Natural Sweeteners: Sucrose (from sugarcane), fructose (from fruits), and honey are common examples.
Popular Artificial Sweeteners:
- Saccharin: One of the oldest artificial sweeteners, about 550 times sweeter than sucrose. Widely used in diet drinks, sweets, and pharmaceuticals, though it can have a bitter aftertaste at high concentrations.
- Aspartame: Formed from aspartic acid and phenylalanine. About 200 times sweeter than sucrose, aspartame is used in soft drinks, desserts, and chewing gum. It has a clean taste but is not heat stable.
- Cyclamate: About 30–50 times sweeter than sucrose. Used in combination with other sweeteners due to its mild taste.
- Alitame: A dipeptide-based sweetener, approximately 2000 times sweeter than sucrose and more stable than aspartame. Used in baked goods and processed foods.
- Sucralose: A trichloro-derivative of sucrose, about 600 times sweeter than sugar. It is heat stable and does not promote tooth decay, making it suitable for baking and cooking.
4.0Common Chemicals Used as Food Preservatives
Sodium Benzoate
Sodium benzoate is the sodium salt of benzoic acid and is widely used as a preservative in acidic foods such as fruit juices, soft drinks, and pickles. It inhibits the growth of bacteria, yeast, and molds, thereby extending the shelf life of food products. Upon ingestion, sodium benzoate is metabolized into hippuric acid and excreted in the urine.
Potassium Metabisulfite
Potassium metabisulfite is used as a preservative in various food products, including fruit juices, wines, and dried fruits. It releases sulfur dioxide, which acts as an antimicrobial agent and antioxidant, preventing spoilage and discoloration. However, it is not suitable for preserving colored foods due to its bleaching effect.
Sorbic Acid and Its Salts
Sorbic acid and its salts, such as potassium sorbate, are effective preservatives against molds and yeasts. They are commonly used in cheese, baked goods, and certain meat products to prevent spoilage and extend shelf life.
Propionic Acid and Its Salts
Propionic acid and its salts, like calcium propionate, are used to inhibit mold growth in bread and other baked goods. They help in preventing spoilage and maintaining the freshness of bakery products.
Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT)
BHA and BHT are synthetic antioxidants used to prevent the oxidation of fats and oils in food products. They help in extending the shelf life of products like cereals, snack foods, and chewing gum by preventing rancidity.
5.0Mechanism of Action of Food Preservatives
Food preservatives work through various mechanisms to prevent spoilage:
- Antimicrobial Action: Inhibiting the growth of bacteria, molds, and yeasts.
- Antioxidant Action: Preventing oxidation of food components, especially fats and oils.
- Enzyme Inhibition: Interfering with the activity of enzymes that cause spoilage.
- pH Modification: Altering the acidity or alkalinity to create an unfavorable environment for microbial growth.
6.0Applications of Food Preservatives
Food preservatives are used in a wide range of products to ensure safety and extend shelf life:
- Beverages: Soft drinks, fruit juices, and alcoholic beverages.
- Baked Goods: Bread, cakes, and pastries.
- Dairy Products: Cheese, yogurt, and butter.
- Processed Meats: Sausages, ham, and canned meats.
- Snack Foods: Chips, crackers, and nuts.
7.0Safety and Regulations
The use of food preservatives is regulated by food safety authorities to ensure consumer safety. Preservatives must be used within specified limits, and their safety is continually evaluated through scientific research. Consumers are encouraged to read food labels to be aware of the preservatives used in food products.