10. What are food preservatives? Explain some common food preservatives.

Food preservatives are substances added to food products to prevent spoilage, extend shelf life, and maintain their quality, flavor, and safety. They inhibit the growth of microorganisms (such as bacteria, molds, and yeasts) and oxidative processes that can lead to food deterioration. Here are some common food preservatives along with brief explanations:

1. Salt (Sodium Chloride): Salt is one of the oldest and most commonly used food preservatives. It works by drawing moisture out of food, creating an environment where microorganisms cannot thrive. Salt is particularly effective in preserving meats, fish, and some vegetables.

2. Sugar: Sugar, in the form of sucrose, glucose, or fructose, acts as a preservative by reducing water activity in food, thereby inhibiting microbial growth. It is commonly used in jams, jellies, syrups, and other sweetened products to extend their shelf life.

3. Acetic Acid (Vinegar): Acetic acid, found in vinegar, is an organic acid that inhibits the growth of bacteria and molds. It is commonly used as a preservative in pickled vegetables, salad dressings, and condiments.

4. Ascorbic Acid (Vitamin C): Ascorbic acid is a natural antioxidant that helps prevent oxidative reactions, such as enzymatic browning and rancidity, in fruits and vegetables. It is often used as a preservative in processed fruits, fruit juices, and canned foods.

5. Sulfur Dioxide and Sulfites: Sulfur dioxide (SO2) and sulfites (such as sodium sulfite and sodium metabisulfite) are commonly used as preservatives in dried fruits, wine, and other foods. They inhibit microbial growth, prevent enzymatic browning, and act as antioxidants to maintain color and flavor.

6. Nitrites and Nitrates: Nitrites (such as sodium nitrite) and nitrates (such as potassium nitrate) are commonly used as preservatives in cured meats, such as bacon, ham, and hot dogs. They inhibit the growth of bacteria, particularly Clostridium botulinum, and impart a characteristic pink color and flavor to cured meats.

7. Sorbic Acid and Sorbates: Sorbic acid and sorbates (such as potassium sorbate and calcium sorbate) are synthetic preservatives commonly used in bakery products, cheese, and beverages. They inhibit the growth of molds and yeasts, extending the shelf life of these products.

8. Benzoic Acid and Benzoates: Benzoic acid and benzoates (such as sodium benzoate and potassium benzoate) are synthetic preservatives commonly used in acidic foods and beverages, such as soft drinks, fruit juices, and pickles. They inhibit the growth of bacteria, molds, and yeasts.

These are just a few examples of common food preservatives used to prevent spoilage and maintain the quality and safety of food products. It's important to note that while food preservatives can be effective in extending shelf life, their use should be regulated and their safety carefully evaluated to ensure they do not pose health risks to consumers.