Question

What are preservatives?

Hint:

Antimicrobials stop bugs; antioxidants stop oxygen. Read labels: E210 (benzoic acid), E300 (ascorbic acid), etc.

Answer 1

Step 1: Definition.
Preservatives are chemical substances added to food, drugs, cosmetics or other perishable materials to prevent spoilage caused by microbes (bacteria, fungi) or by chemical changes such as oxidation.
Step 2: How they work.
They either (i) inhibit microbial growth, (ii) kill microorganisms, or (iii) slow oxidation and rancidity.
Step 3: Common examples.
- Antimicrobial: sodium benzoate, benzoic acid, potassium metabisulphite (K$_2$S$_2$O$_5$), sodium nitrite (meats).
- Antioxidant: BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), ascorbic acid.
Step 4: Conclusion.
Thus, preservatives extend shelf life and maintain safety/quality of products by preventing microbial and oxidative deterioration.