Preservatives

A preservative is a substance added to food, drink, cosmetics or other goods to slow or stop the growth of microorganisms (bacteria, fungi and yeasts) and prevent chemical changes such as oxidation. The purpose is to keep the product viable for an extended period without creating health hazards.

Preservatives are not a modern invention. Salt, sugar, vinegar, smoke and spices were traditional preservation methods. Modern industrial preservatives are standardised chemical substances, typically regulated by government standards that specify the maximum allowable quantities.

Types

They are generally divided into two categories. The first comprises antimicrobials, including salt, acetic acid, benzoic and sorbic acids and their salts, and nitrites added to cured meat. The second comprises antioxidants, which prevent oxygen in the air from causing discoloration or spoilage—for example ascorbic acid (vitamin C) and tocopherols (vitamin E).

How they work

Several mechanisms exist. Some alter acidity (pH) to inhibit microbial growth. Others reduce available water, halting bacterial reproduction. Antioxidants counteract oxidative chain reactions that damage fats. Usually two or three methods are combined, along with heating and anaerobic packaging.

Regulation and safety

Many countries maintain lists of approved substances and set maximum limits per product. Daily acceptable intake levels are commonly defined, based on body weight. Product labelling typically shows the preservative's name or code. Some individuals have sensitivities to specific preservatives, which is why labelling is required.