How Preservatives Keep Food Fresh, Even On The Shelf

Preservatives get a bad rap, but they're actually the key to keeping most of our shelf-stable food fresh and safe to eat. Here's how they work, and what you should know about them when you see them on your food labels.

Most preservatives focus on the two main reasons food goes bad: Microbes (fungi, bacteria) and oxidation. Creating an inhospitable environment for microbes is one way to drive them away. Traditional methods include pickling, fermenting and salting. While these traditional methods are still used today, artificial preservatives are also often used to extend the shelf life of many foods. Artificial acids keep microbes from growing, including benzoic acid in salad dressing and propionic acid in baked goods.

As for oxidation, there are also both traditional (smoking) and modern (BHT, vitamin E) antioxidant methods. Both stop rancid flavours from developing in foods like oil, cheese and cereal. Citric and ascorbic acid stop foods from turning brown, and slowing the enzyme reaction that leads to spoilage. The video above goes into much greater detail, and is worth watching if you're curious about how they work — and why our food industry relies on them so much.

Are Preservatives Bad for You? [TED-Ed (YouTube)]


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