Expiration dates on food products are proof food doesn’t last. In several days, or even hours, bread goes moldy, apple slices turn brown, and bacteria begins to multiply in mayonnaise. Yet, these foods are still found on the shelves at grocery stores thanks to preservatives, but what exactly are they, and are they good or bad for our health?

In TED-Ed’s video, “Are preservatives bad for you?” host Eleanor Nelson explains there are two major factors that cause food to spoil: microbes and oxidation. Microbes, like bacteria and fungi, invade food and feed off its nutrients. Some of these microbes can cause diseases like listeria and botulism, while others turn edibles into a smelly, slimy and moldy mess. Meanwhile, oxidation is a chemical change in food molecules triggered by enzymes or free radicals, which turn fats rancid and brown produce, like apples and potatoes.

Preservatives work by preventing both types of deterioration. Artificial preservatives like butylated hydroxyanisole (BHA), nitrates, and benzoic acid, are all used by food manufacturers to slow maturation or spoilage. BHA is used in everything from bread to medications, but it can also be toxic, especially when ingested in large amounts. Nitrates, a naturally occurring chemical in leafy vegetables, creates carcinogenic properties when added to red meats. Lastly, the widely used preservative benzoic acid is considered a suspect additive because of its potential to create benzene when paired with ascorbic acid (vitamin C), which has been linked to hyperactive behavior.

Man cooking Preservatives help extend shelf life of food products, and can influence our overall health. Photo courtesy of Pexels, Public Domain

Other antimicrobial strategies, like sugar in jam, or salt in salted meats, work by holding on to water that microbes need to grow. They actually suck moisture out of any cells that may be lingering around, and therefore, destroy them. We all know too much sugar and salt can lead to diabetes, and heart disease, respectively.

Some consumers and companies try to find alternatives to these chemicals by using new processing techniques, like flash freezing and hermetic sealing. However, preservatives will likely always play a role in food preparation. Few foods could stay shelf stable for long without them.