00:06 Food doesn’t last.
00:09 In days, sometimes hours, bread goes moldy, apple slices turn brown, and bacteria multiply in mayonnaise.
00:17 But you can find all of these foods out on the shelf at the grocery store, hopefully unspoiled, thanks to preservatives.
00:25 But what exactly are preservatives?
00:28 How do they help keep food edible and are they safe?
00:31 There are two major factors that cause food to go bad:
00:35 microbes and oxidation.
00:37 Microbes like bacteria and fungi invade food and feed off its nutrients.
00:42 Some of these can cause diseases, like listeria and botulism.
00:47 Others just turn edibles into a smelly, slimy, moldy mess.
00:52 Meanwhile, oxidation is a chemical change in the food’s molecules caused by enzymes or free radicals which turn fats rancid and brown produce, like apples and potatoes.
01:05 Preservatives can prevent both types of deterioration.
01:09 Before the invention of artificial refrigeration, fungi and bacteria could run rampant in food.
01:16 So we found ways to create an inhospitable environment for microbes.
01:21 For example, making the food more acidic unravels enzymes that microbes need to survive.
01:27 And some types of bacteria can actually help.
01:30 For thousands of years, people preserved food using bacteria that produce lactic acid.
01:37 The acid turns perishable vegetables and milk into longer lasting foods, like sauerkraut in Europe, kimchi in Korea, and yogurt in the Middle East.
01:47 These cultured foods also populate your digestive track with beneficial microbes.
01:52 Many synthetic preservatives are also acids.
01:56 Benzoic acid in salad dressing, sorbic acid in cheese, and propionic acid in baked goods.
02:03 Are they safe?
02:04 Some studies suggest that benzoates, related to benzoic acid,
02:08 contribute to hyperactive behavior.
02:11 But the results aren’t conclusive.
02:14 Otherwise, these acids seem to be perfectly safe.
02:17 Another antimicrobial strategy is to add a lot of sugar, like in jam, or salt, like in salted meats.
02:25 Sugar and salt hold on to water that microbes need to grow and actually suck moisture out of any cells that may be hanging around, thus destroying them.
02:36 Of course, too much sugar and salt can increase your risk of heart disease, diabetes, and high blood pressure, so these preservatives are best in moderation.
02:46 Antimicrobial nitrates and nitrites, often found in cured meats, ward off the bacteria that cause botulism, but they may cause other health problems.
02:56 Some studies linking cured meats to cancer have suggested that these preservatives may be the culprit.
03:02 Meanwhile, antioxidant preservatives prevent the chemical changes that can give food an off-flavor or color.
03:10 Smoke has been used to preserve food for millennia because some of the aromatic compounds in wood smoke are antioxidants.
03:18 Combining smoking with salting was an effective way of preserving meat before refrigeration.
03:24 For antioxidant activity without a smoky flavor, there are compounds like BHT and tocopherol, better known as vitamin E.
03:33 Like the compounds in smoke, these sop up free radicals and stave off rancid flavors that can develop in foods like oils, cheese, and cereal.
03:44 Other antioxidants like citric acid and ascorbic acid help cut produce keep its color by thwarting the enzyme that causes browning.
03:53 Some compounds like sulfites can multitask.
03:56 They’re both antimicrobials and antioxidants.
04:00 Sulfites may cause allergy symptoms in some people, but most antioxidant preservatives are generally recognized as safe.
04:08 So should you be worried about preservatives?
04:11 Well, they’re usually near the end of the ingredients list because they’re used in very small amounts determined by the FDA to be safe.
04:19 Nevertheless, some consumers and companies are trying to find alternatives.
04:24 Packaging tricks, like reducing the oxygen around the food can help, but without some kind of chemical assistance, there are very few foods that can stay shelf stable for long.