Why do canned foods stay fresh for a long time without the use of preservatives?
Feb 19,2022
In the 1970s and 1980s, enjoying a bowl of tomato-topped noodles during winter was a true delight—and a source of immense pride! Back then, many families would buy tomatoes in abundance when they were in season, turning them into homemade tomato sauce to save for the colder months. Making tomato sauce at home was surprisingly simple: just wash the tomatoes thoroughly, blanch them briefly to remove the skins, transfer the pulp into sterilized saltwater bottles, seal them tightly with rubber stoppers, insert needles for ventilation, and steam the bottles in a bamboo steamer for about 30 minutes. Once removed from the steamer, let the sauce cool completely—ready to be stored until winter arrives, preserving both its rich flavor and vibrant color. Interestingly, the process of making canned foods shares the same basic principle as preparing homemade tomato sauce. After carefully processing the ingredients, they’re packed into containers—whether metal cans, glass jars, or flexible pouches—evacuated of air, sealed tightly, and then subjected to heat treatment for sterilization. After cooling, these containers become safe, shelf-stable products ready for consumption. Once sealed inside the can, the food undergoes a series of steps—including degassing, sealing, and sterilization—that create an airtight environment entirely free of oxygen. This sterile condition prevents any harmful microorganisms or bacteria from growing or multiplying, while also keeping external contaminants like airborne germs from entering the container. As a result, canned foods remain fresh and safe without the need for artificial preservatives—a practice that dates back over 200 years, long before the concept of chemical preservatives even existed! Canned goods are celebrated worldwide for their safety, nutritional value, convenience, and ease of use. They’re especially popular in Europe, North America, and Japan, where they’ve become staples of daily life. In China alone, annual canned food exports reach approximately 3 million tons, reaching consumers in more than 100 countries around the globe. Even in specialized fields like aerospace and submarine operations, canned food is the go-to choice due to its reliability and longevity. Meanwhile, in the culinary world, canned ingredients like sweet corn, tuna, mushrooms, tomato sauce, yogurt with fruit chunks, and even decorative fruits used on birthday cakes have become indispensable. And let’s not forget the classic example of canned food: eight-flavor porridge, a beloved staple found in countless households today!
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