Vacuum packaging, as a mainstream preservation technology in the food industry, has long been integrated into daily life. Also known as reduced-pressure packaging, it does not create a perfect vacuum but involves evacuating air from the package to a vacuum level between 600-1333 Pa before sealing. This technology originated in the 1940s and developed rapidly after the successful application of plastic films in 1950. Its promotion in China began in the early 1980s, and it has now become the standard packaging method for cooked products, cured foods, and other items.
Its core principle is preservation through oxygen removal. Food spoilage is often caused by microbial activity, and most microorganisms require oxygen to survive. When the oxygen concentration inside the package is ≤0.5%, the growth of most microbes is inhibited. Simultaneously, oxygen removal helps prevent the oxidation and rancidity of fats, the loss of vitamins, and the darkening of pigments, effectively preserving the food's original color, aroma, flavor, and nutritional value. It is important to note that vacuum packaging cannot inhibit the growth of anaerobic bacteria and often needs to be combined with auxiliary methods like refrigeration or high-temperature sterilization.
The application scope of vacuum packaging is extensive, covering multiple food categories. It is commonly used for cooked products like ham, spiced beef, and roasted fish fillets; cured products like pickled mustard tuber and cured meats; as well as bean products and dried fruits. For fragile, crispy, or easily caking foods, vacuum gas-flush packaging is often employed. This involves evacuating air and then injecting gases like nitrogen or carbon dioxide, which preserves freshness while preventing the food from being crushed or deformed. This technology can extend the shelf life of food by 2 to 5 times, significantly enhancing product distribution efficiency.
When purchasing, consumers should avoid common misconceptions. Choose products with complete label information and intact, non-leaking packaging, and avoid packages that are bloated or have blurry labels. Some vacuum-packed foods are not ready-to-eat; for example, vacuum-packed zongzi (sticky rice dumplings) require thorough reheating before consumption. Furthermore, packaging materials are crucial for safety. Materials in contact with soups or high-salt foods often use corrosion-resistant stainless steel to ensure food safety.
