Why do we often see the lid of the bottle and can use the tinplate cover, I think this is inseparable from the characteristics of the tinplate itself.
1). Opaque: In addition to causing adverse reactions of food, light can also cause changes in proteins and amino acids. However, when vitamin C is exposed to light, it is more likely to cause it to interact with other food ingredients, resulting in a large loss. According to research and analysis, the loss of vitamin C in milk in clear glass bottles is 14 times higher than that in dark bottled milk. It also causes oxidation and odor of milk, as well as cracking of nuclide and methionine, which loses nutritional value. The opacity of the tin can makes the preservation rate of vitamin C the highest.
2). Good sealing The barrier properties of packaging containers to air and other volatile gases are very important for the preservation of nutrients and sensory qualities. Comparing various juice packaging containers, the oxygen transmission rate of the container directly affects the browning of the juice and the preservation of vitamin C; the metal cans with low oxygen transmission rate, the glass bottle and the aluminum foil, and the preservation of the vitamin C in the carton. It is better, and it is best to use iron cans.
3). Reduction of tin The tin on the inner wall of the tinplate acts on the oxygen remaining in the container during filling, reducing the chance of oxidation of the food ingredients. The reduction of tin has a good preservation effect on the flavor and color of light-colored fruits and juices. Therefore, the juice cans using unpainted iron cans are better preserved than the juice cans of other packaging materials, and the brown change is slight. The flavor quality is better accepted and the shelf life is extended.
4). Provide tinplate tinned foods with effective iron source. Except for a few light-colored fruits and canned juices, most of them use internally painted empty cans to improve the corrosion resistance of the containers. Due to the electrochemical action of metals, paint cans Canned foods have a small amount of iron dissolved during storage and are present in sealed canned food in the form of divalent iron, which is easily absorbed by the body and is present in an amount of about 1 to 10 ppm. In the case of fruit and vegetable products, the raw material itself does not contain much iron. The iron can product is calculated as a pot of 350 ml per can, with an iron content of 5 ppm. Each can provide 1.75 mg of iron, which is about 18 mg per day. One tenth. If the above-mentioned fruit and vegetable juice beverage cans are rich in vitamin C, the iron is more easily absorbed, so the iron canned food and beverage is a good source of iron, and the nutrition for the canned food is more profound. Because of these properties, the tinplate can provide a closed system that completely isolates environmental factors in addition to heat. The color-protected food is deteriorated by light, oxygen, moisture, and is not lightened by the aroma or is exposed to environmental odor. It is more polluted and tastes. The stability of food storage is better than other packaging materials. The preservation rate of vitamin C is the highest, and the preservation of nutrients is also the best.