1. Opaqueness:
In addition to causing a bad reaction to food, light can also cause changes in proteins and amino acids. The exposure of vitamin C to light makes it more likely to interact with other food ingredients, resulting in large losses. According to the research and analysis, the loss of transparent glass bottled milk and vitamin C is 14 times higher than that of dark-colored bottled milk. The light also causes oxidation odor of milk, and the cracking of nuclide, methionine, etc., and loss of nutritional value. The opaque tinplate can make vitamin C the highest preservation rate.
2. Good sealing
The barrier properties of packaging containers to air and other volatile gases are important for the preservation of nutritional components and sensory qualities. Comparison of various juice packaging containers proves that the oxygen permeability of the container directly affects the browning of juices and the preservation of vitamin C; the preservation of vitamin C in metal cans, glass bottles and aluminum foil laminates, cartons with low oxygen permeability Better, of which the best iron cans.
3. The reduction of tin
The tin on the inner wall of tinplate will react with the oxygen remaining in the container during filling, and reduce the chance of oxidation of the food ingredients. The reduction effect of tin has a good preservation effect on the flavor and color of light-colored fruits and juices. Therefore, the use of non-painted iron cans provides better preservation of nutrients than other canned fruit juice cans. The acceptance of flavor quality is better and the shelf life is thus extended.
4. Provide a source of effective iron
Tinplate canned foods, with the exception of a few tinted fruits and canned fruit juices, mostly use internally painted empty cans to improve the corrosion resistance of the containers; due to the electrochemical action of the metal, canned tinned canned foods will have a small amount during storage. The iron is dissolved and is present in the sealed canned food in the form of divalent iron and is easily absorbed by the body. The content is approximately 1 to 10 ppm. For fruit and vegetable products, the amount of iron in the raw material itself is not large. The iron can product is calculated at 5 ppm per can of beverage can with 5 ppm iron content. Each can provides 1.75 mg of iron, which is approximately 18 mg of daily human intake. One tenth. If the above-mentioned fruit and vegetable juice beverage can contains rich vitamin C, iron is more easily absorbed, so iron canned food and beverage is a good source of iron. The significance of nutrition for canned food is far more profound.
Because of these properties, tin cans provide a closed system that is completely insulated from environmental factors except for heat. The foods that are color-rejected are deteriorated by light, oxygen, and moisture, and are not lightened by the aroma or are smelled by the environment. Over-contamination and odor, food storage stability is better than other packaging materials, vitamin C has the highest preservation rate, and nutrient storage is also the best.