Reduction of tin
Tin on the inner surface of tinplate will react with the oxygen remaining in the container during filling to reduce the chance of oxidation of food ingredients. The reduction effect of tin has a good preservation effect on the flavor and color of light fruit and fruit juice. Therefore, the fruit juice can without painting iron can has better nutrition preservation than the fruit juice can with other packaging materials. The brown change is slight, the acceptability of flavor quality is good, and the storage period is extended.
Tinned tinned food, except for a few light colored fruits and juice cans, mostly uses empty cans with internal paint to improve the corrosion resistance of the containers; due to the electrochemical effect of metals, a small amount of iron will be dissolved in the storage of tinned food with paint, which exists in the form of divalent iron in the sealed tinned food and is easily absorbed by the human body, with the content of about 1-10 ppm. In terms of fruit and vegetable products, the iron content of raw materials is not much. The iron can products can provide 1.75mg of iron, about one tenth of the human body’s daily intake of 18mg, based on the calculation of 350 ml of beverage can and 5 ppm of iron content. If the above-mentioned fruit and vegetable juice beverage cans contain rich vitamin C, iron is more easily absorbed. Therefore, iron canned food and beverage is a good source of iron and has a far-reaching significance in providing nutrition for iron canned food.
Because of these properties, tinplate can provide a closed system which completely isolates environmental factors besides heat. The color avoiding food will not deteriorate due to light, oxygen and moisture, nor will it weaken due to fragrance passing through or be polluted by environmental odor. 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 the most OK.