Characteristics and Advantages of Tinplate

Characteristics and Advantages of Tinplate:

1. Lightproof Property Light not only triggers deterioration reactions in food but also induces changes in proteins and amino acids. Vitamin C, when exposed to light, is more susceptible to interactions with other food components, leading to significant loss. Studies reveal that milk packaged in transparent glass bottles loses 14 times more vitamin C compared to those in dark bottles. Light also causes oxidation off-flavors and breakdown of nucleotides and methionine, reducing nutritional value. Tinplate cans, being lightproof, ensure the highest preservation rate for vitamin C.

2. Excellent Sealability The barrier properties of packaging containers against air and other volatile gases are crucial for maintaining nutrient content and sensory qualities. Comparisons among various juice packaging materials demonstrate that the oxygen transmission rate directly influences browning and vitamin C preservation; metal cans, glass bottles, and aluminum foil laminates with low oxygen permeability, including tinplate cans, excel in preserving vitamin C, with tinplate being the optimal choice.

3. Reducing Property of Tin The tin layer inside tinplate cans reacts with residual oxygen during filling, minimizing the chance of food components oxidizing. This reducing effect of tin significantly benefits the flavor and color retention of light-colored fruits and juices. Uncoated tin cans used for juice canning offer better nutritional preservation, less browning, and higher consumer acceptance in terms of flavor quality, thus extending shelf life.

4. Supplying a Source of Dietary Iron Most tinplate canned foods, except for a few light-colored fruit and juice products, utilize internally coated cans to enhance corrosion resistance. Through electrochemical action, trace amounts of iron, in the form of ferrous (Fe²⁺), dissolve into the canned food during storage, typically ranging from 1 to 10 ppm. For a 350 ml beverage can with 5 ppm iron content, it provides approximately 1.75 mg of iron, which constitutes about one-tenth of the recommended daily intake of 18 mg. If these fruit or vegetable juice beverages are rich in vitamin C, iron absorption is enhanced, making tinplate canned food and beverages a good source of dietary iron, contributing significantly to their nutritional value.

Owing to these attributes, tinplate cans create a hermetic system, isolating food from all environmental factors except heat, preventing deterioration due to light, oxygen, and humidity. They prevent flavor dilution from aroma transmission and contamination by external odors, offering superior stability for food storage compared to other packaging materials, with the highest preservation rates for vitamin C and nutrients overall.