When using sodium metabisulfite in processed foods, the following points should be noted:
1) Sodium metabisulfite is a reducing bleaching agent whose solution is unstable and volatile. It should be prepared and used immediately to prevent the instability and volatility of sodium metabisulfite.
2) When metal ions are present in food, residual sodium metabisulfite will be oxidized; It can also oxidize and discolor the reduced pigments, thereby reducing the effectiveness of bleaching agents. Therefore, metal chelating agents are used simultaneously in production.
3) Substances bleached with sodium metabisulfite are prone to discoloration due to the disappearance of sulfur dioxide, resulting in excessive sulfur dioxide residue in food. However, the residual amount must not exceed the standard.
4) Sulfuric acid cannot delay the activity of pectinase and can damage the cohesion of pectin. In addition, after sodium metabisulfite infiltrates the fruit tissue, sulfur dioxide can only be removed by crushing the fruit during processing. So fruits marinated with sodium metabisulfite are only suitable for making jams, dried fruits, fruit wines, preserves, etc., It cannot be used as a raw material for canned food.
5) Sodium metabisulfite can destroy thiamine, so it is not easy to use in fish food.
6) Sodium metabisulfite is prone to react with aldehydes, ketones, proteins, and other substances.
