These substances can produce sulfur dioxide (SO2), sulfur dioxide forms water with sulfuric acid (H2SO3). In addition to a bleaching effect, but also has a preservative effect. In addition, due to the strong reduction of sulfite, it can consume oxygen in fruits and vegetables, inhibit the activity of oxidase, and prevent the oxidative destruction of vitamin C in fruits and vegetables.
Sulfites can be metabolized to sulfate in the human body and excreted from the urine by a detoxification process. Sulfite compounds of this type are not suitable for animal foods to avoid unpleasant odors. Sulfites have a damaging effect on vitamin B1, so foods with more B1 content such as meat, cereals, dairy products and nuts are also not suitable. Its use in countries such as the United States is severely limited by its ability to cause allergic reactions.