Sodium sulfite is an inorganic compound. It is a white granular powder at room temperature, has a sulfur dioxide odor, is stable when dry, and is sensitive to humidity. Soluble in water and glycerin, insoluble in ethanol, the aqueous solution is alkaline, the aqueous solution is alkaline to litmus paper and phenolphthalein, and the reaction with acid produces toxic sulfur dioxide gas, the pH of 1Chemicalbook% aqueous solution is 8.3~9.4, and has strong reducibility. When heated, it decomposes into sodium sulfide and sodium sulfate, which are gradually oxidized to sodium sulfate when placed in the air. In nature, anhydrous sodium sulfite, sodium sulfite heptahydrate and sodium sulfite decahydrate exist in three forms, of which anhydrous sodium sulfite is the most difficult to be oxidized

Reductive bleaching agent, which has bleaching effect on food and strong inhibition of oxidase in plant food. China stipulates that it can be used for preserves, and the maximum usage is 2.0g/kg; Can also be used for glucose, liquid glucose, sugar, rock sugar, caramel, candy, bamboo shoots, mushrooms and canned mushrooms, grapes, black currant juice concentrate, the maximum usage of 0.Chemicalbook60g/kg. Residual amount of bamboo shoots, mushrooms and canned mushrooms, preserves, grapes and black currant concentrate (SO2)≤0.05g/kg; Residual amount of potato starch ≤0.03g/kg; Biscuits, sugar, vermicelli and other varieties of residue less than 0.1g/kg; The residual amount of liquid glucose should not exceed 0.2g/kg