Gluconic acid -S- lactone is white crystal or white crystal powder, almost odorless, sweet first and then sour, easily soluble in water 59g/ 100ml. Slowly hydrolyzed in water to form gluconic acid and its S- lactone and 7- lactone, which are in equilibrium. Slightly soluble in ethanol, almost insoluble in ether. The p H value of the newly prepared 1% aqueous solution was 3.5, which decreased to 2. The thermal stability is low within 5 _ 2 hours, and it decomposes around 153T. It can not only improve the quality, color, smell and taste of food, but also improve the food processing technology and electronic storage, keep the freshness of food and prevent corruption. Non-toxic, easily absorbed by human body, with nutritional value. It is an excellent multifunctional food additive. As protein coagulant, souring agent, leavening agent, flavoring agent, chelating agent and preservative, it is widely used in tofu production, fish and shrimp preservation, flour products, condiments and cold drinks. It can inhibit mold and general bacteria, and enhance the effects of preservatives and color developers. Is the consumption 1 000? 3 0 0 0 mg/kg.