Purple potato (also known as black potato) meat is purple or dark purple. In addition to the nutrients of ordinary sweet potato, it also has special edible and medicinal value, which is mainly attributed to its rich polyphenols such as anthocyanins and flavonoids. Functional ingredients and mineral elements. Purple potato has certain curative effects in preventing cardiovascular disease, anti-oxidation, anti-aging, anti-mutation, liver protection and anti-cancer. It has been reported that purple potato pigment can inhibit premature aging of endothelial cells by blocking NLRP3 inflammatory body, and can significantly reduce the induction of IL-1β, IL-6, IL-8 and TNF-α by hydrogen peroxide in Caco-2 cells. expression. In addition, purple potato has a high yield and a relatively low price, which is a very readily available material. Therefore, the rational development of purple potato products has broad application value and market prospects. Fermented dairy products are favored by consumers because of their unique taste. With the improvement of quality of life, people's demand for food has risen from the initial sensory attribute to the level of nutrition and health care. Therefore, one of the mainstreams of dairy research and development today is to improve nutritional value and health care function. Shi Wentian, Tang Gaoqi, and Zhao Congcong studied the effects of purple potato pulp or purple potato puree on purple potato yoghurt through sensory evaluation, and obtained the best formula and fermentation process. He Hongjun added purple potato powder to make purple potato yoghurt, and studied the volatile flavor of purple potato yoghurt and common yoghurt through temperament. The results showed that purple yoghurt had the most volatile flavors, neroli, guaiacol and vanilla. Aldehydes and the like are only detected in purple potato yoghurt. In this paper, we considered reducing the loss of anthocyanin and its activity in purple sweet potato extract. After the emulsion was sterilized, the purple lyophilized powder of sterilized aqueous solution was added to study the PH and acidity of the water-soluble extract in the fermentation process of yogurt. The effects of viscosity, bacteria content, etc., in order to obtain the influence on the relevant properties of fermented milk; at the same time, the sensory evaluation system was used to optimize the production process of purple potato yoghurt to achieve the best quality of the product; and the purple color was analyzed by GC-MS. The development of potato yoghurt and ordinary yoghurt provides a certain theoretical basis. In addition, on the basis of enriching the fermented milk market, it provides a new way to rationally and effectively develop and utilize purple potato resources. 
