Compared with ordinary sweet potatoes, purple sweet potatoes are rich in anthocyanin-like pigments, polysaccharides, soluble proteins, vitamins, mineral elements and many other nutrients. It has unique physiological effects in addition to the functions of ordinary sweet potatoes, and is therefore an important food ingredient. Coupled with the fact that people’s consumption concepts are gradually changing to nutritious and healthy, green food, and vigorously pursuing health food, the development of purple sweet potato food is an important trend in the food industry.

Processing of purple potato beverage

At present, the development of purple sweet potato beverage new technology is rich and diverse, especially in summer, people can drink purple sweet potato beverage to quench their thirst, and can absorb its nutrients.

Tu Wei to purple sweet potato as raw materials, through the α-amylase, saccharase enzyme together enzymatic digestion of purple sweet potato starch, and then developed a purple sweet potato milk composite milk drink. The study showed that the optimal formula was 50% purple sweet potato juice, 55% fresh milk, 2% sugar, 0.6% citric acid, 0.1% carrageenan, 0.08% xanthan gum, 0.06% guar gum, 0.06% sodium sodomycin.

Zhang Xin et al. used Lactobacillus plantarum to make purple potato juice, and the study showed that: the optimal conditions for the liquefaction of purple potato were 0.4% enzyme addition, pH 7.5, temperature 55 ℃, liquefaction time of 70 min; the optimal conditions for the saccharification of purple potato were 55U-100mL-1 enzyme addition, pH 4.0, temperature 60 ℃, saccharification time 90 min. The optimal fermentation inoculum amount was 9%, the optimal fermentation inoculum amount was 9%, and the optimal fermentation time was 90 min. The optimal fermentation inoculum was 9%, and the fermentation time was 29h.

Purple sweet potato drink not only has anticancer effect, but also can be used as an antioxidant and play the role of anti-hypertension. Purple sweet potato beverage is multi-functional, and nowadays both domestic and foreign countries are researching on the nutritional and health care of purple sweet potato beverage. For example, LeeJY et al. used brewer’s yeast to produce anthocyanin-rich purple sweet potato drink.

Processing of purple sweet potato wine

Purple sweet potato wine is a low-fermented wine made from pure grain. Sango’s purple potato wine, made from purple potato and wheat flour by enzymatic brewing, has a bright color, fragrant aroma and refreshing taste. Its research shows that the anthocyanin content of purple potato wine made by this method is as high as 276.5mg/L, which is significantly higher than that of commercially available purple potato wine. The DPPH-free radical scavenging rate of the wine is 85.2%, which has good antioxidant property and can prevent cardiovascular and cerebrovascular diseases, high blood sugar, high blood fat and cancer, etc. It has high health care value.

Many researchers have taken purple sweet potato as the main raw material to study various new brewing processes of purple sweet potato wine. For example, Wang Shiqing and others showed that: the best process for brewing purple sweet potato wine is based on the main fermentation temperature of 27.90℃, pH3.81, inoculation amount of 3.97%, and liquid loading amount of 60.99%; the preferred storage temperature is 14℃, time is 60d, and alcohol content is 9.80°, which results in the purple sweet potato wine under the process of color clarification, soft taste, and has the original aroma of purple sweet potatoes.

Zhang Ming’s research showed that: the material-liquid ratio was 1:2.3, the amount of liquefying enzyme was 2U/g, the liquefying time was 2.5 h, the amount of saccharifying enzyme was 342U/g, the saccharifying time was 2 h; the optimum yeast inoculum was 0.1%, the optimum fermentation temperature was 25-28℃, the optimum fermentation time was 7-8d, and the purple sweet potato wine was found to be extremely strong in anti-oxidizing property.

The scavenging rate of purple sweet potato wine on NO2- was as high as 99.96%. The maximum scavenging rate was achieved with a very small dosage when the concentration was diluted by 10 times to scavenge DPPH free radicals. Therefore, drinking a moderate amount of purple sweet potato wine every day can effectively remove free radicals and NO2- in the body, which can play a good role in antioxidant and anti-aging.

The purple sweet potato wine brewed by Ray RC contains 0.5509mg/mL anthocyanin, because the purple sweet potato wine still retains the active ingredients of raw material purple sweet potato, so its wine is rich in a variety of health functions.

Processing of purple potato milk

Purple sweet potato milk is nutritious and beneficial to human health. Zheng Qing et al. to make purple sweet potato yogurt the best raw material ratio: purple sweet potato pulp 3%, milk powder dosage of 13%, sugar 7.5%, inoculation amount of 4%. The product has a unique flavor, suitable for sweet and sour, and does not contain any preservatives, coloring, flavoring and other chemical compounds, which is a kind of green food.Zhang D M et al. used purple sweet potato and milk as the main raw material to make purple sweet potato milk.

The results showed that the product contained 80% milk, 6% purple sweet potato, 5% sugar and 0.22% compound stabilizer. This purple sweet potato milk has a smooth taste and very high stability.

Processing of purple sweet potato whole powder

Liu Yang et al. used fresh purple potato as raw material and optimized the preparation of raw whole powder of purple potato by puffing and drying method. The results show that: puffing temperature 80 ℃, pumping temperature 69 ℃, stagnation time of 5min, the purple potato raw whole powder produced under the conditions of bright color, and a greater degree of retention of the original bioactive substances and all the nutrients of purple potatoes, fine taste, easy to digest and absorb, can be used as a good food raw materials or natural food additives, has a wide range of uses in the food industry.