Optimization the Sulfur-free Drying and Color Protection Process of Lycium barbarum by Response Surface Methodology and Its Effect on Quality

In order to study the process of promoting drying and color protection of fresh wolfberry, sodium carbonate, citric acid and soaking time were selected as independent variables, and the water content and color difference were used as response values, the process was optimized by response surface optimization method, and the quality indicators were determined. The results showed that the optimal conditions for promoting drying and color protection of wolfberry were as follows: Sodium carbonate was 1.1%, citric acid was 0.6%, soaking time was 10 min, soaking temperature was 30 ℃, after 50 ℃ hot air drying for 42 h, the water content of wolfberry decreased to 12.41%. The color difference value was 11.09, the color was good and the drying speed was fast, which was 42% faster than that of the untreated wolfberry. Measured Lycium barbarum polysaccharide 2%, total sugar 52.89%, total carotenoids 0.54 g/100 g, total phenols 7.16 mg/g, total flavonoids 1.57 mg/g. The content of total carotenoids, total phenols and total flavonoids in the obtained dried wolfberry was significantly higher than that of the untreated dried wolfberry (P<0.05), and the content of polysaccharide and total sugar was not significantly different from that of the untreated wolfberry (P>0.05). Compared with the control group, this method of promoting drying and color protection can retain more nutrients during the drying process of wolfberry, which had practical reference value.