The reason why kohlrabi turns purple after flooding is that the salt content is low, the air is not isolated during the curing process, and no additives are needed during the curing process. Because kohlrabi is not easy to dehydrate, the traditional kohlrabi processing is basically salt dehydration processing, which takes a long time to dehydrate and is easy to change color and taste.
Purple Nostoc flagelliforme is rich in anthocyanin, which is a powerful antioxidant and can protect human body from free radicals. Anthocyanins are characterized by being red when acidic, usually blue when alkaline, with transition colors such as purple and green in the middle, and turning black and purple when fried, which is normal.