The Extraction of Chaozhou Houlonghong Sweet Potatoes Skin Pigment and the Research of its Stability

In the paper,we use Houlonghong Sweet Potatoes Skin as raw materials to extract pigment,and analyze its stability of the red pigment.The studies show that the best extraction technology is 1% Hydrochloric acid ethanol,60 ℃,5 h and the ratio of solid and liquid as 1∶500.Stability research shows that the pigment has fine heat stability,oxidative stability and reducing stability.Common food additives,such as sugar,have little negative effect on the pigment.Nevertheless,sodium benzoate,citric acid and ascorbic acid has the a slight impact on it,so these food additives shouldn't be used too much.Sunlight has great influence on the pigment,hence direct sunlight should be avoided in the process of production and storage.Ca2+,Mg2+ have greater influence on the pigment than others including K+,Na+,Zn2+,Fe3+,Cu2+ etc.The pigment shows strong acid resistance,but alkali resistance intolerance.when pH values at 12,the pigment changed its color obviously with a large amount of sediment.When pH values no more than 7,the pigment would recover its original color.