Study on the extraction of brown pigment from chestnut shell and its related properties

The extraction of natural brown pigment from chestnut shell by ethanol was studied.The optimal conditions through the orthogonal test were found as follows: the extraction time 2.5 h,extraction temperature 75 ℃,the ethanol concentration 40%,solid-liquid ratio 1∶20.The extraction rate of brown pigment was 5.52%.In addition,the result of the study of its related properties showed: brown pigment was soluble in water,ethanol,methanol and insoluble in benzene,acetone,ethyl acetate,etc;brown pigment in aqueous solution was good at light and heat resistance,anti-oxidation and anti-reducibility;metal ions such as Ca2+,Mg2+,Zn2+,Ba2+,Na+,K+ didn't affect the pigment color significantly.However,Fe3+,Pb2+,Cu2+ could react with the pigment with sedimentation and decolored appeared.