Optimization Of Extraction Technology And Stability Studies Of Pigment From Chestnut Shell

China is the main country of chestnut cultivation.The production of chestnut pulp has been quite large.However,chestnut shells have not been effectively utilized as processing waste.A kind of natural brown pigment can be extracted from the chestnut shell,which has dyeing force,certain anti-oxidation and antibacterial effects.Therefore,it has high development values.In this paper,the optimal extraction conditions,chemical compositions,stabilities and acute toxicity of chestnut shell pigments were studied.The pigment of chestnut shell was extracted by alkaline ethanol solution.The conditions of extraction of the chestnut shell pigment obtained by single-factor experiment and Response Surface Methodology were extraction solvent pH value of 13,ratio of liquid to material 12.5 mL/g,ethanol concentration of 28%,extraction temperature of 83℃,and extraction time of 2.3 h.The color value of the chestnut shell pigment obtained on the conditions can reach 31.25.The chemical components of ethyl acetate fraction of the pigment include phenols,tannin,organic acids,sugars（polysaccharides or oximes）,lactones（coumarins）,flavonoids and phytosterols preliminarily.Three compounds were isolated by silica gel column chromatography,which were myristic acid,palmitic acid and stearic acid.Through a series of pigment stability experiments,it could be learned that the pigment of chestnut shell was sensitive to pH value and heat,stable to light,and had certain tolerance to oxidant H₂O₂ and reducing agent ascorbic acid.Mn²⁺and Zn²⁺had certain enhancement effects on color of the pigments.Cu²⁺,Fe²⁺,Fe³⁺and Al³⁺could destroy the stability of pigment,and caused precipitate.The pigment was also stable to the commonly used as food additives.Acute toxicity experiment of mice showed that the LD₅₀ of pigment of chestnut shell is more than10.0g/kg.According to the acute toxicity classification,the chestnut shell pigment was a non-toxic substance.