广东虫草子实体色素的提取及其稳定性

采用紫外可见分光光度法研究不同溶剂(乙醇、甲醇、石油醚、乙酸乙酯)对广东虫草(Cordyceps guangdongensis)子实体色素的提取效果及色素的稳定性。结果表明,广东虫草色素易溶于80%乙醇溶剂,最大吸收波长为410nm。色素的乙醇溶液分别在光照与黑暗条件下放置5d,其吸光度值分别减少22.3%和16.6%,在有光照条件与无光照条件下色素的吸光度差异显著。与室温25℃相比,在20~50℃下,色素吸光度无显著差异,在60~70℃下,差异显著,而当温度为90、100℃时,差异极显著,色素吸光度分别升高了19.8%和37.7%;强酸条件(pH为2~3),氧化还原剂H2O2,使色素褪色;碱性条件(pH为8~9),氧化还原剂Na2SO3以及部分食品添加剂(麦芽糖、柠檬酸、蔗糖)对色素有增色作用;金属离子影响色素的稳定性,其中Fe3+及Fe2+使色素发生色变。

Extraction and Stability of Pigment from Cordyceps guangdongensis Fruit bodies

Different solvents including ethanol,methanol,petroleum etherand ethyl acetate were used to extract sporocarp pigment from Cordyceps guangdongensis on the basis of UV visible spectrum.The extraction effectiveness of these solvents was compared and the stability of extracted sporocarp pigment was studied.C.guangdongensis pigment was soluble in 80％ ethanol with a maximum absorption wavelength at 410 nm.To study the effect of light on pigment,extract in 80％ ethanol was stored under either light or darkness condition for 5 days.Absorbance reduction of extracts under light and darkness condition were 22.3％ and 16.6％,respectively.Temperatures between 20 ℃ and 50 ℃ did not obviously affect the absorbance of extract.There was a slight increase in absorbance under 60 ～ 70 ℃,and high temperature conditions (90 ℃ and 100 ℃) dramatically affected pigment stability(increased by 19.8％ and 37.7％).Absorbance of pigment decreased with the presence of strong acid (pH 2-3)but on the other hand increased under basic condition or with the addition of food additives such as maltose,citric acid and sucrose.Reducing agent Na2SO3 increased pigment absorbance whereas oxidant H2 O2 reduced pigment absorbance.All tested metal ions showed a negative affect on pigment stability,and Fe3+ and Fe2+ also altered the color of the pigment.