常山胡柚天然色素的初步鉴定及其稳定性研究

以超临界CO2萃取得到的常山胡柚外果皮色素粗产品为原料,对其进行初步鉴定,并研究了pH值、温度、光照、金属离子、氧化还原剂等对常山胡柚天然色素稳定性的影响。结果表明;常山胡柚天然色素属于黄酮类物质,用NaNO2-Al(NO3)3比色法进行定量分析得知,色素液中含有黄酮类的量为2.01 g.L-1,该色素在碱性和中性溶液中较稳定,在酸性溶液中不稳定。光照、高温和氧化剂都会对该色素造成破坏;该色素能耐弱还原剂。低浓度Na 的存在会使最大吸光度增加,具有增色作用,高浓度Na 的存在能使最大吸光度降低。随着Zn2 浓度的增加,色素液的色泽明显变淡,吸光度急剧下降。Ca2 、Cu2 影响趋势基本一致,加入的离子浓度小于0.05 mol.L-1时,色素残存率缓慢下降;大于0.05 mol.L-1时,色素残存率有低幅增加趋势。Mg2 的加入会让色素残存率变小。

Study on In itia l Identif ica tion and Stability of Natural Pigmentof C itrus changshan-huyou

Initial identification and the effects of pH, temperature, light, metal ions reducing and oxidant onstability of natural p igment, which was extracted by supercritical CO₂ extraction from Citrus changshan-huyou wasstudied. The results showed that the p igment was flavonoids, By NaNO₂-Al (NO₃ ) ₃ colorimetric method forquantitative analysis, the flavonoidswas 2. 01 g·L^-1 ; the p igment in alkaline and neutral solution wasmore stablewhile in acidic solution the stability was unstable; the light, heat and oxidant could damage the stability; it wasstable under reducing; low concentration of Na₊ would increase the maximum absorbance, high concentrations ofNa+ would reduce the maximum absorbance. With the increase of concentration of Zn₂₊ , the color of p igmentobviously smeared out. The sharp decline in absorbance; Ca₂₊ , Cu₂₊ had basically the same impact on the trend.When the concentration was less than 0. 05 mol·L^-1 , the residual p igment showed a slow rate of decline, when itwasmore than 0. 05 mol·L^-1 , the rate of residual p igment increased in a low amp litude, Mg₂₊ would diminish therate of residual p igment.