黑糯玉米色素稳定性的研究

Study on Stability of Melanin from Black Waxy Corn

[目的]为黑糯玉米色素的开发利用提供理论依据。[方法]以黑糯玉米为原料,用95%乙醇提取其中的黑色素,并研究光照、温度、pH值、食品添加剂、氧化剂、还原剂和金属离子对色素稳定性的影响。[结果]在日光下放置1 d后,色素的保存率为40%,放置7 d后,色素保存率仅为15%;90℃时色素分解较快,温度低于70℃时色素降解不明显;添加柠檬酸、蔗糖、山梨酸钾和Vc后,色素的吸光度变化不大;H2O2对色素有较强的破坏作用;Fe3+使色素的吸光度明显减小。[结论]黑糯玉米色素的耐光性较差,耐热性较强,对酸、碱、还原剂、食品添加剂及Na+、K+等离子较稳定,对氧化剂和Fe3+、A l3+等离子不稳定。

[ Objective ] The aim was to provide the theoretical basis for development and utilization of melanin from black waxy corn. [ Method] With black waxy corn as the material, the melanin was extracted by 95% ethanol, and the effects of light, temperature, pH value, food additive, oxidant, reducing agent and metal ions on stability of the melanin were studied. [ Result ] The preserving rate of the melanin was 40% when it was placed for 1 d in light, but its preserving rate only was 15% when it was placed for 7 d in light When the temperature was 90 ℃, the decomposition rate of the melanin was fast, but when the temperature was lower than 70℃, the degradation of the melanin was not obvious. When citric acid, sucrose, potassium sorbate and Ve was added resp. the change of absorbance of the melanin was little. H2O2 had strong destructive action on the melanin. Fe^3＋ could obviously decrease the absorbance of the melanin. [ Conclusion ] The lighffastness of melanin from black waxy corn was worse with strong heat resistance, the melanin was stable to acid, alkali, reducing agent, food additive, Na^＋and K^＋ etc, but it was unstable to oxidant, Fe^3＋ and Al^3＋.