酶处理异槲皮苷对辣椒红素光稳定性的影响

Effect of enzymatically modified isoquercitrin on the photostability of capsanthin

目的考察酶处理异槲皮苷(enzymatically modified isoquercitrin,EMIQ)对辣椒红素光稳定性的影响。方法使用氙灯光照老化箱对pH 3、4和5(柠檬酸-柠檬酸钠缓冲体系)下的EMIQ和辣椒红素混合溶液进行光照实验(340 nm,0.4±0.1 W/m^2,(55±5)℃),检测光照4 h中连续取得样品的Lab值和OD464。根据计算得到的总色差△E*和色素分解率评价色素的光稳定性,通过250~800 nm的光谱扫描图分析EMIQ能作为辣椒红素护色剂的原因。结果在排除温度对辣椒红素的稳定性影响后,氙灯老化箱的光照实验表明光是引起辣椒红素褪色的主要原因,溶液p H对辣椒红素的稳定性影响不大,EMIQ能够提高辣椒红素的光稳定性,用量越高效果越好。结论 EMIQ不能对辣椒红素的热稳定性造成影响,但能够显著提高辣椒红素的光稳定性,与以辅色苷的形式提高花青素的光稳定性不同,EMIQ主要通过吸收UV-A对辣椒红素进行保护。

Objective To study the effect of enzymatically modified isoquercitrin（EMIQ） on the photostability of capsanthin. Methods EMIQ and capsanthin mixed solutions in p H 3, 4 and 5（citric acid- sodium citrate buffer） were treated by the xenon lamp light aging instrument（340 nm, 0.4±0.1 W/m2,（55 ±5） ℃）, and the continuous sample Lab values and OD464 were detected. According to the calculated total color difference △E＊ and pigment decomposition rate, the photostability of pigment was evaluated. Through the spectral scan at 250-800 nm, the reason why EMIQ could be a color fixative was found. Results After excluding the fact of thermal stability of capsanthin, the light experiment by xenon lamp aging instrument showed that the light was the major reason of capsanthin fading, the p H value of capsanthin had little effect on the stability, EMIQ could improve the light stability of capsanthin, and the effect was better with the higher dosage. Conclusion EMIQ cannot affect the thermal stability of capsanthin, while significantly improve the photostability of capsanthin. EMIQ can protect capsanthin mainly by absorbing UV-A, which is different from the stabilization of grape skin anthocyanins by copigmentation.