红花黄色素超声辅助提取工艺优化及其稳定性

Optimization and stability of ultrasonic-assisted extraction process of safflower yellow pigment

【目的】探究超声辅助热水提取红花黄色素的最佳工艺,为实现红花黄色素的绿色高效提取提供参考。【方法】以在我国广泛生长的菊科植物红花为试验材料,以去离子水为提取溶剂,以超声处理为辅助提取手段,以红花黄色素的提取率为试验指标,探究不同提取液pH、超声功率、超声时间、水浴温度、水浴时间对红花黄色素提取率的影响。基于单因素试验结果,选取显著影响红花黄色素提取率的3个因素,每个因素设置3水平,通过响应面分析法(RSM)优化红花黄色素的提取工艺。【结果】红花黄色素的提取率在水浴时间34 min、水浴温度90℃、超声功率350 W时达到最大值。验证试验结果表明,模拟值(6.84%)与实际值(6.33%)相近,回归方程与实际情况拟合良好,结果准确可靠。超声处理后,红花黄色素提取液中酮类、羧基和羟基等官能团含量明显增加,红花提取液数均相对分子质量由原来的311 Da减小为220 Da,说明超声处理过程中产生的机械作用和空化作用能有效将大分子物质转化为小分子物质,促进红花黄色素析出。此外,在提取液pH为中性,温度为45℃左右,光照时间小于2 h,氧化剂质量分数不高于5%的条件下,红花黄色素较为稳定。【结论】超声辅助热水抽提的方法是绿色高效提取红花黄色素的有效途径。

【Objective】In order to explore the optimal technological conditions of ultrasonic-assisted hot water extraction of safflower yellow pigment and provide a reference for the green and efficient extraction of safflower pigment.【Methods】The safflower,a widely grown Compositae plant in China,was selected as the experimental material.Deionized water,ultrasonic treatment and the extraction rate of safflower yellow pigment were respectively used as extraction solvent,assist-extraction method and the experimental index to explore the influences of different pH,ultrasonic power,ultrasonic time,water bath temperature and time on the extraction ratio of safflower pigment.Based on singlefactor tests,three factors with significant impact were selected,and three levels were respectively set for each factor.The extraction process of safflower yellow pigment was optimized by response surface method(RSM).【Results】The extraction rate of safflower yellow pigment reached the maximum value when the water bath time,water bath temperature and ultrasonic power were 34 min,90℃and 350 W,respectively.The verification experiment presented that the simulated value of 6.84%was close to the actual value of 6.33%,indicating that the regression equation was fitted well with the actual situation,and the result was accurate and reliable.After ultrasonic treatment,the content of functional groups such as ketones,carbonyl groups and hydroxyl groups increased significantly and the number-average molecular weight of the safflower extract decreased from 311 Da to 220 Da.These suggested that the mechanical action and cavitation during the ultrasonic treatment effectively converted macromolecular substances into small molecules,promoted the precipitation of safflower yellow pigment,and effectively extracted safflower yellow pigment,which could be used as an auxiliary extraction method.In addition,the stability conditions of safflower yellow pigment were as follow:pH was neutral,temperature was about 45°C,light time was less than 2 h,and the mass fraction of oxidant was not higher than 5%.【Conclusion】The ultrasonic-assisted hot water extraction method is effective to extract safflower yellow pigment in a green and efficient way.