亚麻籽水溶蛋白与红曲黄色素相互作用及其对色素稳定性的影响

红曲黄色素是常见的天然食用色素且具有多种生理功效,但其水溶性较差,且对光、热、酸碱敏感,限制了其在食品领域的广泛应用。以亚麻籽水溶蛋白(water-soluble flaxseed protein,FPW)为载体制备其与红曲黄色素的复合物,利用组合光谱分析技术研究两种红曲黄色素(monascin,MS和ankaflavin,AK)与FPW之间的相互作用行为,考察FPW同富含红曲黄色素的红曲色素(Monascus pigments,Mps)复合后,色素在水溶液中的分散性与稳定性变化情况。荧光光谱分析发现,MS和AK均以静态猝灭方式与FPW结合,且均只存在一个结合位点,FPW-AK体系的结合常数大于FPW-MS体系；热力学参数分析表明,维系FPW-MS体系的主要作用力为氢键和范德华力,维系FPW-AK体系的主要作用力为氢键和静电作用。同步荧光光谱、三维荧光光谱分析表明,MS或AK的加入使FPW的氨基酸残基微环境发生改变,从而引起FPW的构象改变。紫外-可见光谱和红外光谱研究结果进一步证明,MS和AK的添加使FPW的二级结构发生改变。此外,与FPW复合后,Mps在水中的分散性提高,且与不同浓度的FPW形成复合物后,在温度为25℃,光照强度为3900Lux,光照时间为72h时,与游离的Mps相比,FPW-Mps的保留率分别提高了9.53%、16.92%、31.37%；在温度为4、25、50℃的避光条件下,FPW-Mps较游离的Mps的保留率分别提高了25.65%、22.04%、25.98%；在温度为25℃,pH值为3、5、7、9、11,避光条件下,FPW-Mps较游离的Mps的保留率分别提高了10.27%、12.96%、12.06%、17.82%、7.27%。与FPW复合后,在不同光照时间、温度和pH值条件下,Mps的保留率均增加,表明FPW可以提高Mps的光稳定性、热稳定性和酸碱稳定性。研究旨在为红曲黄色素稳定性研究提供新的思路。

Interaction Between Water-Soluble Flaxseed Protein and Monascus Yellow Pigments and Its Effect on Stability of Pigments

i>Monascus yellow pigments are common natural food pigments with various physiological effects, but their poor water solubility and sensitivity to light, heat, and pH, which limit their wide application in food field. Water-soluble flaxseed protein (FPW) was used as a carrier to prepare the complex between FPW amd Monascus yellow pigments. The interaction hehavior between two types of Monascus yellow pigments (Monascin, MS and Ankaflavin, AK) and FPW was studied using combined spectral method. The dispersion and stability changes of pigments combined with FPW and Monascus pigments (Mps) which riched in Monascus yellow pigments in aqueous solution were investigated. Fluorescence spectroscopic analysis indicated that both MS and AK bound to FPW in the static quenching mode, and there was only one binding site. The binding constant of FPW-AK system was larger than that of FPW-MS system. The results of thermodynamic parameters demonstrated that the main forces maintaining FPW-MS system were hydrogen bond and van der Waals force, while those maintaining FPW-AK system were hydrogen bond and electrostatic attraction. Synchronous fluorescence spectrum and three-dimensional fluorescence spectrum showed that the addition of MS or AK changed the microenvironment of the amino acid residues of FPW, resulting in the conformational change of FPW. Analysis of UV-Vis and infrared spectroscopy further indicated that the secondary structure of FPW was changed after the addition of MS and AK. In addition, the combination of FPW and Mps could improve the dispersibility of Mps in water. After forming complexes with different concentrations of FPW, the retention rates of FPW-Mps were increased by 9.53%, 16.92%, and 31.37% compared to free Mps at a temperature of 25℃, a light intensity of 3900Lux, and a light duration of 72h. At temperatures of 4,25, and 50℃, and under light avoidance conditions, the retention rates of FPW-Mps increased by 25.65%, 22.04%, and 25.98% compared to free Mps. At a temperature of 25℃, pH values of 3,5, 7,9, and 11, and under light avoidance conditions, the retention rates of FPW-Mps increased by 10.27%, 12.96%, 12.06%, 17.82%, and 7.27% compared to free Mps, respectively. After composite with FPW, the retention rates of Mps increased under different illumination time, temperatures, and pH conditions, indicating that FPW could improve the photostability, thermal stability, and acid-base stability of Mps. This study aimed to provide new ideas for the stability study of Monascus yellow pigments.