憎水性红曲红色素的制备与表征

用乙酐处理醇溶性红曲红色素得到憎水性红曲红色素,其最大吸收波长为507和428nm.根据FTIR测定结果,推测在反应中可能发生酮与酸酐的缩合反应.反应后的红曲红色素可以溶于多种较低极性的溶剂,在pH7.5-12.0的碱性缓冲溶液中,具有较好的溶解性;在酸性和pH13.0缓冲溶液中,则出现浑浊.在加热过程中,添加Al3+和Fe3+的色素溶液稳定性较差,添加Sn2+的色素溶液比较稳定,而添加Mg2+和Ca2+后,色素溶液光密度略有上升.色素溶液光密度随光照时间的延长而呈近乎线性下降;在40、60和95℃水浴中加热,色素溶液光密度随加热时间的延长也呈近乎线性下降.

Preparation and characterization of hydrophobic Monascus red colorant

The hydrophobic Monascus red colorant was prepared by a reaction of alcohol-soluble Monascus red colorant with acetic anhydride, its maximal absorbance waves were at 507 and 428 nm. It was deduced from FTIR that the condensation reaction was caused by a reaction of ketone group with anhydride. The produced Monascus red colorant was soluble in many lower polar solvents. It was soluble in alkali buffers of pH 7.5-12.0, and formed precipitate in acid buffers and alkali buffer of pH 13.0; it was unstable in the solution with Al~(3+) and Fe~(3+), and was stable in the solution with Sn~(2+) in heating process. Adding Mg~(2+) and Ca~(2+) would improve the absorbance of colorant solution. Its absorbance would decrease with the increase of sunlight illumination; its absorbance would decrease with the increase of heating time in the bath of 40, 60 and 95 ℃.