栗子壳色素的分级与稳定性研究

Fractionation and Stability of Chestnut Shell Pigments

根据溶解性不同,将栗子壳色素分级得到3种色素组分Fr.1、Fr.2和Fr.3。Fr.1只溶于碱性水溶液;Fr.2溶于碱性水溶液和亲水性有机溶剂;Fr.3在任何pH值的水溶液中都能溶解,在亲水性有机溶剂中也能溶解。对栗子壳色素各分级组分进行了化学定性分析和紫外-可见光光谱分析,并研究了它们的稳定性。各分级组分均具有酚类物质的性质,但不具有黄酮类化合物的典型性质,也不具有鞣性。3种栗子壳色素组分的紫外-可见光光谱都是随着波长增大而吸光度逐渐减小的曲线,在可见光区没有明显的吸收峰,仅在270 nm左右有一肩峰。3种色素组分的溶液颜色均随着pH值的增大而逐渐加深,Fr.1对加热和紫外线相对稳定,而Fr.3最为敏感。氧化剂可使栗子壳色素褪色,且Fr.1褪色幅度最大,Fr.2最小。各色素组分均对还原剂、蔗糖、Na+、Mg2+稳定而对Al3+、Ca2+、Fe2+、Fe3+、Cu2+和Zn2+的稳定性较差。

A procedure was developed for fractionating the pigments from chestnut shells into 3 fractions（Fr.1,Fr.2 and Fr.3） according to their solubility.Fr.1 was soluble in alkaline water only;Fr.2 was soluble in alkaline water and the hydrophilic organic solvents;Fr.3 was soluble in the water at any pH and hydrophilic organic solvents.The pigment fractions were analyzed by chemical characterization and ultraviolet-visible spectrometry（UV-Vis）,and their stabilities were studied.All the fractions had the similar properties to phenol but not to falconoid and tannin.The UV-Vis spectra showed all three fractions optical absorption were decreased with wavelength.There was no absorption peak,but had a shoulder around 270 nm.The color of the solutions all turned darker with the increase of the pH values.To the heating and ultraviolet,Fr 1 was relatively stable,while Fr.3 was the most sensitive.All the pigment fractions could be bleached by the oxidant,and Fr.1 was least resistance,Fr.2 was the most stable.All the pigment fractions were stable to reductant,sucrose,Na＋ and Mg2＋,but not instable to Al3＋,Ca2＋,Fe2＋,Fe3＋,Cu2＋ and Zn2＋.The results provided a new,simple and inexpensive method to fractionate pigments from chestnut shells.In food production,a suitable fraction can be selected as a colorant according to specific requirements.Thus,the application of the chestnut shell pigments will be wider in the future.