金银花水提液的颜色稳定性

Color stability of water extract from Flos Lonicerae

以金银花水提液为研究对象,以ΔE*值为评价指标,测定和比较了金银花自来水提取液和超纯水提取液间的色差及贮藏过程中的颜色变化差异,并探讨了pH值、金属离子、抗氧化剂及放置时间对金银花水提液颜色稳定性的影响。结果表明:金银花超纯水和自来水提取液间存在明显的色差,且在贮藏过程中颜色稳定性不同。pH值对金银花超纯水提取液颜色变化的影响十分显著:酸性条件下颜色几乎不变,且放置过程颜色稳定;碱性条件下,ΔE*值随pH值增大而增大,最高可达39.01;碱性条件下放置,颜色不稳定,10 h内色差变化可达3.56。Al3+、Zn2+、Mg2+、Cu2+、Fe3+对金银花超纯水提取液的色差影响较大,ΔE*值均在3.00以上,其中Fe3+的影响最为显著。D-异抗坏血酸钠具有减缓金银花提取液颜色变化的作用。因此,避免混入金属离子、酸性环境和使用适当的抗氧化剂能使金银花水提液保持较好的颜色稳定性。

In this study, the color stability of tap water and ultra-pure water extracts of Flos Lonicerae during storage was investigated and compared using the value of ΔE＊ as evaluation index, together with studying the effects on the color stability of four factors including pH, metallic ions, antioxidants and storage period. The results indicated that there was a distinct difference between the color of tap water extract and ultrapure water extract, also during the storage process. The pH had obvious effect on the color stability. The color was stable under acidic condition. While it was unstable under alkaline condition, and the value of ΔE＊ got higher with the value of pH increasing. The value of ΔE＊ could reach to 39.01 when the value of pH was 11.0. The color changed significantly with the increase of 3.56 in ΔE＊ value after storage for 10 hours under alkaline condition. Metallic ions such as Al3＋, Zn2＋, Mg2＋, Cu2＋, Fe3＋, also had obvious effect on the color stability. Among these metallic ions, the effect of Fe3＋ was most significant. The sodium D-isoascorbate could improve the color stability. Therefore, keeping the water extract of Flos Lonicerae under acidic condition, avoiding metallic ions and using antioxidant properly, could keep the color stable.