笃斯越桔花青素在不同pH条件下热稳定性的研究

Study on the thermal stability of Bog bilberry anthocynanins under different pH

研究分析了笃斯越桔花青素提取物(BBAE)在不同pH条件下热稳定性的变化,测量指标包括吸光值、颜色及其ABTS自由基清除能力。研究结果表明:在pH4～6加热时,BBAE的吸光值无明显变化,提示其在酸性条件下有较好的稳定性。在pH7和pH8加热时,尤其在pH7时,BBAE的吸光值明显降低,表明BBAE在pH7条件下的热稳定性最差。通过色差仪测定BBAE溶液的L*、a*、b*值从而算出H(色调)值。随着加热温度的升高,pH为4～8时的BBAE溶液的H值呈现不同程度的升高,且逐渐趋近于90°。这表明在加热过程中,BBAE溶液的颜色由最初的红色逐渐向黄色转变。pH为7时的BBAE溶液在吸光值降低,颜色变黄的同时,其ABTS自由基清除率也有显著性的下降。

The thermal stability of Bog bilberry anthocynanins extracts（BBAE） under different pH was studied, using absorbance（Abs） ,color（ L ＊,a ,＊, b＊ ）and ABTS scavenging measurements.There was no obvious absorbance change when BBAE was heated at pH4-6, while significant decreased in the absorbances were observed when BBAE was heated at pH7-8,especially at pH 7,which suggested that BBAE was the most vulnerable under pH7. Calculated H value of BBAE increased with increasing heating temperature at pH4-8, indicating a color shift from red to yellow.Along with absorbance decreasing and color shifting to yellow,the ABTS radical scavenging ability of BBAE decreased significantly when heated at pH7