乌饭树树叶蓝黑色素对大米蛋白理化性质的影响

Effects of the dark blue pigment from Vaccinium bracteatum Thunb leaves on the physicochemical properties of rice protein

目的:研究乌饭树树叶蓝黑色素对大米蛋白组分结构性质和乳化性质的改善作用。方法:以乌饭树树叶为原料制备蓝黑色素,以乌米饭中大米蛋白为研究对象,模拟乌米饭染色过程并分析染色前后大米蛋白结构性质和乳化性质的变化。结果:乌饭树树叶蓝黑色素可与大米蛋白形成二元复合物,导致色度L*值和b*值降低,复合物颜色向蓝黑色转变。色素—蛋白复合物溶解度增加,而持油性显著降低。利用圆二色光谱分析大米蛋白二级结构,发现其α-螺旋与β-折叠的相对含量下降,β-转角和无规卷曲的相对含量上升。当色素质量分数低于1.5%时,起泡稳定性升高,而起泡性、乳化性和乳化稳定性降低。当色素质量分数高于1.5%后,起泡稳定性下降,起泡性、乳化性和乳化稳定性升高。结论:乌饭树树叶蓝黑色素通过改变大米蛋白二级结构可改善其乳化性质。

Objective:This study was to explore the improvement of structural and emulsifying properties of rice protein by interacted with the dark blue pigment of Vaccinium bracteatum Thunb leaves.Methods:The dark blue pigment was prepared from VBTL,and the changes of structural and emulsifying properties of rice protein before and after dyeing were analyzed.Results:The formation of binary complexes between the dark blue pigment and the rice protein decreased the color values of L*and b*,and the hue of the pigment-protein complex changed to dark blue color with the increase of the pigment concentration.The water solubility of the pigment-protein complex increased,and the oil-holding capacity decreased significantly.The analysis circular dichroism spectroscopy showed the changes in the secondary structure of pigment-protein complex with a decreasing in the relative content ofα-helices andβ-folds and an increasing in the relative content ofβ-turns and random coil.At the concentration of pigment below 1.5%,foam stability increased,while foaming capacity,emulsifying capacity and emulsion stability decreased.When the concentration of pigment was higher than 1.5%,foam stability decreased,while foaming capacity,emulsifying capacity and emulsion stability increased.Conclusion:The dark blue pigment can improve the emulsifying properties of rice protein by changing its secondary structure.