苹果浓缩汁二次混浊物的形态分析

    Morphological analysis of the second haze in concentrated apple juice

    • 摘要: 通过苹果浓缩汁二次混浊物的形态分析以及浊度测定,初步确定混浊物的化学成分,为果汁生产、贮存中混浊的控制提供依据。将二次混浊果汁和后混浊果汁经乙酸双氧铀负染,观察其在透射式电镜下的形态并测定其浊度。结果表明:苹果浓缩汁经-18℃,冷冻8~10 h处理后,苹果浓缩汁混浊减轻;再煮沸冷冻的果汁,混浊增加;二次混浊苹果浓缩汁形成的颗粒经乙酸双氧铀负染在透射式电镜下有蛋白质球状颗粒和链状的多酚类颗粒,或自身聚合或相互聚合形成大的颗粒;贮藏6个月的苹果浓缩汁后混浊比二次混浊严重。初步确定苹果浓缩汁的二次混浊物主要是蛋白质和酚类以及两者自身或相互聚合的产物。

       

      Abstract: The morphological analysis and the turbidity measurement of the second haze in concentrated apple juice were carried out and the composition of the second haze in concentrated apple juice were determined preliminary in order to supply informations for fruit juice processing and preservation. Negatively stained(uranyl acetate) images of the particles in the second haze apple juice and post bottling haze apple juice were observed. The turbidity of apple juice was decreased by freezing(at -18℃, frozen for 8~10 h) but increased by boiling after freezing. Spherical particles of protein and chain polymers of phenolic compounds were detected by negatively stained with uranyl acetate through transmission electron microscopy. Sub-particles were accompanied aggregation into the macroscopic particles with each other or by themselves. The turbidity of post bottling haze was higher than that of the second haze in apple juice after 6 months storage.

       

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