黑莓清汁贮藏期间二次沉淀的研究

Study on sediments of clear blackberry juice during storage

分析了黑莓清汁贮藏六个月后二次沉淀的化学成分,讨论了影响二次沉淀的主要因素。结果表明,冷冻干燥的二次沉淀中含有蛋白质15.67%、多酚50.39%、总糖13.19%、灰分1.73%。氨基酸分析表明黑莓含有较多的脯氨酸等混浊活性蛋白质,而含有组氨酸较多的蛋白质也容易形成二次沉淀。采用气相色谱(GC)、高效液相色谱-质谱联用技术(HPLC-MS)分别分析了黑莓清汁二次沉淀的糖和酚类物质成分。与贮藏前相比,贮藏六个月后,黑莓清汁中的酚酸类、儿茶素及其衍生物大为减少。固体核磁共振检测发现,黑莓清汁二次沉淀中的聚合物是缩合单宁类化合物。在黑莓清汁的贮存过程中,花色苷的C8亲核进攻儿茶素或者表儿茶素的C4,或者儿茶素、表儿茶素的C8亲核进攻花色苷的C4生成缩合单宁,并可能进一步聚合形成多聚体,这些多聚体也会与蛋白质发生相互作用生成二次沉淀。

According to the analysis of the main components of sediment of clear blackberry juice after 6 months storage,the main aspects influencing sedimentation of blackberry juice were discussed.The lyophilized sediment contained 15.67% of protein,50.39% of total polyphenols, 13.19% of total sugars, and 1.73% of ash.Amino acid analyses indicated that blackberry contained more haze- active protein, such as poline. Moreover, protein containing more histidine was another haze-active protein. Monosaccharides determined by GC in the sediment were most probably the glycoside moieties of the anthocyanins, flavonols.After storage, the contents of phenolic acids, catechin and its ramification decreased greatly in clear blackberry juice. The sediments contained condensed tannin when analyzed the composition with NMR.Anthocyanin and catechin could condense to produce tannin ,which could increase degree of polymer and/or interact with protein to produce sediment.