Wu Li-Chen, Siebert Karl J
Department of Food Science and Technology, Cornell University, Geneva, New York 14456, USA.
J Agric Food Chem. 2002 Jun 19;50(13):3828-34. doi: 10.1021/jf011471n.
The nature of the haze-active protein (HAP) in apple juice was investigated. Heat treatment removed protein indiscriminately while polyvinylpolypyrrolidone (PVPP) treatment was fairly specific for proteins of 15 and 28 kDa. Presumably, the PVPP bound to polyphenols, which in turn were complexed with protein. Three candidate apple HAPs were isolated. Two were extracted from juice with acetone and fractionated by hydrophobic interaction chromatography and solid phase extraction with C18 (HAP I) or SAX (HAP II) material. Hydroxyproline-rich protein was extracted from apple tissue (HAP III). The order of haze formation with tannic acid was gliadin > HAP III > HAP II > HAP I > bovine serum albumin, which shows increasing haze formation with increasing proline content. The sizes of HAP I, II, and III were 28, 15, and 12 kDa; the first two corresponded to the sizes of proteins removed by PVPP treatment and are involved in juice haze formation.
对苹果汁中与浑浊相关的蛋白质（HAP）的性质进行了研究。热处理会不加区分地去除蛋白质，而聚乙烯聚吡咯烷酮（PVPP）处理对15 kDa和28 kDa的蛋白质具有相当的特异性。据推测，PVPP与多酚结合，而多酚又与蛋白质形成复合物。分离出了三种候选苹果HAP。其中两种用丙酮从果汁中提取，通过疏水相互作用色谱法以及用C18（HAP I）或SAX（HAP II）材料进行固相萃取进行分离。富含羟脯氨酸的蛋白质从苹果组织中提取（HAP III）。与单宁酸形成浑浊的顺序为：麦醇溶蛋白 > HAP III > HAP II > HAP I > 牛血清白蛋白，这表明随着脯氨酸含量的增加，浑浊形成增多。HAP I、II和III的大小分别为28 kDa、15 kDa和12 kDa；前两者与PVPP处理去除的蛋白质大小相对应，并且参与果汁浑浊的形成。
