鲜切莲藕酶促褐变底物的分析确定

Identification of Enzymatic Browning Substrates in Fresh-cut Lotus Roots

鲜切莲藕贮藏期间的酶促褐变及其褐变底物的研究结果表明：切分后莲藕组织中新合成的及与多酚氧化酶（ＰＰＯ）作用的酚主要为ＦＰ，鲜切莲藕贮藏６ｄ后游离酚（ＦＰ）与褐变度（ＢＤ）两者的变化呈显著的负相关（ｒ＝０．９５９），组织中ＰＰＯ活性与ＦＰ、儿茶酚表现为同步的先升后降的变化规律，采用薄层层析和高压液相色谱确定儿茶酚在鲜切莲藕褐变前后发生明显量的变化，由儿茶酚与ＰＰＯ作用后产物的紫外吸收光谱与鲜切莲藕自然褐变产物基本相同的结果，初步认为儿茶酚是鲜切莲藕的主要褐变底物。

The enzymatic browning and its main substrates in fresh-cut lotus roots were studied during storage period. The results were as followsing: The newly synthesized phenolic substances were mainly the FP, which were the primary phenols catalyzed by PPO to cause browning; The changes of free phenols (FP) and browning degree (BD) after 6 days storage had significantly negative relationship (r=0.959); The FP, catechol and PPO activity showed the synchronous change pattern which increased first and decreased afterwards；The content of catechol in Fresh-cut lotus roots measured by thin layer chromatography and HPLC decreased significantly after browning; The absorption spectrums of catalytic product of catechol and browning product in fresh-cut lotus roots are identical, and Catechol therefore was considered as the major browning substrate in fresh-cut lotus roots.