de Rigal David, Gauillard Frédéric, Richard-Forget Florence
INRA, Station de technologie des Produits Végétaux, Domaine St Paul, Site Agroparc, F-84914 Avignon cedex, France.
INRA, Virologie - IBVM, BP 81, F-33883 Villenave d'Ornon cedex, France.
J Sci Food Agric. 2000 May 1;80(6):763-768. doi: 10.1002/(SICI)1097-0010(20000501)80:6<763::AID-JSFA623>3.0.CO;2-U.
Considering the numerous beneficial effects in human health ascribed to carotenoids, studies were performed to investigate the modification of carotenoid amount and composition during apricot enzymatic browning. First works on bruised apricot purees have shown a trans-β-carotene isomerisation (20%) induced by enzymatic browning. To clarify this isomerisation, oxidation of chlorogenic acid in presence of trans-β-carotene, catalysed by purified apricot polyphenoloxidase (PPO), was followed by HPLC and polarography. Isomerisation rate of trans-β-carotene in its cis isomer was found to increase with chlorogenic acid concentration. Moreover, trans-β-carotene was shown to be a potent inhibitor of phenol degradation. This inhibition was partially ascribed to PPO inhibition (non-competitive inhibitor towards phenol with an apparent Ki close to 0.5 mM, a mixed type inhibitor towards oxygen with an apparent Ki close to 0.15 mM). The additional inhibition was explained by non-enzymatic reactions involving trans-β-carotene and chlorogenic acid o-quinones and leading to phenol regeneration and carotene isomerisation. © 2000 Society of Chemical Industry.
鉴于类胡萝卜素对人体健康有诸多有益影响，人们开展了多项研究来探究杏在酶促褐变过程中类胡萝卜素含量及组成的变化。早期针对破损杏泥的研究表明，酶促褐变会导致反式-β-胡萝卜素发生异构化（异构化率达20%）。为阐明这种异构化现象，利用高效液相色谱法（HPLC）和极谱法对纯化的杏多酚氧化酶（PPO）催化下，反式-β-胡萝卜素存在时绿原酸的氧化过程进行了跟踪研究。结果发现，反式-β-胡萝卜素向顺式异构体的异构化速率随绿原酸浓度的增加而提高。此外，反式-β-胡萝卜素被证明是酚类降解的有效抑制剂。这种抑制作用部分归因于对PPO的抑制（对酚类为非竞争性抑制剂，表观抑制常数Ki接近0.5 mM；对氧气为混合型抑制剂，表观抑制常数Ki接近0.15 mM）。额外的抑制作用则由涉及反式-β-胡萝卜素和绿原酸邻醌的非酶促反应来解释，该反应导致酚类再生和胡萝卜素异构化。© 2000化学工业协会
