Bernal-Lugo I, Parra C, Portilla M, Peña-Valdivia C B, Moreno E
Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México D.F.
Plant Foods Hum Nutr. 1997;50(2):141-50. doi: 10.1007/BF02436033.
The characteristic of proteins, starch and pectic substances in cotyledons of two bean cultivars varying in cooking time were determined to investigate their possible contribution to bean cooking quality. Both cultivars showed the same enthalpies of starch gelatinization but different protein denaturation enthalpies. The proportion of hot water soluble pectins was higher in Michigan, the cultivar with the lower cooking time, than in Ojo de Cabra, the cultivar with the higher cooking time. These results were not due to differences in pectin methylation or in the ratio of monovalent to divalent cations in the tissue, suggesting that in fresh beans the beta-elimination reaction is not the sole or predominant route of thermal pectin degradation. Overall, this study indicates that varietal differences in bean cooking quality may be reflections of the rate of pectin loss during soaking/heating and that the thermal properties of starch and protein fractions seem to have a minor contribution. Researchers involved in this study propose that in fresh beans, the thermal pectin loss results from a two step mechanism: pectin enzymic breakdown during the bean soaking followed by thermal solubilization rather than beta-elimination during the bean heating.
测定了烹饪时间不同的两个菜豆品种子叶中蛋白质、淀粉和果胶物质的特性，以研究它们对菜豆烹饪品质的可能贡献。两个品种的淀粉糊化焓相同，但蛋白质变性焓不同。烹饪时间较短的品种密歇根州产菜豆中热水溶性果胶的比例高于烹饪时间较长的品种奥霍德卡布拉产菜豆。这些结果并非由于组织中果胶甲基化或一价阳离子与二价阳离子比例的差异，这表明在新鲜菜豆中，β-消除反应不是热果胶降解的唯一或主要途径。总体而言，本研究表明，菜豆烹饪品质的品种差异可能反映了浸泡/加热过程中果胶损失的速率，而淀粉和蛋白质部分的热性质似乎贡献较小。参与本研究的研究人员提出，在新鲜菜豆中，热果胶损失是由两步机制导致的：菜豆浸泡过程中果胶的酶促分解，随后是热溶解，而不是菜豆加热过程中的β-消除。
