Liu K
Jacob Hartz Seed Co., Inc., Stuttgart, AR 72160, USA.
Crit Rev Food Sci Nutr. 1995 Jul;35(4):263-98. doi: 10.1080/10408399509527702.
This review integrates current knowledge on the hard-to-cook (HTC) defect in legume seeds, with emphasis on the cellular and biological changes during storage and soaking, and the physicochemical changes during heating. Several postulated mechanisms, including the pectin-cation-phytate model, cell lignification, pectin beta-eliminative degradation, and protein denaturation in relation to starch gelatinization, are discussed in the context of current evidence. Subsequently, a developmental model of legume hardening is presented. It is held that the HTC defect develops during aging and soaking and is exhibited through cooking. During the process, there are many events involved. Free radical formation, lipid peroxidation, acid formation, membrane deterioration, protein denaturation, and leakage are events associated with aging and soaking, whereas pectin decomposition and solubilization, protein coagulation, and starch gelatinization are events that occur during cooking. Cooked HTC seeds are characterized by limited cell separation and restricted starch gelatinization. These defective features result from a restriction in pectin decomposition and solubilization as well as the protein coagulation that prevails over starch gelatinization during heating. This multichannel mechanism points to the direct involvement of two amphoteric colloids, cell wall pectin and storage protein, both of which are sensitive to pH and/or ion composition. The model also indicates the indirect involvement of cell membranes and starch granules. Except for events that occur during aging and soaking, it is likely that heat-related textural problems in other plant tissues may proceed via a mechanism similar to legume hardening.
本综述整合了目前关于豆类种子难煮（HTC）缺陷的知识，重点关注储存和浸泡过程中的细胞及生物学变化，以及加热过程中的物理化学变化。结合当前证据讨论了几种假定的机制，包括果胶 - 阳离子 - 植酸盐模型、细胞木质化、果胶β - 消除降解以及与淀粉糊化相关的蛋白质变性。随后，提出了豆类硬化的发育模型。认为HTC缺陷在老化和浸泡过程中形成，并通过烹饪表现出来。在此过程中，涉及许多事件。自由基形成、脂质过氧化、酸形成、膜劣化、蛋白质变性和渗漏是与老化和浸泡相关的事件，而果胶分解和溶解、蛋白质凝固以及淀粉糊化是烹饪过程中发生的事件。煮熟的HTC种子的特征是细胞分离有限和淀粉糊化受限。这些缺陷特征是由于果胶分解和溶解受限以及加热过程中蛋白质凝固优先于淀粉糊化所致。这种多通道机制表明两种两性胶体，即细胞壁果胶和储存蛋白直接参与其中，它们都对pH和/或离子组成敏感。该模型还表明细胞膜和淀粉颗粒间接参与其中。除了老化和浸泡过程中发生的事件外，其他植物组织中与热相关的质地问题可能也通过类似于豆类硬化的机制进行。
