KU Leuven, Department of Microbial and Molecular Systems (M(2)S), Laboratory of Food Technology, Kasteelpark Arenberg 22, Box 2457, 3001 Leuven, Belgium.
KU Leuven, Department of Microbial and Molecular Systems (M(2)S), Laboratory of Food Technology, Kasteelpark Arenberg 22, Box 2457, 3001 Leuven, Belgium.
Food Res Int. 2021 Feb;140:109794. doi: 10.1016/j.foodres.2020.109794. Epub 2020 Oct 16.
A material science approach was explored towards understanding storage stability of common dry bean seeds. State diagrams of powders from distinct bean varieties were generated through determination of their glass transition temperatures (Tgs) using differential scanning calorimetry. Confronting the state diagrams with dry matter-temperature combinations during storage facilitated establishing the link between the relative position of the bean storage conditions along the Tg line and extent of hard-to-cook (HTC) development. Generally, Tg increases with dry matter content of the bean powders implying stability at increasingly higher temperatures attributed to the reduced plasticizing effect of water. Whereas Tg lines of powders of the different bean varieties were very similar, distinct differences were observed for the powders of bean substructures. At a given moisture content, the Tg of the cotyledon material was lower than that of the seed coat material and the Tg values of the whole bean powders were dominated by the cotyledon material. Cooking time analysis showed that whole beans stored above their Tg developed the HTC defect, this extent being correlated with the difference between storage temperature and Tg value. Considering the HTC development rate, (R-value, rate of change in cooking time with storage time over a period of 0-4 months or at 0 months of storage) the higher the difference between the storage temperature and the Tg value, the faster the change in cooking time during storage. Exploring the role of the major polymer components of bean cotyledon revealed that at a given moisture content, the cell wall material showed the lowest Tg values compared to the protein and starch isolates (Tg cell wall < Tg protein < Tg starch isolate). Confronting these values with the HTC development rates (change of cooking time with storage time) supports involvement of the cell wall material and probably protein changes in the development of this defect.
采用材料科学方法研究了常见干豆种子贮藏稳定性。通过差示扫描量热法测定其玻璃化转变温度（Tg），生成了来自不同豆种粉末的状态图。将状态图与贮藏过程中的干物质-温度组合进行对比，有助于确定豆贮藏条件沿 Tg 线的相对位置与难煮（HTC）发展程度之间的关系。通常，Tg 随豆粉干物质含量的增加而升高，这意味着在更高的温度下稳定性增加，这归因于水的增塑作用降低。尽管不同豆种粉末的 Tg 线非常相似，但豆亚结构粉末之间存在明显差异。在给定的水分含量下，子叶材料的 Tg 低于种皮材料的 Tg，整豆粉末的 Tg 值主要由子叶材料决定。烹饪时间分析表明，储存在 Tg 以上的整豆会产生 HTC 缺陷，这种程度与储存温度与 Tg 值之间的差异有关。考虑到 HTC 发展速度（R 值，即烹饪时间随储存时间的变化率，在 0-4 个月或 0 个月储存期间），储存温度与 Tg 值之间的差异越大，储存过程中烹饪时间的变化越快。研究豆子叶主要聚合物成分的作用表明，在给定的水分含量下，细胞壁材料的 Tg 值最低，与蛋白质和淀粉分离物相比（Tg 细胞壁< Tg 蛋白质< Tg 淀粉分离物）。将这些值与 HTC 发展速度（烹饪时间随储存时间的变化）进行对比，支持细胞壁材料和可能的蛋白质变化参与该缺陷的发展。
