Schäfer Judith, Trierweiler Bernhard, Bunzel Mirko
Department of Food Chemistry and Phytochemistry, Institute of Applied Biosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI), Karlsruhe, Germany.
J Sci Food Agric. 2018 Feb;98(3):1016-1023. doi: 10.1002/jsfa.8550. Epub 2017 Sep 13.
Lignified cell walls are important factors for textural and physiological properties of plant-based foods. However, carrot lignins and their modifications during maturation are poorly described. The objective of this study was to describe carrot lignins in detail and to study lignin structural alterations at later stages of maturity.
Klason and acetyl bromide soluble lignin contents of insoluble fibers of carrots harvested at different times (26, 29 and 35 weeks after seeding) ranged between 46.38 and 62.68 g kg and between 19.79 and 28.08 g kg , respectively. As determined by both 2D-nuclear magnetic resonance and the derivatization followed by reductive cleavage method, coniferyl alcohol heavily dominated the traditional monolignol composition in carrot lignins, independently of harvest times. By using 2D-nuclear magnetic resonance experiments on isolated lignins, p-hydroxybenzoate was identified as a less common lignin constituent, attached to lignin γ-hydroxyl groups and being increasingly incorporated with maturation. β-Aryl ethers, phenylcoumaran, resinol and dibenzodioxocin structures were identified as lignin interunit linkages, largely independent of harvest times and with β-aryl ethers being expectedly dominant.
Carrots contain guaiacyl-rich lignins that incorporate increasing amounts of p-hydroxybenzoate with maturation. All other lignin characteristics appear to be widely independent of harvest times. © 2017 Society of Chemical Industry.
木质化细胞壁是影响植物性食品质地和生理特性的重要因素。然而，胡萝卜木质素及其在成熟过程中的修饰情况却鲜有描述。本研究的目的是详细描述胡萝卜木质素，并研究其在成熟后期的结构变化。
不同播种时间（播种后26、29和35周）收获的胡萝卜不溶性纤维的克拉森木质素和乙酰溴可溶性木质素含量分别在46.38至62.68 g/kg和19.79至28.08 g/kg之间。通过二维核磁共振和衍生化后还原裂解方法测定，无论收获时间如何，松柏醇在胡萝卜木质素的传统单木质醇组成中占主导地位。通过对分离出的木质素进行二维核磁共振实验，对羟基苯甲酸被鉴定为一种不太常见的木质素成分，附着在木质素γ-羟基上，并随着成熟而逐渐增加。β-芳基醚、苯基香豆素、树脂醇和二苯并二恶英结构被鉴定为木质素单元间的连接方式，在很大程度上与收获时间无关，且β-芳基醚预计占主导地位。
胡萝卜含有富含愈创木基的木质素，随着成熟会掺入越来越多的对羟基苯甲酸。所有其他木质素特征似乎在很大程度上与收获时间无关。© 2017化学工业协会。
