Department of Chemistry, University of Jyväskylä, Survontie 9, 40500 Jyväskylä, Finland.
Natural Resources Institute Finland, Teknologiakatu 7, 67100 Kokkola, Finland.
Molecules. 2022 Feb 10;27(4):1186. doi: 10.3390/molecules27041186.
The current practices regarding the procurement chain of forest industry sidestreams, such as conifer bark, do not always lead to optimal conditions for preserving individual chemical compounds. This study investigates the standard way of storing bark in large piles in an open area. We mainly focus on the degradation of the most essential hydrophilic and hydrophobic extractives and carbohydrates. First, two large 450 m piles of bark from Norway spruce () were formed, one of which was covered with snow. The degradation of the bark extractives was monitored for 24 weeks. Samples were taken from the middle, side and top of the pile. Each sample was extracted at 120 °C with both -hexane and water, and the extracts produced were then analysed chromatographically using gas chromatography with flame ionisation or mass selective detection and high-performance liquid chromatography. The carbohydrates were next analysed using acidic hydrolysis and acidic methanolysis, followed by chromatographic separation of the monosaccharides formed and their derivatives. The results showed that the most intensive degradation occurred during the first 4 weeks of storage. The levels of hydrophilic extractives were also found to decrease drastically (69% in normal pile and 73% in snow-covered pile) during storage, whereas the decrease in hydrophobic extractives was relatively stable (15% in normal pile and 8% in snow-covered pile). The top of the piles exhibited the most significant decrease in the total level of extractives (73% in normal and snow-covered pile), whereas the bark in the middle of the pile retained the highest amount of extractives (decreased by 51% in normal pile and 47% in snow-covered pile) after 24-week storage.
目前，林业副产品（如针叶树皮）的采购链实践并不总是能为保持个别化合物的最佳条件。本研究调查了将树皮以大堆形式存放在露天场地的标准方法。我们主要关注最基本的亲水性和疏水性提取物和碳水化合物的降解。首先，形成了两个来自挪威云杉（）的 450 米大堆树皮，其中一个用雪覆盖。监测了树皮提取物的降解情况，为期 24 周。从堆的中间、侧面和顶部取了样品。每个样品都在 120°C 下用正己烷和水提取，然后用气相色谱法（火焰离子化或质量选择性检测）和高效液相色谱法对生成的提取物进行色谱分析。然后用酸水解和酸甲醇解分析碳水化合物，接着对形成的单糖及其衍生物进行色谱分离。结果表明，在储存的前 4 周内，降解最为剧烈。在储存过程中，亲水性提取物的水平也急剧下降（正常堆中为 69%，雪覆盖堆中为 73%），而疏水性提取物的下降相对稳定（正常堆中为 15%，雪覆盖堆中为 8%）。堆顶的提取物总量下降最明显（正常堆和雪覆盖堆中为 73%），而堆中间的树皮保留的提取物最多（正常堆中下降 51%，雪覆盖堆中下降 47%）经过 24 周的储存。
