Influence of storage on the physical and chemical properties of Scots pine bark

Abstract

Bark is currently used mainly to produce energy, but the extraction of valuable compounds before combustion offers an interesting cascading use for debarking biomass. Buffer storage is an inevitable part of bark biomass logistics, but substantial dry matter and extractive losses can degrade the properties and reduce the economic value of the raw material during storage. In this study, moisture and ash content, calorific value, and extractives content and composition of Scots pine (Pinus sylvestris) sawmill bark were determined over 2 months of buffer storage, and the change in energy content during storage was calculated. The results showed that the energy content (MWh m−3) of the bark increased 3% during storage, while at the same time the moisture content decreased 16%. The content of acetone-soluble extractives decreased markedly, with only 56% of the original amount remaining after 8 weeks of storage. In particular, hydrophilic, phenolic extractive compounds were rapidly lost after debarking and piling of the bark. About 60% of condensed tannins (CT) and about 26% of the quantified lipophilic compounds were lost after 2 weeks of storage. The fastest rate of decrease and the most significant changes in extractives content and composition occurred within the first 2 weeks of storage. Utilization of these valuable compounds necessitates fast supply of material for further processing after debarking. The comprehensive utilization of bark requires efficiency at all levels of the supply chain to ensure that tree delivery times are kept short and loss of bark is avoided during harvest and transport.

Chemical and Morphological Composition of Norway Spruce Wood (Picea abies, L.) in the Dependence of Its Storage

“…From chemical components, the stilbenes are very sensitive to degradation [ 37 ]. According to Routa et al [ 13 ], after eight weeks of pine bark storage, we obseved types of extractive substances, which are predominate in the bark: triglycerides, steryl esters, sterols, resin acids, and fatty acids.…”

“…Bark contains much more extractives than wood from the trunk [ 9 ], considerable amounts of bioactive components such as antioxidants (polyphenols), and also structural polysaccharides such as pectins [ 10 , 11 , 12 ]. Degradation of biomass is influenced by photodegradation (UV light), high temperatures during storage in piles, microorganizms, etc., Routa et al [ 13 ] describe the major reactions of lipophilic extractive compounds during wood storage, which can be divided into three types: (1) hydrolysis of triglycerides (rapid reaction) and steryl esters and waxes (proceeds slower); (2) oxidation/degradation/polymerization of resin acids, unsaturated fatty acids, and to some extent, other unsaturated compounds; and (3) evaporation of volatile terpenoids, mainly monoterpenes.…”

“…Bark can roughly be divided into the fraction: fibers, corok cells and fine substance (including parenchyma cells) [1]. Bark contains much more extractives than wood Polymers 2021, 13, 1619 2 of 11 from the trunk [9], considerable amounts of bioactive components such as antioxidants (polyphenols), and also structural polysaccharides such as pectins [10][11][12]. Degradation of biomass is influenced by photodegradation (UV light), high temperatures during storage in piles, microorganizms, etc., Routa et al [13] describe the major reactions of lipophilic extractive compounds during wood storage, which can be divided into three types: (1) hydrolysis of triglycerides (rapid reaction) and steryl esters and waxes (proceeds slower);…”

Comparison of different approaches to estimate bark volume of industrial wood at disc and log scale

“…Bark therefore often remains an unutilized industrial by-product which is used to produce energy only. However, the extraction of valuable compounds offers interesting uses for bark, but its potential for new value-added products is not yet fully exploited 27 , 28 . This is why, the interest in bark factors, which allow to estimate the proportion of bark of logs increased 29 .…”

Mathematical planning of experiments to optimize the extraction of extractive substances from needles of Pinus sylvestris

“…В оптимальном режиме был получен экстракт с выходом ЭВ 9,84% от массы сухого сырья, что сопоставимо с результатами, полученными при экстракции сырья органическими растворителями. При экстракции ДЗ сосны гексаном выделяется до 14% от массы сухого сырья экстрактивных веществ [Рощин, Султанов, 2004], диэтиловым эфиром 9,3 -14,8% [Васильев и др., 1995], ацетоном 9,9% [Routa et al, 2020].…”