The bark of Norway spruce (Picea abies) contains up to 13% pectins that can be extracted by pressurized hot water, which constitute a valuable renewable resource in second-generation lignocellulosic biorefineries. This article proposes, for the first time, structural molecular models for the pectins present in spruce bark. Pectin fractions of tailored molar masses were obtained by fractionation of the pressurized hot water extract of the inner bark using preparative size-exclusion chromatography. The monosaccharide composition, average molar mass distribution, and the glycosidic linkage patterns were analyzed for each fraction. The pectin fraction with high molecular weight (M-w of 59,000 Da) contained a highly branched RG-I domain, which accounted for 80% of the fraction and was mainly substituted with arabinan and arabinogalactan (type I and II) side chains. On the other hand, the fractions with lower molar masses (M-w = 15,000 and 9000 Da) were enriched with linear homogalacturonan domains, and also branched arabinan populations. The integration of the analytical information from the macromolecular size distributions, domain composition, and branch lengths of each pectin fraction, results in a comprehensive understanding of the macromolecular architecture of the pectins extracted from the bark of Norway spruce. This paves the way for the valorization of spruce bark pectic polymers in targeted applications based on their distinct polymeric structures and properties.

The inner bark of Norway spruce (Picea abies) was sequentially extracted with hot water at 100 degrees C, 140 C and 160 degrees C. The hot-water extracts (IB 100 degrees C, IB 140 degrees C and IB 160 degrees C) contained pectic polysaccharides and showed immunostimulating activities. Structural analyses of their carbohydrate content, including glycosidic linkage analyses, revealed the presence of pectins with a large rhamnogalacturonan RG-I domain ramified with highly-branched arabinans. IB 100 degrees C also contained a large amount of terminal glucosyl residues, indicating the presence of highly substituted polymers. IB 160 degrees C was mainly composed of starch. The hot-water extracts were tested for two biological activities, namely complement fixation and macrophage stimulation. IB 100 degrees C exhibited the highest complement fixation activity, with a 1.7-times higher IC(H)50 than the control pectin, while IB 140 degrees C and IB 160 degrees C gave similar IC(H)50 values as the control. Macrophages were stimulated by IB 100 degrees C and IB 140 degrees C in a dose-dependent manner, but not by IB 160 degrees C. IB 100 degrees C presented the highest activity toward macrophages, comparable to the control pectin.

The present study reports for the first time the isolation of cellulose fibers and cellulose nanocrystals (CNCs) from the bark of Norway spruce. The upgrading of bark cellulose to value-added products, such as CNCs, is part of the "bark biorefinery" concept. The removal of non-cellulosic constituents was monitored throughout the isolation process by detailed chemical composition analyses. The morphological investigation of the CNCs was performed using AFM and showed the presence of nanocrystals with an average length of 175.3 nm and a diameter of 2.8 nm, giving an aspect ratio of around 63. X-ray diffraction (XRD) analyses showed that the crystallinity index increased with successive treatments to reach a final value greater than 80% for CNCs. The thermal degradation of the isolated bark CNCs started at 190 degrees C Spruce bark appeared to be a new promising industrial source of cellulose fibers and CNCs.

The purpose of the bark biorefinery concept is to upgrade the different constituents present in bark to multiple value-added bio-based products. Non-cellulosic polysaccharides (NCP) and cellulose nanocrystals (CNC) sequentially isolated from the inner bark of Norway spruce were used as raw materials for the formulation of renewable nanocomposites. The film formation abilities of NCP/CNC formulations prepared with different proportions of CNC were studied. Homogeneous transparent films with a glossy appearance were obtained when more than 30 wt% CNC was incorporated. The influence of the CNC content on the NCP/CNC films was assessed in terms of structural, thermal, mechanical and oxygen-barrier properties. All the films showed better performances with increasing CNC content, which was explained by the strong interactions between the two components. The effect on the film performances of adding sorbitol as a plasticizer was also evaluated. The presence of sorbitol decreased the thermal stability, the stiffness and the oxygen permeability of the films at 80 % RH. However, the addition of sorbitol enhanced the elongation of the films and further improved their oxygen-barrier properties at 50 % RH. The composite properties could thus be tailored by adding different amounts of sorbitol and CNC, resulting in all-carbohydrate materials with performances similar to or even better than the conventional barrier materials used in packaging.

Non-cellulosic polysaccharides (NCP) from bark offer large potential as a class of natural raw materials for functional materials development and production of biochemicals. We have elaborated a process for sequential extraction of NCP from industrial Norway spruce bark using an accelerated solvent extraction (ASE) with water at 100 to 160°C. Carbohydrates, Klason lignin and ash content as well as size-exclusion chromatography (SEC) analyses were performed for all hot-water extracts. NCP were mainly composed of glucose, arabinose and galacturonic acid units which revealed the presence of starch, arabinose-rich hemicelluloses and pectins. In total, the industrial bark of Norway spruce contained up to 20% of NCP which were extracted with pressurized hot water. NCP were mainly extractable at 140°C and started to undergo degradation at higher temperature.

In industrial spruce bark, up to 20 % of the dry mass consists of non-cellulosic polysaccharides. These polysaccharides can easily be extracted with pressurized hot water and have a large potential as a starting polymeric biomass for functional materials development. In this study, spruce bark was collected directly after the debarking process. The different steps of extraction were performed in an Accelerated Solvent Extractor (ASE). Bark was first extracted with acetone at 100 degrees C to remove extractives. Spruce bark polysaccharides could then be extracted with pressurized water at 100-460 degrees C with the highest yield at 140 degrees C. They were mainly composed of glucose, arabinose and galacturonic acid units which revealed the presence of pectic substances, starch and arabinose-rich hemicelluloses, e.g. arabinans. Molecular weight estimations showed the presence of rather large polysaccharides with a Mw varying between 10 to 30 kDa, depending of the extraction conditions.

Bark of Norway spruce (Picea abies) contains 20 to 30% of hemicelluloses and pectins which could be extractedwith pressurized hot water. Hemicelluloses and pectins from the fresh inner bark were extracted with anAccelerated Solvent Extractor (ASE) with water at 100 °C, 140 °C and 160 °C. A large amount of arabinose andgalacturonic acid units in the water extract obtained at 140 °C revealed the presence of arabinans and pectins. Atthis temperature, the extraction of hemicelluloses and pectins was the most effective and generated high-molarmassnon-cellulosic polysaccharides with an average molar mass Mw around 40 kDa. Aromatic substancespresent in the hot-water extract at 140 °C could partly be removed by sorption on DAX-8 polyacrylate resin.