Browsing by Subject "Spruce"
Now showing items 1-3 of 3
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(2020)Biogenic Volatile Organic Compounds play a major role in the atmosphere by acting as precursors in the formation of secondary organic aerosols and by also affecting the concentration of ozone. The chemical diversity of BVOCs is vast but global emissions are dominated by isoprene and monoterpenes. The emissions of BVOCs from plants are affected by environmental parameters with temperature and light having significant impacts on the emissions. The Downy birch and Norway spruce trees consist of heavy and low volatile compounds but published results are limited up to observing sesquiterpenoid emissions from these two trees. In this study, the Vocus proton-transfer-reaction time-of-flight mass spectrometer is deployed in the field to examine BVOC emissions from Downy birch and Norway spruce trees. With higher mass resolution, shorter time response and lower limits of detection than conventional PTR instruments, the Vocus can effectively measure a broader range of VOCs. For the first time, real-time emissions of diterpenes and 12 different oxygenated compounds were observed from birch and spruce trees. The emission spectrum of birch was dominated by C10H17+, while for spruce C5H9+ contributed the most. The sum emissions of oxygenated compounds contributed significantly to the observed total emissions from both the trees. The emission rates of all compounds varied dramatically throughout the period due to fluctuations in temperature and light. Due to lack of data from spruce, conclusive results for temperature and light response on terpene emissions could not be drawn. For birch, the emission rates were well explained by the temperature and temperature-light algorithms. The terpene emissions modelled using both algorithms correlated similarly with experimental data making it difficult to decisively conclude if the emissions originated from synthesis or pools.
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(2023)The current trend in the food and forest industries is to utilize sustainable and renewable products. One such product is galactoglucomannans (GGM), water-soluble hemicelluloses covering 25–35 % of the dry wood mass. GGM can be extracted from spruce sawdust or branches using a safe and environmentally friendly pressurized hot water extraction (PHWE) method. Deacetylation of GGM happening during extraction and concentration by membrane filtration at alkali conditions possibly enables gel formation. This thesis aims to observe if low acetyl GGM has the ability to form a gel and which factors have an impact on its gelation and gel properties. Low acetyl PHWE GGM powders were provided by the Natural Resources Institute of Finland (Luke). The GGM solutions at different pH values (4, 7, and 10) and solid concentration levels (5, 10, and 15 %) were prepared using a magnetic stirring rod and then ultrasonicated (50% amplitudes for 5 min). Viscosity, rheological properties, water holding capacity (WHC), hardness, and adhesiveness were measured on days 1, 2, 3, and 5 during storage at room temperature (22 °C). The results showed that GGM was able to form a gel at all investigated conditions, except for the samples at pH 4 and a solid concentration of 5 %. GGM solutions at high pH (7–10) and solid concentrations (10–15%) formed gels without ultrasonication. All GGM gels had high WHC (≥ 90 %). Gel viscosity increased with prolonging of storage time and increased solid concentration. The frequency sweep analyses showed that all investigated samples had a gel-like behavior. Gel hardness and adhesiveness increased in all the samples during storage and increased solid concentration. The thesis demonstrated that low acetyl GGM could form a gel, which could be used as a gelling agent, where solid concentration and pH impacted to gel structure. Thus, the study could widen industrial applications of GGM or at least engage interest.
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(2023)The current trend in the food and forest industries is to utilize sustainable and renewable products. One such product is galactoglucomannans (GGM), water-soluble hemicelluloses covering 25–35 % of the dry wood mass. GGM can be extracted from spruce sawdust or branches using a safe and environmentally friendly pressurized hot water extraction (PHWE) method. Deacetylation of GGM happening during extraction and concentration by membrane filtration at alkali conditions possibly enables gel formation. This thesis aims to observe if low acetyl GGM has the ability to form a gel and which factors have an impact on its gelation and gel properties. Low acetyl PHWE GGM powders were provided by the Natural Resources Institute of Finland (Luke). The GGM solutions at different pH values (4, 7, and 10) and solid concentration levels (5, 10, and 15 %) were prepared using a magnetic stirring rod and then ultrasonicated (50% amplitudes for 5 min). Viscosity, rheological properties, water holding capacity (WHC), hardness, and adhesiveness were measured on days 1, 2, 3, and 5 during storage at room temperature (22 °C). The results showed that GGM was able to form a gel at all investigated conditions, except for the samples at pH 4 and a solid concentration of 5 %. GGM solutions at high pH (7–10) and solid concentrations (10–15%) formed gels without ultrasonication. All GGM gels had high WHC (≥ 90 %). Gel viscosity increased with prolonging of storage time and increased solid concentration. The frequency sweep analyses showed that all investigated samples had a gel-like behavior. Gel hardness and adhesiveness increased in all the samples during storage and increased solid concentration. The thesis demonstrated that low acetyl GGM could form a gel, which could be used as a gelling agent, where solid concentration and pH impacted to gel structure. Thus, the study could widen industrial applications of GGM or at least engage interest.
Now showing items 1-3 of 3