Isolation of phenolic compounds from larch wood waste using pressurized hot water: extraction, analysis and economic evaluation

The main aim of this study was to evaluate pressurized hot water as a green and environmentally friendly extraction medium for the isolation of phenolic compounds from larch waste wood. Such isolates could find applications in the food, feed, pharmaceutical and cosmetics industries or as natural ingredients for adhesives or biocidal coatings in the wood industry. In the first step different larch wood fractions were extracted using batch system aiming to determine the most suitable fraction for isolation. The content of extractives, total phenolic and tannin content of obtained extracts and their antioxidant activity were evaluated. Secondly, semi-continuous operation was applied, where effects of temperature, addition of ethanol and flow rate were studied. Extraction yield was monitored and extracts were again analyzed for their total phenolic content and antioxidant activity. HPLC analysis was performed, in order to study the effect of temperature and addition of ethanol on the hydrothermal degradation of phenolics during semi-continuous operation. Finally, the economics of pilot-scale and industrial-scale processes with different extractor capacities, ranging from approximately 12 to 1200 kg of woody material per day and operating at optimal conditions for isolation of larch wood extractives was evaluated, in order to determine the cost of manufacturing of such a product.