Pilot Scale Tannin Extraction from Chestnut Wood Waste using Hydrodynamic Cavitation

Abstract

Abstract Tannins, extracted from various plant sources, are worldwide commodities used in several different fields, including leather manufacturing and the production of bio-based adhesives, with emerging use in technical, environmental, food and feed sectors, pharmacology. Due to increasing market demand, few emerging techniques were proposed besides the usual hot water extraction usually performed under pressurized conditions. For the first time, hydrodynamic cavitation, an emerging and straightforwardly scalable green extraction technique, was applied to the extraction of tannins from chestnut wood waste in water only and at room pressure, without any pretreatment of the raw material. Promising performances were shown based on tests carried out from room temperature up to 100°C. Extraction rates close to 300 mg of tannin per gram of chestnut wood material (dry basis) were observed, as well as high levels of the antioxidant activity of the obtained extract (IC50 about 10 µg of chestnut wood waste, or 2.45 µg of extracted tannin, per mL of solution). Specific energy consumption was less than 80 Wh per mg of tannin extracted from 1 g of chestnut wood material. The proposed technique would be suitable for both small-scale and industrial extraction facilities.