Physicochemical characterization, chemical composition and antioxidant activities of pyroligneous acids from cocktails of wood and agricultural residues from Ivory Coast
2024
Ouattara, Hakim Abdel Aziz | Niamké, Bobelé Forence | Ahoke, Mandji Eliane Marie Frédéric | N'Guessan, Jean Louis Lepetit | Yao, Jean Claude | Amusant, Nadine | Dumarçay, Stéphane
Physical, chemical characterization and antioxidant activities were assessed on six pyroligneous acids from four wood cocktails (WCV1, WCV2, WCV3, WCV4) and two types of agricultural residues (PA1, PA2) from Ivory Coast. Physical and chemical parameters of pyroligneous extracts were determined using a density meter, refractometer, pH meter, colorimetric titration, drying and sensory test. WCV2 alone simultaneously met all the standards set by the Japanese Pyroligneous Liquor Association, with a distinct smoky odour, a clear light-brown color, a pH of around 3, a density in the 1.010–1.020 g/mL range, and an ignition residue content of less than 0.2 %. In addition, WCV3, blackish in colour, had the highest Brix value (9) with a lower moisture content than the others (89.92 %), thus reflecting a high soluble tar content. Furthermore, all pyroligneous liquids had a high moisture content (89.92–99.08 %) and a low total acid content (0.90–2.10 %) compared with the literature. However, the results of GC-MS analysis revealed the presence of major compounds such as acetic acid, propionic acid, phenol, guaiacol and 3-methylphenol in the organic phase of pyroligneous extracts. FTIR analysis identified alkaloids, phenolic compounds and flavonoids in the aqueous phase of pyroligneous extracts. The presence of these compounds was confirmed by a phytochemical screening test. Finally, antioxidant activities with DPPH and ABTS methods showed that WCV2 had the best antioxidant properties due to its high guaiacol and syringol content. On the other hand, WCV3 showed a good antioxidant efficacy only by the DPPH method, probably due to its high flavonoid content.
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