Unraveling the anatomical and chemical complexity of wood and bark of Omone (Isoberlinia angolensis): Potential applications

This study aimed to identify and compare the wood and bark of Isoberlinia angolensis, a dominant Miombo species widely used for charcoal production in Angola, focusing on its anatomical, chemical, and thermal properties. The bark is grey-brown and black on the outside, brown on the inside, and is cracked and scaly. The heartwood is brown or yellowish-brown, with distinct growth rings and a medium to coarse texture. The secondary xylem is diffuse-porous and non-storied, with growth rings delimited by marginal parenchyma cells. Chemically, the bark contains higher amounts of ash (5.2 % vs. 1.2 %), extractives (33.3 % vs. 11.5 %), and lignin (35.2 % vs. 25.5 %) but with lower polysaccharides (31.84 % vs. 58.22 %) compared to wood. Fatty acids and triterpenes were the main compounds in bark extracts, while wood had higher fatty acids and phytosterols. Ethanol-water extracts contained phenolics, flavonoids, and tannins. The bark exhibited more antioxidant activity than wood in FRAP and DPPH assays. Thermally, the bark exhibited a higher moisture content (10.8 % vs. 7.5 %), ash (4.3 % vs. 1.3 %), and total volatiles (31.8 % vs. 18.9 %). However, it had a lower fixed carbon percentage (63.9 % vs. 79.6 %) and a higher heating value (19.1 MJ/kg vs. 18.1 MJ/kg). Potassium, calcium, and magnesium were the most abundant minerals in both samples. Bark and wood from I. angolensis have qualities that make it ideal for producing high-value products in the food and pharmaceutical industries and bioenergy applications.