ENERGY POTENTIAL AND FUEL CHARACTERISTICS OF DURIAN (DURIO ZIBETHINUS L.) PEEL AS A LIGNOCELLULOSIC BIOMASS FEEDSTOCK

Durian (Durio zibethinus L.) peel is a lignocellulosic by-product that accounts for a large proportion of waste generated from the rapidly expanding durian processing industry in Vietnam and Southeast Asia. This study evaluates the physical, mechanical, chemical, and calorific properties of durian peel to assess its potential use as a feedstock for biomass energy and biochar production. The results show that fresh durian peel has a very high moisture content (76.47 ± 0.10%), resulting in an extremely low apparent energy value. Its peel thickness is 28.5 ± 2.6 mm, hardness 30.98 ± 1.82 N, compressive strength 1.85 ± 0.21 MPa, and tensile strength 0.96 ± 0.12 MPa. After drying, the durian peel exhibits a bulk density of 0.26 ± 0.02 g/cm³, water activity of 0.31 ± 0.02, and reduced thickness of 17.8 ± 1.9 mm, while mechanical properties increase significantly, with hardness reaching 62.8 ± 4.1 N, compressive strength 3.45 ± 0.30 MPa, and tensile strength 2.05 ± 0.20 MPa. In terms of chemical characteristics, dried durian peel has a pH of 5.63 ± 0.02, high volatile matter content (72.37 ± 0.09%), an appropriate fixed carbon content (20.05 ± 0.13%), ash content of 7.58 ± 0.04%, cellulose content of 32.27 ± 0.12%, and lignin content of 19.69 ± 0.07%. After drying, the higher heating value (HHV) increases to approximately 17.8 MJ kg⁻¹, comparable to that of many common agricultural residues. These results indicate that the low energy value of fresh durian peel is mainly due to its high moisture content rather than its intrinsic material properties. With appropriate drying and pretreatment methods, durian peel represents a promising agricultural by-product for biomass energy and biochar production, contributing to agricultural waste reduction, greenhouse gas emission mitigation, and the promotion of a circular economy in Vietnam’s durian processing industry.