BAOBAB (ADANSONIA DIGITATA) FRUIT SHELL LIGNOCELLULOSE FOR SUSTAINABLE BIO COMPOSITES: A SCOPING REVIEW OF BIOFIBER COMPONENTS, PROCESSING TECHNOLOGIES, AND INDUSTRIAL APPLICATIONS

Abstract

Baobab (Adansonia digitata L.) fruit shell lignocellulose is an underutilized agricultural waste stream with high potential for sustainable bio composite development. Despite its promise, a critical knowledge gap exists regarding the integrated relationship between its unique chemical composition, processing outcomes, and industrial scalability, particularly in how these factors influence the performance and market viability of bio composites made from baobab fruit shell lignocellulose. Following the PRISMA-ScR framework, this scoping review synthesized evidence from 87 peer reviewed studies (2015–2025) and 60 supplemental sources. The analysis specifically focused on the mechanistic contributions of the fruit shell's high lignin content (51–54%) compared to traditional bast fibers. Findings reveal that the fruit shell's unique composition (51–54% lignin, 24–26% cellulose) provides 60–75% superior moisture resistance over sisal-based composites and >95% tensile strength retention after accelerated weathering. Furthermore, the shell demonstrates inherent flame retardancy (UL 94 V-1) and low thermal conductivity (0.08–0.12 W/m·K). In application, 10 wt% alkali-treated shell particles in epoxy matrices achieved tensile strengths of ~48 MPa. The distinct profiles of bark versus shell fibers necessitate part-specific composite design, as each type of fiber contributes differently to the mechanical properties and overall performance of the composite material, which is crucial for optimizing the application of bio composites in industries such as automotive, insulation, and active packaging. While baobab bio composites show immense promise for the automotive, insulation, and active packaging sectors, the transition to a circular bioeconomy requires addressing persistent gaps in standardized extraction protocols and comprehensive life-cycle assessments. Baobab fruit shell lignocellulose is a scientifically grounded, high-performance alternative to traditional biofibers, offering a multifunctional and economically viable pathway for advanced green material engineering.