Effect of ultrasonication on extraction yield, and the rheological and physicochemical characteristics of Mucuna sloanei gum

Abstract

Mucuna sloanei flour is widely used as a thickening agent in Southern Nigerian cuisine, contributing to its texture and nutritional value. Additionally, it is gaining attention in pharmaceuticals for its health benefits, biodegradability, biocompatibility, and role in pharmaceutical formulation and controlled-release systems. However, there is a notable gap in the understanding of Mucuna gum extraction and its characterisation. This study investigated ultrasound-assisted extraction to improve gum extraction yield, as well as the physicochemical and rheological properties of M. sloanei gums. The ultrasound process improved extraction yields to 45.81 % and 47.09 % at 30 % and 60 % amplitudes, respectively, compared to 41.5 % for unsonicated extraction, reflecting enhancements of approximately 10.2 % and 13.3 % in yield while preserving or enhancing thermal properties. Thermal analysis indicated gelatinisation temperatures ranging from 92.12 to 103.40 °C, with no significant differences (p > 0.05) among gums. Thermogravimetric analysis revealed that extracted gums exhibited higher degradation onset temperatures than raw flour, indicating enhanced thermal stability which seems promising for industrial application. Furthermore, sonication reduced levels of D-xylose, d-fructose, L-(+)-arabinose, and sorbitol. Viscoelastic testing showed that the extracted gums had reduced shear-thinning behaviour and greater yield stress than the flour, suggesting their effectiveness as binders and viscosifiers. These findings underscore the potential of Mucuna sloanei gum as a commercially viable thickener in food formulations where flour is predominantly used and in the pharmaceutical industry as a natural binder, disintegrant, and controlled-release agent. The study also highlights the efficiency of ultrasound-assisted extraction as a scalable and sustainable method for gum extraction and modification.