Preliminary characterisation of the Thaumatococcus daniellii fruit as a potential biomass source for biorefinery

Abstract

The inherent variability of biomass composition and structure, as well as the increased trends towards blending of biomass feedstock for energy, chemicals and materials, requires the systematic characterisation of biomass from both established and new sources. The high-value sweet protein thaumatin is produced from Thaumatococcus daniellii (T.d) fruit, native to West Africa, leaving about 90% of the fruit as waste. In this study, the proximate, ultimate, compositional and thermochemical characterisation of T.d fruit pulp and seeds, are determined, with a view to establishing the potential for a T.d biorefinery platform. Extractives content was determined through ethanol soxhlet extraction; cellulose, lignin and pectin contents by alkali hydrolysis, Klason method and acid hydrolysis respectively; while the thermochemical properties were determined by FTIR, EA, EDS and TGA. The proximate composition for pulp and seed biomass, respectively were; ash 17.47%/11.64%, moisture 16.29%/9.56%, fixed carbon 12.5/14.2%, extractives 15.7/3.4%, cellulose 25.34/26.82%, hemicellulose 21.61/15.89%, lignin 10.75/18.20%, pectin14.78/20.85%; elemental composition; C 34.27%/43.09%, H 4.7%/5.72%, N 1.08%/2.16% S 0.33%/ 0.15%, O 59.62%/48.88%. Analyses of the Thaumatococcus daniellii pulp and seed biomass samples revealed a relatively low lignin content, and high pectin and ash content. These characteristics indicate their potential as feedstock for low to medium value products such as pectin, cellulose and mineral-rich biochar. The potential for the recovery of a wide range of low to high value products from this biomass merits its consideration for a biorefinery platform. This should increase the economic value of this local plant while simultaneously alleviating pollution problems.