A biorefinery strategy for spent industrial ginger waste

Abstract

An integrated biorefinery approach using spent industrial ginger waste for resource recovery is reported. Valuable products including ginger oil, starch, microfibrillated cellulose (MFC), bio-oil and hydrochar were obtained. Approximately 4 % ginger oil, with a profile similar to commercial ginger oil, can be recovered via Soxhlet or Supercritical CO₂ + 10 %EtOH extraction. The oil-free ginger residues were processed using two microwave techniques: starch, MFC and sugar-rich hydrolysates were firstly gained through hydrothermal microwave processing (120-200 °C in water alone), whilst chemical-rich bio-oils and energy-dense hydrochar (20-24.5 MJ kg^-1) were obtained via conventional microwave pyrolysis (220-280 °C). The ginger MFC exhibited increased propensity to form microfibrillated cellulose (as evidenced by Transmission Electron Microscopy) with increasing temperature. Nanocrystalline cellulose was produced at the highest processing temperature (200 °C). These changes are commensurate with the leaching and decomposition of the amorphous regions within cellulose. The molecules and materials isolated have further downstream applications and, thus, compared to current low value resolution methods (dumping, burning or animal feed), spent industrial ginger waste is a significant resource for consideration within a biorefinery concept.

Keywords: Biorefinery; Ginger oil; Microfibrillated cellulose; Microwaves; Spent industrial ginger.