Bioethanol Production from Waste Flying Powder (Tobiko), Generated in the Manufacturing Process of Konjac-derived Products

Abstract

A large amount of Konjac flying powder (Tobiko) is generated in the manufacturing process of Konjacderived products, which are popular Japanese traditional foods. Almost all of the Konjac flying powder is discarded because it currently has minimal effective utility. The aim of the present study was to produce bioethanol, a form of biomass energy, from Konjac flying powder to establish an effective application of this waste product. First, polysaccharides contained in Konjac flying powder were decomposed to monosaccharides (e.g., glucose) by sulfuric acid, hydrochloric acid, or nitric acid. Second, ethanol was generated from the monosaccharides by fermentation and refined by single distillation. Components analysis was performed with high-performance liquid chromatography and gas chromatography at each step: saccharification, fermentation, and distillation. The results revealed that ethanol (9.1 g/L, 600 mL, before distillation) could be successfully produced from Konjac flying powder (30 g) similar to other food industry waste products. In conclusion, we have demonstrated bioethanol production as a new manner of utilization of Konjac flying powder, in addition to its use as fertilizer and livestock feed.