The present work investigated an effective low-cost production of bioethanol by the use of rejected cashew apples (CAs) in Ivorian plantations. Fresh CAs were cut into 8-10 mm slices and submitted to a drying cycle of...The present work investigated an effective low-cost production of bioethanol by the use of rejected cashew apples (CAs) in Ivorian plantations. Fresh CAs were cut into 8-10 mm slices and submitted to a drying cycle of two periods (for the sake of easing their rehydration) in an oven with forced air convection. Temperature was first set at 30˚C for 3 hours, and then raised at 50˚C until constant weight. Drying brought about 82% weight loss, and the dried slices were rehydrated in a ratio of 1:4 (w/v) in warm distilled water to reconstitute a 10 Brix degree (˚B) juice with 1.042 g/cm<sup>3</sup> density. The sugar content of the juice was increased to 20˚B (syrup) by thermal evaporation. The process was optimized using a response surface methodology (RSM) by applying a central composite plan in order to minimize heat-sensitive compound degradation. The optimal operating conditions for temperature and time of heating were precisely 68,239˚C and 83,314 min, respectively. The commercial baker’s yeast Saccharomyces cerevisiae was used to seed the 20˚B cashew apple syrup following a batch fermentation at 30˚C. The total alcohol content recorded after 24 hours was 8.24% ± 0.11% made up of almost 97% of ethanol and isobutanol (a higher alcohol). Analysis of alcoholic profiles by flam ionization detector-gas chromatography (GC-FID) showed an ethanol content of 3.92% and an almost similar but higher quantity of isobutanol (4.05%) with the latter being a by-product. As bio-based isobutanol attracts more and more attention due to its wide application and excellent fuel performance as compared to ethanol, it emerged from this study that neglected cashew apples can be successfully employed as valuable raw material for the simultaneous production of both biofuels currently used as sustainable sources of renewable energy.展开更多
文摘The present work investigated an effective low-cost production of bioethanol by the use of rejected cashew apples (CAs) in Ivorian plantations. Fresh CAs were cut into 8-10 mm slices and submitted to a drying cycle of two periods (for the sake of easing their rehydration) in an oven with forced air convection. Temperature was first set at 30˚C for 3 hours, and then raised at 50˚C until constant weight. Drying brought about 82% weight loss, and the dried slices were rehydrated in a ratio of 1:4 (w/v) in warm distilled water to reconstitute a 10 Brix degree (˚B) juice with 1.042 g/cm<sup>3</sup> density. The sugar content of the juice was increased to 20˚B (syrup) by thermal evaporation. The process was optimized using a response surface methodology (RSM) by applying a central composite plan in order to minimize heat-sensitive compound degradation. The optimal operating conditions for temperature and time of heating were precisely 68,239˚C and 83,314 min, respectively. The commercial baker’s yeast Saccharomyces cerevisiae was used to seed the 20˚B cashew apple syrup following a batch fermentation at 30˚C. The total alcohol content recorded after 24 hours was 8.24% ± 0.11% made up of almost 97% of ethanol and isobutanol (a higher alcohol). Analysis of alcoholic profiles by flam ionization detector-gas chromatography (GC-FID) showed an ethanol content of 3.92% and an almost similar but higher quantity of isobutanol (4.05%) with the latter being a by-product. As bio-based isobutanol attracts more and more attention due to its wide application and excellent fuel performance as compared to ethanol, it emerged from this study that neglected cashew apples can be successfully employed as valuable raw material for the simultaneous production of both biofuels currently used as sustainable sources of renewable energy.
