แนวโน้มของการใช้เส้นใยมันสำปะหลังเหลือทิ้งจากอุตสาหกรรมเอทานอลเป็นวัตถุดิบสำหรับการหมักเอทานอล / ภณิดา นิ่มศึกษา = Trend of using cassava fiber waste from ethanol industry as raw material for ethanol fermentation / Panida Nimsuksa
Due to high cellulose content (39.8%w/w, dry weight basis,) and suitable particle size (20-40 mesh), cassava root fiber waste obtained from cassava root ethanol production process was studied for potential to be raw materials for ethanol production. The cassava root fiber waste was more susceptible to cellulase hydrolysis after pretreatment with dilute sulfuric acid than with calcium hydroxide. Optimal sulfuric acid pretreated cassava root fiber (10%w/v cassava root fiber waste suspended in 6.67%(w/v) sulfuric acid and steam heated by autoclave at 121°C, 15psi for 45 min) saccharified with 1.17 CMC units/g dry weight of AccelleraseTM1500 while suspended in 100 mM sodium citrate buffer pH 5.0 at 50°C for 6 h yielded glucose 0.1g/g dry weight. Increase of the AccelleraseTM1500 to 11.68 CMC units /g dry weight resulted in an increase of glucose yield to 0.13g/g dry weight. Highest glucose yield (0.15 g/g dry weight) was obtained when the cassava root fiber waste was saccharified while suspended in pretreatment hydrolysate and the AccelleraseTM1500 was increased to 16.35 CMC units /g dry weight. Factorail Design (2[superscript k] ; k = 3) was used to determine factors (time of inoculation after cellulase addition, fermentation pH and temperature) effected on ethanol produced from Simultaneous Saccharification and Fermentation of dilute acid pretreated cassava root fiber waste using mid log phase cell of Saccharomyces cerevisiae G 5-7(2) at 10%(v/v) inoculums size. Maximum ethanol yield (2.72 g/l or 0.027 g/g dry weight) was obtained when S. cerevisiae G 5-7 (2) was inoculated immediately after cellulase addition and fermented at 40°C, pH 5.0 for 96 h. Statistical analysis indicated that the longer the period after cellulase addition before S. cerevisiae G 5-7 (2) inoculation, the lower an ethanol yield was.
