Screening Study on Bioethanol Production From Sweet Sorghum (Sorghum bicolor L. Moench) SPV 422 Syrup using Saccharomyces cerevisiae 2011
Author : Pagsolingan, Vesel Solis
Major Adviser : Demafelis, Rex B.
Committee Members : Bambase Jr., Manolito E.; Movillon, Jovita A.; Gatdula, Kristel M.; Dizon, Lisa Stephanie H.
Year : 2017
Month : June
Type : Thesis
Degree: BS
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Abstract
A screening study on bioethanol production from sweet sorghum (Sorghum bicolor L. Moench) SPV 422 syrup using Saccharomyces cerevisiae 2011 was conducted using 2ᵏ⁻² factorial design. Sweet sorghum stalks were processed to obtain the syrup. The syrup was subjected to different conditions set according to the parameters of the study. The syrup was fermented for 72 hours using Saccharomyces cerevisiae 2011 in a 250-ml Erlenmeyer flask. The experiment involved testing the effect of temperature (30, 40 °C), inoculum loading (10, 30%), Brix of the syrup (20,30), sterility condition (sterile, unsterile) and pH (4,6) on fermentation efficiency and bioethanol concentration. Reducing sugar concentration were obtained through DNS Analysis in each fermentation broth and was determined that the highest initial reducing sugar concentration peaked at 275 mg/ml. Gas chromatography was employed in determining the bioethanol concentration of each fermentation run. The highest yield was recorded at 9.2 %v/v. Using analysis of variance (ANOVA), it was found that effect of pH, Brix of the syrup and inoculum loading have significant effect on fermentation efficiency and bioethanol concentration. The model of the experiment was significant and fit for optimization for further study as showed from the Post ANOVA results (R² = 0.8722, AdjR² = 0.7262). Fermentation efficiency was calculated from the theoretical ethanol yield and was determined to be highest at 59.95%. Also time profile was done to show the effect of agitating the fermentation broth in the ethanol yield. Agitation was determined to shorten the lag phase of the yeast thus increasing the ethanol productivity, producing 8.9 %v/v of bioethanol.
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