Modeling of Gelatinization Time against Water Content for Some Starch Feedstock for Bioethanol Production

Abstract

The modeling of gelatinization time against water content of some biomass feedstock viz. ; Acha ( Digitaria exilis ), Finger millet ( Eleusine coracana ), Tacca ( Tacca nvolucrate ) and Tigernut ( Cyperus esculentus ) for bioethanol production was studied. The starches were extracted from the feedstocks by wet and dry milling methods. They were gelatinized at slurry concentrations of 2.0, 2.5, 3.0 and 3.5 mL/g for acha, slurry concentrations of 2.5, 3.0, 3.5 and 4.0 mL/g for finger millet, slurry concentrations of 1.0, 2.0, 3.0 and 4.0 mL/g for Tacca and slurry concentrations of 3.5, 4.0, 4.5 and 5.0 mL/g for tigernut. The starch content of the feedstocks determined the quantity of water used. The gelatinization processes were carried out under different temperature ranges 62 °C- 86°C and time 18 - 59 min. Amylose/amylopectin determinations of the starch feedstocks were also carried out. Modeling was carried out using NLREG 6.3 version a specialized computer programme designed for non-linear regression analysis. Results showed that the acha variant gave the best R 2 values (99.90%). This was followed by the tigernut starch (R 2 = 98.70%) and millet starch ((R 2 = 96.10%). The tacca starch models gave a poorer result(R 2 = 90.50%). General results indicate that acha starch has the best model within the lowest water content, temperature range and time range amongst the feedstocks studied.