Ethanol and lactic acid production as affected by sorghum genotype and location

Abstract

Genotype, environment, location, and their interactions have a significant effect on end-use quality characteristics of grain sorghum ( Sorghum biocolor (L.) Moench). The objective of this research was to study the effect of sorghum genotype and production environment on ethanol and lactic acid production. Eight sorghum varieties from two locations were used. Whole sorghum grain was ground, liquefied, saccharified, and fermented to ethanol using Saccharomyces cerevisiae ( S. cerevisae, ATCC 24860). For lactic acid fermentation, whole ground sorghum grain was liquefied and fermented to lactic acid with Rhizopus oryzae NRRL 395; saccharification depended upon native gluco-amylase. Results with this limited number of sorghum varieties and locations showed that both sorghum genotype and location had a significant effect on ethanol and lactic acid yields. Variations of 5 and 15% in ethanol and lactic acid yields were observed among the 16 sorghum samples. The effect of location on the fermentation yields was as much as 5% for ethanol and 10% for lactic acid. The effects of variety and location on ethanol and lactic acid production are strongly related to chemical composition and physical properties of grain sorghum samples. Ethanol and lactic acid production increased as starch content increased, whereas the ethanol and lactic acid production decreased as protein content increased. Chemical composition had a greater effect on the ethanol and lactic acid yields than physical properties of the sorghum kernels. The effect of physical properties on ethanol and lactic acid yields was not significant ( P>0.05).