Maize proximate composition and physical properties correlations to dry-grind ethanol concentrations

Authors: RAMCHANDRAN, DIVYA - University Of Illinois; Hojilla-Evangelista, Milagros - Mila; MOOSE, STEPHEN - University Of Illinois; RAUSCH, KENT - University Of Illinois; TUMBLESON, M - University Of Illinois; SINGH, VIJAY - University Of Illinois

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2016
Publication Date: 6/7/2016
Citation: Ramchandran, D., Hojilla-Evangelista, M.P., Moose, S.P., Rausch, K.D., Tumbleson, M.E., Singh, V. 2016. Maize proximate composition and physical properties correlations to dry-grind ethanol concentrations. Cereal Chemistry. 93(4):414-418. doi: 10.1094/CCHEM-09-15-0187-R.

Interpretive Summary: In this research, we used statistical tools to determine which among the qualities of incoming corn influence the inconsistency of ethanol yields from the dry grind process. Seasonal variation in ethanol yields causes enormous economic losses for dry grind ethanol plants. There is little published information on the factors that create such variation in dry grind ethanol concentrations. For the current work, we collected corn samples from a Midwestern ethanol plant at specified intervals over a two-year period and processed the corn into ethanol using a laboratory-scale dry grind method. We determined the relationships between dry grind ethanol concentrations and corn quality traits, such as physical parameters (test weight, kernel weight, true density, percent stress cracks, and moisture content) and chemical composition (starch, protein, oil, and soluble sugars contents). Our calculations showed that there were low correlation coefficients for starch content and final ethanol concentration (r = 0.36) and total soluble sugar content and ethanol concentration (r = -0.38). Multiple regression methods also gave low correlations between combinations of grain quality factors and ethanol concentrations. Our results showed that variations in physical quality and chemical composition of incoming corn do not cause the variation in ethanol yields. Further research would be needed to evaluate other factors, such as structural and physiological attributes of corn grain.

Technical Abstract: Dry grind ethanol plants incur economic losses due to seasonal variations in ethanol yields. One possible cause associated with ethanol yield variability is incoming grain quality. There is little published information on factors causing variation in dry grind ethanol concentrations. The objective of this study was to determine relationships between rapidly measurable corn quality attributes (physical parameters and chemical composition) and dry grind ethanol concentrations. Corn samples obtained from a Midwestern ethanol plant were analyzed for physical quality parameters (test weight, kernel weight, true density, percent stress cracks, and moisture content) and composition (starch, protein, oil, and soluble sugars contents) and then processed using a laboratory scale dry grind procedure. There were significant (P < 0.05) variations in corn quality parameters and ethanol concentrations. Correlation coefficients were significant (P < 0.05) but low (r < 0.40) between starch content and final ethanol concentrations (72 h) and total soluble sugar content and ethanol concentrations at 72 h and 48 h. Ethanol concentrations (at 24, 48, and 72 h) were predicted as a function of a combination of grain quality factors using multiple regression methods; however, the R2 values obtained were low. Variations in ethanol concentrations were not related to physical and chemical composition quality factors. Other factors, such as structural and physiologic attributes of corn grain, need to be evaluated.