Seasonal variability in ethanol concentrations from a dry grind fermentation operation associated with incoming corn variability

Corn from an ethanol plant (commodity corn) and an identity preserved corn hybrid from a seed company (control corn stored at 4 degrees C) were used to study the effects of incoming corn on dry grind ethanol concentrations. Ethanol concentrations were determined every 2 weeks for 1 year using conventional dry grind procedure. Variations in ethanol concentrations were significant and variability patterns for commodity and control corn followed the same trend. Highest ethanol concentrations were seen in the month of January. Variation with control corn suggested that storage time is a significant factor affecting ethanol concentrations. Effects of different enzyme treatments on mean ethanol concentration over a year were evaluated. Two liquefaction enzymes (optimum pH - 5.8 and 5.1, respectively), two saccharification enzymes (optimum pH - 5.0) and one protease were used in five enzyme treatments (I-V). Final ethanol concentration with enzyme treatment V was (17.5 +/- 0.486)%v/v. This was 0.6% higher than enzyme treatment I resulting in an additional ethanol production of 600,000 gallons/year in a 100 million gallon/year ethanol plant. Using more effective enzymes increases overall dry grind ethanol production and ethanol plant profitability. (C) 2015 Elsevier B.V. All rights reserved.