Research Accomplishment Reports 2007

Management of Grain Quality and Security for World Markets

M.D. Montross, S.G. McNeill
Department of Biosystems and Agricultural Engineering

 

Project Description

Several major seed corn companies, such as Pioneer Hi-Bred and Monsanto, are marketing corn hybrids for dry and wet mills. The dry mill process is being used by Commonwealth Agri-Energy in Hopkinsville, KY. A primary factor in ethanol production from dry mills is the quantity of starch in the feedstock and the percentage available for fermentation. A feedstock with a higher quantity of fermentable starch would be more economical for the plant and could represent a niche opportunity for producers to grow specific hybrids. The seed corn industry has recognized this potential niche market and has started identifying hybrids for ethanol production. Both Pioneer and Monsanto have proprietary assays and NIR (near infrared transmittance) calibrations to determine potential ethanol production. These hybrids could offer dry mill plants up to a 7% increase in ethanol yield (Pioneer, Industry Select Program, Johnston, IA). However, the assays and protocols to validate the NIR calibrations have not been published. In addition, each ethanol plant has slightly different yields of ethanol due to differences in enzyme and yeast products. These differences could affect the calibrations developed by the seed corn industry.

Samples during corn harvest from Fall 2005 and 2006 have been analyzed. We have utilized four separate measurements of ethanol production; gas chromatograph, enzymatic assays, Fourier Transform Infrared Spectroscopy, and CO2 production (weight loss). The ethanol production measured using everything except the weight loss gives identical results. The weight loss measurement substantially underestimates the ethanol production. There were statistically significant differences between some of the hybrids. However, maximizing ethanol yield for a processing plant or producer also depends on the corn yield and testweight.

There were significant differences in the ethanol yield per acre, however it was a different ranking than the ethanol production for each hybrid. A high ethanol yielding variety did not result in the highest ethanol production per acre due to its lower grain yield and testweight relative to other hybrids. Some of the hybrids were not entered into the yield trial during 2006. Due to the drought in 2006, some of the hybrids reversed their position in terms of ethanol production per g of corn. For instance, one hybrid in 2005 produced 0.34 g ethanol per g of corn. In 2006, the same hybrid produced over 0.38 g ethanol per g of corn. During 2006, the ethanol production per gram of corn was higher. This could have been due to the drought conditions.

There has been concern by individuals in the ethanol industry that drying and storage has a significant impact on ethanol yield from corn. This was simulated by cutting the seed tip off of the corn or storing the corn in a plastic bag at 35C to speed mold development. Based on this data it appears that storage and drying have a significant impact on ethanol yield, a maximum reduction of 20% was observed.

Impact

Ethanol production is influenced by numerous variables. Comparing the effects of agronomic, hybrid, drying and storage practices on ethanol yield will result in better decision making tools for producers and processors. Mold development during storage had a 15% reduction in ethanol yield.

Publications

Montross, M.D., C.L. Crofcheck, C.D. Lee. 2007. Influence of Hybrid on Laboratory Scale Dry Grind Ethanol Production. Paper No. 076149 Presented at the 2007 ASAE Annual Meeting, Minneapolis, MN.