Maize Processing Innovators, Inc.
216 Sauk Ridge Drive
South Beloit, IL 61080

Ph: 779.475.0571
Fax: 779.475.0572
Email:  info@maizepi.com

History of Prefractionation:

The concept of prefractionation of maize (corn) prior to use in a dry grind ethanol facility was developed at the University of Illinois as a means to enhance coproduct revenue.  The initial research performed by Singh and Eckhoff (1997) involved recovery of a germ fraction through the use of a short soak and wet mill degermination and recovery.  The economics of this Quick Germ process showed a payback of less than two years (Singh and Eckhoff, 1999).

The industry was receptive to the concept but was skeptical of what was determined to be an even bigger advantage to recovering the germ as a coproduct.  Singh and Eckhoff saw that the major advantage of the process was the removal of the germ from the fermenter.  By removing the non-fermentable germ, the space occupied by the germ could be filled with additional degermed corn resulting in an increase in sugar concentration at the same solids level.  They postulated that this should result in higher ethanol concentrations in the beer, based on the work of Ingeldew (1999), who showed that with proper yeast nutrition, ethanol concentrations as high as 23% were possible, compared to the 12% commonly achieved by the industry at that time.

The process was enhanced by development of the recovery of coarse fiber (pericarp) in the Quick Germ/Quick Fiber (QQ) process (Wahjudi, et al, 2001).  This addition to Quick Germ increased the total nonfermentables removed from the fermenter and decreased the concentration of fiber.  Singh, et al. (2005) showed that the QQ process not only increased the ethanol concentration in the beer but increased the rate of ethanol production, validating the economic value originally proposed by Singh and Eckhoff.

In the last several years, there have been a number of other prefractionation procedures being proposed, with several even being installed in selected plants. The alternative processes have been mostly dry frac (for dry fractionation) processes which Murthy et al (2006) has shown to suffer from stuck fermentations and slower fermentations. Dry fractionation uses conventional dry milling equipment to separate out the germ and pericarp fractions.  Dry milling technology is known to be inferior to wet milling technology in recovering clean (low starch) fractions and appears to be more capital and energy intensive.

Maize Processing Innovators (MPI) licensed the QQ process from the University of Illinois on an exclusive basis in 2006 and is currently bringing the technology to market.

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References:

Singh, V. and S.R. Eckhoff. 1996. Effect of soak time, soak temperature and lactic acid on germ recovery for dry grind ethanol. Cereal Chemistry 73(6):716-720.

Singh, V. and S.R. Eckhoff. 1997. Economics of germ preseparation for dry-grind ethanol facilities. Cereal Chemistry 74(4):462-466.

Wahjudi, J., L. Xu, P. Wang, P. Buriak, V. Singh, M.E. Tumbleson, K.D. Rausch and S.R. Eckhoff. 2000. The "quick fiber" process: effect of temperature, specific gravity and percentage of residual germ. Cereal Chemistry 77(5):640-644.

Singh, V., D.B. Johnston, K. Naidu, K.D. Rausch, R.L. Belyea and M.E. Tumbleson. 2005. Comparison of modified dry grind processes for fermentation characteristics and DDGS composition. Cereal Chemistry 82:187-190.

Ingledew, W.M. 1999. Alcohol production by Saccharomyces cerevisiae: a yeast primer, In: The Alcohol Textbook (edited by K.A. Jacques, T.P. Lyons and D.R. Kelsall, Nottingham Press, Nottingham, England.

Murthy, G.S., V. Singh, D.B. Johnston, K.D. Rausch and M.E. Tumbleson. 2006. Evaluation and strategies to Improve fermentation characteristics of modified dry-grind corn processes. Cereal Chemistry 83(5):455-459.

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