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item Johnston, David

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2004
Publication Date: 7/20/2004
Citation: Johnston, D., Singh, V. 2004. Enzymatic milling of corn: optimization of enzymes addition and first grind. Cereal Chemistry. Cereal Chemistry 81(5):p.626-632

Interpretive Summary: Corn wet milling, the process used to separate corn into starch, oil, and animal feeds, uses a lot of energy and chemicals that are hazardous to humans and the environment. A goal of our research is to develop new alternative methods for milling corn that use less energy and hazardous chemicals. Enzymatic milling is one such technology we have developed. This process utilizes enzymes (proteases) that require controlled conditions for optimal activity. Work has been proceeding to optimize the conditions necessary to use this technology efficiently. The work discussed in this paper details the optimization of multiple factors determined to be of critical importance for the time and cost effective application of this technology. This information will be of importance to all corn wet millers in the U. S. and abroad.

Technical Abstract: In order to optimize the overall procedure and minimize the enzyme associated costs, a series of experiments were done to determine the best first grind parameters and the optimal enzyme additions. The yields for germ, germ quality and starch recovery were used for evaluation of effectiveness. The first grind procedure was optimized by evaluating a combination of different soaking and grinding conditions followed by a fixed enzyme addition and incubation step. The pH profile of Bromelain for enzymatic milling was evaluated from pH 3.5 to 6.5 and the optimum was determined to be pH 5.0. Enzyme addition was then evaluated using the optimized first grind conditions and Bromelain additions varied from 0 to 1.9 g enzyme (based on protein) per Kg of corn. Results showed that the minimum addition of Bromelain to reach starch yields equivalent to conventional yields were approximately 0.4 g protein per Kg of corn. This amount is significantly less than what was previously used and reported.