Progress 05/03/09 to 04/30/10
Outputs
Progress Report Objectives (from AD-416) To develop new environmentally safe aqueous/enzymatic processes to extract the edible oil from corn germ (obtained from new-generation dry- grind corn-to-ethanol plants) and develop processes to fractionate the de- oiled germ into value-added protein and carbohydrate coproducts, to improve the overall economics of making fuel ethanol in new-generation plants. Approach (from AD-416) Corn germ from several new generation processes will be treated with mechanical (various forms of milling, homogenization and pressing), chemical (e.g. pH adjustment) and various enzymatic treatments, with the goal of causing the oil to coalesce and float upon centrifugation or other means of separation. This is the final report for the project 1935-41000-074-00D, which was a bridge project created at the termination of 1935-41000-069-00D. Over the course of the 5 year project, significant progress was made. Bench scale processes were developed to extract corn oil from corn germ using only enzymes and water, without pressing, and with no hexane or other organic solvents. Different process parameters were identified for corn germ obtained from various sources, including germ from a commercial corn wet mill, corn germ from a commercial corn dry mill, commercial �new generation� corn germ obtained via a dry fractionation process from a corn dry grind ethanol plant, and �E-germ,� an experimental corn germ obtained by a new process called enzymatic milling. Oil yields ranged from about 70% with the dry milled corn to about 90% with wet milled corn germ and E-germ. A column was developed for corn oil separation after aqueous enzymatic extraction and 70-80% of the oil in corn germ could be collected with a foam overflow. A computer model of the aqueous extraction was used to estimate that the capital cost reduction from reducing centrifugation by prior concentration of oil in the foam is about $1.2 million for a standard dry grind plant (which could supply 3000 kg/h of germ. Cooking or microwaving corn germ was found to change its ultrastructure and increase its oil yields by both mechanical pressing and by aqueous enzymatic oil extraction. It was discovered that when �raw� (uncooked or undried) dry milled corn germ is used as feedstock for our aqueous enzymatic extraction method, no oil is obtained unless the corn germ is cooked or heat-dried. We compared various methods of cooking and drying the germ in microwave and conventional ovens before AEOE. Cooking probably weakens or disrupts the oil body membrane and cooking or protease treatment appears to be required to release the oil. Bioactive peptides were generated when commercial wet- and dry-milled corn germ were treated with proteases to convert the protein polymers to shorter peptide oligomers. These peptide inhibited angiotensin converting enzyme, ASE, and may be useful for lowering blood pressure. Although, all commercial corn oil is obtained by pressing corn germ and/or extracting the germ with hexane, another type of corn oil can obtained by the extraction of ground corn with ethanol. This new type of corn oil contains about 3 mg of lutein + zeaxanthin per tablespoon of corn oil, so consumption of 2 tablespoons per day would supply the amount (~6 mg) that that most experts currently believe is required to slow the progression of age-related macular degeneration. If such oil was commercially available, all consumers, and especially the aged, could greatly benefit from its composition.
Impacts
(N/A)
Publications
- Dickey, L.C., Kurantz, M.J., Johnston, D., Mcaloon, A.J., Moreau, R.A. 2010. Grinding and cooking dry-mill germ to optimize aqueous enzymatic oil extraction. Industrial Crops and Products. 32:36-40.
|