Aqueous Fractionation of Dry-Milled Corn Germ for Food Protein Production

摘要

Soaking dry-milled germ was an effective method for improving germ protein and oil contents (criteria for germ purity) and reducing attached endosperm starch. In the lab-scale experiments, starch was reduced from 33 to 9 % and protein content (moisture-free, oil-free basis) was increased from 18 % to an average of 29 % for all soak conditions. Oil content increased from the starting composition of 16 % to as much as 39 % for the clean (soaked and separated) germ. Pilot-scale experiments were consistent with the lab-scale studies with little variation in final protein and starch composition and higher oil content with higher temperature soaking. Highest protein and oil contents were reached after only 2 h of soaking at 60°C. The oil content of the clean germ (46 %) was within the 42-50 % (dry basis) range typically seen in traditional wet milling (Johnson and May 2003), which uses 24 h soaking of whole kernels. Clearly, soaking germ instead of the entire kernel was advantageous since the same oil content could be achieved in only 2 h.