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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 4/21/2010 Publication Date: 6/7/2010 Citation: Hojillaevangelist, M.P. 2010. Characterization and Functionality of Corn Germ Proteins [abstract]. National Corn Grower's Association, Corn Utilization and Technology Conference, June 7-9, 2010, Atlanta, Georgia. 2010 CDROM. Interpretive Summary: Technical Abstract: This study was conducted to evaluate the functional properties of protein extracted from wet-milled corn germ and identify potential applications of the recovered protein. Corn germ comprises 12% of the total weight of normal dent corn and about 29% of the corn protein (moisture-free and oil- free basis)[1]. Of this protein, more than 75% are albumins and globulins, which give higher nutritional value to germ protein than endosperm protein. Most of the germ (germ meal) goes into animal feeds as corn gluten feed, where it serves as a high-protein additive because of the meal’s favorable amino acid balance [1]. Corn germ flour has been reported to have functional properties that have been put to use as extenders, stabilizers, and emulsifiers in ground meats [2]. The high nutritional quality and desirable functional properties of corn germ protein should be exploited for higher-end uses than just for feed. Protein was extracted from both wet germ and finished (dried) germ using 0.1M NaCl at 45ºC. The method involved homogenization, stirring, centrifugation, dialysis and freeze-drying. The starting germ samples, freeze-dried protein extracts and spent solids after extraction were analyzed for moisture, crude protein (%N x 6.25), and crude oil contents by using standard methods The recovered protein was also analyzed by SDS-PAGE and for functional properties [solubility, emulsification, foaming, water-holding capacity (WHC)]. Protein yields were about 35%, which improved to 44% when enzyme was added during extraction, and nearly doubled (56%) with addition of 2% SDS and 1% ß-mercaptoethanol; however, PAGE indicated that SDS caused protein denaturation. The recovered freeze-dried protein from finished germ was least soluble (20%) at pH 2.0-4.0 and increased slightly at higher pH (Fig. 1). Wet germ protein extract was more soluble than finished germ protein at all pH values (Fig. 1). Finished germ protein was superior to wet germ protein with respect to emulsifying and foaming properties and WHC; however, both protein extracts showed poor foam stabilities. |
