Location: Corn Insects and Crop Genetics ResearchTitle: Kernel Composition, Starch Structure, and Enzyme Digestibility of Opaque-2 Maize and Quality Protein Maize) Author
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/9/2009
Publication Date: 2/10/2009
Citation: Hasjim, J., Srichuwong, S., Scott, M.P., Jane, J. 2009. Kernel Composition, Starch Structure, and Enzyme Digestibility of Opaque-2 Maize and Quality Protein Maize. Journal of Agricultural and Food Chemistry. 57:2049-2055. Interpretive Summary: Corn grain is used for many different purposes, ranging from animal feed to ethanol production. It is possible to develop corn that is better suited to a particular use, resulting in lower costs of production and higher quality products. Corn containing a gene called opaque 2 has different kernel properties than normal corn. This corn has been evaluated extesnsively for it's suitability for animal feed, but it has not been evaluated for its suitability for ethanol production. We evaluated opaque 2 corn for several traits related to ethanol production and found that it was superior to normal corn for several of these traits. This information will help scientists develop corn that is better suited to production of ethanol, ultimately decreasing the cost of production of ethanol while increasing the yeild of ethanol from a given amount of grain. This will benefit the environment by reducing the amount of land devoted to corn production to meet our ethanol needs.
Technical Abstract: Objectives of this study were to understand how opaque-2 (o2) mutation and quality protein maize (QPM) affect maize kernel composition and starch structure, property, and enzyme digestibility. Kernels of o2 maize contained less protein (9.6âˆ’12.5%) than those of the wild-type (WT) counterparts (12.7âˆ’13.3%). Kernels of a severe o2 mutant B46o2 also contained less starch (66.9%) than those of B46wt (73.0%). B46o2 and QPM starches contained less amylose (28.0 and 26.0%, respectively) than others (31.9âˆ’33.7%). The B46o2 starch also consisted of amylopectin with the fewest branch chains of DP 13âˆ’24. Thus, the B46o2 starch was the most susceptible to porcine pancreatic Î±-amylase (PPA) hydrolysis. Starches of the dry-ground o2 maize and QPM were hydrolyzed faster than that of the dry-ground WT maize, resulting from the reduced protein content of the o2-maize kernels and the reduced amylose content of the B46o2 and QPM starch. Starch in the dry-ground maize sample was hydrolyzed faster by PPA (85âˆ’91%) than was the isolated starch (62âˆ’71%), which could be attributed to the presence of mechanically damaged starch granules and endogenous amylases in the dry-ground maize samples. These results showed that o2 maize and QPM had highly digestible starch and could be desirable for feed and ethanol production.