Contribution of zein content and starch characteristics to vitreousness of commercial maize hybrids

Fast, simple laboratory methods were used to analyze 22 maize samples varying in kernel vitreousness from 50.23% to 76.41%. Samples were analyzed in terms of zein content (53.86-86.37 g/kg endosperm DM), amylose content (190.76-259.77 g/kg endosperm DM), amylose to amylopectin ratio in starch (0.28-0.43), as well as starch granule size (10.95-14.89 μm in equivalent diameter) and starch granule shape (circularity, 0.85-0.94). More vitreous samples had higher zein and amylose content, as well as smaller and less circular starch granules. Nearly all grain traits on their own significantly affected vitreousness, and a multiple regression model to account for their combined effects was able to explain 61.8% of variability in kernel vitreousness. Zein content contributed most to the model, followed by starch granule projected area and circularity. In contrast, the amylose content contributed only 5.1% to the model. These results suggest that starch-protein interactions influence maize kernel vitreousness more strongly than starch molecular properties do.