Image mapping of biological changes and structure-function relationship during rice grain development via Synchrotron FTIR spectroscopy
Ashoka Ranathunga, Kanjana Thumanu, Worawikunya Kiatponglarp, Supatcharee Siriwong, Rungtiva Wansuksri, Prisana Suwannaporn
Abstract
The spatial distribution of compositional elements in milky, dough, and mature rice, together with the structure-function relationship was studied using synchrotron-FTIR. The dough stage aleurone and endosperm had high lipid, protein (amide I and II), and hemicellulose. The amylopectin chain length distribution of starch exhibited small differences among developmental stages. Dough starch featured a greater portion of A and B1 chains, implying a more crystalline and high in resistant starch. The protein in milky-to-dough stage aleurone and endosperm had higher contents of α-helixes than β-sheets, resulting in higher protein digestibility and availability. There were high intensities of the glycosidic peaks of hemicellulose and cellulose, pectin, carbohydrates, and β 1–6 glucans in milky-to-dough stages. They corresponded to higher total, insoluble, and soluble dietary fiber contents in milky-to-dough stage than in mature stage. Young-stage rice was found to be more nutritious and could thus be a functional food source.