Anthocyanin composition and changes during kernel development in purple-pericarp supersweet sweetcorn

The current study reports the anthocyanin profile of purple 'supersweet' sweetcorn, recently developed from purple Peruvian maize, and the effect of kernel maturity on anthocyanin accumulation. Twenty anthocyanin compounds, consisting of cyanidin-, peonidin-, and pelargonidin-based glucosides, were identified and quantified in purple- and reddish-purple-pericarp sweetcorn accessions. For the first time, four isomers of cyanidin-3-malonylglucoside, four isomers of pelargonidin-3-malonylglucoside and two to three isomers each of cyanidin-3-dimalonylglucoside, peonidin-3-malonylglucoside and pelargonidin-3-dimalonylglucoside, were identified in the new pigmented sweetcorn. While cyanidin-based glucosides predominated in the purple-pericarp accession, pelargonidin-based glucosides predominated in the reddish-purple accession. Total anthocyanin concentration increased significantly (p < 0.05) during the optimum sweetcorn eating period (23 to 28 DAP) and continued to increase as the kernels further matured (>28 DAP). As kernels continued to mature, pigment coverage across the pericarp progressively increased from a small spot at the stigma end of the kernel, to gradually spreading over the entire kernel.