Influence of variety and maturity on bioactive compounds and antioxidant activity of purple waxy corn (Zea mays L. var. ceratina)

Variety and maturity influence on phytochemical and its antioxidant activity. Coloured corn has natural pigment, promising health benefits. Purple waxy corns were bred to improve eating quality and bioactive content of original waxy corn. The proximate chemical analysis the content of total sugar, dietary fiber, starch, total phenolic (TP), total flavonoid (TF), total anthocyanin (TA) contents as well as trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) of different varieties (KGW1 and KND) and maturity stages (eating- and mature-stage) of purple waxy corn in cob and kernel were investigated. The result showed that the kernels contained high amounts of starch, protein and dietary fiber accounting for 66-71%, 9-13% and 10-15%, respectively. Phytochemical contents and antioxidant activity in corn cob were higher than those in kernels. The highest TA content in kernels was at eating-stage of KGW1 variety (141.58±5.19 mg CGE/100g DM) and phytochemical contents in kernels significantly decreased in late harvesting (p≤0.05). Therefore, the KGW1 kernel is an alternative choice for consumers who concern about health due to its high bioactive contents and antioxidant activities. However, the bioactives were not only rich in the purple kernels, but also in the purple cobs and even richer than those in kernels. The highest level of TA content in cob was found in mature-stage of KND variety (705.64±45.84 mg CGE/100g DM). For waste utilization, the purple corn cob had a promising potential as a raw material for anthocyanin source due to high anthocyanin contents and antioxidant activities. In addition, a strong correlation between TA content and antioxidant activities was noticed. This finding indicated that KGW1 and KND varieties purple waxy corn provided high antioxidant compounds and activity which potential to be a healthy food at a proper maturation.