Effects of domestic cooking on enzyme activities, bioactives and antioxidant capacities in mini-ear supersweet corn.

Sitthitrai, K.; Lertrat, K.; Tangwongchai, R.

Sweet corn is a rich source of bioactives. Naulthong (Zea mays L. var saccharata Bailey) is new hybrid bicolor mini-ear supersweet corn. The Naulthong corn was prepared in whole-ear and cut-piece forms, boiled (ca. 100oC), atmospheric-steamed (ca. 100oC), and pressure-steamed (ca. 15 lb/in2, 121oC) for 4-20 min, and subsequently determined for lipoxygenase (LOX) and peroxidase (POD) activities. It was found that both enzyme activities were inactivated more effectively in kernels than in cobs. It was worth noting that LOX activity was completely inactivated by the three cooking methods at 8 min, regardless of serving form, while POD in cobs needed longer times of 12 and 16 min to inactivate for cut-piece and whole-ear corn, respectively. The corn on the cob of both serving styles was cooked at the selected cooking times using the three cooking methods, then, the edible part (corn kernels) was investigated for physical and chemical attributes. It was found that all cooked kernels had visually brighter color with higher redness (a*) and yellowness (b*, p≤0.05). There was no significant difference in lightness (p>0.05). Boiling caused more effective heat transfer and leaching, resulting in the lowest firmness and total soluble solids (p≤0.05). The two steaming methods showed no significantly different color and firmness. In both serving forms, atmospheric-steamed kernels had higher lutein, zeaxanthin, ferulic acid, total phenolic contents, and antioxidant capacities than those of pressure-steamed and boiled kernels. Boiling resulted in reduction of antioxidant capacities by means of DPPH and ABTS assays, but not for FRAP assay. Steaming at normal pressure, rather than at high pressure, is endorsed for corn cooking in order to maximize health benefits from the delivery of bioactives.

SWEET corn; OXIDANT status; LIPOXYGENASES; PEROXIDASE; CORN seeds; ZEAXANTHIN; FERULIC acid

International Food Research Journal, 2016, Vol 23, Issue 4, p1564

1985-4668

Academic Journal