Microwave drying of germinated corn and its effect on phytochemical properties.

Background: Drying is a preservation method that removes or reduces the moisture content of a product. This process can affect the nutritional properties of agricultural crops. Therefore this research sought to investigate the effect of microwave drying power (100-700 W) on the drying rate, effective diffusivity, β-carotene content (BCC), total flavonoid content (TFC), total phenolic content (TPC) and antioxidant capacity of sprouted corn, which can be applied as a rich antioxidant source.

Results: With increasing microwave drying power from 100 to 700 W, the effective diffusivity was in the range from 1.50 × 10 to 1.81 × 10 m s , while BCC ranged from 614.20 ± 3.10 to 229.90 ± 1.00 µg β-carotene equivalent g dry weight (DW), decreasing gradually by 62.57%. Meanwhile, TPC and TFC of samples dried at 300 W were the highest, with levels of 315.94 ± 0.69 mg gallic acid equivalent g DW and 190.16 ± 1.33 mg catechin equivalent g DW respectively, which were higher by 8.66 and 98.97% as compared with samples dried at 100 W. Similar development was found in the antioxidant ability of germinated corn.

Conclusion: Drying at a microwave power of 300 W provided the highest nutritive and antioxidant values. The results of this study are useful in the selection of optimal drying conditions during microwave drying of germinated corn, as a baseline for other agricultural crops. © 2016 Society of Chemical Industry.