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 −6 to 1.81 × 10 −5 m 2 s −1 , while BCC ranged from 614.20 ± 3.10 to 229.90 ± 1.00 µg β ‐carotene equivalent g −1 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 −1 DW and 190.16 ± 1.33 mg catechin equivalent g −1 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