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 m2 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.