Comparative studies on chemical composition and antioxidant activity of corn silk from two varieties of sweet corn and purple waxy corn as influenced by drying methods

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Abstract

Characterization of chemical composition and antioxidant activities of two varieties of silk from sweet corn and purple waxy corn as influenced by different drying processes (freeze-dried and hot-air-dried) were investigated. Both corn silk had a high moisture (89.14-89.57%) ash (5.39-5.55%) and fiber content (52.08-53.49%). However, corn silk from sweet had the higher L*- and b*-values than those prepared from purple waxy corn (p˂0.05). Purple waxy corn silk using freeze-dried (PCFD) showed the highest total phenolic content of 55.62 mg gallic acid equivalents/g samples. Nevertheless, PCFD had the higher in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities and ferric reducing antioxidative power (FRAP) of 52.36, 728.82 and 352.92 µmol TE/g sample than purple waxy corn using tray-dried (PCTD), sweet corn using freeze-dried (SCFD) and sweet corn using tray-dried (SCTD) (p˂0.05). However, SCTD had the highest metal chelating activity of 35.51 μmol EDTA/g sample. Types of corn silks and drying processes had no effect on the likeness of corn silk beverage. Results obtained indicated that corn silk extracts can be used as valuable bioactive source of natural antioxidants.