2.6. Observation of scanning electron microscopy (SEM)
The preparation and observation of samples were according to the conventional method (Shen & Zhiguo, 2008). In brief, the cilantro samples were fixed with 2.5% glutaraldehyde, then dehydrated in graded ethanol series, coated with gold–palladium and observed under a scanning electron microscope (HITACHI, S-3400N, Japan).