*2.3. Scanning Electron Microscope and Pericarp Microstructure*

Longan pericarps were prepared by following the protocols of Yao et al. [1] and Chitbanchong et al. [26], with slight modifications. Briefly, pericarps of 3 mm squares were washed twice with 0.1 M of phosphate buffer (pH 7.4). The pieces were immediately shifted to the 2.5% glutaraldehyde prepared in 0.1 M of phosphate buffer and kept overnight for 24 h at 4 ◦C. Samples were then rinsed in the same buffer and postfixed in 1% osmium tetroxide for 2 h and stepwise exposed to a series of ethanol–buffer mixtures of 30%, 50%, 70%, 80%, 90%, and 100% ethanol for 15 min for dehydration. The dried samples were then mounted on specimen stubs, sputter-coated with gold, and viewed under SEM (InspectTM, FEI company, Hillsboro, OR, USA) with an accelerating voltage of 20 kV.
