The samples of pollen were analyzed directly without treatment after crushing. ATR-FTIR spectral analysis of untreated samples was performed using Nicolet iS5 ATR-FTIR Spectrometer (Thermo Fisher Scientific, United States). The IR absorption spectra of all the samples were recorded from in the region of 500-4000 cm -1 with 32 scans/min and resolution of 16 cm -1 .