Chiang Mai Journal of Science

 The antioxidant capacity of extracts from 33 local Thai vegetables was determined by ABTS, DPPH, FRAP and FCRC assays.  The extracts had a wide range of antioxidant activities and could be categorized into three groups: high, moderate and low antioxidant activities.  The antioxidant activities of the four different assays were highly correlated 

(r > 0.98).  Fourier transform infrared (FTIR) spectra and partial least square (PLS) regressions were used to predict the measured antioxidant capacities.  The adjusted R² was higher than 0.97 for prediction models and higher than 0.89 for cross-validation models, which could be applied on liquid extracts or freeze-dried extract.  FTIR spectroscopy in combination with PLS regression successfully predicted the antioxidant capacity of several Thai vegetables.