Potential for Fourier transform infrared (FTIR) spectroscopy toward predicting antioxidant and phenolic contents in powdered plant matrices

Abstract

Mid-infrared spectroscopy is finding an increasing number of applications; however, many of its potential uses remain unexplored. In this study, mid-infrared spectroscopy is applied to predict total antioxidant capacity and phenolic contents of powdered matrices of 14 diverse plant species. In all instances, the optimum prediction models were found using standard normal variate smoothing as a pre-processing method. The results show high correlation between the FTIR predicted and chemically determined values, namely R² values of 0.962 for total phenolics, 0.829 for cupric reducing antioxidant potential (CUPRAC) and 0.911 for ferric reducing antioxidant potential (FRAP). The relative RMSE found for validation indicated that total phenolic content could be predicted with higher accuracy than CUPRAC or FRAP. This pilot study highlights the promise of this technology for plant breeders and a range of industries where rapid screening of many samples for antioxidant and/or phenolic content is envisaged.

Keywords: Attenuated total reflectance (ATR); Cupric reducing antioxidant potential (CUPRAC); Ferric reducing antioxidant potential (FRAP); Fourier transform infrared (FTIR) spectroscopy.