Fourier transform near infrared spectroscopy as a tool for predicting antioxidant activity of propolis

Abstract

The propolis chemical composition is complex, varied, and closely related to characteristics of the vegetation and location where the hives are located. The objective of this work was to determine the antioxidant activity through FRAP methodology in propolis (raw, macerated, ethanolic extract and concentrated ethanolic extract) using a rapid and non-destructive method namely Fourier transform near-infrared (FTNIR) spectroscopy. By the results obtained for the antioxidant activity it can be verified that the samples of propolis present a very diversified chemical profile, for the FRAP methodology the samples of propolis collected in Três Barras – SC and Campo Magro – PR showed the highest activities: 1.8 × 103 and 1.6 × 103 μmol of Fe2+ g−1 respectively. It was possible to conclude that the macerated propolis presented the best multivariate calibration model established with the Savitzky-Golay (SG) + Constant Offset Elimination (COE) preprocessed spectra, where the R2 and 0.95 and 113 for FRAP determination. The error values RMSEC, RMSECV and RMSEE were 73, 1.3 × 102 and 81 μmol Fe2+ g−1, respectively. The FRAP model for macerated propolis was validated and can be used for quantification of antioxidant activity of new extracts of propolis, being useful as an alternative to rapid analysis, reducing waste generation and cost.