Thermal stability of total phenolic compounds and antioxidant activities of jaboticaba peel: Effect of solvents and extraction methods

Abstract

The objective was to evaluate the effect of temperature on the degradation of total phenolic compounds (TPC) and antioxidant activities (AA), in addition to the effects of solvents (water, ethanol and methanol) and methods of maceration and ultrasound in the extraction of polyphenols from the jaboticaba peel powder (JPP). The thermal stability of the TPC and AA (DPPH, FRAP and ABTS) from JPP at different temperatures (90, 110 and 130 °C) was monitored over time (0–360 min). The effect of solvents (water, ethanol and methanol) and methods of maceration and ultrasound on the extraction of polyphenols from JPP was also evaluated. The best conditions for extracting polyphenols were quantified by HPLC. After extraction, the morphology of the powders was evaluated by scanning electron microscopy (SEM). The study of thermal stability showed that the ABTS radical presented a lower stability with time when compared to the other radicals. In addition, it was observed that the thermal degradation of TPC at the studied temperatures and that there is a positive correlation between TPC and AA. In the ultrasonic extraction using ethanol and methanol in the mass ratio of JPP/volume of solvent 1:20, the maximum TPC amounts were obtained. In the analysis by HPLC, a content of gallic acid (16.28 mg L−1) and hesperidin (9.26 mg L−1) were found for ethanol and methanol, respectively. The SEM images indicated that the changes in the structure favored the formation of pores contributing to the solubilization of TPC and consequently AA.