Microwave-assisted extraction of bioactive compounds from blueberry (Vaccinium ashei Reade) and their antioxidant and antimicrobial capacity
2017
Mello, R. de O. | Viera, V. B. | Vaucher, R. de A. | Dressler, V. L. | Piovesan, N. | Bizzi, C. A. | Santos, R.C. V. dos. | Fries, L. L. M.
The aim of this study was to evaluate the content of phenolic compounds, flavonoids and total anthocyanins, as well as the antioxidant and antimicrobial activity of blueberry extracts (Vaccinium ashei Reade) of the Climax variety. The extracts were obtained by focused microwave extraction at different temperatures (30, 40, 50 and 60°C) and solvent concentrations (60% and 80% hydroethanolic). The antioxidant activity of the extracts was quantified by the DPPH radical sequestration method, inhibition of auto-oxidation of the β-carotene system, ABTS+, FRAP and IC50. The antimicrobial activity was evaluated by the disk diffusion method. The antioxidant activity (FRAP, ABTS+ and DPPH), total phenolics and total anthocyanins showed a positive linear trend in relation to the extraction temperature, with no significant difference between the solvent concentrations (60 and 80%). The IC50 and β-carotene showed the greatest inhibition at 60°C at solvent concentrations of 60% and 80%, respectively. The flavonoids showed no significant difference in terms of the extraction temperature or the concentration of solvent that was used. No antimicrobial activity was detected in the extracts in relation to the tested microorganisms. The results showed a positive correlation between the total phenolic content and the determined antioxidant activities. This study confirms the potential of this fruit as a source of phenolic compounds with high antioxidant activity and it also provides a new and efficient technique to extract bioactive compounds using microwaves.
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