engleski

Optimizing microwave-assisted extraction parameters for polyphenols recovery from sage (Salvia officinalis L.)

Introduction: Medicinal and aromatic plants (MAPs) contain bioactive compounds (BACs) (e.g. polyphenols, carotenoids, organosulphur compounds) that can positively affect the nutritive, chemical, microbiological, and sensory quality of food products. Due to large structural diversity among different groups of BACs and their physical/chemical properties, it is important to identify/optimize the most effective extraction parameters required to isolate and/or separate BACs from other plant components. Sage (Salvia officinalis L.) is rich with polyphenols that are known for their antioxidative activity and positive influence on human health (e.g. risk reduction for: cardiovascular disease, diabetes, obesity, hypertension etc.). Innovative extraction techniques as microwave-assisted extraction (MAE) is a process that uses microwave energy, along with solvent, to extract target compounds from various matrices. The highly localized temperature can cause selective migration of target compounds from the material at a faster rate, thus providing enriched extracts compared to conventional extractions. Objectives: Aims of this study were to identify optimal MAE parameters for extraction of total phenols (TP) from sage. Method / Design: Study was full factorial randomized design with independent variables: (i) time (3, 5, 7, 9, 10 min) ; (ii) temperature (30, 50, 60, 80°C) ; (iv) solvent (30% ethanol, 30% acetone, water) ; and (v) acidity (addition or not of HCl 10%). The TP content was evaluated by the Foin-Ciocalteu colorimetric method, calibrated against gallic acid calibration curve as the reference standard. Data were analyzed with multivariate analysis at α=0.05. Results: Average amount of TP in study was 6945.81±121.03 mg/100 g d.m. Optimal extraction time was from 7-9 minutes, at T=80°C/500W, and with 30 % ethanol or acetone that yielded roughly two times more TP than water. Addition of HCl did not significantly increase amount of totally extracted polyphenols regardless of solvent. Conclusions: Microwave-assisted extraction with aqueous solutes (ethanol or acetone) is appropriate approach for extraction of polyphenols from sage.

microwave-assisted extraction; medicinal and aromatic plants; sage; Salvia officinalis L.; total polyphenols

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