Comparison of Conventional and Ultrasound-assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from Sage (Salvia officinalis L.)

M. Dent, V. . Dragović-Uzelac, I. Elez Garofulić, T. Bosiljkov, D. Ježek and M. Brnčić

Abstract
An innovative ultrasound-assisted extraction (UAE) is the rapid non-thermal extraction technique, which in comparison to conventional extraction (CE), offers high reproducibility in a short time with simplified manipulation, reduced solvent consumption and lower energy. Optimization of ultrasonic conditions was conducted for devices with nominal output power of 100 and 400 W, including the influence of geometrical parameters of probes regarding ultrasound-assisted extraction. The results showed that the optimal parameters for extraction of total phenols and rosmarinic acid as a dominant compound in sage extracts were as follows: solvent: 30 % ethanol, extraction duration of 11 minutes, and ultrasonic device output power of 400 W. The antioxidant capacity of the obtained extract correlated with the concentration of total phenols and flavonoids, and among individual phenols the rosmarinic acid contributed the most to the antioxidant capacity. The achieved results and statistical analysis (p ≤ 0.05) have shown how UAE resulted in shorter extraction time, and increased extraction capacity of phenolic compounds by using solvents with a less amount of organic phase.

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Keywords
conventional extraction, flavone glycosides, polyphenols, rosmarinic acid, sage, ultrasound-assisted extraction