engleski

Isolation of bay laurel (Laurus nobilis L.) leaf polyphenols using green extraction techniques

Bay laurel leaves have been known for their beneficial effects, which can be attributed to polyphenols. Recently, there is a growing demand on functional products enhanced with naturally derived polyphenols so new technologies are emerging for their fast and effective isolation. The main focus has been put on green extraction techniques such as microwave- (MAE) and ultrasound-assisted extraction (UAE). Therefore, the aim of this study was to evaluate the effect of solvent polarity (50, 70% ethanol), temperature (40, 60, 80℃), irradiation time (5, 10, 15 min) and power (400, 800W) on MAE of bay laurel leaf polyphenols as well as the effect of solvent polarity (50, 70 % ethanol), amplitude (50, 75, 100%) and sonication time (5, 10, 15 min) during UAE. Both techniques were compared to 30 min conventional reflux extraction in order to evaluate their effectiveness regarding the obtained total phenolic content (TPC) determined by Folin-Cioacalteu method. Temperature, irradiation time and power showed significant influence on MAE of bay laurel leaves polyphenols, resulting with 53.57 mgGAE/g of TPC when applying 50% ethanol, during 10 min extraction at 80℃ and 400W. During UAE, solvent polarity showed significant influence, implicating higher extraction yield with 70% ethanol, as well as the sonication time, showing 10 min to be the most effective, while amplitude showed no significance and was chosen to be 50% as the least energy consuming. These conditions resulted with TPC of 32.85 mgGAE/g. For comparison, conventional reflux extraction resulted in 42.93 mgGAE/g and 41.13 mgGAE/g of TPC depending on the solvent polarity (50 and 70% ethanol). The results showed that MAE can be considered as effective tool for fast and environment friendly isolation technique of bay laurel leaves polyphenols as it significantly reduced the extraction time and provided higher polyphenols' extractability in comparison with conventional extraction.

bay laurel, polyphenols, microwave-assisted extraction, ultrasound-assisted extraction

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