Abstract
The lemon-scented tea tree (LSTT) is an Australian native herb and is a rich source of essential oil and phenolics. The ETHOS X extraction system is known as a commercial microwave-assisted extraction (MAE) system for extracting bioactive compounds from plant materials. This study investigated the influence of soaking time, radiation time, microwave power, and sample to solvent ratio on the extraction efficiency of polyphenols and antioxidant properties from lemon-scented tea tree leaves and optimized the extraction conditions using response surface methodology (RSM). The effectiveness of ETHOS X was further compared with ultrasound-assisted extraction (UAE) and shaking water bath (SWB) techniques. The results revealed that soaking time did not significantly affect the recovery of phenolics from the leaves (p > 0.05). Thus, soaking is not required for the ETHOS X extraction of polyphenols from LSTT leaves. RSM was successfully applied to explore the impact of ETHOS X extraction conditions and optimize the extraction conditions. Radiation time significantly affects the recovery yield of phenolics (p < 0.05) positively, whereas irradiation power and sample to solvent ratio adversely influenced the extraction yields of phenolics. The optimal ETHOS X extraction conditions were: radiation time of 60 min, irradiation power of 600 W, and sample to solvent ratio of 2 g/100 mL. Under these conditions, 119.21 ± 7.09 mg of phenolic, 85.31 ± 4.55 mg of flavonoids, and 137.51 ± 12.52 mg of proanthocyanidins can be extracted from a gram of dried LSTT leaves. In comparison with UAE and SWB, ETHOS X is not more effective for the extraction of phenolics than UAE and SWB. However, this technique can save half of the solvent volume compared to UAE and SWB techniques.
Highlights
Phytochemicals derived from plant materials have been used as the key ingredient in many foods, nutraceuticals, and pharmaceuticals products [1]
This study investigated the impact of microwaveassisted extraction (MAE) parameters, including soaking time, microwave power, and radiation time, and sample to solvent ratio on the phenolics and antioxidant level in lemon-scented tea tree (LSTT) extract optimized the commercial MAE conditions for recovery of phenolics and compared its effectiveness with ultrasound-assisted extraction (UAE) and shaking water bath (SWB)
The results show that extraction time positively and significantly (p < 0.05) influenced the extraction yield of polyphenols and antioxidant properties
Summary
Phytochemicals derived from plant materials have been used as the key ingredient in many foods, nutraceuticals, and pharmaceuticals products [1]. Polyphenols are known as a major group that has been linked with numerous health benefits. Polyphenols have been widely applied in the food, pharmaceutical, and cosmetic industries and have anti-inflammatory, antimicrobial, and anti-aging properties, among other health benefits [2,3]. It is important to effectively extract and isolate phenolics from plant materials using optimal conditions and suitable techniques [4,5]. Novel extraction, and a combination of modern and conventional extraction techniques have been applied to extract phenolics from plant materials [6,7]. The suitability and selection of the right extraction method and conditions vary depending on the type/nature of the sample, yield of targeted chemical compounds, and cost of extraction
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