Ultrasound assisted extraction (UAE) is widely used in recent times for its benefits, but it is difficult to find literature that comprehensively addresses the effect of UAE-specific parameters such as temperature, frequency, power, solvent type, and solvent to material ratio on extracted compounds and their functionality. There is no review done so far on the effects of all UAE parameters on polyphenol extracts to guide the design of extraction protocols. This review therefore focuses on the effects of UAE parameters on the yield and composition, as well as the effects of the UAE on the antioxidant, anticancer, and antimicrobial properties of phenolic extracts. Higher extraction temperatures above 50 °C are degradative to polyphenols in extracts; lower frequencies within the power ultrasound range below 40 kHz are most effective; polyphenol yield generally increases with increasing power, but with a threshold, beyond which no significant increase is observed; and higher ultrasound power produces free hydroxyl radicals which degrade polyphenols, especially in the presence of high water content. A comparative assessment of literature showed that, UAE does not only contribute to increased extraction yield of polyphenols, but also better preserves and increases the biological activity of polyphenol extracts compared to traditional maceration and Soxhlet extraction. A full picture of UAE is given to serve as a reference material on the control of UAE parameters for desired results and efficiency.

The effects of ultrasound assisted extraction on yield, antioxidant, anticancer and antimicrobial activity of polyphenol extracts: A review

Novel lactic acid-based natural deep eutectic solvents: Efficiency in the ultrasound-assisted extraction of antioxidant polyphenols from common native Greek medicinal plants

Optimization of ultrasound-assisted extraction of biomass from olive trees using response surface methodology.

Chlorogenic acids (CQAs), the esters of caffeic and quinic acid, are biologically important phenolic compounds present in many plant species. Nowadays the knowledge about their pro-health properties including anti-cancer activity is great. Yet the supposition that they may be helpful in fighting obesity and modify glucose-6-phosphatase involved in glucose metabolism has led to some revival of research on CQAs properties and their natural occurrence. Considering the growing interest in natural products rich in CQAs, it is not surprising that more efficient extraction methods, leading to obtained extracts with increased CQAs content, are currently being sought. It is worth mentioning here that this task is not very easy since these compounds readily degrade/transform to others. Much attention is also paid to the proper analysis of CQAs content in plants and plant products due to the fact that the main CQAs representative in nature i.e. 5-O-caffeoylquinic acid (5-CQA) is commonly employed as a marker in the quality control of various natural products. Yet due to their structural similarity and instability, and the fact that the number of commercially available standards of CQAs is limited to just a few, the correct analysis of these compounds in plants is another challenge that should be faced. The aim of this review is to summarize the recent advances in the chemical analysis of chlorogenic acids, including their natural sources, properties, and methods that have been developed to improve CQAs extraction and analysis, with special attention paid to 5-CQA as the compound of the CQAs family with many beneficial effects on human health.

/pdf/recent-advances-in-extraction-and-analysis-procedures-of-2nxya5w4x3.pdf

Recent advances in extraction and analysis procedures of natural chlorogenic acids

In this study, extraction of polyphenols using different solvents (acetone, ethanol, methanol and water) with ultrasound and conventional method from whole mung bean (WMB), hull and cotyledon was conducted. Total phenolic content (TPC), total flavonoids content (TFC), total antioxidant activities (TAA), ferric reducing power (FRP) and DPPH radical scavenging activity were determined. Ultrasound treated extracts exhibited higher TPC, TFC, TAA, FRP and DPPH in different mung bean fractions than CSE. Among the solvents, acetone showed better TPC, TFC, TAA, FRP and DPPH. Hull had significantly higher TPC, TFC, TAA, FRP and DPPH than WMB and cotyledon. Sinapic acid (SA) was the major polyphenol in different fractions. Acetone extract of hull showed high polyphenol content. SA, ferulic acid, catechin, p-coumaric acid, resveratrol, quercetin and luteolin were the major contributors to antioxidant activity of acetone extract. Mung bean hull contained the maximum polyphenols and acetone was observed to be the best extraction medium for polyphenols in combination with ultrasound.

/pdf/ultrasound-assisted-extraction-of-polyphenols-and-their-p50xhqam4a.pdf

Ultrasound assisted extraction of polyphenols and their distribution in whole mung bean, hull and cotyledon

Sage (Salvia officinalis L.) is a popular herb which is native to the Mediterranean region and cultivated worldwide. Sage is an important source of antioxidants used as preservatives and has wider implications for the dietary intake of natural antioxidants.1,2 This antioxidant effect has been attributed to the main phenolic components, caffeic acid dimer – rosmarinic acid1 and flavonoids, being mostly present as flavones and their glycosides. Flavone glycosides are apparently common in sage, and most of them are flavones 7-glycosides represented by apigenin and luteolin 7-glucoside and their corresponding 3and 7-glucuronides.2 In the last few decades, research regarding the extraction of phenolic compounds found in plants have attracted special interest regarding their application in the food industry. Extraction is a very important step in the isolation, identification, and use of polyphenols.3 The conventional extraction methods, which have been employed for decades, require prolonged extraction times and relatively larger quantities of solvent.4,5 Therefore, various novel extraction techniques have been developed for the extraction of bioactive compounds from herbs, including ultrasound-assisted extraction,6–8 microwave-assisted extraction,9 supercritical fluid extraction.10 Ultrasound-assisted extraction is an upcoming extraction technique that can offer high reproducibility in shorter time, higher yields of bioactive compounds, simplified manipulation, decreased temperature during processing, reduced solvent consumption, and lower energy input.11–13 In our previous paper,5 the influence of solvent polarity and composition, time and temperature of conventional extraction on mass fraction of polyphenols from sage were researched. The mixtures of ethanol and water are possibly the most suitable solvents for the extraction of sage due to different polarities of the active constituents, and acceptability of this solvent system for human consumption.4,5 Albu et al.3 and Sališova et al.14 have investigated the difference in the application of conventional extraction and ultrasonic-assisted extraction on the concentration of biologically active compounds in sage. They concluded that the content of biologically active compounds is approximately 60 % higher under the influence of ultrasound. Rosmarinic acid is the more active of these antioxidants, but it is relatively easily degraded in solvent and the rate of degradation is solvent-dependant.6 The ultrasonic-assisted extraction has been widely used for obtaining polyphenols from plants using ethanol, mixture of ethanol/waComparison of Conventional and Ultrasound-assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from Sage (Salvia officinalis L.)

/pdf/comparison-of-conventional-and-ultrasound-assisted-4k0pjz0qa3.pdf

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

The medicinal and aromatic plants as ingredients in functional beverage production

The aim of this research was to obtain a high value powder of olive leaf extract (OLE) rich in polyphenols by spray drying. Since carrier, polyphenols/carrier ratio, and inlet temperature could have an impact on process yield and polyphenol retention, to deﬁne the most promising drying conditions for OLE experiment with gallic acid model solutions (GAS) was conducted. Inﬂuence of carrier type (maltodextrin, inulin, gum arabic, and their two-component blends), polyphenols/carrier ratio, and temperature on process yield of spray dried GAS was examined, and for each carrier the most promising temperature and ratio were selected. Optimal temperature for all GAS samples was 150 °C, and optimal gallic acid/carrier ratio for samples with inulin or gum arabic was 3:1, while for all other combinations it was 5:1. In OLE powder produced under these conditions, polyphenol content and physical properties (rehydration, bulk density) were determined. Mixture of maltodextrin and gum arabic resulted in the highest OLE product yield (54.48%) and the highest polyphenol retention (56.50%) obtaining good physical properties (bulk density=0.31 g ml–1, rehydration time=98 s), while use of inulin resulted in the lowest yield (32.71%), polyphenol retention (28.24%), bulk density (0.25 g ml–1), and the highest rehydration time (140 s).

I. Elez Garofulić

Papers

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

The medicinal and aromatic plants as ingredients in functional beverage production

Microencapsulation of Olive Leaf Extract by Spray Drying

Comparative assessment of Prunus spinosa L. flower extract in non-neoplastic hepatocytes and hepatoblastoma cells