Ultrasonic Quercetin Extraction

Quercetin is one of the most widely studied plant polyphenols, prized for its antioxidant activity and its role in dietary supplements, functional foods, and nutraceuticals. Because quercetin and its glycosides (e.g. rutin, isoquercetin) are thermally and oxidation‑sensitive, producing a high‑purity extract requires an efficient yet mild, non‑thermal extraction technique. This is exactly where ultrasonic quercetin extraction excels.

High-Performance Ultrasonics for High-Quality Quercetin Extracts

Ultrasound‑assisted extraction (UAE) uses high‑power, low frequency ultrasound to mechanically disrupt plant cell walls and dramatically increase mass transfer, releasing quercetin into the solvent within minutes instead of hours Compared with maceration, Soxhlet, or heat‑based digestion, ultrasonic extraction delivers higher yields, shorter processing times, lower solvent volumes, and better‑preserved bioactivity – making it an attractive option for labs, pilot plants, and industrial‑scale production of botanical and polyphenol extracts.

Effects of ultrasonication on cellular structure: The ultrasonically induced disruption of the cell walls allows the release of quercetin and rutin from Euonymus alatus.
Picture and study: ©Yang and Zhang, 2008.

Why Quercetin Demands a Gentle Extraction Method

Quercetin occurs in many fruits, vegetables, and herbs – including apples, onions, berries, tea, grapes, and leafy greens. As a polyphenol/flavonol it can degrade under prolonged heat, strong alkaline conditions, or long solvent contact, which lowers yield and compromises the quality of the final extract. A mild, non‑thermal, short‑duration method therefore helps preserve both the quantity and the functional quality (antioxidant capacity) of the extracted quercetin.

How Ultrasonic Extraction of Quercetin Works

The role of acoustic cavitation 
High‑intensity ultrasound creates microscopic cavitation bubbles in the liquid. Their implosive collapse generates localized hot spots, shear forces, and micro‑jets that rupture plant cell walls and break up tissue matrices. This opens the cellular compartments where quercetin is stored and accelerates its diffusion into the surrounding solvent, so the active compound is released faster and more completely.

Typical Process Flow for Ultrasonic Quercetin Extraction

1. Preparation: grind, cut, or freeze‑dry the raw plant material (e.g. leaves, peels, seeds) to increase surface area.
2. Solvent selection: choose a green, food‑grade solvent such as water, ethanol, or a water–ethanol mix.
3. Sonication: extract in batch mode (with stirring) or in continuous flow‑cell mode for 5–30 minutes.
4. Separation: filter or centrifuge the extract and recover the quercetin‑rich liquid.
5. Concentration / purification: optionally dry, precipitate, or purify as needed.

Note: the specific times, amplitudes, and solvent ratios depend on the plant species and target matrix – our process experts can help you to optimize process parameters for your raw material.

Case Study: Ultrasound-Assisted Quercetin Extraction

Sharifi et al. (2017) have shown that ultrasonic extraction is an effective and practical method in order to extract flavonoids such as quercetin from medicinal plants. They used the Hielscher UP400St (400W, see pic. left) at 50% amplitude setting. The radish (Raphanus Sativus) leaves were placed in methanol and sonicated for 10 min., which resulted in a quercetin yield of 11.8% yield.The superiority of ultrasonically assisted extraction in comparison to conventional techniques such as maceration, Soxhlet extraction and thermal digestion. Ultrasonic extraction excels with higher yields, significantly shorter extraction times and lower amounts of solvents. The application of ultrasonic waves generates cavitation, which disrupts the cell walls of plant material and promotes mass transfer. Thus, ultrasonic extraction is more effective than traditional methods and excels in quercetin extraction from organic matrices. Although ultrasonic extraction needed only 10 min. – compared to extraction times of 24hrs for maceration, 60min. for thermal digestion, and 24hrs for Soxhlet extraction – the amount of ultrasonically extracted quercetin was higher than that of digestion, maceration and Soxhlet extraction.

Ultrasonic extraction (UAE) gives significantly higher quercetin yields in shorter extraction times when compared to conventional extraction methods.
source: Sharifi at al., 2017

Ultrasonic Extraction Equipment

Hielscher Ultrasonics is specialized in manufacturing high-performance ultrasonic processors for the production of high-quality extracts from botanicals.
Hielscher offers a broad product portfolio that ranges from small, powerful lab ultrasonicators to robust bench-top and fully industrial systems, which deliver high intensity ultrasound for the efficient extraction and isolation of bioactive substances (e.g. polyphenols, gingerol, piperine, curcumin etc.). All ultrasonic devices from 200 watts to 16,000 watts feature a coloured display for digital control, an integrated SD card for automatic data recording, browser remote control and many more user-friendly features. The sonotrodes and flow cells (the parts, which are in contact with the medium) can be autoclaved and are easy to clean. All our ultrasonicators are built for 24/7 operation, require low maintenance and are easy and safe to operate.
A digital colour display allows for a user-friendly control of the ultrasonicator, which makes the process precisely adjustable. Our systems are capable to deliver from low up to very high amplitudes. For the extraction of polyphenols such as quercetin, we offer special ultrasonic sonotrodes (also known as ultrasonic probes or horns) that are optimized for the sensible isolation of high-quality active substances. The robustness of Hielscher sonicators allow for 24/7 operation at heavy duty and in demanding environments.
The precise control of the ultrasonic process parameters ensures reproducibility and process standardization.