Using ultrasonics is an effective method for the extraction of caffeine and other active compounds from coffee. Powerful ultrasonic devices assist the extraction process whilst maximizing yield and shortening processing time.

Improve Caffeine Extraction with Power Ultrasound

The flavour of coffee and the effects of caffeine are a passion shared by millions around the world for centuries. As coffee aficionados and scientists alike seek ways to enhance the extraction of caffeine, bioactive compounds and flavours from coffee beans, innovative techniques have emerged to revolutionize the process. One such method, harnessing the power of ultrasound, has emerged as a promising tool to improve caffeine extraction efficiency. Hielscher sonicators allow to extract higher yields of caffeine and unlocking new dimensions of flavours and aroma in the coffee beverages, food additives and extracts.

The Advantages of Coffee Bean Extraction using Sonication

High efficiency and superior coffee extract quality are only two criteria, which make the use of Hielscher probe-type sonicators the best method for the extraction of caffeine and coffee compounds from coffee beans. Below are the most important benefits of ultrasonic coffee extraction listed:

• Efficiency: Probe-type sonicators generate intense ultrasonic waves that can penetrate solid materials effectively. This helps break down the coffee bean structure and facilitates the extraction of caffeine.
• Precise Control: Probe-type sonicators allow for precise control of the ultrasonic energy and exposure time. This control is essential to avoid over-extraction, which can lead to unwanted flavours and bitterness in the coffee extract.
• Speed: Sonication is a rapid process, and probe-type sonicators can significantly reduce the extraction time compared to traditional methods, making the process more efficient.
• Uniformity: The ultrasonic waves can provide more uniform extraction throughout the coffee bean material, ensuring that caffeine is extracted evenly.
• Reduced Solvent Usage: Ultrasonic extraction often requires less solvent compared to traditional methods. This can be environmentally friendly and cost-effective.
• Preservation of Flavor Compounds: Probe-type sonication can be optimized to selectively extract caffeine while leaving other flavor compounds largely intact. This is important for maintaining the quality and taste of the coffee extract.
• Scalability: With Hielscher Ultrasonica, ultrasonic extraction processes can be linearly scaled up for industrial applications. This means, feasibility and process optimization can be on lab scale and then risk-free and easily scaled to production throughput.

Ultrasonic Extraction of Coffee Compounds

Ultrasound-assisted extraction is a common method utilized to isolate bioactive substances from plant material [Dong et al. 2010]. Regarding coffee beans, the caffeine and antioxidant phenolic compounds might be the most valuable compounds for extraction due to their wide applications in pharma and food industry. But also flavonoids, chlorogenic acid and protocatechuic acid are extracts which are used as additives.
Using traditional extraction methods such as the liquid-liquid extraction in solvents, generally the extraction efficiency increases with increasing extraction temperatures. This causes often damages and quality loss of the extract as temperature affects the stability of the phenolic compounds.
The ultrasound-assisted solid-liquid extraction has been shown as an effective and time-saving extraction method. The highly powerful ultrasonic forces provide the necessary energy for the extraction, so that less or even none solvents are needed. The temperature can be well controlled as the sonicated batch or flow cell reactor can be efficiently cooled (or heated if necessary).
Due to the intense extraction forces of ultrasound, also the already spent coffee ground (coffee waste) is still a raw material rich in extractable compounds. As coffee waste material is cheap and available in large amount, it is an ideal raw material for the extraction of the remaining active compounds. Although the content of caffeine and other components in coffee waste is lower than in unused coffee powder, still a large amount remains and is extractable. To release these compounds from the coffee ground, the full influence on the processing parameters becomes especially significant. High-power ultrasound is able to extract high amounts of active compound within a short processing time.

High Power Ultrasound for Extraction

To ensure a more easy understanding of the ultrasound assisted extraction procedure, the effect of ultrasound in liquids must be explained.
Ultrasound – introduced in liquids – causes locally very extreme effects. When sonicating liquids at high intensities, the sound waves that propagate into the liquid media result in alternating high-pressure (compression) and low-pressure (rarefaction) cycles, with rates depending on the frequency. During the low-pressure cycle, high-intensity ultrasonic waves create small vacuum bubbles or voids in the liquid. When the bubbles attain a volume at which they can no longer absorb energy, they collapse violently during a high-pressure cycle. This phenomenon is termed acoustic cavitation. During the implosion very high temperatures (approx. 5,000K) and pressures (approx. 2,000atm) are reached locally. The implosion of the cavitation bubble also results in liquid jets of up to 280m/s velocity. [Suslick 1998] By these extreme forces sonolysis occurs, cell walls are disrupted, and intracellular material is extracted.
The ultrasonically assisted extraction is an inexpensive, simple and efficient alternative compared to conventional extraction techniques. The main advantages of ultrasound in solid–liquid extraction include the increase of extraction yield and faster kinetics. Ultrasonic extraction is a frequently used technique for the extraction of plant materials using liquid solvents and is proven for a fast and more complete extraction process in comparison with traditional methods because the surface area between the solid and liquid phase is significantly larger due to the cell disruption and particle dispersion.
By the use of sonication also the operating temperature can be reduced, allowing the extraction of temperature-sensitive components. Compared with other novel extraction techniques such as microwave-assisted extraction, the ultrasound apparatus is cheaper and its operation is easier. Furthermore, the ultrasonically assisted extraction can be used with any solvent, such as the Soxhlet extraction, for extracting a wide variety of natural compounds. [Wang et al. 2006]
A substantial advantage of ultrasonics is the influence on the most important processing parameters: amplitude, time, temperature, pressure, and viscosity. Thereby, the extraction process can be optimized to ensure that the structure of the extracts does not become damaged.

Caffeine Extraction Improved by Sonication

Caffeine can be claimed the most commonly consumed stimulant. As caffeine is not only consumed by drinking brewed coffee, caffeine extract is used in the industry to treat other product with caffeine as additive. Thereby it becomes possible to create stronger coffee or to formulate soft drinks (e.g. cola), energy drinks or other food (e.g. chocolate).
But caffeine is not only used as additive in food production, it is also an important active compound in pharmaceuticals. A common application of caffeine extract is e.g. the admixture in drugs for headache and migraine or in pain relievers.
To extract caffeine, the main alkaloid in coffee, ultrasonication is a suitable method. Wang and his colleagues found that only a short extraction time is needed to reach a saturated state, if ultrasonication is used. This means that ultrasound a very efficient and time saving technique for gaining caffeine. [Wang et al. 2011]

Aromatic Molecules and Flavour Compounds

The volatile coffee compounds are the most valuable fraction of the roasted coffee bean and imparts coffee its unique flavour and fragrance. The quality of soluble coffee can be substantially improved by the addition of aroma-absorbed coffee oils to the coffee powder.
A comparison study, examinating the extraction of phenolic compounds from strawberries, showed that ultrasonic extraction causes less degradation of phenolics and is a much faster extraction process compared with other extraction methods including solid-liquid, subcritical water and microwave-assisted method. [Herrera et al. 2005]
The study of Wang and his colleagues shows that low frequency, high power ultrasound is more efficient for the extraction of coffee flavours. Especially for 4-Tridecanone and 2-Methoxy-3-Methylpyrazine, they found the ultrasonic extraction more easy and efficient technique obtaining very high extraction yields. Further, it is shown that the temperature must be controlled as coffee flavor components are very volatile at high temperatures. They achieved good extraction results in the temperature range between 35~65 °C under relatively short-time ultrasonic irradiation. [Wang et al. 2011]

Tea Extraction Improved by Sonication

The results achieved by ultrasonically assisted extraction are also suitable for the extraction of tea compounds (e.g. green tea leafs). A study by Xia et al. showed a significantly higher content of tea polyphenols, amino acid and caffeine in ultrasonically treated tea infusions than in those obtained by conventional extraction. This results in improved results during an organoleptic evaluation that turned out: the sensory quality of tea infusion with ultrasonic-assisted extraction was better than that of tea infusion with conventional extraction. [Xia et al. 2005]

Conclusion: Highly Efficient Caffeine Extraction with Ultrasound

Ultrasonically-assisted extraction is an efficient, time-saving and controllable method for the extraction of active compounds from coffee. The most interesting and valuable compounds are caffeine, and the antioxidants such as phenolic diterpenes (cafestol, kahweol), and ascorbic acids. The main advantages of the ultrasound-assisted extraction are extract of excellent quality at high yields. These benefits of ultrasonic extraction are achieved by optimization and precise control of the ultrasonic extraction parameters.

High-Performance Sonicators for Caffeine Extraction

When it comes to caffeine extraction at any processing scale, Hielscher Sonicators stand as the pinnacle of innovation and efficiency. Whether you are a small-scale artisanal producer or a large-scale industrial manufacturing facility, Hielscher sonicators offer a precise and powerful solution for extracting the pure essence of caffeine from your source material.

• Precision and Consistency: Hielscher probe-type sonicators are designed to deliver precise control over the extraction process. Their state-of-the-art technology ensures consistent results batch after batch, allowing you to maintain the quality and potency of your caffeine extract.
• Scalability: Hielscher offers a range of sonicators suitable for various processing scales. From compact benchtop models for research and development to robust industrial systems capable of handling high volumes, Hielscher provides the flexibility needed to meet your production requirements.
• Efficiency: With Hielscher sonicators, you can significantly reduce extraction times compared to traditional methods. The ultrasonic waves generated by these machines create intense cavitation forces, rapidly breaking down cell walls and releasing caffeine molecules, resulting in shorter processing cycles.
• Versatility: Hielscher sonicators are not limited to caffeine extraction alone. Our sonicators are adaptable to a wide range of applications in the food, pharmaceutical, and cosmetic industries. Whether you are extracting caffeine from coffee beans, tea leaves, or other botanical sources, Hielscher sonicators offer versatility to suit your needs.

Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.

The table below gives you an indication of the approximate processing capacity of our ultrasonicators: