Hielscher Ultrasound Technology

Superior Catechin Extracts with Ultrasonics

Catechin such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC) are polyphenols, which show significant health benefits. Whilst catechin are found in smaller amounts in green tea, cocoa, fruits and some other foods, for high dose intakes catechin extracts are preferred. Ultrasonic extraction is a facile and rapid green technique to isolate catechins from plants, e.g. green tea leaves, using water as solvent. Ultrasonically produced catechin extracts are high-quality, solvent-free compounds for the use in nutritional supplements and pharmaceuticals.

Ultrasonic Extraction of Catechins

Green tea leaves are rich in catechins such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC), which can be extracted by ultrasonication.Ultrasonic extraction is a non-thermal technique, which is based on the application of pure mechanical forces. Low-frequency, high-intensity ultrasound waves are coupled via an ultrasonic probe (sonotrode) in a liquid medium. The intense shear forces of acoustic cavitation perforate and disrupt cell membranes, enhance mass transfer between the cell interior and the solvent, and release the intracellular compounds into the solvent.
In their extensive review of extraction methods from green tea (Camellia sinensis), Banerjee and Chatterjee (2015) found that probe-type ultrasonicators are significantly more efficient than ultrasonic baths. Furthermore, the authors state that ultrasonic extraction is the preferred mode of tea catechins extraction due to increased efficacy of extraction process at lower temperature, which prevents the thermal degradation of heat-sensitive compounds and preserves their medicinal value. High temperature extraction often leads to degradation of polyphenols and increases protein and pectin release, which interfere with the organoleptic quality of tea by cream formation. The advantage of sonication lies in its non-thermal mechanism. Ultrasonic extraction can increase tea polyphenol yield at 65°C whilst compared to traditional extraction at 85°C.
Ultrasonic extraction gives a high yield of high-quality nutrients. As a non-thermal process, ultrasonic extraction avoids the loss of heat-sensitive nutrients.
Ultrasonic extraction can be also performed at room-temperature or in cooled liquids. Click here, to read more about ultrasonically cold-brew tea!

Advantages of Ultrasonic EGCG Extraction

  • Solvent-free / water-based
  • High extraction yield
  • High quality extracts
  • Full spectrum extracts
  • Rapid process
  • Green, environmental-friendly
  • Simple and safe operation
  • Low maintenance
  • Fast RoI
Ultrasonic processor UIP2000hdT (2kW) with stirred batch reactor

Ultrasonic homogenizer UIP2000hdT (2kW) with continuously stirred batch reactor

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Case Study of Ultrasonic Catechin Extraction

Ultrasonic extraction can be performed using various solvents, including water, ethanol, water:ethanol mix, isopropanol, vegetable oil, glycerine, etc.
In a study from 2018, Ayyildiz et al. compared ultrasonic extraction using water and ethanol as solvents with the conventional hot water extraction method. For this study on pilot scale, the used a Hielscher UIP2000hd (2kW, 20kHz) ultrasonicator in batch and in continuous flow setup.
The results showed that ultrasonic extraction with ethanol was significantly (p < 0.05) more efficient to extract higher yields of EGCG, EGC, ECG, and EC than conventional hot water extraction and ultrasonic water-based extraction. Under optimised process conditions, almost 100% and 50% more EGCG content was obtained ultrasonic ethanol extraction than conventional hot water extraction and ultrasonic extraction with water, respectively. The optimal conditions for the ultrasonic extraction of EGCG with ethanol were 66.53ºC, 43.75 min and, 67.81% ethanol. Ultrasonic extraction is the preferred mode of tea catechins due to the increased efficacy of extraction process at lower temperature by retaining their antioxidant activity. [/two_thirds] [one_third_last] [/one_third_last] [two_thirds]

High-Performance Ultrasonic Extractors

Hielscher Ultrasonics’ extraction systems are used worldwide in food and pharma for the commercial production of high quality plant extracts used as dietary supplements and pharmaceuticals. Wether you want to produce smaller batches of cold-brew tea or process large quantities of high-quality polyphenol / catechin extracts, Hielscher Ultrasonics has the suitable ultrasonic extractor for you. The ultrasonicators are easy and safe to operate. Intuitive software and digital control via touch-display allow for a precise process control. The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments.

Process Standardization with Hielscher Ultrasonics

Food- and pharma-grade extracts should be produced in accordance to Good Manufacturing Practices (GMP) and under standardised processing specifications. Hielscher Ultrasonics’ digital extraction systems come with intelligent software, which makes it easy to set and control the sonication process precisely. Automatic data recording writes all ultrasonic process parameters such as ultrasound energy (total and net energy), amplitude, temperature, pressure (when temp and pressure sensors are mounted) with date and time stamp on the built-in SD-card. This allows you to revise each ultrasonically processed lot. At the same time, reproducibility and continuously high product quality are ensured.
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:

Batch Volume Flow Rate Recommended Devices
1 to 500mL 10 to 200mL/min UP100H
10 to 2000mL 20 to 400mL/min UP200Ht, UP400St
0.1 to 20L 0.2 to 4L/min UIP2000hdT
10 to 100L 2 to 10L/min UIP4000hdT
n.a. 10 to 100L/min UIP16000
n.a. larger cluster of UIP16000

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Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers for dispersion, emulsification and cell extraction.

High-power ultrasonic homogenizers from lab to pilot and industrial scale.

Literature/References



Facts Worth Knowing

Ultrasonic Extraction – Working Principle

Ultrasonic extraction is a mechanical method to release and isolate intracellular compound from cell matrices such as plant cells. When high-power ultrasound waves are coupled into a slurry (e.g. consisting in macerated plant particles in water or solvent), the highly energetic ultrasound waves generate cavitation. The phenomenon of cavitation leads locally to extreme temperatures, pressures, heating/cooling rates, pressure differentials and high shear forces in the medium. When cavitation bubbles implode on the surface of solids (such as particles, plant cells, tissues etc.), micro-jets and interparticlular collision generate effects such as surface peeling, erosion and particle breakdown. Additionally, the implosion of cavitation bubbles in liquid media create macro-turbulences and micro-mixing.
Ultrasonic irradiation represents an efficient way to enhance mass transfer processes, since sonication results in cavitation and its related mechanisms such as micros-movement by liquid jets, compression and decompression in the material with the subsequent disruption of cell walls, as well as high heating and cooling rates.

Ultrasonic disruptors are used for extractions from phyto sources (e.g. plants, algae, fungi)

Ultrasonic extraction from plant cells: the microscopic transverse section (TS) shows the mechanism of actions during ultrasonic extraction from cells (magnification 2000x) [resource: Vilkhu et al. 2011]

Ultrasonication of plant material fragments the matrix of plant cells and enhances the hydration of the same. Chemat et al. (2015) conclude that ultrasonic extraction of bioactive compounds from botanicals is the result of different independent or combined mechanisms including fragmentation, erosion, capillarity, detexturation, and sonoporation. These effects disrupt the cell wall, improve mass transfer by pushing solvent into the cell and sucking phyto-compound loaded solvent out, and ensure liquid movement by micro-mixing.

What are the Major Advantages of Ultrasonic Extraction?

  • Rapid process and high output
  • Low energy consumption
  • Reduced processing cost
  • Non-thermal technology
  • Higher purity
  • Green technology

Acoustic Cavitation and its Effects

In the liquid, the ultrasound waves create intense alternating high-pressure / low-pressure cycles, which result in the formation of cavitation bubbles. Over several pressure cycles, the cavitation bubbles grow until they reach a limit, where the bubble cannot absorb more energy. At this point the bubble implodes violently. During the bubble implosion extreme conditions such as high temperatures of up to 5000K, pressures of up to 2000atm, very high heating/cooling rates and pressure differentials occur. Since the bubble collapse dynamics are faster than mass and heat transfer, the energy in the collapsing cavity is confined to a very small zone, also called “hot spot”. The implosion of the cavitation bubble also results in microturbulences, liquid jets of up to 280m/s velocity and resulting shear forces. This phenomenon is known as ultrasonic or acoustic cavitation.

Ultrasonic / acoustic cavitation creates highly intense forces which opens the cell walls known as lysis (Click to enlarge!)

Ultrasonic extraction is based on acoustic cavitation and its hydrodynamic shear forces

Catechins

Green tea is known to be rich in polyphenols such as caffeic acid, gallic acid, catechin, epicatechin, gallocatechin, catechin gallate, gallocatechin gallate, epicatechin gallate, epigallocatechin, and epigallocatechin gallate (EGCG), which makes green tea a popular health food consumed as beverage and as extract. EGCG is a well-known catechin, which is present in high amounts in the dried leaves of green tea (7380 mg per 100 g), white tea (4245 mg per 100 g), and in smaller quantities in black tea (936 mg per 100 g). During black tea production, the catechins are mostly converted to theaflavins and thearubigins via polyphenol oxidases.

Health Benefits of Epigallocatechin Gallate (EGCG)

From the group of catechins, epigallocatechin gallate (EGCG) is the most researched and most promising one. From anti-cancer, antioxidative, anti-inflammatory, anti-fibrosis, anti-collagenase to immune system boosting and anti-ageing effects, EGCG shows many benefits and is therefore consumed in form of green tea beverage as well as in form of dietary supplements such as capsules, powders, tablets etc.
Research studies suggest that catechins like epigallocatechin gallate (EGCG) might reduce inflammation and can prevent certain chronic conditions, such as heart disease, diabetes, and some forms of cancer.

EGCG and its Anticancer Effects

Since cancer is an often life-threatening disease, the anticancer properties of EGCG are under heavy research. Studies suggest that EGCG can inhibit tumorigenesis by reducing or eliminating carcinogen effects. There are findings suggesting that EGCG prevents diethylnitrosamine-induced obesity-related liver tumorigenesis by inhibiting the IGF/IGF-1R axis, improving hyperinsulinemia, and attenuating chronic inflammation. Another mechnaism of EGCG’s anticancer effect is the inhibition of angiogenesis and thereby restraining tumor proliferation.

EGCG and its Antioxidative Effects

Innumerable antioxidative processes occur in the human body and contribute to health, strength and well-being. EGCG is an antioxidant. Antioxidants can protect against cellular damage by scavenging free radicals and neutralising them. The phenol rings in EGCG structure act as electron traps and scavengers of free radicals, inhibit the formation of reactive oxygen species, and reduce thereby damages caused by oxidative stress.

EGCG and its Anti-Inflammatory Effects

Inflammation is can be caused by disease, chronic stress and environmental pollution. The body reacts to such stress factors with inflammation, which is characterised by the aggregation of a large number of immune cells at the inflammatory sites, the release of proinflammatory cytokines, and reactive oxygen/nitrogen species (ROS/RNS). ROS/RNS are related to the activation of transcription factor NF-B and activator protein-(AP-)1. After activation, NF-jB and AP-1 transfer from the cytoplasm to the nucleus and upregulate a variety of inflammatory gene expressions, which subsequently cause an exacerbated inflammatory response and tissue damage.
EGCG inhibits the transmission of NF-B and AP-1 that the expression of iNOS and COX-2 is downregulated mainly by scavenging nitric oxide, peroxynitrite, and other ROS/RNS and the production of inflammatory factors is reduced.

EGCG and its Effects on Osteogenesis Promotion

Osteoporosis is a severe disease characterized by the degeneration of the bone matrix and the loss of bone density. EGCG shows regulatory effects on bone metabolism. EGCG can induce the apoptosis of osteoclasts and inhibit the formation of osteoclasts by blocking the generation of NF-B and IL-1b. Furthermore, it can promote the formation of mineralized bone nodules.
[cf. Chenyu Chu; Jia Deng; Yi Man; Yili Qu (2017): Green Tea Extracts Epigallocatechin-3-gallate for Different Treatments. BioMed Research International Vol. 2017]