Ultrasonic Solvent-Free Garlic Extraction
Garlic (Allium sativum) is rich in organosulfur compounds (e.g. allicin, glutathione), which promote many health benefits. Ultrasonic extraction is a reliable and efficient technique to produce highly concentrated garlic extracts. Ultrasonication results in high yields of high quality, full spectrum extracts within very short extraction time.
Ultrasonic Extraction
The working principle of ultrasonic extraction (also known as sono-extraction) is based on the phenomenon of acoustic cavitation. Ultrasonically generated cavitation creates high shear forces, micro-turbulences, liquid jets, and locally confined, extreme temperature and pressure differentials. The mechanical effects of high-performance ultrasound disrupts cell walls, promote the penetration of solvent into the cell interior and increase mass transfer. As a non-thermal extraction technique, sonication prevents the thermal degradation of bioactive compounds. Ultrasonic process parameters can be precisely tuned to the raw material and the target substances, so that superior extract quality is ensured.
Ultrasonic Water-Based Allicin Extraction
Allicin is the most abundant thiosulfinate molecule found in garlic extract. Allicin features anti-bacterial, anti-viral, anti-fungal, anti-protozoal, anti-cancer and hypoglycemic effects and is also known to support cardiovascular health and the immune system. Garlic’s pharmacological activities are mostly related to thiol-disulphide exchange reactions with the thiol-containing proteins.
For the production of highly concentrated garlic extracts with high amounts of organosulfur compounds, ultrasonic extraction is a reliable and efficient technique to isolate thiols and other bioactive substances from garlic. Sonication releases the thiols from the interior of the garlic cells and enables to prepare a full spectrum extract of garlic biomolecules. For ultrasonic extraction of garlic, water can be used as solvent, which is non-toxic, inexpensive and environmental-friendly.
Transverse section of garlic clove before and after sonication
study and pictures by Bose et al. 2014
Ultrasonic homogenizer UIP2000hdT (2kW) with continuously stirred batch reactor
Ultrasonic Allicin Extraction Protocols
Arzanlou et al. (2010) report the ultrasonic extraction of allicin from garlic cloves using water as solvent. They used 20g of manually crushed garlic cloves. They sonicated the macerated garlic in 600mL distilled water for 5 min, using the Hielscher UP200S (200watts) at 100 % amplitude. An ice bath was used for heat dissipation. After ultrasonic extraction, the garlic mash was pressed through a five layer cheesecloth. The suspension was transferred into a 50mL tube and centrifuged at 1258g at 4ºC for 20 min to separate the remaining debris from the liquid. The supernatant was transferred into a sterile 50mL tube and sealed for storage.
Ismail et al. (2014) report the efficient ultrasonic extraction of the sulphur-containing biomolecules cysteine and glutathione from garlic bulbs. They applied the water-based ultrasonic extraction to extract thiols from garlic bulbs using a UP100H at 100% amplitude setting. They found that optimal garlic concentration was 10% (w/v) in an open beaker extraction. Quantification of thiols was done by using Ellman’s reagent method. They obtained an extract yield of 0.170mM thiols. The researchers conclude that ultrasonic water-based extraction is a simple, safe and cost effective method to isolate thiols from garlic.
Bose et al. (2014) compared ultrasonic probe-type extraction with traditional maceration, bath sonication and microwave extraction. The results showed that ultrasonic probe-type extraction gave the highest yields of allicin.
- Solvent-free / water-based
- High extraction yield
- High quality extracts
- Non-thermal
- Full spectrum extracts
- Rapid process
- Green, environmental-friendly
- Simple and safe operation
- Low maintenance
- Fast RoI
High-Performance Ultrasonic Extractors
Hielscher Ultrasonics’ extraction systems are used worldwide in the food and pharma industry for the commercial production of high quality plant extracts used as food additives, dietary supplements and therapeutics. Wether your goal is to produce smaller batches of garlic extracts or process large quantities of high-quality botanical extracts, Hielscher Ultrasonics has the ideal ultrasonic extractor for you.
Competitive Advantages by Ultrasonic Extraction
The major benefits of ultrasonic extraction of bioactive compounds from botanical materials such as garlic include the significantly reduced extraction and processing time, its environmental-friendliness due to water-based extraction or reduced solvent use and negligible small CO2emissions, the low amount of energy used, as well as the simple and safe operation of the ultrasonic systems.
Process Standardization with Hielscher Ultrasonics
Extracts, which are used in food or pharmaceuticals, 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 robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments.
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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High-power ultrasonic homogenizers from lab to pilot and industrial scale.
Literature / References
- Nur Izzah Ismail, Yumi Zuhanis Has-Yun Hashim, Parveen Jamal, Hamzah MohdSalleh, Rashidi Othman (2014): Ultrasonic-Assisted Extraction of Thiols from Garlic Bulbs. Advances in Environmental Biology, 8(3) Special 2014. 725-728.
- Mohsen Arzanlou; Shahab Bohlooli (2010): Inhibition of streptolysin O by allicin – an active component of garlic. Journal of Medical Microbiology (2010), 59, 1044–1049.
- Sankhadip Bose, Bibek Laha, Subhasis Banerjee (2014): Quantification of allicin by high performance liquid chromatography‐ultraviolet analysis with effect of post‐ultrasonic sound and microwave radiation on fresh garlic cloves. Pharmacognosy Magazine Vol 10, Issue 38. April-June 2014, S288-S293.
Facts Worth Knowing
Garlic and its Health Benefits
Garlic is rich in bio-molecules, which give garlic its potency as medicinal plant and dietary supplement. 200 different compounds contribute to garlic’s many beneficial health effects. Garlic cloves have an exceptionally high content of organosulfur compounds, such as alliin, allicin and γ-glutamylcysteine compounds such as γ-glutamyl-S-allylcysteine, γ-glutamyl-S-trans-1-propenylcysteine. Garlic contains at least four times more sulfur than other sulphur-rich vegetables such as onion, broccoli, and cauliflower. Those sulphur-containing compounds give garlic its pungent smell and taste.
Sulphur-containing biomolecules are termed sulphhydryl compounds and belong to the group of thiols. They are found in all tissues and cells of the human body and play a crucial role in many vital biochemical reactions. Cysteine and glutathione (GHS) are two important thiols present in garlic. Cysteine is a sulphur-containing amino acids which features a chemically very reactive sulfhydryl group. Glutathione (GHS), a tripeptide consisting of the amino acids glutamate, cysteine and glycine, is the most ubiquitous low molecular mass sulfhydryl compound in the human body. Glutathione acts as a super-antioxidant and has a vital function in the human body (e.g., immune system).
Allicin
Allicin is one of the most important biomolecules in garlic showing various health-promoting effects. Allicin is not present in the intact garlic clove, but is synthesised, when garlic is sliced or crushed. By maceration the garlic tissue, an enzyme called alliinase is activated. Allinase initiates the transformation of the amino acid alliin to allicin and other allylthiosulfinates. The formation of allicin is rapid process, which is completed within a few seconds after crushing a fresh garlic bulb.