Hielscher Ultrasound Technology

Efficient Production of Hops Extracts by Sonication

Hops and hop extracts are essential ingredients for the production of beer. The alpha-acids a-caryophyllene (humulone) and beta-caryophyllene (humulene) are important flavour compounds, which give beer its bitterness and contribute to its aroma, foam structure, and microbiological stability. Ultrasonic extraction is a highly efficient technique to release the bioactive compounds from the hops cell matrix to produce a flavour-rich and full hop extract.

Ultrasonic Extraction of Bitter Acids from Hop

Hop bitter acids are distinguished into α- and β-acids. Bitter α-acids are composed of three main components: n-humulone, ad-humulone and co-humulone. Likewise, bitter β-acids consist of n-lupulone, ad-lupulone and co-lupulone. For breweries and beer production, α-acids are the essential acid form. By boiling alpha-acids under weakly acidic conditions, the alpha-acids are isomerized and thereby transformed into iso-α-acids. By isomerization the poorly water-soluble alpha-acids are turned into a more soluble iso-form, which exhibits the characteristic organoleptic bitterness. The β-acids, which are even less water-soluble than the α-acids, are less important for brewery production as the beta-acids show a very low isomerization rate during wort boiling.
Besides its use as flavouring ingredient, hops is also known for its health-promoting properties, which include antioxidative, sedative, anti-inflammatory, anticarcinogenic, and estrogenic effects. For instance, xanthohumol, a prenylflavonoid found in hops, is known for its strong antioxidative effects. These natural hops substances are used in supplements and medicinal products to support health or to treat diseases.

Ultrasonic Terpene Extraction from Hops: Ultrasonic extraction is performed using the Hielscher UP100H isolating caryophyllene and other terpenes from hop cones.

Ultrasonic Terpene Extraction of Hops with UP100H

Ultrasonically prepared hops extracts are full spectrum extracts, which offer the full range of active ingredients of the hops cones. Besides the alpha-acids a-caryophyllene (humulone) and beta-caryophyllene (humulene), ultrasonic extraction also releases further terpenes such as linalool and farnesene as well as other phyto-chemicals such as polyphenols and flavonoids. Full spectrum extracts are valued for their so-called entourage effect.
During ultrasonic extraction, plant materials, such as hops and other herbs, are processed at mild temperatures, limiting thereby thermal degradation. Sonication allows the use of mild, safe, environmental-friendly solvents – avoiding the use of toxic solvents.
The high effectiveness of ultrasonic extraction allows even to produce hops extracts from spent hops. The intense ultrasonic extraction process releases the remaining photo-compounds from the spent hops and helps to deplete the spent hops from all valuable substances so that no bioactive substances are wasted.

The bioactive compounds of hops such as alpha-acids alpha-caryophyllene (humulone) and beta-caryophyllene (humulene) can be efficiently extracted by sonication.

Hops cones

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Why Using Hops Extracts?

When used flavouring ingredient, extracts allow for very precise dosing of bitterness and aroma since hop extracts are standardized regarding specific amounts and compositions of alpha acids. This enables for producing the same flavour profile and thereby a continuously high-quality product fulfilling customer expectations.
When used as active ingredient in supplements and medicinal products, hops extracts offer a highly concentrated amount of bioactive substances, e.g. terpenes, flavonoids. Thereby, it is possible to ingest a high amount of the active photo-compund in order to achieve the targeted effect.

GC analysis of ultrasonic caryophyllene oxide extract from hops buds

Gas chromatography analysis of ultrasonic hops extract prepared with ultrasonic homogenizer UP100H: β-caryophyllene oxide, α-caryophyllene, α-pinene, mycrene, limonene, α-caryophylene, and caryophylene oxide and others.

Ultrasonic Hops Extraction

Ultrasonically accelerated solvent extraction is an simple, rapid and save method for the extraction of bitter acids from hops. Being a low-temperature treatment, ultrasonic hop extraction gives high yields in a short process time, which are significant advantages in comparison to the conventional bitter acid extraction from hop.
Low processing temperatures, high yields, superior extract quality (i.e. full flavour / full spectrum extracts) and a very short processing time are the main advantages of ultrasonic hops extraction.
Ultrasonic Hop Extraction – Advantages:

  • More complete extraction
  • Higher yield
  • Full flavour profile
  • Variety-specific aroma preserved
  • Consistent bittering / flavouring
  • Batch and Inline processing
  • Safe and easy to operate
  • Economical, Fast RoI
Hielscher Ultrasonics' SonoStation is an easy-to-use ultrasonic setup for production scale. (Click to enlarge!)

SonoStation – an ultrasonic system with 2x 2kW ultrasonicators, stirred tank and pump – is a user-friendly system for extraction.

High Performance Ultrasonic Extractors

Hielscher Ultrasonics is long-time experienced in designing, manufacturing and suppling high-performance ultrasonic extractors for small to large industrial scale to renowned companies and institutes worldwide. Hielscher ultrasonicators deliver high-power ultrasound, are robust and can easily run 24/7 under heavy load. This makes Hielscher ultrasonic extractors the trusted work horse in the food, pharma, and chemical industry.
All digital ultrasonic processors are equipped with a coloured touch-display, through which you can set and control the process parameters easy and precisely. On the built-in SD-card all process parameters are automatically recorded as soon as you turn the ultrasonic extractor on.
UIP4000hdT flow cell for inline sonication on industrial scaleThe sophisticated design of Hielscher’s batch and inline sonication setups is extensively tested and optimized for user-friendliness and high-quality output. Flow cell reactors are available at various sizes and with different geometries. The broad range of sonotrodes (ultrasonic probes) with various shapes, sizes, and lengths as well as additional accessories allow for the ideal configuration of your ultrasonic system in accordance to your extraction process and plant material.
Another advantage of Hielscher Ultrasonics’ industrial ultrasonic processors is the delivery very high amplitudes of up to 200µm, which can be easily and continuously run in 24/7 operation. For even higher amplitudes, customized ultrasonic sonotrodes are available. The precise control over the amplitude and the option of running very low to very high amplitudes enables for an optimal and efficacious process. The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments.
Hielscher high-performance ultrasonic extractors for superior extracts!
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

  • Maša Knez Hrnčič; Eva Španinge; Iztok Jože Košir; Željko Knez; Urban Bre (2019): Hop Compounds: Extraction Techniques, Chemical Analyses, Antioxidative, Antimicrobial, and Anticarcinogenic Effects. Nutrients 2019, 11, 257.
  • Steffen Arctander (2019): Perfume and Flavor Materials of Natural Origin. Orchard Innovations; October 2019.


Facts Worth Knowing

Bioactive Compounds in Hops

The common hop plant Humulus lupulus is rich in photo-chemicals, which are used as flavouring ingredients in foods and beverages (e.g. for bittering beer) as well as in perfumes and fragrances. In dietary supplements and medicinal products, hops extracts are used to support health and to cure or alleviate diseases. Find a description of the most prominent hops phyto-compounds below:

Alpha acids

Alpha-acids or humulones are the most important chemical compound within hops. During wort boiling, the humulones are thermally isomerized into iso-alpha-acids or isohumulones, which are responsible for the bitter taste of beer.

Beta acids

Hops contains so-called beta-acids or lupulones. These compound are mostly valued for their aroma contributions to beer.

Essential oils

The main components of hops essential oils are terpene hydrocarbons consisting of myrcene, humulene and caryophyllene. Myrcene gives fresh hops its pungent smell. Humulene and its oxidative reaction products contribute to the prominent hop aroma in beer. Together, myrcene, humulene, and caryophyllene represent 80 to 90% of the total content of hops essential oils.

Flavonoids

Xanthohumol is the main flavonoid in hops. Other well-studied and important prenylflavonoids are 8-prenylnaringenin and isoxanthohumol. Whilst xanthohumol’s propertires and effects are still under research, the prenylflavonoid 8-prenylnaringenin is already known as a potent phytoestrogen.