Polyphenol-Rich Wines with Power-Ultrasound
Ultrasonication improves the extraction of phenolic compounds from grape to must, which contributes to the total polyphenol content – thereby improving the further ageing process of wine. The application of power ultrasound gives higher extraction yields and accelerates the maturation of wines. Therefore, power ultrasound is an approved method for the treatment of crushed grapes and is applied for polyphenol extraction, wine ageing / maturation and oaking.
Power-Ultrasound for Polyphenol Extraction and Wine Maturation
The mechanism of ultrasound in winemaking are based on ultrasonic / acoustic cavitation. Cavitational high shear forces break up cell structures and expand the pores in cell walls. This results in a release of intracellular material (e.g. starch, enzymes, proteins, phenolic components). The sono-mechanical forces of the ultrasound waves support the distribution of the solvent in the tissue and the penetration of the solvent into the cellular material, this leads to a significantly increased mass transfer. Additionally, sonication promotes biochemical reactions such as the polymerization and condensation of polyphenols and induces micro-oxygenation. All these effects of ultrasonics contribute to the ageing and maturation of wines.
Ultrasonic Polyphenols Extraction from Grapes
Polyphenols in Wine: In wines, polyphenols and quality of the wine are closely interconnected. These secondary metaboiltes of grapes significantly influence organoleptic characteristics in wine and impact thereby quality factors such as color, astringency, and bitterness. Ultrasonication for polyphenol extraction during winemaking process (e.g., sonication of must before fermentation) and during wine ageing (with or without wood contact) produce endless reactions giving rise to complex transformations (micro-oxygenation, copigmentation, cycloaddition, polymerization, and oxidation) of polyphenols and tannins.
Sonication of Must before Wine Fermentation
When ultrasound is applied to grape must, the release of polyphenols from the grape pulp is increased. Since acoustic cavitation – which is the working principle of sonication – breaks cell structures and opens intracellular structures very effectively, much more bioactive compounds are released from the grapes and grape skin when compared to traditional pressing. These bioactive compounds include flavour compounds, pigments and health-promoting substances such as tannins, anthocyanins, flavan-3-ols, proanthocyanidins and flavonols; stilbenoids such as resveratrol; phenolic acids such as benzoic, caffeic and cinnamic acids; catechins, as well as tartaric acid and malic acid, amongst others. Additionally, natural sugars such as glucose and fructose are extracted, which are crucial for the fermentation process of wine making. Sonication can be applied at various steps during winemaking. García-Martín and Sun (2013) present ultrasound in their study as a quick ageing technique, that could provide wines with a higher content in anthocyanins and a decrease in tannins, which is regarded as positive to produce high-quality wines. Many studies have proven the positive effects of power ultrasound during winemaking. Therefore, sonication is considered one of the most promising technologies for several purposes in winemaking processes. Furthermore, ultrasound is an officially approved method for use in crushed grapes. (cf. Natolino and Celotti, 2022)
Studies under the supervision of Prof. Thomas Kleinschmidt from the university Hochschule Anhalt, Institut for Wine Research of Central Germany demonstrate clearly the significant increase of polyphenols in sonicated wine. For instance, in German red wine of the type Blauer Zweigelt the polyphenolic content was increased by more than 40%. For the study, 1.5L red wine Blauer Zweigelt was sonicated at 100% amplitude setting (amplitude 43 μm, sonotrode surface 9 cm2). Extinction was at 520 nm for the red colouring. Folin-Ciocalteu assay was used to measure the total polyphenol content as catechins, which showed a 40% increase in total polyphenols.
- more intense flavours
- more polyphenols
- darker colour
- less astringency
- higher HCl index
- softer, rounder mouth feel
Another study from Natolino and Celotti (2022) also demonstrated the superior wine quality after ultrasound treatment. The researchers from the University of Udine in Italy used the Hielscher ultrasonicator UP200St with sonotrode S26d14 to investigate the effects of sonication on red wine. As the graphs below demonstrate, ultrasound enhances the HCl index for all the sonicated samples from 68.06 ± 1.72 of the untreated sample, to 73.78 ± 1.52 as the mean value of treated samples. No clear trend could be highlighted between increasing amplitude and sonication time, though it is possible to observe a significant increase in the HCl index between sonicated samples at 30% and 2 min (71.59 ± 1.06) and at 90% and 10 min (74.25 ± 1.53). At the same time, ultrasound decreases astringency from 91.8 ± 1.2 for untreated wine to 82.7 ± 3.7 as mean value for sonicated samples (see graphs on the right).
The particle size of colloidal substances, such as tannins and polysaccharides is reduced by sonication, which contributes to improved stability and final sensorial perceptions.
- more intense flavour bouquet
- more polyphenols
- darker colour
- less astringency
- higher HCl index
- softer, rounder mouth feel
Ultrasonic Ageing and Maturation of Wine
Ultrasound waves accelerate wine ageing by applying purely physical, so-called sono-mechanical forces. If adjusted to grape and wine type, ultrasonication can enhance the condensation reaction rate between anthocyanin and tannins, decreasing the conventional times of natural wine color development thereby reducing the time required for wine ageing.
Ultrasonic Wine Ageing using Enological Tannins
Enological tannins, extracted from oak wood, grape seed and skin, plant gall, chestnut, quebracho, gambier and myrobalan fruits, can be added at different stages of the wine production to improve flavour profile and color durability. Ultrasonication can promote wine ageing using enological tannins. Ultrasonic oaking is the significantly accelerated process of transferring wood-derived tannins and flavour compounds from oak staves or chips. Ultrasonically oak-aged wines offer a great flavour profile, which is developed within a short treatment of several minutes in comparison to various months of barrel ageing. Ultrasonic extraction releases the oak aroma compounds (e.g., vanillan, eugenol, isoeugenol, furfural, 5-methylfurfural, guaiacol, 4-methulguaiacol) by increased mass transfer.
High-Performance Ultrasonicators for Industrial Winemaking
Hielscher Ultrasonics processors are well established in the field of winemaking and spirit ageing. Winemakers – both, exclusive boutique vineyards as well as large-scale wine producers – find at Hielscher‘s broad equipment range the ideal ultrasonication equipment for their production requirements in wine polyphenol extraction and maturation. Batch as well as continuous inline process setups are readily available and can be shipped off at the same day.
Automatic Data Protocolling
In order to fulfil the production standards of food and beverage products, manufacturing processes must be detailed monitored and recorded. Hielscher Ultrasonics digital ultrasonic devices feature automatic data protocolling. Due to this smart feature, all important process parameters such as ultrasonic energy (total and net energy), temperature, pressure and time are automatically stored onto a built-in SD-card as soon as the device is switched on. Process monitoring and data recording are important for continuous process standardization and product quality. By accessing the automatically recorded process data, you can revise previous sonication runs and evaluate the outcome.
Another user-friendly feature is the browser remote control of our digital ultrasonic systems. Via remote browser control you can start, stop, adjust and monitor your ultrasonic processor remotely from anywhere.
Fulfilling Highest Quality Standards – Designed & Manufactured in Germany
The sophisticated hardware and smart software of Hielscher ultrasonicators are designed to guarantee reliable ultrasonic extraction results from your botanical raw material with reproducible outcomes and user-friendly, safe operation. Robustness, reliability, 24/7 operation under full load and simple operation from the worker’s view are further quality factors, which make Hielscher ultrasonicators favourable.
Hielscher Ultrasonics extractors are used worldwide in high-quality extraction of food and beverage products. Proven to give high yields and superior quality, Hielscher ultrasonicators are not only used by smaller boutique winemakers, but mostly in the industrial production of commercially distributed wines. Due to their robust hardware and smart software, Hielscher ultrasonic processors can be easily operated and monitored.
Hielscher Ultrasonics in Teltow, Germany is an owner-managed family business. Hielscher Ultrasonics is ISO certified. 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:
|Batch Volume||Flow Rate||Recommended Devices|
|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.||2 to 15L/min||UIP6000hdT|
|n.a.||10 to 100L/min||UIP16000|
|n.a.||larger||cluster of UIP16000|
Contact Us! / Ask Us!
Literature / References
- Parthey, Beatrix; Lenk, Matthias; Kleinschmidt, Thomas (2014): Ultraschallbehandlung von Traubenmaische und Wein. Präsentation der Hochschule Anhalt, Mitteldeutsches Institut für Weinforschung, 2014.
- Andrea Natolino, Emilio Celotti (2022): Ultrasound treatment of red wine: Effect on polyphenols, mathematical modeling, and scale-up considerations. LWT Volume 154, 2022.
- Ceferino Carrera; Ana Ruiz-Rodríguez; Miguel Palma; Carmelo G. Barroso (2012): Ultrasound assisted extraction of phenolic compounds from grapes. Analytica Chimica Acta 732, 2012. 100–104.
- Dent M., Dragović-Uzelac V., Elez Garofulić I., Bosiljkov T., Ježek D., Brnčić M. (2015): Comparison of Conventional and Ultrasound Assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from sage (Salvia officinalis L.). Chem. Biochem. Eng. Q. 29(3), 2015. 475–484.
- Fooladi, Hamed; Mortazavi, Seyyed Ali; Rajaei, Ahmad; Elhami Rad, Amir Hossein; Salar Bashi, Davoud; Savabi Sani Kargar, Samira (2013): Optimize the extraction of phenolic compounds of jujube (Ziziphus Jujube) using ultrasound-assisted extraction method.
Facts Worth Knowing
Bioactive Substances in Wine
The phenolic content in wine refers to the phenolic compounds – natural phenol and polyphenols, which include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include phenolic acids, stilbenoids, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). This large group of natural phenols can be broadly separated into two categories, flavonoids and non-flavonoids. Flavonoids include the anthocyanins and tannins which contribute to the color and mouthfeel of the wine. The non-flavonoids include the stilbenoids such as resveratrol and phenolic acids such as benzoic, caffeic and cinnamic acids.
Polyphenols are secondary metabolites found in plants. As bioactive substances, polyphenols can be classified as plant pigments, flavour components, protective agents for the photosynthesis system or building blocks for biopolymers (e.g., lignin and suberin). The class of polyphenols include flavonoids and anthocyanins, procyanidins, benzoic acid derivatives (e.g. hydroxybenzoic acids such as vanillic acid, trihydroxybenzoic acids such as gallic acid and dihydroxybenzoic acids such as protocatechuic acid), cinnamic acid derivatives (hydroxycinnamic acids such as caffeic acid and p-coumaric acid) and stilbene derivatives (e.g. resveratrol).
Today, more than 8000 polyphenolic compounds have been identified in plants.