Higher Pectin Yields with Ultrasonic Extraction
Ultrasonic extraction results in high yields of superior quality pectins. Using sonication, valuable pectins can be efficiently produced from fruit waste (e.g., by-products from juice processing) and other biological raw material. Ultrasonic pectin extraction excels other extraction techniques by producing higher yields, giving superior pectin quality, and a rapid extraction procedure.
Intensified Pectin Extraction by Sonication
Pectin is utilized as a gelling, emulsifying and thickening agent in numerous food products as well as an ingredient in cosmetics and pharmaceuticals. Conventional industrial pectin extraction is done via hot water extraction, where the raw material such as citrus peels, apple pomace and other fruit waste is soaked in 60–100°C hot water at low pH (approx. pH 1.5 – 3.5) for a long period of time. This turns conventional hot water extraction a time- and energy-consuming process, that is often not even efficient enough to release the complete amount of pectins available in the raw material.
In order to overcome the inefficiency of the conventional production method, ultrasonic extraction is applied as a process intensifying technique that reduces the extraction time and maximises pectin yield significantly when compared to the traditional hot water extraction.
The Advantage of Ultrasonic Pectin Extraction
Ultrasonic extraction is applied in many fields of extract production, e.g. botanical and herbal extracts for foods, supplements, pharmaceuticals, and cosmetics. A very prominent example of ultrasonic extraction is the extraction of cannabidiol (CBD) and other compounds from the cannabis plant.
Ultrasonic extraction is a non-thermal extraction technique, which prevents thereby the bioactive compounds against thermal degradation. All ultrasonic process parameters, such as amplitude, intensity, time, temperature and pressure, can be exactly controlled. This allows for precise process and quality control and makes it easy to repeat and reproduce once obtained extraction results. Extract producers value ultrasonication for the reliable process repeatability, which helps to standardize processes and products.
- Sonication intensity
- Temperature
- pH value
- Time
- Particle size of raw material
The ultrasonic extractor UIP4000hdT is a 4kW powerful extractor for industrial pectin production.
The determination of relevant process parameters allow to optimize the ultrasonic extraction process to highest efficiency and superior extract quality.
For instance, the particle size of raw material (e.g., citrus peels) is an important factor: A smaller particle size means a higher surface area for the ultrasonic waves to act on. A small particle size results thereby in higher pectin yields, a lower degree of methylation and larger ratio of rhamnogalacturonan regions.
The pH value of the extraction solvent (i.e. water + acid) is another essential parameter. When pectin is extracted under acidic conditions, many rhamnogalacturonan branched regions of the polymer are decomposed, so that mainly homogalacturonan “straight” regions with a few neutral sugar molecules attached on or in the main linear chain remain.
Ultrasonic pectin extraction reduces the extraction time and lowers the required process temperature, which reduces the chance of undesired pectin modification by acids. This enables to use acids under confined conditions in order to modify pectins precisely to product requirements.
What makes Ultrasonic Pectin Extraction so Efficient?
The impact of ultrasonic extraction directly affects the swelling, perforation and breakage of cell walls. Ultrasonically induced mass transfer causes the hydration of pectinous material in the middle lamella leading to the break-up of vegetal tissues. Ultrasonic cavitation and shear forces directly impact cell walls and break them open. These mechanisms result in the highly efficient results of ultrasonic extraction.
Ultrasonically-extracted pectin (also acoustic cavitation assisted extracted pectin, abbrev. ACAE) which had lower molecular weight and degree of methoxylation was richer in rhamnogalacturonan-I region with long side chains compared with conventional heat extracted pectin from chemical and FT-IR analysis. The energy consumption for ulgtrasonic pectin extraction was significantly lower than the conventional heating method, which indicates its promising application for industrial production scale.
(cf. Wang et al., 2017)
Wang and his colleagues (2017) also underpin that ultrasonically-assisted extraction is been proven to be a more economical and environmental-friendly process with higher efficiency and less cost compared with conventional heating extraction.
SEM of residual sugar beet pulp at 1000x magnification: (a) before extraction, and after extraction of pectin using (b) Xylanasae (250 U/g), (c) Cellulase (300 U/g), (d) Xylanasae+Cellulase (1:1), and (e) Xylanasae+Cellulase (1:1.5), and (f) Xylanasae+Cellulase (1:2).
(study and images: Abou-Elseoud et al., 2021)
How Does Ultrasonic Pectin Extraction Work?
Ultrasonic extraction is based on the sonomechanical effects of high-intensity ultrasound. To promote and intensify pectin extraction via ultrasonication, high-power ultrasound waves are coupled via an ultrasonic probe (also called ultrasonic horn or sonotrode) into the liquid medium, i.e. the slurry consisting in the pectin-containing raw material and the solvent. The ultrasound waves travel through the liquid and create alternating low-pressure / high-pressure cycles. During low-pressure cycles, minute vacuum bubbles (so-called cavitation bubbles) are created, which grow over several pressure cycles. During those cycles of bubble growth, the dissolved gases in the liquid enter the vacuum bubble, so that the vacuum bubble transform into growing gas bubbles. At a certain size, when the bubbles cannot absorb more energy, they implode violently during a high-pressure cycle. The bubble implosion is characterised by intense cavitational forces, including very high temperature and pressure reaching up to 4000K and 1000atm, respectively; as well as corresponding high temperature and pressure differentials. These ultrasonically generated turbulences and shear forces break plant cells up and release the intracellular pectins into the water-based solvent. Since ultrasonic cavitation creates highly intense mass transfer, sonication results in exceptionally high yields within a very short processing time.
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]
Ultrasonic batch extractor UIP2000hdT with cascatrode horn
Pectins Extracted from Fruit Waste
Fruit waste such as peels, fruit pulp residues (after fruit juice pressing), and other fruit by-products are often rich pectin sources. Whilst fruit waste products are often used as animal feed, pectin extraction is a more valuable use of fruit waste.
Ultrasonic pectin extraction is already successfully performed with citrus peels (such as oranges, tangerines, grapefruit), melon peels, apple pomace, sugar beet pulp, mango peels, tomato waste, as well as jackfruit, passion fruit, fig peels amongst others.
Case Studies of Ultrasonic Pectin Extraction
Due to the drawbacks of conventional pectin extraction by heat, research and industry have already investigated innovative alternatives such as ultrasonic extraction. Thereby, plenty information of process parameters for various raw materials as well as process optimization data are available.
Ultrasonic Extraction of Pectin from Apple Pomace
Dranca and Oroian (2019) investigated the ultrasonically-assisted extraction process of pectin from apple pomace applying various ultrasonic conditions and using Box-Behnken response surface design. They found that the ultrasound amplitude strongly influences the yield and the degree of esterification of the extracted pectin, while the extraction pH had a great impact on all three responses, i.e. yield, GalA content, and degree of esterification. The optimal conditions for extraction were 100% amplitude, pH of 1.8, solid-liquid ratio of 1:10 g/mL, and 30 min sonication. Under these conditions, pectin yield was 9.183% and had a 98.127 g/100 g GalA content and 83.202% degree of esterification. To set the results of ultrasonically extracted pectin into relation with commercial pectin, pectin sample obtained by ultrasonic extraction under optimal conditions were compared to commercial citrus and apple pectin samples by FT-IR, DSC, rheological analysis, and SEM. The first two techniques highlighted some particularities of the pectin sample extracted by ultrasonic extraction such as the narrower distribution range of molecular weight, the orderly molecular arrangement, and the high degree of esterification that was similar to that of commercially available apple pectins. The analysis of the morphological characteristics of ultrasonically obtained sample indicates a determination pattern between the distribution of the fragment sizes of this sample and its GalA content on one side, and the water uptake capacity on the other side. The viscosity of ultrasonically extracted pectin solution was much higher than that of the solutions made using commercial pectin, which maybe because of the high concentration of galacturonic acid. When also considering the high degree of esterification, this might explain why the viscosity were higher for the ultrasonically extracted pectin. The researchers conclude that the purity, structure and rheological behaviour of pectin extracted by ultrasonic extraction from Malus domestica ‘Fălticeni’ apple pomace indicates promising applications of this soluble fiber. (cf. Dranca & Oroian 2019)
- higher yields
- faster processing
- milder processing conditions
- improved overall efficiency
- simple and safe operation
- fast RoI
High-Performance Ultrasonic Extractor for Pectin Production
Ultrasonic extraction is a reliable processing technology, which facilitates and accelerates the production of high-quality pectins various raw materials such as citrus fruit by-products and peels, apple pomace and many others. Hielscher Ultrasonics portfolio covers the full range from compact lab ultrasonicators to industrial extraction systems. Thereby, we at Hielscher can offer you the most suitable ultrasonicator for your envisaged process capacity. Our long-time experienced staff will assist you from feasibility tests and process optimisation to the installation of your ultrasonic system on final production level.
The small foot-print of our ultrasonic extractors as well as their versatility in installation options make them fit even into small-space pectin processing facilities. Ultrasonic processors are installed worldwide in food, pharma and nutritional supplement production facilities.
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 |
| 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 |
Contact Us! / Ask Us!
Hielscher Ultrasonics – Sophisticated Extraction Equipment
Hielscher Ultrasonics product portfolio covers the full range of high-performance ultrasonic extractors from small to large scale. Additional accessories allow for the easy assembly of the most suitable ultrasonic device configuration for your pectin extraction process. The optimal ultrasonic setup depends on the envisaged capacity, volume, raw material, batch or inline process and timeline.
Batch and Inline
Hielscher ultrasonicators can be used for batch and continuous flow-through processing. Ultrasonic batch processing is ideal for process testing, optimisation and small to mid-size production level. For a producing large volumes of pectin, inline processing might be more advantageous. A continuous inline mixing process requires sophisticated setup – consisting in a pump, hoses or pipes and tanks -, but it is highly efficient, rapid and requires significantly less labour. Hielscher Ultrasonics has the most suitable extraction setup for your extraction volume and process goals.
Ultrasonic Extractors for Every Product Capacity
Hielscher Ultrasonics product range covers the full spectrum of ultrasonic processors from compact lab ultrasonicators over bench-top and pilot systems to fully-industrial ultrasonic processors with the capacity to process truckloads per hour. The full product range allows us to offer you the most suitable ultrasonic extractor for your pectin-containing raw material, process capacity and production targets.
Ultrasonic benchtop systems are ideal for feasibility tests and process optimization. Linear scale-up based on established process parameters makes it very easy to increase the processing capacities from smaller lots to fully commercial production. Up-scaling can be done by either installing a more powerful ultrasonic extractor unit or clustering several ultrasonicators in parallel. With the UIP16000, Hielscher offers the most powerful ultrasonic extractor worldwide.
Precisely Controllable Amplitudes for Optimum Results
All Hielscher ultrasonicators are precisely controllable and thereby reliable work horses in production. The amplitude is one of the crucial process parameters that influence the efficiency and effectiveness of ultrasonic extraction of pectin from fruit and bio-waste.
All Hielscher sonicators allow for the precise setting of the amplitude. Sonotrodes and booster horns are accessories that allow to modify the amplitude in an even wider range. Hielscher industrial ultrasonic processors can deliver very high amplitudes and deliver the required ultrasonic intensity for demanding applications. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation.
Precise amplitude settings and the permanent monitoring of the ultrasonic process parameters via smart software give you the possibility to treat your raw material with the most effective ultrasonic conditions. Optimal sonication for best extraction results!
The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments. This makes Hielscher’s ultrasonic equipment a reliable work tool that fulfils your extraction requirements.
Easy, Risk-free Testing
Ultrasonic processes can be completely linear scaled. This means every result that you have achieved using a lab or bench-top ultrasonicator, can be scaled to exactly the same output using the exactly same process parameters. This makes ultrasonication ideal for risk-free feasibility testing, process optimization and subsequent implementation into commercial manufacturing. Contact us to learn how sonication can increase your pectin extract production.
Highest Quality – Designed and Manufactured in Germany
As a family-owned and family-run business, Hielscher prioritizes highest quality standards for its ultrasonic processors. All ultrasonicators are designed, manufactured and thoroughly tested in our headquarter in Teltow near Berlin, Germany. Robustness and reliability of Hielscher’s ultrasonic equipment make it a work horse in your production. 24/7 operation under full load and in demanding environments is a natural characteristic of Hielscher high-performance mixers.
Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers for mixing applications, dispersion, emulsification and extraction on lab, pilot and industrial scale.
About Pectins
Pectin is a branched heteropolysaccharide consisting of long-chain galacturonan segments and other neutral sugars such as rhamnose, arabinose, galactose, and xylose. To be more specific, pectin is a block of co-polymer comprising of 1,4-α-linked galacturonic acid and 1,2-linked rhamnose with side branches of β-D-galactose, L-arabinose and other sugar units. Since in pectin several sugar moieties and different levels of methyl esterification are found, pectin does not have a defined molecular weight like other polysaccharides. Pectin, that is specified for the use in foods, is defined as a heteropolysaccharide containing at least 65% galacturonic acid units. By applying specific extraction conditions, pectins can be successfully modified and functionalized in order to fulfil specific requirements. The production of functionalized and modified pectins are of interest for special applications, e.g. low-methoxylated pectin for pharmaceuticals.
How is Pectin Separated from the Extract Solution?
Pectin Precipitation after Ultrasonic Extraction: Adding ethanol to an extract solution can help to separate pectin through a process called precipitation. Pectin, a complex polysaccharide found in the cell walls of plants, is soluble in water under normal conditions. However, by altering the solvent environment with the addition of ethanol, the solubility of pectin can be reduced, leading to its precipitation from the solution.
Below, we explain you the chemistry behind pectin precipitation using ethanol:
- Disruption of Hydrogen Bonds: Pectin molecules are held together by hydrogen bonds, which contribute to their solubility in water. Ethanol disrupts these hydrogen bonds by competing with water molecules for binding sites on the pectin molecules. As ethanol molecules replace water molecules around the pectin molecules, the hydrogen bonds between pectin molecules weaken, reducing their solubility in the solvent.
- Decreased Solvent Polarity: Ethanol is less polar than water, meaning it has a lower ability to dissolve polar substances like pectin. As ethanol is added to the extract solution, the overall polarity of the solvent decreases, making it less favorable for pectin molecules to remain in solution. This leads to the precipitation of pectin out of the solution as it becomes less soluble in the ethanol-water mixture.
- Increased Pectin Concentration: As pectin molecules precipitate out of the solution, the concentration of pectin in the remaining solution increases. This allows for easier separation of the pectin from the liquid phase through filtration or centrifugation.
Literature / References
- Wafaa S. Abou-Elseoud, Enas A. Hassan, Mohammad L. Hassan (2021): Extraction of pectin from sugar beet pulp by enzymatic and ultrasound-assisted treatments. Carbohydrate Polymer Technologies and Applications, Volume 2, 2021.
- Marina Fernández-Delgado, Esther del Amo-Mateos, Mónica Coca, Juan Carlos López-Linares, M. Teresa García-Cubero, Susana Lucas (2023): Enhancement of industrial pectin production from sugar beet pulp by the integration of surfactants in ultrasound-assisted extraction followed by diafiltration/ultrafiltration. Industrial Crops and Products, Volume 194, 2023.
- Wang, Wenjun; Wu, Xingzhu; Chantapakul, Thunthacha; Wang, Danli; Zhang, Song; Ma Xiaobin; Ding, Tian; Ye, Xingqian; Liu, Donghong(2017): Acoustic cavitation assisted extraction of pectin from waste grapefruit peels: A green two-stage approach and its general mechanism. Food Research Journal Vol.102, December 2017. 101-110.
- Drance, Florina; Oroian, Mircea (2019): Ultrasound-Assisted Extraction of Pectin from Malus domestica ‘Fălticeni’ Apple Pomace. Processes 7(8): 488; 2019.
- Owais Yousuf; Anupama Singh; N. C. Shahi; Anil Kumar; A. K. Verma (2018): Ultrasound Assisted Extraction of Pectin from Orange Peel. Bulletin of Environment, Pharmacology and Life Sciences Vol 7 [12], November 2018. 48-54.
- Lena Rebecca Larsen; Julia Buerschaper; Andreas Schieber; Fabian Weber (2019): Interactions of Anthocyanins with Pectin and Pectin Fragments in Model Solutions. J Agric Food Chem 2019 Aug 21; 67(33). pp. 9344-9353.