Ultrasonic Pomace Extraction – Sustainable Recovery of Bioactive Compounds

Fruit processing by-products, especially pomace, represent an untapped reservoir of bioactive compounds with potential applications in nutraceuticals, food fortification, and pharmaceuticals. Yet, the efficient and sustainable recovery of these compounds remains a technical challenge. Among emerging green extraction technologies, ultrasound-assisted extraction using probe-type sonicators achieves outstanding recovery yields. Ultrasonication enables a rapid, solvent-efficient extraction of phenolic compounds, triterpenic acids and other bioactive compounds from plant matrices such as apple pomace.

Efficient Fruit By-Product Valorization with Ultrasound Extraction

Ultrasonic pomace extraction is a efficient way to valorize the by-product of juice, wine and cider production – it is a scientifically validated, industrially scalable and adopted, and an economical solution for fruit waste valorization. As sonication is efficient and versatile, it offers a green extraction strategy to utilize the potential of agri-food by-products like apple pomace.
As evidenced by recent research, combining short sonication times, moderate ethanol concentrations, and controlled amplitude allows for selective, efficient recovery of health-promoting compounds.
In the pursuit of circularity, sonication is not just a tool – sonication means process intensification and efficiency.

Pomace Valorization Using Ultrasonic Extraction

Fruit pomace, a by-product of juice and wine production, comprises peel, pulp, seeds, and stems. Traditionally underutilized or relegated to low-value applications such as livestock feed or biomass, pomace is now recognized as a valuable source of polyphenols (e.g., quercetin glycosides, phloridzin), flavonoids, dihydrochalcones, and triterpenic acids (notably ursolic acid). These molecules are associated with antioxidant, anti-inflammatory, and antimicrobial properties.
Ultrasonic extraction offers a transformative approach to pomace valorization by enabling the efficient release of these bioactives. Compared to conventional extraction methods, ultrasonic extraction provides:

• Shorter processing times
• Lower solvent consumption
• Higher yields
• Milder extraction conditions, preserving heat-sensitive compounds

What Science Says About Ultrasonic Pomace Extraction

Two exemplary studies demonstrate scientifically the benefits of ultrasonically-assisted extraction (UAE) for apple pomace.

Study 1: Pando Bedriñana et al., 2024
Using a central composite design, researchers optimized the simultaneous extraction of total polyphenols and ursolic acid from cider-industry pomace using a Hielscher UP200Ht sonicator. Under optimized conditions (5.1 min, 68% ethanol, 90% amplitude), whole apple pomace yielded:

• ~1300 µg/g of flavonols
• ~1200 µg/g of dihydrochalcones
• ~4200 µg/g of ursolic acid

Notably, the apple peel fraction exhibited even higher concentrations, with ursolic acid reaching 8500 µg/g dry matter. The antioxidant activity of extracts correlated strongly with polyphenol content, and mathematical modeling confirmed extraction efficiency.

Study 2: Razola-Díaz et al., 2022
This work focused on optimizing the extraction of phloretin and phloridzin – two potent antioxidant dihydrochalcones. Using a Hielscher UP400St probe-type sonicator, the obtained the following extraction yields:

• ~13 µg/g of phloretin
• ~67 µg/g of phloridzin
• ~1878 µg/g dry weight of total phenolics
• Antioxidant activity (FRAP): up to 3.58 mg TE/g

Versatility – Sonication for Pomace, Juices and Smoothies

Ultrasonic extraction is not limited to apple pomace; it has been successfully applied to a wide range of fruit matrices. In the pulp of fruits such as orange, sonication enhances the release of polyphenols, flavonoids, and antioxidants, preserving their functional integrity. Similarly, the peels of citrus fruits – including grapefruit, lemon, and orange – are rich in pectins and phenolic compounds, which can be efficiently liberated through cavitation-driven cell wall disruption. Even grape seeds, known for their dense polyphenolic content (e.g., catechins and proanthocyanidins), respond well to ultrasonic treatment, yielding high concentrations of antioxidants. This versatility across plant tissues highlights sonication as a robust tool for the green extraction of bioactives from diverse agro-industrial by-products.

Furthermore, the versatility of Hielscher sonicators extends to various products and applications:

• Liquid-phase extraction in juices and purees
• Homogenization of plant-based beverages and emulsions
• Microbial and enzymatic inactivation for shelf-life extension without thermal damage

In juice and smoothie production, high-performance sonication ensures:

• Stable dispersion of fibers and solids
• Improved mouthfeel
• Enhanced bioavailability of phenolics
• Preservation of sensory and nutritional properties

The versatile use of Hielscher sonicators easily bridge the gap between pomace and juice processing – allowing for extraction, homogenization and pasteurization with the same ultrasonic setup.

Sustainability Spotlight

Ultrasonication contributes significantly to sustainability by enabling the high-value recovery of bioactive compounds from fruit processing by-products that would otherwise contribute to global food waste. In the context of the juice industry, where up to 25% of fruits and vegetables are discarded post-harvest or during processing, sonication offers a targeted, efficient solution. For example, ultrasonic treatment of orange pulp–peel mixtures has been shown to enhance key dietary fiber properties, supporting their reuse as novel food ingredients. This valorization pathway not only reduces the environmental burden of agri-food waste but also aligns with the UN Sustainable Development Goal 12 – promoting responsible consumption and production.
Importantly, sonication is an energy-efficient and green technology – requiring low energy consumption and reducing the use of harsh extraction solvents as it works with water, aqueous ethanol and NADES.
By transforming waste streams into functional ingredients, sonication contributes to a circular economy and improves both ecological and economic sustainability within the food processing sector.

Improve Your Pomace Process with Hielscher Sonicators

Hielscher Ultrasonics is a leading manufacturer of high-performance ultrasonic systems designed for both laboratory and industrial applications. Their industrial sonicators – such as the UIP2000hdT, UIP4000hdT, UIP6000hdT, and UIP16000hdT – offer:

• Scalable throughput (from liters to tons per hour)
• Precise amplitude control
• 24/7 operation in demanding environments
• Pressurizable ultrasonic reactors
• Compatibility with inline continuous processing
• Simple integration into (existing) production lines

Hielscher sonicators are already validated in published research for extracting polyphenols, antioxidants and other bioactive compounds, with proven efficiency and reproducibility.

The table below gives you an indication of the approximate processing capacity of our ultrasonicators:

Design, Manufacturing and Consulting – Quality Made in Germany

Hielscher ultrasonicators are well-known for their highest quality and design standards. Robustness and easy operation allow the smooth integration of our ultrasonicators into industrial facilities. Rough conditions and demanding environments are easily handled by Hielscher ultrasonicators.

Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.

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