The Effects of Sonication on Legumes and Seeds

Ultrasonic processing has become a valuable technology for modifying, conditioning, and analyzing plant materials such as lentils and legumes. Through acoustic cavitation and controlled mechanical forces, sonication enhances hydration, accelerates extraction, alters microstructures, and improves mass transfer. These effects are highly attractive for seed research, food science, agriculture, biorefining, and analytical research.

Ultrasonic Processing of Seeds and Pulses at Any Scale

A major advantage of power ultrasound is the ability to precisely control amplitude, intensity, and energy input, especially when using Hielscher Ultrasonics’ probe-type sonicators. These systems – available for laboratory, pilot, and industrial scale – allow for reproducible, tunable processing that ranges from gentle seed priming or sprouting by accelerated hydration and enzyme activation to efficient nutrient extraction.

Acoustic Cavitation and Its Effects on Legume Materials

Sonication relies on acoustic cavitation – the rapid formation and collapse of microbubbles in liquids. The resulting micro-jets, shear forces, and pressure fluctuations interact with lentil and legume tissues in highly specific ways.

Three primary mechanisms define the impact on seeds:

1. Hydration Acceleration

   Cavitation disrupts the boundary layer between water and the seed surface, enhancing water transport into the seed coat and cotyledons.

   Effects include:

   • Faster soaking/hydration
   • More uniform swelling
   • Improved water diffusion through the testa
2. Sonoporation and Microstructural Changes
   Mechanical stress from collapsing cavitation bubbles creates nano- and micro-pores in the seed coat and internal tissues – known as sonoporation.

   Consequences:

   • Increased permeability
   • Faster leaching or uptake of solutes
   • Enhanced enzymatic accessibility
   • Improved germination potential
3. Extraction Enhancement
   Ultrasound facilitates the release of:
   • Proteins
   • Polyphenols
   • Oils and lipids
   • Dietary fibers
   • Bioactive compounds

This results from cell wall disruption, improved solvent penetration, and higher mass transfer.
 

Schematic summary of the ultrasound effects on seeds and the mechanisms of action.
Study and scheme: ©Nogueira et al., 2023

Influence of Ultrasound Amplitude and Intensity on Seeds

Ultrasound amplitude directly determines the mechanical energy imparted to the seeds. Adjusting amplitude allows operators to fine-tune the process to the sensitivity and purpose of the application. All Hielscher sonicators allow for a precise amplitude tuning, which makes them versatile tools for seed priming, sprouting and nutrient extraction.

Low Amplitudes – Ideal for Seed Priming & Imbibition

• Gentle cavitation
• Increased hydration by sonoporation, but without tissue damage
• Controlled seed imbibition for priming
• Activation of metabolic pathways
• Improved germination rate and seed vigor

Seed imbibition – the initial water uptake phase before germination – can be precisely accelerated and optimized with ultrasound:

• Cavitation breaks surface tension
• Water enters the micropyle more efficiently
• Dormancy-related barriers soften
• Primed seeds exhibit faster sprouting and stronger seedlings

Medium Amplitudes – Structural Modification & Moderate Extraction

• Enhanced cell permeability
• Partial cell wall loosening
• Faster hydration for food processing
• Improved extraction yields without full tissue breakdown

Ideal for:

• Improving protein solubility
• Modifying starch properties
• Preparing materials for fermentation

High Amplitudes – Cell Disruption & Extraction

• Intense cavitation and shear
• Complete structural breakdown
• Optimal for protein isolation or phytochemical extraction
• Used when seeds are not intended to remain viable

This is the typical range for industrial extraction of:

• Oils / Lipids
• Proteins and peptides
• Polyphenols
• Functional fibers

Hielscher Sonicators for Seed Priming, Sprouting, Hydration and Extraction

Hielscher sonicators offer a versatile and scientifically robust method for modifying lentils and legumes. From accelerating seed imbibition and priming to enhancing extraction and enabling industrial-scale ingredient production, power ultrasound provides unique advantages across research and commercial sectors.

With Hielscher Ultrasonics’ precisely controllable probe-type sonicators – available at lab and fully-industrial scale – , users can fine-tune processing conditions for gentle physiological enhancement or intense mechanical disruption–making ultrasound a cornerstone technology for next-generation plant research, food ingredient processing, and sustainable biorefining.

 
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.