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Improving Onion Dehydration with Pulsed Electric Field (PEF)

Drying onions presents well-known obstacles: high moisture content, risk of browning, flavor degradation, and uneven drying. OptiCept’s CEPT® technology based on Pulsed Electric Field (PEF) is transforming how onions are dehydrated—delivering faster, more uniform drying with improved texture and rehydration quality.

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The Useful (Dried) Onion

Dehydrated onion is used widely in food manufacturing, cooking, and even some non-culinary applications because it provides the flavor and aroma of fresh onion in a shelf-stable, convenient form. Some examples of the use of dehydrated onions:

 

  • Seasonings and spice blends – Used in dry rubs, soup mixes, instant noodles, and snack seasonings.

  • Processed foods – Added to sauces, dressings, soups, canned foods, and ready-to-eat meals for flavor enhancement.

  • Meat products – Included in sausages, burgers, meatballs, and marinades for added taste and aroma.

  • Baked goods – Used in flavored breads, bagels, and savory pastries.

The Onion Dehydration Dilemma

Conventional dehydration methods—typically heat-based—introduce several quality and efficiency challenges:

  • High initial moisture slows drying.
  • Flavor loss or alteration, particularly of delicate sulfur compounds.
  • Color degradation and browning, due to prolonged enzyme activity and heat.
  • Uneven drying, leading to poor texture and inconsistent rehydration.
How PEF Makes a Difference in Dehydration of Onions

PEF pre-treatment creates microscopic pores in onion cell membranes (a process called electroporation).

This allows water to escape more easily during drying.

Pulsed Electric Field Ilustration
Faster Drying
  • As water to escape more easily, PEF significantly reduces drying times. As shown below, by 14% depending on conditions.
  • Faster dehydration means higher throughput and lower energy costs.
Improved Energy Efficiency

  • Because moisture is removed more easily, less heat and time are required, lowering overall energy consumption.

  • The process is non-thermal, so it doesn’t rely on high temperatures to start removing moisture.

Better Product Quality

  • Color retention: Lower drying temperatures preserve the natural white or light-yellow color of onion.

  • Flavor and aroma preservation: PEF minimizes the loss of volatile sulfur compounds responsible for onion’s characteristic taste.

  • Nutrient retention: Vitamins, antioxidants, and other heat-sensitive compounds degrade less during drying.

  • Texture: Dehydrated pieces rehydrate faster and maintain a better texture.

Industrial and Economic Benefits

  • Higher yield and uniform dehydration — less product shrinkage or burning.

  • Integration-friendly – PEF systems can be added as a pre-treatment before existing drying equipment (air, freeze, or vacuum dryers).

  • Sustainability – lower energy and water use makes it more environmentally friendly.

In summary, PEF technology enhances onion dehydration by creating cell permeability that speeds up moisture removal while preserving flavor, color, and nutrients — leading to a more efficient, higher-quality, and sustainable drying process.

Key Results: Dried Onion with PEF
PEF treated onion pieces

In a lab trial using the OPTICEPT® SD7 PEF system whole peeled onions were PEF-treated, then blanched and sliced. The results were compelling:

  • Drying time shortened by 14%, with more efficient moisture removal.

 

  • Moisture content dropped dramatically—from 89.5% to 5%.

 

  • Energy consumption and costs significantly reduced.

 

  • PEF treatment improves membrane permeability, reducing enzyme-driven browning and yielding more uniform drying, better texture, and enhanced rehydration quality.
What This Means for Producers

With PEF pre-treatment and SD7 integration in your onion dehydration line, you can expect:

  • Accelerated drying cycles, boosting production capacity and throughput.
  • Lower energy use, delivering operational cost savings.
  • Superior product quality, with consistent texture and excellent rehydration.
  • Visually appealing and flavorful dried onions, ideal for culinary and food industry applications.
Why PEF Beats Traditional Drying

By targeting cell membranes with electrical pulses, PEF accelerates water release while maintaining integrity. This non-thermal process avoids excessive heat damage—preserving flavor, color, and nutrients that conventional methods often compromise.

The method can be applied in a wide range of commodities, from pineapple and mango to carrots and cranberries.

PEF: The Smart Upgrade for Onion Drying

OptiCept’s OPTICEPT® SD7 platform delivers tangible, lab-backed improvements—from drying speed to product quality. If you’re looking to streamline operations and elevate your dried onion offerings, this is the tech to explore.

The OPTICEPT® SD7 PEF system leverages advanced PEF technology to enhance the dehydration of vegetables and fruits, delivering considerable improvements in energy efficiency, processing throughput, and product quality.

This cutting-edge system is designed to meet the high demands of large-scale food production, enabling significant operational improvements while aligning with sustainability targets.

Developed in collaboration between OptiCept Technologies and FPS Food Process Solutions, the SD7 system reflects the synergies of expert knowledge in PEF technology and decades of engineering experience in hygienic food processing equipment.

Further Reading >> Harnessing PEF in dehydration of pineapple

Learn more about PEF in dehydration of fruits and vegetables!

Contact OptiCept today, and let’s discuss how we could help you in your dehydration process.

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