Webinar Recap: Leakers in Softgel Capsules
Last week, on September 30, 2025, we hosted a technical webinar on leakers in softgel capsules that attracted hundreds of attendees from pharmaceutical companies, CDMOs, and supplement manufacturers worldwide. The strong turnout confirms that leakage remains one of the most critical quality challenges in softgel manufacturing.
Introduction to Leakers
Leakage is classified by USP as a critical defect because it directly impacts product quality, safety, and efficacy. Even small amounts of leakage can contaminate entire batches, making production expensive and reducing yields. Our webinar brought together two industry experts to share practical strategies for understanding, preventing, and managing this persistent challenge.
Understanding the Four Main Types of Leakers
Our very own Yanitsa Miteva opened the webinar by examining the most common types of leakers and their root causes. Leakage is particularly challenging because it can compromise product quality, safety, and efficacy, while potentially contaminating entire batches. She highlighted four main categories:
Pinhole leakers occur when particles in the fill mass interfere with capsule sealing, or when surface-active substances like lecithin disrupt seam formation. These typically appear several days after encapsulation as the capsule shell dries and shrinks.
Brittleness-related leakers develop during storage when water and plasticizer migrate from the shell into hygroscopic fills. These often don't appear until 6-12 months into stability testing, making them particularly challenging to address.
Defects in gelatin ribbon result from improper handling of the gelatin mass during manufacturing, such as air bubbles creating holes in the capsule wall.
Thin seam leakers occur due to inadequate encapsulation settings or gelatin mass properties.
Yanitsa emphasized that prevention requires attention to both formulation and process aspects. On the formulation side, controlling particle size distribution, using hydrophobic excipients for hygroscopic fills, and selecting appropriate plasticizer systems are essential. Process-wise, regular wedge inspection, proper seam thickness monitoring, and appropriate drying conditions all play critical roles.
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The Science of Seam Formation and EASYSEAL Technology
Dr. Ulrich Mach from GELITA Pharma Institute provided detailed insights into how gelatin properties affect seam formation. He explained the three-phase process of seam formation: superficial melting of the ribbon at the wedge, pressing the molten surfaces together, and rapid re-gelling to stabilize the newly formed seam.
A key revelation was the role of microgel content in gelatin. Microgel consists of cross-linked molecules that don't participate in seam formation and can significantly inhibit proper sealing. Standard gelatins typically contain 4-8% microgel, but Dr. Mach demonstrated that reducing this content dramatically improves seam quality.
He introduced GELITA's EASYSEAL gelatin, which uses enzymatic treatment to eliminate microgel entirely while converting it into functional gelatin. Trial results showed impressive improvements: up to 90% reduction in leakers with lecithin-containing formulations, 50-100% increases in trailing seam thickness, and even 50% faster drying times.
Dr. Mach also addressed machine parameters, noting that wedge temperature, casting drum temperature, and machine speed are the most effective process levers for optimizing seam formation.
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Key Takeaways
The webinar made clear that while leakers present significant challenges, they can be largely prevented through smart formulation development and proper material selection. Understanding the specific causes of leakage in your formulation is essential for implementing effective prevention strategies.
Several practical insights emerged from the Q&A session:
Gelatin bloom strength is often overemphasized; other factors like microgel content and protein chain length matter more
Tray drying is strongly recommended for products prone to leakage to enable early detection
Natural colorants and pigments can impact seam formation and should be carefully controlled
Late leakage typically results from plasticizer migration and can be mitigated through formulation design
For pharmaceutical products, the stakes are particularly high given the USP's classification of leakers as critical defects. The rigorous AQL testing requirements mean that even small amounts of leakage can result in expensive batch rework or rejection.
This webinar was made possible through collaboration between GELITA Pharma Institute and The Science of Soft Capsules.
Stay tuned for our next webinar! Follow us on LinkedIn or subscribe to our newsletter to be the first to know about our upcoming expert sessions on softgel capsule development.
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