The sticking of gummies during storage in humid conditions is a complex interplay of surface sweating and bulk softening, but the primary trigger is almost always surface sweating. Understanding the distinction is key to preventing the problem.
Surface Sweating: The Immediate Culprit
Gummy candies are hygroscopic-they readily attract and hold water molecules from the surrounding air. When the ambient humidity is high, the surface of the gummy absorbs moisture, creating a thin film of water. This water dissolves sugars and other soluble components present at the surface, forming a concentrated syrup that is inherently sticky. The phenomenon is often called "sweating" because the gummy appears to exude moisture. This sticky syrup acts like an adhesive, causing individual pieces to cling together. Even a slight increase in surface moisture content can drastically increase surface tack.
Bulk Softening: The Accelerant
Over a longer exposure period or under extreme humidity, moisture doesn't stay confined to the surface. It gradually migrates into the gummy matrix, increasing the overall water activity and moisture content throughout the piece. This bulk softening reduces the structural integrity of the gel network, making the gummy more pliable and prone to deformation. While a soft gummy on its own may not necessarily be sticky, a softened gummy that is already sweating will compress under its own weight or stacking pressure, increasing the surface contact area and further exacerbating the clumping. In practice, the two mechanisms feed into each other: surface sweating initiates sticking, and bulk softening makes the gummy more susceptible to it.
Why an Either/Or Answer Misses the Point
Treating the issue as simply "sweating vs. softening" overlooks the moisture migration gradient. The surface layer always has the highest moisture content when exposed to humid air. Thus, the sticky interface between two gummies is a result of surface phenomena first. Bulk softening lowers the mechanical resistance, but without the initial surface moisture layer, adhesion would be minimal. Effective mitigation strategies-like optimized drying, specialized coatings, and moisture-barrier packaging-must address both the hygroscopic surface properties and the bulk moisture stability of the formulation.
At KorNutra, our manufacturing processes incorporate a deep understanding of these mechanisms. From precise control over gelatin or pectin setting and drying curves to the application of moisture-resistant finishing agents, we design gummies that resist sweating and maintain firmness, ensuring they stay free-flowing throughout their shelf life, even in challenging climates.