The boundary between a gummy and a hard candy is defined by the critical moisture content-the point at which the texture transitions from chewy and elastic to brittle and glassy. For a standard pectin or gelatin-based gummy, this threshold is typically around 8-12% moisture (by weight). Below that, the hydrocolloid network can no longer retain enough water to maintain its plastic, deformable structure, and the matrix enters a glassy state-essentially becoming a hard candy.
However, this number is not universal. The critical moisture content is strongly influenced by the type and concentration of the hydrocolloid used. Here’s how different gelling agents shift that boundary:
- Gelatin: Gelatin gummies can tolerate slightly lower moisture levels (around 8-10%) before becoming brittle. The protein network provides some flexibility even as water leaves, but once moisture drops below ~8%, the gummy will snap rather than stretch.
- Pectin (especially high-methoxyl pectin): Pectin-based gummies are more sensitive to moisture loss. At ~12% moisture, they begin to lose their signature chew and can become sticky or crumbly. Below 10%, pectin gummies turn into a glassy, hard candy-like texture more quickly because pectin forms a more rigid gel network that lacks the plasticity of gelatin.
- Modified starches or blends: Starches (like tapioca or cornstarch) combined with gelatin can lower the critical moisture point slightly-allowing the gummy to remain chewy at 8-9% moisture. The starch granules help retain water and add compressibility, pushing the hard-candy transition to a lower moisture content.
- Agar or carrageenan: These hydrocolloids create gels that are already more brittle at higher moisture levels. For agar-based gummies, the critical moisture may be as high as 14-15% before they become chalky or hard.
At KorNutra, we focus on precise formulation to keep gummies in their optimal chewy zone-usually 10-14% moisture-while ensuring long-term stability. The hydrocolloid type dictates not only the moisture threshold but also how the gummy behaves during storage and at varying temperatures. A well-formulated gummy will resist moisture migration, and the right blend can push the “too dry” point lower, extending shelf life without sacrificing texture. Remember: no single moisture number applies to all gummies-it’s the hydrocolloid that defines the boundary.