Determining the precise maximum concentration of invert sugar in a gummy formulation before it becomes overly hygroscopic is not a fixed number-it depends on several interrelated factors including the complete sugar profile, water activity (aw), processing conditions, and the specific texture goals. However, industry experience and standard practices offer clear guidelines.
General Threshold Guidelines
In most gummy formulations, invert sugar is typically used at levels between 10% and 30% of the total sweetener weight. Above this range, the risk of excessive moisture absorption increases significantly:
- Below 15% invert sugar: Generally low hygroscopic risk; gummies remain stable with minimal stickiness under normal humidity (below 60% RH).
- 15% - 25% invert sugar: Moderate hygroscopic behavior. Gummies may become tacky if exposed to high humidity (>65% RH) or if the water activity exceeds 0.55.
- Above 25% invert sugar: High hygroscopic risk. Stickiness often becomes unacceptable, especially when the total moisture in the gummy exceeds 18%. At these levels, the gummy can absorb ambient moisture, leading to a soft, sticky surface and clumping in packaging.
When Stickiness Becomes Unacceptable
Stickiness is unacceptable when it leads to:
- Packaging failure: Gummies adhere to packaging or each other, causing product damage or unsaleable units.
- Consumer rejection: The surface feels tacky to the touch, or the gummy leaves residue.
- Increased microbial risk: Higher water activity (above 0.65) due to moisture uptake supports mold and bacterial growth.
To stay within acceptable limits, manufacturers should monitor water activity closely. For invert sugar concentrations over 20%, maintaining aw below 0.55 is critical. If stickiness is observed, reducing invert sugar or balancing with less hygroscopic sugars (e.g., sucrose or isomalt) is recommended. KorNutra’s standard gummy formulations avoid exceeding 25% invert sugar to ensure stability without compromising chewability.
Practical Tip
Always conduct accelerated stability tests at 40°C/75% RH for two weeks. If the gummy develops visible wetness or tackiness during this period, the invert sugar level is too high for that specific formulation. Adjust downward by 5% and retest.