The 1980s brought continuous vacuum cooking into gummy manufacturing. The shift changed the maximum achievable solids content in gummy syrups compared to open kettles, because cooking under vacuum removes water at a lower temperature and avoids the scorching that limits open-kettle solids.
From Open Kettles to Vacuum Cooking
In an open kettle, syrup cooks at atmospheric pressure, so water has to be driven off at high temperature. That heat causes caramelization, degrades heat-sensitive ingredients, and sets a practical limit on how much water can be removed. Open kettles typically reach 75-80% solids, depending on the recipe. Push much past that and the batch scorches or picks up off-flavors.
Continuous vacuum cooking runs the syrup under reduced pressure. Lower pressure lowers the boiling point, so water leaves at a lower temperature and the syrup avoids the scorching that open-kettle heat produces. In a typical line, the slurry cooks briefly at high temperature to hydrate the gelling agents, then flashes into a vacuum chamber where the pressure drop removes water and cools the mass in one step. The same formulas that top out near 80% solids in an open kettle reach roughly 82-84% in a vacuum cooker, with less heat damage to flavors and colors along the way.
Key Advantages of Higher Solids in Gummy Syrups
- Improved texture and shelf stability: Higher solids reduce water activity, which limits microbial growth and extends shelf life. The finished gummies have a firmer, more consistent chew.
- Faster drying and production cycles: Less water left to evaporate in the drying stage means shorter processing times and higher throughput.
- Tighter Brix control: Vacuum cooking holds sugar concentration to a narrow range, cutting batch-to-batch variability.
- Preservation of flavors and colors: Lower cooking temperatures limit degradation of delicate ingredients, so taste and appearance hold up better.
Continuous vs. Batch Processing
Both continuous and batch vacuum systems exist, but continuous vacuum cooking established itself for large-scale production during the 1980s. Ter Braak, for example, developed its static cooker for gum and jelly masses in 1983. In a continuous system, syrup flows steadily through a heated, sealed chamber under vacuum. That gives constant output, precise dwell times, and consistent solids content, unlike batch processes with their repeated stops and starts.
Viscosity and gel set limits on solids
Higher solids content is not always better. As a syrup climbs past roughly 84 Brix, its viscosity rises enough to make clean depositing harder, and the mass can tail at the depositor (leaving strings instead of clean drops) or start to gel in the line before it reaches the mold. Gelatin gummies set best around 78-80 Brix, and pectin gummies around 80-82 Brix with a pH of 3.2-3.6. Vacuum cooking earns its keep by reaching the top of that functional range consistently and without scorching, while holding Brix steady from batch to batch. Beyond 84 Brix, you trade depositing trouble for drying time you no longer need.
At KorNutra, we run continuous vacuum cooking to reach the high end of the solids range in our gummy syrups, which gives clients consistent texture, stability, and active potency. The same process that arrived in the 1980s is now standard equipment in modern gummy manufacturing, and it still beats open kettles on both solids control and protection of heat-sensitive ingredients.