There's no single threshold for Maillard browning because it depends on temperature, time, water activity, and which sugar you're using — not just concentration. Still, at typical gummy cooking temperatures (180-200°F or 82-93°C), the risk becomes real when reducing sugars — glucose, fructose, or invert sugar — hit roughly 5-10% of total formula weight. Below that, the reaction is too slow to see visible browning during standard cook times (5-10 minutes). Above 10%, the rate takes off, especially with longer heating.
pH moves the goalposts. For example:
- At pH 4.5-5.5 (typical with citric or malic acid), browning is slow. The acidic environment gums up the open-chain form of reducing sugars needed for the reaction. Even at 10-12% reducing sugar, browning may stay minimal during normal cook times.
- At pH 6-7 (less acidic), the rate jumps 2-3 times. Here, just 5-8% reducing sugar can produce visible browning after 5 minutes.
- At pH 7.5 or above (alkaline ingredients or aged syrups), browning becomes a problem even at 3-5% reducing sugars. The high pH accelerates things so much that brief heat can darken the batch and create off-flavors.
The practical takeaway: these are guidelines, not fixed thresholds. The specific sugar source (glucose syrup vs. honey), amino acids from gelatin or fruit purées, and cooking method (open kettle vs. vacuum) all matter. To keep browning under control, use non-reducing sugars like sucrose, keep pH below 5, and avoid prolonged high heat. Run small-batch tests under your exact conditions for precise control.