Nougat problems rarely come from a single fault. They come from a temperature, moisture or aeration parameter drifting outside its window. This guide maps the five most common defects to the parameters that cause them, so your operator can diagnose instead of guess.
Quick diagnosis table
| Defect | Likely cause | First correction |
|---|---|---|
| Grainy / crystalline | Incomplete sugar dissolution, or sucrose re-crystallisation during cooling | Raise dissolving temperature and hold time; check for undissolved seed crystals |
| Too hard after cooling | Over-cooked (moisture too low) or insufficient aeration | Lower final cook temperature; increase aeration volume or whipping time |
| Sticky and soft | Under-cooked (residual moisture high) or insufficient setting time | Extend vacuum cooking time; verify cooling tunnel temperature profile |
| Collapses / flattens in storage | Unstable foam structure, often large uneven bubbles | Switch to staged double aeration; reduce whip speed, extend whip duration |
| Batch-to-batch variation | Parameters set by operator judgement rather than stored recipe | Program recipes into the controller; log vacuum, temperature and whipping time per batch |
1. Grainy or crystalline nougat
Crystallisation almost always traces back to undissolved sugar crystals acting as seeds, or to sucrose re-crystallising because the cooling curve was too slow. Glucose syrup content acts as the crystallisation inhibitor — if the syrup ratio is too low for your recipe, graininess will appear regardless of machine settings.
- Verify sugar is fully dissolved before the boil starts — check visually, not by timer
- Review glucose syrup to sucrose ratio with your formulator
- Shorten the cooling curve so the mass sets quickly through the critical range
2. Nougat that turns out too hard
Hardness is usually insufficient aeration rather than a cooking problem. If the moisture content is within specification but the product reads hard, the foam structure is too coarse — the piece has density but no tenderness.
- Increase aeration volume in controlled steps, not in one jump
- Extend whipping duration at moderate speed rather than raising speed further
- Confirm the mass is still within its aeration temperature window when whipping begins — too cold and aeration cannot form
3. Sticky, soft nougat
The opposite problem: residual moisture above target. Either the vacuum cooking stage ended too early, or the cooling tunnel is running too warm and the mass never sets properly. Both are measurable — you should not be diagnosing this by feel.
4. Product collapsing in storage
Collapse is a structural failure. It happens when the bubble structure is uneven: large bubbles migrate and merge over time, and the piece flattens under its own weight. Single-stage high-speed whipping is the usual culprit. Two-stage aeration produces a finer distribution that holds its shape.
Note — If your product is fine on day one and flat after two weeks, you do not have a packing problem — you have an aeration problem. Check the foam structure before changing the film or box.
5. Inconsistency between batches or shifts
This is the most expensive defect because it destroys customer trust while being hard to prove. The cause is nearly always operator-controlled parameters. The fix is procedural: store the recipe in the machine controller and log vacuum level, temperature curve and whipping time for every batch, so any deviation is visible before it becomes a quality claim.
A practical daily checklist
- Confirm dissolution before the boil begins
- Record the actual vacuum level achieved, not the setpoint
- Verify the aeration temperature window was respected
- Check cooling tunnel temperature at three points, not one
- Compare today’s batch log against the last approved batch
None of these defects is exotic, and none requires a new machine to solve. They require the parameters to be measured, recorded and repeatable — which is a control-system and procedure question, and one worth putting to any supplier you are evaluating.