In 2002, reports of acrylamide in a range of fried and oven-cooked foods caused worldwide concern, because the compound had been classified as probably carcinogenic in humans. The same year, a paper in Nature showed how it forms: in the Maillard reaction between amino acids and reducing sugars during heating, with asparagine, a major amino acid in cereals and potatoes, as a crucial participant.
Two ways to less acrylamide
The Maillard reaction is also what gives biscuits their colour and baked flavour, so slowing it down tends to cost quality. A review in Food Chemistry explains the appeal of the alternative: asparaginase converts asparagine to aspartic acid, taking away one of the two reactants while leaving the rest of the chemistry alone.
How well it works
| Product | Acrylamide reduction | Source |
|---|---|---|
| Dough-based products including semi-sweet and ginger biscuits and crispbread | 34% to 92% | Hendriksen and others, 2009 |
| Rotary cut biscuits | 96% | Gazi and others, 2023 |
| Crackers | 80% | Gazi and others, 2023 |
| Wire cut cookies | 54% | Gazi and others, 2023 |
| Rotary moulded biscuits | No significant decrease | Gazi and others, 2023 |
The spread is the story. In the first study, enzyme dose, dough resting time and water content were the critical factors.
Why the dough decides
Water. The rotary moulded biscuits that showed no benefit had a low water activity, 0.70, and a high fat content. The authors concluded that a dough water activity above 0.75 is needed for asparaginase to work effectively. A study of short dough biscuits found the same pattern: more water helped the reactants move, raising both acrylamide formation and the enzyme's ability to reduce it.
Fat. In the same short dough work, fat reduced acrylamide formation but also reduced the enzyme's effect, probably by hindering contact between the reactants in the watery phase of the dough.
pH and raising agents. In a cookie model system, ammonium bicarbonate raised acrylamide about six times compared with no raising agent, while sodium bicarbonate suppressed it by up to 52%. Asparaginase worked best near neutral pH, the longer it had to act the more acrylamide it removed, and raising agents that pushed the dough pH away from neutral reduced its effect. Another biscuit study found no effect of raising agent on acrylamide, so this needs testing in your own product.
Time and temperature. Modelling of enzyme level, incubation time and incubation temperature found that the best conditions came from considering all three together.
Colour and spread
Asparaginase did not significantly change biscuit colour in the modelling study, and did not change surface colour or spread in the study of different dough types. That is the main reason it is attractive compared with changing the recipe or the bake.
The bake still matters
In a baking experiment, acrylamide rose steeply as the thermal input increased, especially at higher temperatures. An enzyme complements a sensible bake profile rather than replacing it.
A practical plan
- Classify your dough: water activity, fat level and how it is formed.
- Check the dough pH and the raising agents.
- Build a resting step into the process if the enzyme is to have time to act.
- Trial against a control made the same day, and have acrylamide measured by an accredited laboratory.
- Check colour, spread and flavour alongside the acrylamide result.