Acrylamide

Acrylamide is a substance that forms during baking, frying, deep-frying and roasting when sugar reacts with asparagine, an amino acid (one of the building blocks of protein) – from around 120 °C, and mainly where food turns dark brown. Starchy foods are affected: chips, crisps, fried potatoes, crispbread, bread crust, biscuits, breakfast cereals and coffee. It doesn't form during boiling or steaming, because the temperature stays at 100 °C.

Why it matters: the International Agency for Research on Cancer (IARC) classifies acrylamide as “probably carcinogenic to humans” (Group 2A), and in 2015 the European Food Safety Authority (EFSA) concluded that intake from food is a health concern. Since 2018, binding measures and benchmark levels have applied to manufacturers and the catering trade in the EU. Relative to their body weight, children take in the most, because they love chips, biscuits and crisps.

The German Federal Institute for Risk Assessment (BfR) has summed up the rule for home cooking in three words: “Golden, not burnt.” In practice: don't store potatoes in the fridge (the cold produces sugar, which leads to more acrylamide when they're fried), soak raw potato pieces in water for 30 minutes before frying, heat frying oil to no more than 175 °C, bake at no more than 200 °C with conventional heat and 180 °C in a fan oven, toast bread only until light brown, and cut off dark spots and edges. Chunky potato wedges are better than thin fries, because less surface area browns.

Don't panic: acrylamide can't be avoided completely, and the occasional tray of oven-roasted potatoes is no cause for concern. It's the habits that count – a daily bag of crisps matters more than the Sunday roast. If you steam and boil more often and eat plenty of vegetables anyway, you'll lower your intake automatically.