Want perfect roasties? Cut them at 30-degree angles

COOKS have long argued over how to make the perfect roast potato but it appears the answer has come from an unlikely source – mathematicians.

Celebrity chefs including Heston Blumenthal and Jamie oliver suggest cutting potatoes to maximise their flat edges but the details are left to the individual and many people just chop their potatoes in four.

But students at the University of Essex used mathematics to come up with a precise slice for your roasties. Using a typical large potato measuring about 5in by 2in they found that cutting it at 30- degree angles into four fan- shaped portions increases its surface area by 65 per cent. This apparently allows more flavour to be absorbed by the potato, while creating the perfect golden brown crispy coating.

The students roasted 100 ‘fan’ potatoes and put them to a taste test against potatoes cut in the conventional way. A number of chefs were among those asked to rate the roasties and the fan method came top in each of four categories – taste, crunch, appearance and overall.

Adrian Martin, vice-principal of the university’s Edge Hotel School, said: ‘We tested multiple-angled cuts which delivered four equal portions, eventually arriving at the final fan shape cut as the mathematical maximum possible surface area.

‘I think it tastes better because the surface area allows more flavour to be absorbed by the potato. Furthermore, the reduced width creates a greater crunch.’

Surface area is thought to be important when it comes to crunchy roast potatoes because a greater area offers more routes for moisture to escape.

Mr Martin said: ‘The reduced width of the potato creates a greater “snap” effect when biting down on the potato. Coupled with the greater absorption of fat they combine for a higher crunch value in the test. The reduced depth of the potato also means the internal substance is cooked more.

‘It turns out the magic ingredient for the best roast potato is maths – anyone looking for a fun application for advanced mathematics need look no further.’