by Peter Török
As part of his MSci project Karim Bahsoon has been investigating the effects of varying blanching time on the properties of french fries. Jason Chang, who works with Karim, is involved in measuring surface starch content and crunchiness of the ready chips.
Potatoes were cut into fries and placed in boiling water for times varying from 0-12 minutes. These were then submerged in vegetable oil at 170C for 4 minutes and then fried again at a higher temperature of 190C for a further 2 minutes. The second fry is thought to help with crust formation and adds to the crunchiness of the fries.
By measuring the density of the fries before and after the cooking process, we found that the density ratio of the fries decreased with increasing blanching time. We also saw thicker crust formation and sustained crunchiness of fries blanched for longer. Unfortunately prolonged blanching times also meant the fries were fragile and almost falling apart before frying, so care had to be taken when handling these.
We plan to test alternative methods such as introducing a drying stage to the process as well as looking at the transportation of starch during blanching to get a better understanding of how to make the perfect french fries.