Maximum quality and minimum acrylamide content were on the agenda for a recent link-up between Swiss food scientists. The results of their quest? The optimum conditions are now defined.
Food scientists at the Swiss Official Food Control Authority and the School of Hotel Management in Zurich set out to prepare French fries in oil and in ovens, with the ultimate aim of achieving 'optimum culinary quality combined with a minimum acrylamide content'.
Reporting their findings in the latest issue of European Food Research and Technology Koni Grob and colleagues said that French fries with 40-70 g/kg acrylamide were consistently produced, in other words, with five to 10 times less acrylamide than normally found in French fries.
So what's the method? According to the scientists, the raw potato should be low in reducing sugars - a suitable cultivar - and stored at temperatures of no less than about 10 degrees C.
After cutting and elimination of the fines, the potato was immersed in standing cold or boiler-warm water for about 15 minutes in order to extract asparagine and sugars from the surface without washing out the starch.
Pre-frying in oil - 140 degrees C for 2.5 min - improves crispiness but frying should occur at an initial oil temperature of about 170 degrees C, adding some 100 g potato per litre of oil, said the researchers.
The scientists warned that since acrylamide formation increases exponentially towards the end of the process, the most important factor to cut acrylamide content is the determination of the proper end point of the frying process.
"French fries should be crispy with slight browning of the tips to achieve the typical flavour, but without general browning. Preparation in the oven, starting from frozen prefabricates, requires temperatures of around 190 degrees C or 220 degrees C, depending on whether or not the air is circulated. The proper determination of the end point is again the most critical step," said the study authors.
The full findings of the study are published in the September issue of European Food Research and Technology (2003, 271 (3): 185-194, DOI: 10.1007/s00217-003-0753-9 ).