Abstract: Surface and internal temperatures, water vapor pressure and oil adsorption rate changes in different stages were measured during the deep-frying and cooling processes of cylindrical potato strips. It was found that continuous water vapor escape from the porous shell layer could prevent oil from entering potato strips during the deep-frying process. During the cooling process, over 70% of oil was absorbed into the porous shell layer, providing an impetus for oil absorption—The difference in water vapor pressure between the inside and outside of the shell layer was very sensitive to ambient pressure. Cooling of fried potato strips was studied in different vacuum environments. The results obtained showed that under an absolute pressure of 80 kPa, the total oil absorption rate was decreased from 40% to 13.6%, suggesting that vacuum environments could reduce the water vapor pressure difference between the inside and outside of the shell layer, effectively promote the detachment of adherent oil droplets from the surface, impeding their absorption into the structure of fried potato strips and therefore reducing oil uptake.

Key words: vacuum method, oil absorption rate, fried food, low oil food