DYNAMICS OF OIL UPTAKE DURING DEEP-FAT FRYING OF POTATO SLICES

The uptake of oil during deep-fat frying of potato slices was followed by frying slices for an equal length of time, introducing a fat-solub le and heat stable dye bite the oil at different times before the end of frying and measuring the fraction of dyed oil compared to the total oil content. Total oil content was measured by a refractometric metho d, and the content of dyed oil by a spectrophotometric method. Results from these measurements were compared to those obtained by removing s lices after various periods of frying and analysing far content. The e xperiments with dyed oil showed conclusively that oil does not penetra te the potato slices during frying, but is taken up by the slice only when it is removed from the frying pan due to adhesion of oil to the s urface of the slice. Therefore, oil uptake is primarily a surface phen omenon involving art equilibrium between adhesion and drainage of oil upon retrieval of the slice from the oil bath. (C) 1996 Academic Press Limited