Ni and Datta (1999) also reported the pressure to rise with evaporation and attaining a maximum value at the evaporation front. During the latter stages of frying, the pressure drops rapidly andattains a negative value at the end of frying. The pressure stays negative throughout the cooling period, but the drop was not as steep as it was during the frying period. The pressure drop inside the product could be due to the collapse of the cellular structure, escape of vapors from the cellular cavities, capillary forces or a combination of these factors. The negative pressure inside the product is expected to enhance oil uptake. This negative pressure can act as a driving force for oil uptake inside the product. The pressure drop begins during middle of frying period, which may result in the oil uptake and absorption during frying. Moreira et al. (1997) reported that for tortilla chips only 20% of the oil uptake happens during frying while 64% of final oil content is absorbed during cooling period. The pressure drop during the frying period may initiate the movement of oil into the product during the frying stage itself, which continues till the end of frying. When the product is taken out of the oil for cooling, the oil is expected to be distributed non-uniformly between the surface and interior of the product as shown during numerical simulations by Halder et al. (2007). The continuous pressure drop and negative pressure during cooling can act as a mechanism, which further forces the oil from the surface to move into the core of the product.