Microscopic examination of potato chips and French fries has provided conclusive demonstration that the cellular structure remains intact and that the cell walls rarely, if ever, rupture during the deep-fat frying process. Blistering of chips is a result of simple cell separation due to expansion of steam trapped within the slices when the surface become dehydrated and sealed. Deep-fat frying is essentially a cooking and dehydration process during which the starch content of the cells is gelled and dehydrated and and some of the water in the tissue is replaced with oil. Most of the oil in finished chips is distributed in the cell walls, inter-cellular spaces and blister areas. Apparently much less of the oil present in chips is held between the gelled starch granules within the cells although oil penetrates some intact cells at the original surface of the slices.