Fresh potato tubers (Agria variety, all from the same producer,geographical region and harvesting period) were stored and conditioned under regulated temperature and relative humidity as described by Lisin´ ska and Gołubowska (2005). It must be stressed here that our interest is on direct frying of raw potatoes since frying of raw potatoes can serve as reference for comparisons in subsequent work with pre-processed potatoes. The potato tubers were graded with regards to their specific gravity by putting them in salt solutions of appropriate densities (the accuracy of setting the salt solution density was better than 0.03%). From the inherent variability tests it was found that 90% of the potato stock had a specific gravity between 1.070 and 1.100 g/cm3 and only these potatoes were used during frying experiments. The potatoes were
cut in sticks (40 9.8 9.8 mm).