Osmotic dehydration is a process for partial removal of water content, based on immersing plant or animal tissue in a suitable hypertonic solution. In this study, the effect of osmotic dehydration (as a pretreatment to freezing and frying potato strips (var. agria) to produce low-fat French fries) on the quality of final product was studied. To determine the conditions for osmotic dehydration, the effect of different parameters such as concentration as well as composition of solutions (binary or ternary composed sucrose, corn syrup DE=42 and NaC1) on osmotic dehydration was studied. The effects on water loss along with solute gain (specially salt gain) on potato strips as more practical observeation were determined. After determination of the best condition for osmotic dehydration, osmo-dehydrated and control samples were frozen then fried (in the same conditions). The effect of osmotic dehydration on the quality attributes (color, shape and taste) along with the oil uptake of French fries was studied. The results show that osmotic pretreatment using a ternary solution composed of 50% (W/W) corn syrup and 5% (W/W) NaC1 at 60°C during 1 hour provides the desired dehydration level (about 35-40%). In this way, solid gain into strips was very low with its main portion being salt. Also sensory analysis showed that the sample pretreated with this solution is of a better quality considering either of the taste or color properties. A comparison between control and the osmosed samples shows that osmotic pretreatment can significantly decrease (about 50%) oil uptake in French fries.
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