Deep fat frying of potato strips - Quality issues

Moisture loss and oil adsorption kinetics, structural properties (apparent density, true density, specific volume and internal porosity), color change s and viscoelastic behavior (compression tests, crispness) were investigate d during deep fat frying of french fries. The effect of frying conditions t oil temperature, sample thickness and oil type), drying pretreatment and os motic dehydration pretreatment on the above properties was also examined. T he results showed that oil temperature and thickness of potato strips have a significant effect on oil uptake, moisture loss and color parameters of f rench fries, while the use of hydrogenated oil in the frying medium does no t affect these properties. The porosity of french fries increases with oil temperature increases and sample thickness and it is higher for products fr ied with hydrogenated oil. Maximum stress and maximum strain increase durin g frying, while crispness of potato strips is higher for hydrogenated oil, and lower for refined oil. Air drying and osmotic pretreatment increase por osity of fried potatoes but decrease their oil and moisture content. A nega tive effect on color development with drying time was also observed. Pre-fr y drying as well as osmotic pre-treatment increases the maximum stress and maximum strain of french fries during frying. Air drying pre-treatment incr eases the crispness of potato strips while osmotic pre-treatment does not a ffect it, with the exception of sugar solutions.