POROSITY DEVELOPMENT AND ITS EFFECT ON OIL UPTAKE DURING FRYING PROCESS

ABSTRACT The objective of this work was to study certain physical properties of French fries, such as density and porosity, and their relationship with oil absorption during the frying process. The effects of oil temperature and frying time on moisture loss, oil content and crust thickness were first studied. Changes in apparent density, absolute density as well as porosity during two successive periods of frying process (frying and cooling) were then investigated, and possible reasons for these changes were discussed. Finally, the porosity changes were related to oil uptake. Potatoes were cut into rectangular shapes and were fried at different oil temperatures (140, 155, 170 and 185C) for periods ranging from 60 to 240 s. Results showed that during frying, the porosity of the product increases, reaching a maximum at the end of frying, whereas during the cooling period, it decreases because of oil absorption and collapse phenomena. PRACTICAL APPLICATIONS This study shows some physical changes that can be related to oil absorption during the frying process of French fries. Many food research projects attempt to understand oil uptake during the frying process in order to control and reduce the fat content of fried products. The results of this work may lead to finding the way(s) to produce less greasy fried products.