Analysis of wheat gluten and starch matrices during deep-fat frying

An important quality parameter of fried food is the amount of oil uptake, which is incompatible with recent consumer trends towards healthier food. The oil penetration mechanism is not fully understood but study of formulated products is a good way to elucidate the role of the food matrix in oil absorption.In this context, the oil absorption capacity of a restructured matrix, made with native wheat starch and vital wheat gluten, was examined. Four different product formulations were analysed, using 2 levels of gluten content (8% and 12% d.b.) and 2 levels of water content (38% and 44% w.b.). Dough was sheeted into 2 thicknesses (1 and 2 mm) and cut into discs that were either directly fried or fried after predrying with dry air (2 min at 150 °C).Results showed that gluten had a predominant role in the structure, making the dough more elastic and less permeable to oil absorption. High gluten content resulted in lower oil uptake in products with low moisture content. Overall, predried discs absorbed, on average, half of the oil of undried samples. Interestingly, even though predried products with high gluten content had a higher moisture content before frying, they absorbed a low amount of oil, suggesting that oil uptake is not clearly related to the amount of moisture lost but rather to product microstructure.