Influence of Drying Conditions on the Hazelnut Quality. III. Browning

Abstract

The influence of drying conditions on browning in hazelnut (Corylus avellana L.) has been studied by means of color measurement. Samples of unshelled and shelled hazelnuts were dried under six air temperatures (30. 40, 50, 60, 70 and 80°C). The drying experiments were done with forced air circulation, and two varieties of hazelnut were investigated, Negret and Pauetet. CiELab system was used to evaluate changes in total color (δE^∗), lightness (L^∗), chroma (C^∗) and hue angle (H^∗) on dried hazelnuts. Browning of hazelnut was observed to occur a1 all temperatures studied. The rate of pigment formation was determined from the δE' values with zero-order kinetic model, and temperature dependence was described by the Arrhenius equation with an activation energy (E_a) varying from 28 to 39 kJlmol. Negret variety showed the highest rate of browning.