ANALYSIS AND MODELING OF BROWNING OF THE GRANNY-SMITH APPLE DURING DRYING

After proposing simple empirical models for drying kinetics and for so rption isotherms, the authors show that browning during drying of Gran ny-Smith apple samples can be calculated from models developped in sta tic conditions. The time at which the browning begins (tg) is similar to the induction time deduced from the static conditions; it correspon ds to a very low sample water content (around 1% dry basis) and to a s ample temperature equal io the heating temperature. The ''thermic past '' (drying method, drying rate, heating temperature before t(B)...) ha s no influence on the browning rate, only the heating temperature afte r t(B) is important.