Résumé
Moisture sorption isotherms of apples and pears were determined at 30, 45, and 60°C and water activity (a
w
) range of 0.04-0.83 using a standard static gravimetric method. The sorption isotherms of both fruits decreased with increasing temperature and exhibited type III behavior according to Brunauer-Emmett-Teller (BET) classification. The moisture desorption data fitted well with the Peleg model (0.997 ≤ r ≤ 0.999, 0.009 ≤ SE ≤ 0.071, and 4.840 ≤ p ≤ 13.779).
The glass transition temperature (T
g
) of both fruits decreased linearly with the increase in water activity (a
w
). The variation in glass transition temperature versus water activity (T
g
∼ a
w
) and glass transition temperature versus solid fraction of pears and apples (T
g
∼ W
s
) were adequately predicted by Khalloufi et al.'s model (0.998 ≤ r ≤ 0.999 and 0.007 ≤ SE ≤ 4.088) and the Gordon and Taylor model (0.879 ≤ r ≤ 0.979 and 9.798 ≤ SE ≤ 18.507). The thermal transition and desorption isotherms data were used to establish state diagrams of pear and apple and evaluate suitable fruits storage conditions.