Integrated approach for interpreting browning rate dependence with relative humidity in dehydrated fruits

Maillard reaction is relevant to define dehydrated food stability. The objective of this work was to evaluate the browning development in freeze-dried fruits as a function of relative humidity (RH) in relation to the physical properties of fruit materials. Intact tissue discs of melon and pear were freeze-dried and equilibrated in a broad RH range. The changes in reflectance were analyzed using a computer vision system, which was appropriate to determine the appearance changes during storage of dehydrated fruits. Time resolved 1H NMR, thermal transitions, structural collapse and water sorption isotherms were evaluated. The browning rate versus RH curve presented a bell shape which could be related to the information provided by the determinations of the physical properties. The results allowed the integration of water sorption information, 1H NMR relaxation times, T–Tg, and structural collapse to interpret the browning rate versus RH behavior of fruit systems.