Application of Peleg's equation in desorption studies of food systems: A case study with sago (Metroxylon Sagu Rottb.) starch

Moisture desorption is pertinent to the modelling of dehydration of food sy stems. The variation of moisture content with time during desorption of sag e starch from six towns in Papua New Guinea was analysed using Peleg's equa tion. Three temperatures (30 degrees, 40 degrees and 45 degrees C) and four a(w) ranging from 0.103 - 0.923 were studied. The equation gave a highly s ignificant fit to the experimental data (r(2) = 0.998 - 1.000), the two con stants (K-1 and K-2) were obtained and both constants varied significantly (p < 0.05) with the source of the starch, temperature and aw. K-2 was used to calculate the (true) equilibrium moisture content and this was unaffecte d by the length of the curve used in the computation. The true equilibrium moisture content approximated the moisture content that would have been obt ained when weight changes were fairly constant (pseudo-equilibrium moisture content). The true equilibrium moisture content was shown to be more relia ble and consequently recommended for sorption studies.