MONOLAYER VALUES AT 30-DEGREES-C OF VARIOUS SPICES AS COMPUTED BY THEBET AND GAB MODELS

The monolayer values at 30 degrees C of 17 spices of various botanical families, obtained from different parts of the plant and commercially marketed in diverse forms, were determined from stepwise moisture ads orption data at four relative humidities over the lower 50% of water a ctivity (a(w)) values by using the BET and GAB equations. Fitting was similarly good for five spices, better by the BET equation for five ot her spices, and better by the GAB equation for another three, the expe rimental results provided by the remaining four species being fitted b y neither equation. The monolayer values determined by the three-param eter GAB model were not always larger than those obtained by use of th e simpler two-parameter BET equation, which appears to be more accurat e in those cases where only sorption data for the low a(w) range are a vailable.