Twelve sources of equilibrium moisture content (EMC)/equilibrium relat
ive humidity (ERH) data for rapeseed were identified from which 668 ex
perimental points were extracted. Among them, ten sources covered a wi
de range of temperatures, thus producing 21 sub-sets of data suitable
for the evaluation of EMC/ERH isotherm equations. Four commonly cited
rapeseed EMC/ERH equations, i.e. modified Henderson, modified Chung-Pf
ost, modified Halsey and modified Oswin equations were compared for th
eir ability to fit these data sub-sets based on the residual sum of sq
uares (RSS), standard error of estimate (SEE) and mean relative deviat
ion (MRD). The comparisons show that the modified Halsey equation is t
he best equation for describing the EMC/ERH isotherms of rapeseed. The
modified Halsey equation was then used to fit the data sets merging a
ll the data for adsorption, desorption and the combined data set in tu
rn. The best fitted coefficients for both equilibrium relative humidit
y h(r)=f(M, T) and equilibrium moisture content M =f(h(r), T)are given
, where T is the temperature. These fitted equations are based on a la
rge data set and therefore provide a useful basis for future work on d
rying and storage of rapeseed. (C) 1998 Silsoe Research Institute.