By having a closer look at the effect of overnight tempering at
ambient during the first tempering period (TP1) moisture reduction was greatest in the 60C as compared to those at 70C and
80C(Table 2). The reduction in moisture content during TP2
was about 0.15% and not as significant as compared to TP1 in the
60C treatment. The drop in moisture content was due to two factors namely the residual heat inside the beans still sufficient to
evaporate small amount of moisture and also due to the driving
force (moisture gradient) exist between the inner core and the
drier outer surface.Table 2shows that the higher the moisture
content before TP1 (e.g. 24.18% at temperature 60C), the greater
is the moisture content reduction and vice versa.Thakur and Gupta
(2006) reported similar observation in paddy grain drying with
intervening rest period where moisture diffusivity was higher
when the grain was rested at higher moisture content as compared
to those at lower moisture content. The diffusivity at this stage is a
function of both residual grain temperature and moisture content