to obtain a 20% and 40% weight reduction with 5000 W/m2
radiation intensity as compared to 11.2 and 37.3 min for hot
air drying, respectively. This was a 72.3% and 83.4% time reduction
or improvement of processing efficiency for the 20%
and 40% weight reduction, respectively.
The rate of weight reduction increased with the increase in
radiation intensity. It took 15.9, 9.5 and 6.2 min to achieve
40% weight reduction with the radiation intensities of 3000,
4000, and 5000 W/m2, respectively. This could be because
more heat was absorbed by the banana slices at a higher IR
intensity.
Nonlinear regression equations were developed for predicting
the weight reduction with the three radiation intensities at
a given time (Eqs. (1)e(3) for radiation intensity at 3000,
4000, and 5000 W/m2, respectively).
WR¼0:0559t2 þ3:4956t ð1Þ
WR¼0:0641t2 þ4:698t ð2Þ
WR¼0:1153t2 þ7:0529t ð3Þ
where WR is the weight reduction (%) and t is the time (min).
The predicted weight reduction fits well (R2 ¼ 0.99) with the
experimental weight reduction (Fig. 4). Therefore, the empirical
regression equations can be used to predict the weight reduction
under known drying process conditions.