Vegetable tissues undergo some degree of shrinkage during
drying process. This statement is supported by Brennan et al. 43
who showed the fact that usually in the early stage of drying, at
low rates, the amount of shrinkage bears a simple relationship
to the amount of moisture removed. Towards the end of drying,
shrinkage is slowly reduced so that the final size and shape of
the material is fixed before drying is completed. Other
researchers also reported that shrinkage of foodstuffs during
drying may influence their drying rates due to the changes in
drying surface area and the setting up of pressure gradients within
the material 44.
Colour (L, a and b): To assess the colour of dried kaffir lime
leaves, the value of L (lightness), -a (greenness) and b
(yellowness) were investigated. Both the quadratic and the main
terms showed significant (p0.05) influence (Table
4). The results revealed that both main effect of drying time and
drying temperature and their quadratic effects had no significant
(p>0.05) influence on colour-L. Also, the interaction effect of the
independent variables had no effect on colour-L. The individual
region led to maximum values for colour-L, colour-a and colour-b
(Y4 = 46.90 ± 0.67), (Y5 = -0.89 ± 0.17), (Y6 = 11.28 ± 0.46) predicted
to be obtained at 4.9 h of drying time, 60°C drying temperature
and 1.4 kg/m2 loading capacity.