A number of researchers have investigated the application of annatto seeds in animal feed (SILVA et al.
A feasible option for annatto seeds is the powder form, which can be incorporated to other seed powders traditionally consumed in breads and cookies, among others.
Annatto seeds were donated by the Marata food company, whose headquarters is located in Sergipe State, Brazil.
For obtaining powders, annatto seeds were processed in two ways: in the first, seeds were preserved with the oil layer remaining from the bixin extraction, and in the second, the oil layer was removed by washings with water and neutral detergent.
In this respect, the aim of this study was to dry annatto seed powder in the sun, with and without the oil layer, resulting from bixin extraction, to fit different mathematical models to experimental data and to calculate effective moisture diffusivity of the samples.
Figure 1 shows temperature, relative humidity and sunlight values observed during sun drying of annatto seed powder with (Treatment 1) and without (Treatment 2) oil.
Table 2 lists initial and final moisture content of annatto seed powder.
Table 3 displays the parameters for Diffusion Approach, Two Terms, Midilli, Page and Thompson models fitted to the experimental points of sun drying kinetics of annatto seed powders, and their respective correlation coefficients ([R.
Table 4 shows mean values of effective moisture diffusivity determined for annatto seed powders.
Sun drying of annatto seed powder with and without oil was effective in lowering initial moisture content from approximately 20% w.