Characterization of thin layer drying of Spirulina platensis utilizing perpendicular air flow

Spirulina is the most extensively used microalgae for animal and human nutrition mostly because of its high protein content, 60-65% on a dry weight basis. The drying is the most expensive operation. The aim of the study was to characterize drying of Spirulina platensis in thin layer. A Statistical model was applied to analyze the effects of independent variables (air temperature and loads of solids in the tray) on the response of solubility in acid medium. The analysis of phycocyanin content was determined at the best drying condition. The Spirulina isotherm data were adjusted through Guggenheim, Anderson and de Boer (GAB) and Brunauer, Emmett and Teller (BET) correlations. The nonlinear regression analysis of isotherms data showed that the GAB equation more effective adjusted the experimental data (R2 > 99% and E% < 10%). Drying curves of Spirulina showed only a decreasing rate-drying period. The material load and the interaction between the air temperature and material load were significant effects (P ⩽ 0.05), and the best results of solubility in acid medium (≈79%) occurred at 60 °C and 4 kg/m2. In under these conditions the phycocyanin content was determined to be 12.6% of dried Spirulina.