Determination of Biological Activities and Color Kinetics of Spirulina platensis During Convective Air Drying

Abstract

Spirulina platensis (S.platensis), procaryotic microalgae, is favored as a functional food owing to\rthe high protein content, fatty acid, phenolics, vitamins, and minerals preferred by consumers. Producers prefer\rto sell it in dry form because of the shipping and shelf-life advantages. This study intends to describe the effect\rof convective drying on biological activities and color changes of S.platensis. Firstly, mass production of S.\rplatensis was accomplished in flat-panel bioreactor, and harvested cells were dried by a convective hot air dryer.\rConvective drying treatments were carried out at 40, 45, and 50 °C. On the contrary of the total phenolic\rcontent values, an increase in the temperature from 45ºC to 50 ºC was more effective than the increase from 40\rºC to 45 ºC on the antioxidant capacity of the samples. Activation energy values were calculated for the\rantioxidant capacity and total phenolic content were about 24.46 kJmol-1 and 24.94 kJmol-1, respectively. The\rcolor values (L, a, b) were measured, and the total color difference (?E) was calculated as 3.019, 2.98, and 2.94\rat 40, 45, and 50°C, respectively. ?E characterized by a zero-order model and the activation energy (Ea) for\rchange in ?E was calculated as 50.15 kJ.mol-1. The results indicated that the most suitable temperature most\rsuitable temperature for convective drying for S.platensis would be nearly 50°C.