Spray-Drying Optimization for Dunaliella salina and Porphyridium cruentum Biomass

Abstract

The compositions and cultivation advantages of microalgae increase their importance as sustainable food and feed sources. However, drying and encapsulation processes are needed for widespread use. In this study, Dunaliella salina and Porphyridium cruentum biomass were encapsulated by using spray-dryer (SD) and combined D-optimal methods. The independent variables were SD inlet temperature (170-190°C), maltodextrin (25-75%, w/w, in dm) and microalgae biomass (25-75%, w/w, in dm). Prior to spray drying, P. cruentum and D. salina were cultivated in a pilot scale tubular photobioreactor (PBR) and than harvested using a conical plate centrifuge. Significant models were determined for the effects of independent variables on total carotenoids, chlorophyll-a, crude protein, moisture content and encapsulation yield, water activity, average particle size, wettability, hygroscopity, L* and C* properties for both microalgae species (P<0.05). It was determined that biochemical and cell properties and composition need to developed unique spray-drying process for each alga. Also, due to the low moisture content (>6.27 g 100 g-1) and water activity (>0.277), the average particle sizes (>143.7 µm) of the samples with high stability were advantageous for various food applications and storage. However, due to the low encapsulation yield (11.1-33.1%), we recommend encapsulation and drying of P. cruentum biomass with alternative methods to spray dryer. The extracellular, as well as the cell wall and storage polysaccharides released into the culture medium of these microalgae are possible reasons for the low encapsulation yield.