Evaluation of Spirulina biomass as a protein alternative in spray dried powders: From initial suspension to powder properties

Proper operation of spray drying is essential to produce optimal algae-plant protein powder. Therefore, this study explores the behavior of Spirulina biomass compared to pea protein alone and in mixture, as potential milk analogues, in comparison with skim milk during spray drying at laboratory scale to produce instant powder. In particular, the particle size distribution, the rheological behavior and the physical stability of the initial liquid feed for the different formulations were characterized and their influence on the physical and end-use properties of the powders produced was highlighted. The results revealed that the feeds containing Spirulina had a shear-thinning behavior, with a very high viscosity that contributed to the physical stability of the suspension. The addition of pea protein was interesting to decrease the feed viscosity. In the chosen conditions, spray dried powders were obtained with a satisfying process yield (> 50 %) and water activity (< 0.2). Due to their small size (<16 μm), the powders were cohesive with a poor flowability, but compared to skim milk, and pea protein alone, it was better for Spirulina based powders. Powder rehydration was obtained readily, with a very good wettability of the powders with Spirulina but the initial suspended particle size distribution was not totally recovered probably due to some changes under high shear during atomization and high temperature during drying that also had an impact on the color of the powders. From the powder and process point of view Spirulina biomass and pea protein appear as promising candidates for creating alternative milk analog powders, but the sensory and functional aspects must be further considered.