Using phycocyanin as a marker to investigate drying history and structure formation in spray drying

Abstract

Knowledge of drying history and structure formation is essential for the quality of spray dried products. In this study, these factors are investigated using the denaturation of phycocyanin. By studying the denaturation kinetics of this marker, added to the feed solution, it was found that denaturation can neither occur in the constant drying rate regime nor in the final stage of drying, as the temperature (T < 60 °C) and the moisture content (aw < 0.6) is too low, respectively. Thus, it was concluded that phycocyanin denaturation is influenced by the crust formation during spray drying. This was applied to pilot scale spray drying, where the effect of air inlet and outlet temperature, air moisture content, feed solids content and particle residence time was investigated. The qualitative agreement between phycocyanin denaturation and the determined particle structure provides a basis for the validation of models, predicting structure development during drying.