Fluidised bed agglomeration of strawberry powder mix obtained for spray drying

Abstract

BACKGROUND: The microencapsulation process using spray drying (SD) represents an effective alternative in protecting the active components present in strawberries. However, microcapsules of strawberry powder mixtures present problems of instantanisation and flowability; an aspect that can be solved by agglomeration of the particles. OBJECTIVE: The aim of this study was to evaluate the influence of the fluidised bed agglomeration process on the flow, instantaneity and antioxidant properties of strawberry powder obtained by SD. METHODS: The response surface methodology (RSM) was used with a centred composite central design (α=1), considering the factors: fluidisation air temperature (50-70°C), time (30-50 min) and atomisation air pressure of the binder agent (1-2 bar). RESULTS: An increase in particle size was observed in the agglomeration process; the agglomerated particles showed a decrease in wetting time, the agglomerates of strawberry powder mixtures presented excellent instantanisation and fluidity, solving the problems identified in the microcapsules obtained by SD. CONCLUSIONS: Although the moisture and aw levels were increased in the agglomeration process, the values are within the microbiological and physicochemical food safety range; moreover, there was no effect on the phenol content and antioxidant capacity. The experimental optimisation achieved desirability of 68.4%, the optimum conditions being 70°C, 30 min and 1 bar.