The aim of this work was to evaluate the influence of inlet air temperature (160 or 180 ºC) and maltodextrin concentration (5, 15 or 25%) on the physicochemical characteristics of powdered blackberry juice produced by spray drying. The final product was analysed with respect to moisture content, hygroscopicity, water activity, anthocyanin content, colour, particle size distribution and microstructure. Higher inlet air temperatures resulted in decreases in moisture content, water activity and anthocyanin retention, besides the formation of larger sized, more hygroscopic particles. Temperature only showed a significant effect on the reduction of the L* and C* values for treatments carried out with 25% maltodextrin concentration. Regarding the microstructure, particles produced at 180 ºC showed smooth surfaces and a greater degree of uniformity in comparison with samples spray dried at 160 ºC. An increase in maltodextrin concentration promoted the production of less hygroscopic particles with lower moisture content. Furthermore, these powders showed lower anthocyanin contents, due to dilution of the fruit pigments, leading to an increase in the L* values and reduction in the chroma and hue angle values. The treatment carried out at 160 ºC with 5% maltodextrin was the most effective in maintaining the anthocyanin content of the powder, with a pigment retention of about 80%.
Blackberry powder; Particle size; Anthocyanin; Hygroscopicity; Microstructure
