Optimization of spray drying condition and wall material composition for myrtle extract powder using response surface methodology

This study was aimed to optimize spray drying conditions (inlet air temperature: 120–180 °C) and wall material composition (maltodextrin (MD), gum Arabic (AG)) to obtain the powder of myrtle berry (Myrtus communis L.) extract having higher biological activities. Response surface methodology was used where maximum drying yield and minimum loss of total phenolics were dependent variables. Two optimum conditions were obtained: (1) a composition of 5.75 g maltodextrin/100 mL extract and 9.25 g gum Arabic/100 mL extract as wall materials at 180 °C inlet air temperature; (2) a composition of 3.75 g maltodextrin/100 mL extract and 11.25 g gum Arabic/100 mL extract as wall materials at 120 °C inlet air temperature. The second one was preferred due to lower phenolic losses. Optimum drying conditions provided the highest powder yield (39.89%) and least phenolic loss (16.95%). The bulk and tapped densities of the obtained powders were determined as 375.6 ± 9.7 and 609.6 ± 22.5 kg/m3, respectively. Total phenolics content and antioxidant activity of the obtained powder were found as 0.78 ± 0.01 g gallic acid equivalent (GAE)/100 g dry basic (db) and 1.69 ± 0.07 g trolox equivalent antioxidant activity (TEAC)/100g db, respectively. Particle size distribution was found between 0.69 and 16.175 µm. Epicatechin-3-0-gallate (EGC) and myricetin were main phenolics while D-limonene and α-pinene were main volatile components in the crude extract as well as in final powder product.