Effect of inlet air temperature and carrier type and concentration on physicochemical and antioxidant properties of microencapsulated Marjoram extract by spray drying

The aim of this work is to investigate the inlet air temperature (140, 160 and 180 °C) and carrier type (maltodextrin vs. Arabic gum) as well as carrier concentration (10, 20 and 30% W/V) on the physicochemical and antioxidant properties of spray dried sweet Marjoram extract. Samples were evaluated for moisture content, water activity, bulk and tapped density, solubility, wettability, hygroscopicity, flowability behavior (Hausner ratio and angle of repose), color indices, microstructure, total phenolic content and DPPH free radical scavenging activity. Powder production yield in the spray drier was also determined. The results showed that powder production yield (21.47-44.62%), moisture content (1.18-2.22%) and water activity (0.106 to 0.206) of powders were significantly affected by the carrier type, concentration and the inlet air temperature. Bulk and tapped density and flowability indices (higher flowability) of powders decreased with an increase in carrier ratio and inlet air temperature. Hygroscopicity and solubility was positively affected by inlet air temperature and negatively affected by increasing carrier concentration. Increasing inlet air temperature and carrier concentration led to deterioration of powder color. Total phenolic content and radical scavenging capacity of spray dried powders were decreased by increasing in air temperature. Increasing in carrier concentration led to an increase in total phenolic content. Microstructure of samples showed that the powders produced with Arabic gum had similar size and higher shrinkage than those produced with maltodextrin. However, the latter had smoother surface.