Optimization of Spray Drying Parameters and Wall Material Composition of Juniper (Juniperus drupacea L.) Extract Using Response Surface Methodology

The aim of this study was to produce a juniper extract powder rich in some bioactive and volatile components such as phenolics, α-pinene and d-limonene with a high yield. For this purpose, the juniper extract, which can be used in various food formulations, was spray-dried under optimized conditions. In this optimization, inlet air temperature (120°C - 180°C) in the spray drying process and the carrier composition were selected as independent variables, while dependent variables included drying efficiency and the total phenolic (TPC), and α-pinene contents of the extract powder. Response surface methodology was used to maximize product yield, TPC and volatile levels, especially α-pinene. The optimum inlet air temperature and carrier ratio were 180ºC and 15 g gum Arabic (GA) per 100 mL extract, respectively. The highest powder yield (37.92%), TPC (9.91 mg GAE/g dm powder) and α-pinene content (peak area 1.3×107) were obtained under the optimum conditions while the bulk and compressed bulk densities, TPC and antioxidant activity of the extract powder were 0.39±0.01 g/cm3 and 0.51±0.02 g/cm3, 9.89±0.27 g gallic acid equivalent (GAE)/100 g (dm) and 4.12±0.14 g Trolox® equivalent antioxidant activity (TEAC)/100 g dm, respectively. The particle size of the powder produced under optimum conditions ranged from 1.09 to 22.39 µm. Fifteen volatiles in both juniper extract and the reconstituted form of the extract powder were identified, and the major components of juniper extract were d-limonene, α-pinene and γ-muurolene.