Optimization of spray drying parameters for encapsulation of Nettle (Urtica dioica L.) extract

Abstract

This study aimed to optimize spray drying conditions using response surface methodology to investigate the effect of maltodextrin concentration (MC) (10–20 g/100 g), inlet air temperature (110–150 °C), and feed flow rate (2–6 ml/min) on some product and process aspects. According to the results, increasing maltodextrin concentration and inlet air temperature could significantly improve the process yield, and encapsulation efficiency. However, nettle extract's functional properties could be preserved via the retention of total phenolic compounds and the antioxidant activity of nettle extract by decreasing inlet air temperature. The optimum spray drying conditions to obtain the encapsulated nettle extract powder (ENEP) were determined as 150 °C inlet air temperature, 16.9 g/100 g maltodextrin concentration, and 3.4 ml/min feed flow rate. Additionally, X-ray diffraction (XRD) analysis showed the amorphous structure of ENEP at optimum conditions. Moreover, the scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the efficiency of encapsulation process.