Optimization of encapsulation of stevia glycosides through electrospraying and spray drying

Stevia rebaudiana represents a promising, natural sweetener. Stevia's sweet ingredients are called steviol glycosides and although they are absolutely safe for consumption, their bitter and metallic aftertaste acts as inhibitory agent for the widespread use of the sweetener. In this study, two encapsulation methods, spray drying and electrohydrodynamic method (electrospraying) were applied in Stevia in order to improve its quality and limit the unpleasant aftertaste of its glycosides. Maltodextrin-inulin (50:50) at concentrations of 5 and 10% for spray drying and zein at concentrations of 10 and 15% for electrospraying were used as matrices. Various operating parameters were examined during each method and their effect on the quality of the produced structures was evaluated so that the encapsulation process is optimised. HPLC showed that spray drying showed satisfactory encapsulation efficiency with a maximum value of 66.37%, while electrospraying achieved 67.47% as the best yield. SEM analysis of electrosprayed and spray dried products showed spherical particles with mean diameters of 1.35 μm and 6.02 μm, respectively. DSC analysis demonstrated that glass transition temperature ( T g ) of the encapsulated structures was lower than that of the pure matrices and was highly affected by the process conditions. The encapsulation of stevia by both techniques and the development of no chemical bonds between the matrices and stevia glycosides were confirmed in the ATR-FTIR spectra of the encapsulated particles. The success of stevia glycosides encapsulation by electrospraying and spray drying is a possible alternative to masking Stevia's bitter taste and finally to its introduction into innovative products. • The encapsulation of steviol glycosides into the polymer matrices is successful. • The operating parameters significantly affect the particle size and EE. • Spray drying using maltodextrin: inulin results in EE of 73.81%. • Electrospraying using zein achieves slightly higher EE equal to 75.87%. • The produced particles can be used as functional ingredient for food systems.