Effects of Spray Drying Conditions on the Stability and Antioxidant Properties of Spray-Dried Soluble Mate

The aim of this research was to evaluate the stability of spray-dried soluble mate (Ilex paraguariensis) and its total polyphenol content determined with the Folin-Ciocalteu assay, after it was elaborated with three different maltodextrin concentrations (0, 7.05 and 14.10% w/ v) using experimental data of water activities and glass transition temperatures. Adsorption isotherms were determined for these three materials at 25 degrees C between water activity values (a(w)) of 0.1 and 0.85 (resulting in values of water content between 0.04 and 0.33 g of water/ g of dried solid). Glass transition temperatures varied from 15 to 52 degrees C. At room temperature powder containing 14.10% of maltodextrin at a(w) = 0.55 was below the glass transition temperature, while the two other compositions were below their T-g and stable at a(w) = 0.40. In the spray drying conditions analyzed, the loss of polyphenolic compounds is negligible. The total polyphenol content varied between 28 and 45 chlorogenic acid equivalents (g % dry powder).