Effect of spray drying at 150, 160, and 170 °C on the physical and chemical properties of maqui extract ( Aristotelia chilensis   (Molina) Stuntz)

Maqui (Aristotelia chilensis (Molina) Stuntz) is a native Chilean berry that has the highest antioxidant level compared with other fruit. Anthocyanins, which are the compound with the highest functional level found in maqui, are relatively unstable and quite susceptible to degradation during processing and storage. In addition, maqui is a highly perishable seasonal fruit and it is necessary to find conservation methods for the developed products. Microencapsulation is one way to protect anthocyanins from degradation reactions; it is defined as a process by which certain bioactive substances are introduced in a matrix or wall systems aimed at impeding their loss and protecting them from the reaction with other compounds and/or prevent them from suffering oxidation reactions caused by light or oxygen. The objective of the present study was to evaluate the effect of drying inlet temperature on the physical properties, total polyphenol content, total anthocyanin content, and antioxidant activity of spray-dried maqui extract. Inlet temperatures were 130, 150, and 170 °C, while other parameters were constant, such as feed flow (18 mL min^-1) and encapsulating agent concentration (maltodextrin and gum Arabic). The best drying inlet temperature was 170 °C; it produced powders with lower moisture content (1.61%), water activity (0.15), and L* coordinate (11.16), as well as increased hygroscopicity (24.01%) and solubility (92.70%). The lowest total polyphenol content loss (23.05 mg gallic acid equivalents g^-1), total anthocyanin content (21.46 mg cyanidin-3-glucoside g^-1), and antioxidant activity (85.76% 2,2-diphenyl-1-picrylhydrazyl inhibition) occurred at 170 °C. The size of the powder particles allowed classifying them as microcapsules. Maqui extract microencapsulation provides powders with adequate stability during storage.