Elderberry juice from Argentine Patagonia encapsulated by freeze-drying and spray-drying using different carriers: characterization and stability against heating and storage

Abstract

Elderberry is a rich source of bioactive compounds, particularly anthocyanins, making the development of stable ingredients containing these compounds of considerable interest. In this study, elderberry juice was microencapsulated using spray-drying and freeze-drying techniques with three carriers: maltodextrin (MD), whey protein concentrate (WPC), and soy protein isolate (SPI). The resultant powders were characterized for several physicochemical properties, including moisture content, water activity, hygroscopicity, water sorption isotherms, glass transition temperature (Tg), caking/visual aggregation, and colorimetric parameters. Although high anthocyanin retention was observed in all powder formulations, notable differences in physicochemical attributes were evident. The drying method significantly influenced water sorption isotherms and caking behavior under conditions of 38°C at 44% or 58% relative humidity (RH). Powders containing WPC and SPI demonstrated greater resistance to caking compared to MD-based powders; however, these differences could not be explained solely by Tg values, which were similar across all carriers at comparable moisture levels (48–53°C). After 9 days of storage at 38°C and 44% or 58% RH, powders formulated with WPC (spray-dried or freeze-dried) remained free-flowing, whereas spray-dried powders formulated with SPI exhibited limited agglomeration. In contrast, MD-based powders showed caking under all tested conditions. During thermal treatment at 85°C, freeze-dried powders exhibited a similar trend, with MD formulations displaying higher anthocyanin retention but lower resistance to caking, indicating that protein-based powders maintained superior physical functionality and anti-caking properties after thermal exposure or storage at elevated RH.