The Influence of Carriers on the Physicochemical Properties of Freeze-Dried Purple Sweet Potato

Physicochemical Properties of Freeze-Dried Purple Sweet Potato

Abstract

Purple sweet potato (Ipomoea batatas L.) is a rich food with vibrant color and a variety of beneficial phytochemicals. Purple sweet potato is increasingly being encapsulated for several reasons, primarily to enhance its antioxidant effects, improve its stability, and facilitate its use in food applications. By encapsulating extracts or powders, beneficial compounds are better protected from environmental factors, increasing their overall stability and bioavailability. Encapsulated forms of purple sweet potato show improved shelf life and stability during storage. Microencapsulation is an important technique used to improve the physical properties of powders. This study investigates the physicochemical properties of freeze-dried purple sweet potato powders encapsulated with various wall materials such as carboxymethyl cellulose (CMC), maltodextrin (MD), whey protein isolate (WPI), and gum arabic (GA), compared to a control sample. The primary properties evaluated include bulk density (ρb), compressed density (ρt), Carr Index (CI), and Hausner Ratio (HR), as well as wettability, water absorption capacity (WAC), and water solubility index (WSI). The results showed significant differences in physical properties depending on the wall material selection. MD has the highest bulk density (0.55 g/cm³) and excellent flow properties, as evidenced by its low CI (0.16) and HR (1.20) values. In contrast, CMC had the lowest bulk density (0.23 g/cm³) and a higher CI (0.34), indicating weaker flow properties. Wettability results similarly highlighted the superior hydration properties of MD and GA, with rapid water absorption times of 1.44 and 1.26 seconds, respectively, while WPI had the longest wettability time (32.97 seconds). Additionally, the control sample had a WAC value of 2.06 g/g, which was higher than the values for MD (1.07 g/g) and GA (0.63 g/g). These findings highlight the significant impact of wall materials on the functional properties of freeze-dried potato powders and indicate opportunities for specialized product formulations in food processing and functional ingredient applications.