Improving freeze-dried Cleistocalyx nervosum powder: Influence of maltodextrin addition on physical properties, microstructure, bioactive compounds, and antioxidant activity

• MD addition (0–40%) altered physical and bioactive properties of freeze-dried C. nervosum powder. • Low MD (0–10%) retained bioactives but resulted in agglomeration and unsuitable handling. • High MD (40%) led to >80% loss of C3G and anthocyanins, highlighting a critical dilution effect. • CN-MD 10% identified as the ideal balance between bioactivity and stability. • PCA revealed clear separation between low and high MD treatments based on bioactivity. Cleistocalyx nervosum contains high levels of bioactive compounds, including phenolics, flavonoids, and anthocyanins, which are recognized for their strong antioxidant properties. However, its short maturation period, seasonal production, and irregular harvesting present significant challenges for its consistent availability and incorporation into functional food products. Therefore, this study aimed to investigate the effect of different concentrations of maltodextrin (MD) on the physical properties, stability, retention of bioactive compounds—total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and cyanidin-3-glucoside (C3G)—and antioxidant activities (DPPH, ABTS, FRAP) of freeze-dried C. nervosum powder. Results indicated that MD significantly affected various physical properties of the powder. Moisture content decreased from 10.75% to 1.91%, while water activity declined, resulting in improved product stability. Solubility increased from 14.82% to 65.01%, and degree of caking was reduced, leading to enhanced particle morphology. Regardless, increasing MD concentration reduced the retention of bioactive compounds. TPC decreased from 772.53 to 195.99 mg GAE/100g DW, TAC from 12.65 to 2.09 mg C3G/100g DW, and C3G from 612.14 to 97.16 mg/100g DW as MD increased from 0% to 40%. Similarly, antioxidant activity declined noticeably, with DPPH activity decreasing by 71.22% at the highest MD level. While low MD concentrations (0–10%) maintained antioxidant activity, higher concentrations (20–40%) improved powder handling and storage stability. Overall, incorporating 10% MD provided the optimal balance between physical properties and the retention of functional bioactive compounds. The mixture has significant promises for incorporation into antioxidant-enriched food applications such as beverages, gummies, and jellies.