Extending the use of Centella asiatica extract in poultry applications using distinct freeze-drying wall materials

Centella asiatica is a promising phytogenic feed additive for poultry because of its bioactive compounds; however, its heat instability and poor palatability limit direct feed incorporation. Microencapsulation can enhance stability and controlled release; however, comparative studies of wall materials for poultry applications are limited.

The leaf powder ethanolic extract of Centella asiatica was microencapsulated by freeze-drying with maltodextrin+gum arabic (MD+GA), polyethylene glycol (PEG), albumen, gelatin, and sodium alginate across four treatments (T1-T4, core-to-wall ratios 1:10 to 1:4). Encapsulation efficiency (EE %), total phenolic content (TPC), DPPH antioxidant activity, intestinal digestibility, thermal stability (Tm), water activity (aw), and morphology (SEM and FTIR) were evaluated. Data were analyzed using ANOVA and Tukey's honest significant HSD (p < 0.05).

MD+GA exhibited the highest EE % (98.67 ± 0.47%, T1), followed by albumen (94.14 ± 0.94%, T2) and gelatin (85.12 ± 0.85%, T3). Gelatin and albumen showed the highest TPC (35.81 and 36.44 mg GAE/g) and DPPH activity (27.51 ± 0.41%, T4; 22.07 ± 0.33%, T4), whereas MD+GA showed moderate values (32.73 mg/g; 20.50 ± 0.31%, T4). Intestinal digestibility was high for MD+GA (82.38 ± 1.24%, T1) and gelatin (93.21 ± 1.40%, T3). Albumen (a_w 0.34 ± 0.01, T2) and gelatin (0.39 ± 0.01, T3) provided excellent moisture control, whereas MD+GA was moderate (0.67 ± 0.01, T3). SEM revealed smooth, spherical protein-based microcapsules and rougher polysaccharide-based microcapsules.

MD+GA provided optimal EE % and intestinal release compared with protein-based materials, while also maintaining good phenolic retention and antioxidant activity, supporting their use in antibiotic-free poultry feed.