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. Although microencapsulation can enhance stability and controlled release, there have been few comparative studies of wall materials for poultry applications.

The leaf powder ethanolic extract of Centella asiatica was freeze-dried and microencapsulated with maltodextrin+gum arabic (MD+GA), polyethylene glycol, 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 (scanning electron microscopy [SEM] and Fourier-transform infrared spectroscopy) were evaluated. The data was analyzed using analysis of variance and Tukey's honest significant honest significant difference (p<0.05).

MD+GA exhibited the greatest 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 greastest 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). MD+GA and gelatin had good intestinal digestibility (82.38±1.24%, T1 and 93.21±1.40%, T3, respectively). Albumen (a_w 0.34±0.01, T2) and gelatin (0.39±0.01, T3) were effective moisture controllers, whereas MD+GA was moderate (0.67±0.01, T3). SEM revealed smooth, spherical protein-based microcapsules and rougher polysaccharidebased microcapsules.

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