Abstract
Background:
The application of nanoencapsulation technology to mangosteen rind aims to increase the stability, bioavailability, and solubility of bioactive compounds. The nanoencapsulation using chitosan and sodium tripolyphosphate (STPP) via ionic gelation yielded the best nanocapsule characteristics compared to other methods.

Aim:
To investigate the formulation and characterization of mangosteen rind extract nanocapsules (MREN) using chitosan cross-linked with STPP at different ratios as a candidate poultry feed additive.

Methods:
Ethanol was used as a solvent in the maceration process to extract mangosteen rind. After weighing the mangosteen rind, a solvent was added at a 1:5 (w/v) ratio. At room temperature, maceration lasted for 24 hours. A rotary vacuum evaporator was used to concentrate the filtrate from each extraction process for 20 minutes at a temperature between 40°C and 45°C. Mangosteen rind extract (MRE), chitosan, and STPP were combined to obtain MREN. Chitosan and STPP were used at the following ratios: 1:1, 2:1, 3:1, 4:1, and 5:1 (MREN1–MREN5, respectively). Following mixing, the mixture was homogenized for 5 minutes using a homogenizer, hydrated for 18 hours at 4°C, and then homogenized once more for 30 seconds. With an input temperature of 170°C, feed rate of 15 ml/min, and nozzle atomizer pressure of one bar, spray drying was performed using a spray drier. The final nanocapsule products were then examined for particle size, zeta potential, and morphology.

Results:
The application of MREN as a candidate poultry feed additive was investigated based on the results of its characterization. The findings demonstrated that the addition of chitosan and STPP to the nanoencapsulation of mangosteen rind extract significantly affected the particle size, zeta potential, and morphology. The particle size increased with increasing chitosan content relative to STPP; the smallest particle size was obtained in the 1:1 treatment at the lowest chitosan dosage. In comparison with the other characteristics, the best and most stable zeta potential was obtained when chitosan was used at 2:1 and 3:1. Compared with the other treatments, the 1:1 treatment resulted in the ideal nanocapsule morphology in terms of morphological features.

Conclusion:
The mangosteen rind extract nanocapsule product, at a 1:1 ratio, has great potential for application as a feed additive in poultry. Nanoencapsulated mangosteen rind extract products have great potential as feed additives for poultry.

Key words: Characterization, Feed additive, Formulation, Mangosteen rind extract nanocapsules, Poultry