Synthesis and Characterization of ZnO Nanoparticles Encapsulated in Pectin-Protein Complex: Antibacterial and Anti-Inflammatory Properties Evaluation

Abstract

Stunting remains a major public health concern in Indonesia. Adequate zinc intake is crucial in mitigating stunting, as zinc plays an essential role in growth and immune function. This study explored the application of zinc oxide nanoparticles (ZnO-NPs) as a food additive in yogurt to improve zinc intake and potentially address stunting. The ZnO-NPs, which possess antibacterial and anti-inflammatory activity, are encapsulated in edible materials like pectin and protein to enhance their physical characteristics and minimize contact with the beneficial bacteria in yogurt. The encapsulation process was optimized using heat treatment to strengthen the pectin-protein interaction, forming a protective coating around ZnO-NPs. This study evaluated the encapsulation layer formation through the physicochemical characterization and antibacterial and anti-inflammatory assays. The encapsulation process was conducted using a simple precipitation method. The synthesized and encapsulated material was characterized using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM), and biological activity analysis was also performed. The FTIR analysis confirmed the absence of Zn-O peaks, indicating effective coating. Encapsulated ZnO nanoparticles displayed antibacterial activity similar to that of blank yogurt, suggesting that the coating effectively reduced the direct antimicrobial effects on probiotic bacteria. In contrast, bare ZnO exhibited moderate anti-inflammatory activity by suppressing IL-6, TNF-a, and iNOS expression, while encapsulated forms showed reduced anti-inflammatory effects. All samples were non-cytotoxic, confirming their safety for food use. In conclusion, this study demonstrated that ZnO nanoparticles can be effectively encapsulated using a pectin-protein complex derived from yogurt, enhancing their stability and safety as a food additive. While encapsulation slightly reduced anti-inflammatory activity, it maintained beneficial properties suitable for food fortification. These findings support the potential use of ZnO-based fortification strategies to improve zinc intake and contribute to stunting prevention, with further optimization needed to enhance bioactivity and efficacy.