Microencapsulation of clove and tamarind extract using xanthan gum and whey protein isolate: Physicochemical, structural, and storage stability characterization

Abstract

Clove and Tamarind (CT) extracts are rich in bioactive compounds; however, these compounds are highly susceptible to degradation during processing and storage, leading to reduced functionality and fewer food applications. Encapsulation of protein-polysaccharides has proven effective in retaining and stabilising bioactive compounds. This study investigated the influence of different Xanthan gum (XG): Whey Protein Isolate (WPI) blending ratios (designated XW formulations) on the physicochemical properties and storage stability of freeze-dried CT microcapsules to identify the best carrier system for functional food applications. The extracts and microcapsules were analysed for their physicochemical and structural properties, as well as thermal stability. The CT blend had the highest total phenolic content and DPPH antioxidant capacity. XW 35 (35% XG and 65% WPI) had the highest encapsulation efficiency, while XW 80 (80% XG and 20% WPI) showed the highest solubility. The particle size decreased with increasing xanthan gum proportion, while the low PDI indicated homogeneous systems. Formulations with high xanthan gum ratios exhibited superior thermal stability and better retention of bioactive compounds during storage. The Fourier-transform infrared spectroscopy (FTIR) supported interactions between the wall materials and encapsulated bioactives. At the same time, X-ray diffraction (XRD) revealed predominantly amorphous structures, and scanning electron microscopy (SEM) images showed compact matrices at higher xanthan gum ratios. This study offers new insight into the impact of the XW formulation ratio on the structural and functional dynamics governing the stability and performance of microcapsules containing phenolic-rich plant extracts, demonstrating its potential as a delivery system for functional food, nutraceutical, and pharmaceutical applications.