Microencapsulation of green tea polyphenols: Utilizing oat oil and starch-based double emulsions for improved delivery

Abstract

The stability and bioavailability of green tea polyphenols, crucial for their health benefits, are compromised by environmental sensitivity, limiting their use in functional foods and supplements. This study introduces a novel water-in-oil-in-water double emulsion technique with microwave-assisted extraction, significantly enhancing the stability and bioavailability of these compounds. The primary objective of this study was to assess the effectiveness of several encapsulating agents, such as gum Arabic as control and native and modified starches, in improving encapsulated substances' stability and release control. Native and modified starches were chosen for their outstanding film-forming properties, improving encapsulation efficiency and protecting bioactive compounds from oxidative degradation. The combination of maltodextrin and tapioca starch improved phenolic content retention, giving 46.25 ± 2.63 mg/g in tapioca starch microcapsules (GTTA) and 41.73 ± 3.24 mg/g in gum arabic microcapsules (GTGA). Besides the control, modified starches also had the most potent antioxidant activity, with a 45 % inhibition (inh%) in the DPPH analysis. Oat oil was utilized for its superior viscosity and nutritional profile, boosting emulsion stability and providing the integrity of the encapsulated polyphenols, as indicated by the microcapsules' narrow span index (1.30 ± 0.002). The microcapsules' thermal behavior and structural integrity were confirmed using advanced methods such as Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FT-IR). This study highlights the critical role of choosing appropriate wall materials and extraction techniques. It sets a new standard for microencapsulation applications in the food industry, paving the way for future innovations.