Stability and controlled release enhancement of Labisia pumila's polyphenols

The thermal stability and controlled release of Labisia pumila's polyphenols was increased using a surface protein encapsulated microcapsule. The polyphenols were measured using an ultra-performance liquid chromatography, whereas the degradation mechanism was elucidated using a mass spectroscopy analysis. The microencapsulation increased the polyphenols retention from 29.9 (without encapsulation) to 92.1% with spray drying. The mixture of gum Arabic and whey protein isolate 9:1 gave the best retention of gallic acid (95.2%), protocatechuic acid (91.2%), epigallocatechin (86.0%) and rutin (95.9%) with an average polyphenol retention of 92.1%. The X-ray photoelectron spectroscopy analysis showed the formation of surface protein that acted as a protective layer, which increased the polyphenols stability. Decarboxylation was the primary degradation mechanism for gallic acid and protocatechuic acid, while rutin underwent hydrolysis. The degradation of epigallocatechin was due to deprotonation or dehydroxylation. The microcapsule with surface protein increased the overall polyphenols release with the simulated gastric and intestinal conditions by ~5% with an average release of 96.3%. The polyphenols release kinetics was analysed using Baker-Lonsdale, Korsmeyer, Higuchi, and Hixson-Crowell models. The release mechanism of the polyphenols best fit the Hixson-Crowell model indicating a surface erosion dependent release. Labisia pumila's polyphenols thermal stability and controlled release using surface protein encapsulated microcapsules. [Display omitted] •GA:WPI encapsulation reduced the L. pumila's polyphenols degradation up to 62.2%.•UPLC-QTOF-MS analysis confirmed the thermal degradation mechanism of polyphenols.•XPS analysis confirmed the existence of a protective surface protein.•GA:WPI encapsulation enhanced release of polyphenols in simulated intestinal fluid.•Release mechanism of polyphenol from microcapsule was controlled by matrix erosion.