Pea protein-potato peel starch complex coacervation for the encapsulation of bioactive date seed extract: Bio-functional characterization and in vitro release

The demand for eco-friendly encapsulation systems has boosted interest in the use of plant protein-polysaccharide coacervates to deliver bioactive compounds. This study investigated the potential of pea protein concentrate (PPC) and gelatinized potato peel starch (GPPS) as wall materials for the complex coacervation of date seed extract. The physicochemical properties, stability, bioactive compound retention, in vitro release, and bio-accessibility of the encapsulated extract were evaluated. The coacervates exhibited high encapsulation efficiency (79.43–83.05 %) and low water activity with varied flow properties. FTIR analysis revealed protein-starch molecular interactions, while the retention of total phenolics was significantly affected by pH and ionic strength. The coacervates exhibited high lipid oxidation resistance and antioxidant activity (74.69–87.20 %). In vitro digestion simulations showed a notable controlled release (69.07–96.92 %) and bio-accessibility of up to 62.69 %. The diffusion-controlled release mechanism was best described by the Weibull and Peppas-Sahlin models, where the release rate was influenced by the type and concentration of the matrix. A balanced interaction between protein and starch composition (PPS₁) resulted in controlled phenolic release, stability, and enhanced absorption. These findings demonstrate the effectiveness of PPC-GPPS as a sustainable carrier for encapsulating date seed extract, offering controlled release, high antioxidant activity, and enhanced bio-accessibility, highlighting its potential for functional food-nutraceutical applications.