Formulation and characterization of a corn starch-soy protein isolate coacervate for encapsulation of fennel essential oil and its application in the pre-velveting of chicken cubes.

Abstract

Pre-velveting foods suffer from significant flavor loss and limited shelf life during storage, motivating a demand for multifunctional starch-based carriers. To address this, corn starch (CS)-soy protein isolate (SPI) coacervates with varying CS ratios were fabricated to encapsulate fennel essential oil (FEO), yielding a pre-velveting material with antimicrobial and flavor-enhancing properties. Results indicated that higher CS/SPI ratios (4,1 and 5,1) enhanced viscoelasticity and reduced particle size by forming a dense polysaccharide-protein network that inhibited FEO aggregation compared with the lower ratios. The resulting microcapsules (CSSP4 and CSSP5) similarly demonstrated improved DPPH radical scavenging capacity (59.49% and 56.15%, respectively) and enhanced thermal stability. SEM and XRD confirmed increased cross-linking of CS upon coacervation with SPI, which provided the basis for the improved encapsulation efficiency of FEO via the dense structure, while FTIR and molecular dynamics simulations indicated that this structure was primarily driven by hydrogen bonding and electrostatic interactions between CS and SPI, and the starch-protein interface was visualized. Electronic nose combined with GC-MS analyses identified anethole as the primary flavor compound of FEO microcapsules and showed that the stable structure delayed its release, with CSSP4 exhibiting the slowest release due to its higher density. Furthermore, among all formulations, CSSP4 showed the lowest TBARS values and pH increase, as well as the most favorable volatile profile and improved textural properties in cooked chicken cubes. This study presents a novel starch-based carrier designed to improve flavor retention and extend the shelf life of pre-velveting foods.