Influence of thermal treatment on physical, structural characteristics and stability of lactoferrin, EGCG and high methoxylated pectin aggregates

Abstract

Colloidal system is an ideal protection and delivery vector of functional components. Its stability during thermal processing directly affects its protection and delivery efficiency. In the present study, the effects of heat treatments on physical, structural characteristics and thermal stability of lactoferrin (LF), high methoxylated pectin (HMP) and epigallocatechin-3-gallate (EGCG) binary and ternary aggregates were investigated. The average particle size of binary and ternary complexes decreased significantly with the increase of treatment temperature. The absolute ζ-potential value of all the aggregates were higher than native LF treated at the same thermal condition except LF-EGCG complex treated at 75 and 85 °C. The outcome of fluorescence spectroscopy and circular dichroism suggested thermal treatment resulted in the change of secondary structure of LF in the aggregates with molecular unfolding and conformation transition. However, its combination with HMP and EGCG hindered the effect of heat treatment caused denaturation of LF. Also, different assembly sequence affected the stability of the ternary aggregates after heat treatment. Therefore, binary or ternary composition is an effective strategy to improve the thermal stability of protein and overall nutritional value of the complex.