Nanogel particles formed from ethanol-treated whey proteins: Effect of heating, pH and NaCl on their stability.

Abstract

Whey protein particles have gained significant attention for their ability to enhance the functional properties of foods as they can be used for emulsions and foams stabilization or fat substitution. This study explores the ability of whey protein nanogel particles formed in the presence of ethanol (30–70 % w/w) by controlling pH and ionic strength, to retain their morphological properties after ethanol removal. The stability of the produced nanogel particles after the removal of ethanol was investigated under various conditions, including heat treatment (90 °C, 20 min), pH modification (4−7), and the addition of NaCl (50–300 mM). Morphological analysis was conducted using confocal laser scanning microscopy, laser diffraction analysis, and scanning electron microscopy. The results showed that the exclusion of ethanol resulted in the formation of spherical-like nanogel particles with different sizes ranging from 100 to 200 nm in diameter. The pH of the solution affected the stability of the ethanol-free particles, leading to aggregation when the net charge of the protein approached zero. However, no aggregation phenomena were observed away from the isoelectric point. High concentrations of NaCl led to extensive aggregation, but no substantial changes were found upon heating. The production of nanogel particles is a promising advance with potential for a wide range of food applications.