In-situ disintegration of egg white gels by pepsin and kinetics of nutrient release followed by time-lapse confocal microscopy

Publication date: Available online 17 July 2019Source: Food HydrocolloidsAuthor(s): Geeshani Somaratne, Francoise Nau, Maria J. Ferrua, Jaspreet Singh, Aiqian Ye, Didier Dupont, R. Paul Singh, Juliane FlouryAbstractDigestion behaviour of food protein-based hydrogels is greatly influenced by the gel characteristics and in particular the microstructure. Using egg white gels (EWGs) as a model food, this study aimed to explore the real time disintegration by pepsin of different microstructures and subsequent nutrient release kinetics. Using thermal treatment at 80 °C, EWGs with two different microstructures but similar protein concentration (10%) were produced by varying the pH conditions (pH 5 and pH 9). The in situ spatiotemporal disintegration of the microstructure during static in vitro gastric digestion was followed using a high resolution confocal microscopic technique. Tetramethylrhodamine isothiocyanate (TRITC)-dextran (4400 Da) was incorporated into the gels as a model fluorescent molecule of peptide-like size, to trace its release due to the pepsin action. The looser microstructure of pH5-EWG caused the gel to disintegrate more quickly and to a greater extent, leading to a higher rate of TRITC-dextran release. In contrast, the compact-dense microstructure of the pH9-EWG showed slower kinetics of disintegration and (TRITC)-dextran release, likely due to a reduced accessibility of pepsin to its substrates. Pepsin activity being highly pH-dependent, high local pH and ...
Source: Food Hydrocolloids - Category: Food Science Source Type: research