Konjac gum and maltodextrin compound tablets as carriers of IgY for sustained release in stomach

Abstract

Egg yolk immunoglobulin (IgY) is a biologically active ingredient with high immunogenicity; however, its instability in the acidic environment of the upper gastrointestinal tract limits its application in oral formulations. In the present work, an encapsulation system based on maltodextrin (MD) and konjac gum (KGM) was developed as a protective carrier for IgY for targeted release to retain stability. A simulated gastric model was used to compare the release characteristics of the different formulations, and to explore the optimal release mode. To better understand the controlled release mechanism of MD and KGM composite tablets, the release curve, macrostructure, microstructure, and water mobility were analysed. Results indicated that the sustained release of IgY from MD and KGM composite tablets was mainly driven by Fick diffusion and dissolution. As the concentration of KGM increased, the release rate of IgY from the tablets decreased, and the release mechanism gradually changed from diffusion to erosion. The dense cross-linkage between MD and KGM helped prevent tablet disintegration, and slowed down the release of IgY. In addition, the dissolved KGM formed a film on the tablet surface to control the erosion rate. It can be concluded that the optimal formulation of an IgY-loaded tablet was a mass fraction of 50% MD, 30% KGM, and 20% IgY. The present work provided a practical method to protect the biologically active ingredients from acidic destruction in the stomach during oral treatment.