Study on the Stabilization Technique by Encapsulation of Biomolecules Such Food Proteins

Abstract

One of the methodologies for avoiding the deterioration of labile food and biological substances during drying is to embed the labiles in amorphous matrix of sugar. In a series of the authors’ studies, various sugars were first compared for the stabilizing effect on proteins in freeze-drying as well as the physicochemical properties in the amorphous state. Based on the experimental results, three generally accepted hypotheses on the protein stabilization by amorphous sugar matrix (water substitution hypothesis; glassy state hypothesis; partition effect) were merged into the compromised one. Next, in order to further improve the protein stabilization technique, the remaining enzyme activities after freeze-drying in the presence of various classes of substances were analyzed. The combination of disaccharide with polysaccharide(s), certain types of surfactants (e.g., sugar esters), and proteinaceous substances were found to exhibit markedly high protein stabilizing effect. Furthermore, the amorphous-sugar-based matrix was applied to homogeneously encapsulating oil droplets and nanoparticles during freeze-drying, which successfully avoided the aggregation of the particulates and the dropout from the resulting dried objects. The application of amorphous sugar matrix was expanded to the solid dispersion of hydrophobic flavors at molecular level, by utilizing the finding on the over-saturation of sugars in an organic solvent.