Influence of environmental stresses on the stability of W/O/W emulsions containing enzymatically modified starch

Abstract

The present study was performed to investigate the stability of W/O/W emulsions containing 4-α-glucanotransferase (4αGTase)-treated starch against environmental stresses such as heating, shearing, and repeated freeze-thawing. W/O/W emulsions were subjected to thermal processing at different temperatures ranging from 30 to 90°C for 30min, constant shear for 0–7min, and freeze–thaw cycling between −20°C and 30°C, respectively, and followed by encapsulation efficiency (EE) measurement. As for the case of thermal stress, it was clearly shown that addition of 4αGTase-treated starch in the internal aqueous phase of emulsions helped to maintain higher EE during thermal processing. However, at lower PGPR level (2%), the addition of 4αGTase-treated starch dramatically reduced EE at temperatures higher than 70°C, which was probably related to the melting of 4αGTase-treated starch gel. The incorporation of 4αGTase-treated starch improved the stability of emulsions during shearing process, but could not prevent W/O/W emulsions from creaming and destabilizing during freeze–thaw cycling.