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

The present study was performed to investigate the stability of W/O/W emulsions containing 4-alpha-glucanotransferase (4 alpha GTase)-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 degrees C for 30 min, constant shear for 0-7 min, and freeze-thaw cycling between -20 degrees C and 30 degrees C, respectively, and followed by encapsulation efficiency (EE) measurement. As for the case of thermal stress, it was clearly shown that addition of 4 alpha GTase-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 4 alpha GTase-treated starch dramatically reduced EE at temperatures higher than 70 C, which was probably related to the melting of 4 alpha GTase-treated starch gel. The incorporation of 4 alpha GTase-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. (C) 2012 Elsevier Ltd. All rights reserved.