Molecular structures of octenyl succinic anhydride modified starches in relation to their ability to stabilize high internal phase emulsions and oleogels

Abstract

Structuring edible oil into solid fat without trans fat is massive technological challenge in the food industry. Here, amphiphilic octenyl succinic anhydride (OSA) starches with different molecular structures (OSA-1, OSA-2, and OSA-3) were used as stabilizers to transform liquid oil into soft-solid high internal phase emulsions (HIPE), and HIPE as template were further constructed oleogels, which explored molecular structures of OSA starches in relation to their ability to stabilize HIPE and oleogels. OSA-3 with the highest degree of substitution (DS) and smallest hydrodynamic radius (Rh), could decrease interfacial tension effectively, but exhibit weak rheological behavior of HIPE. DS of OSA-1 was the lowest, which displayed the lowest adsorption towards interface. Compared with OSA-1 and OSA-3, OSA-2 exhibited larger Rh and moderate DS, could form compact structure as crosslinkers in the bulk phase and at the interface to create higher values of storage modulus of HIPE, even resisted the structural deformation under large strain. These results indicated emulsification was controlled by DS, but the structure and rheological behavior of HIPE depended principally on Rh. Additionally, among three OSA starches, OSA-2 was an appropriate material for preparing oleogels with stable structure and higher mechanical strength, which could be used as margarine alternative and displayed comparable textural property to the standard cake. This finding demonstrates deep understanding of structure-function relationship between molecular structures of OSA starches and ability to stabilize HIPE and oleogels, providing the technical support for the application of OSA starches in the field of trans free fat.