Effect of high-pressure treatment on the structural and rheological properties of resistant corn starch/locust bean gum mixtures

In this study, effects of a 30 min high pressure (HP) treatment (200-600 MPa) at room temperature on the rheological, thermal and morphological properties of resistant corn starch (RS) (5% w/w) and locust bean gum (LBG) (0.25, 0.50 and 1.0% w/v) dispersions were evaluated. Results showed that the storage modulus (G'), loss modulus (G"), and apparent viscosity values of starch/gum (RS/LBG) mixtures were enhanced with an increase pressure level, and demonstrated a bi-phasic behavior. HP treated RS/LBG samples were predominantly either solid like (G' > G") or viscous (G" > G'), depending on the pressure level and LBG concentrations. Differential scanning calorimetry (DSC) analysis of the pressurized mixtures showed a major effect on gelatinization temperatures (To, Tp,), and it was observed that RS/LBG mixtures gelatinized completely at >400 MPa with a 30 min holding time. Confocal laser scanning microscopy (CLSM) images confirmed that at 600 MPa, RS/LBG mixtures retained granular structures and their complete disintegration was not observed even at the endpoint of the gelatinization. (C) 2016 Elsevier Ltd. All rights reserved.