Characterization of enzymatically interesterified canola oil and fully-hydrogenated canola oil blends under supercritical CO₂.

摘要

Blends of canola oil and fully-hydrogenated canola oil (FHCO) containing 10, 30, and 50 wt% FHCO were interesterified enzymatically using Lipozyme TL IM (6% of initial substrates, w/v) under supercritical CO₂ at 10 MPa and 65 degrees C for 2 h. Changes in polymorphic behavior and crystal morphology of non-interesterified initial blends (NIB) and purified enzymatically interesterified products (PEIP) were studied using X-ray diffraction spectroscopy (XRD) and polarized light microscopy. As well, the effects of blend ratio and enzymatic interesterification on rheological behavior were investigated. XRD analysis demonstrated the predominance of alpha form in FHCO while blending it with canola oil induced the formation of beta form after crystallizing the samples at 24 and 5 degrees C for 12 h. Enzymatic interesterification caused the appearance of beta ' forms and dramatically changed crystal morphology. The PEIP samples contained fewer crystal particles compared to NIB, but the crystals were more symmetrical. The elastic modulus (solid-like behavior) (G') was lower in NIB with 30 wt% FHCO compared to the one with 50 wt% FHCO. Enzymatic interesterification also had a strong effect on G' of the samples as it decreased after interesterification. The results of this study will help the development of conversion technologies under supercritical conditions in order to formulate more healthy fats having appropriate functional properties to address the industrial demand for the production of margarine and pastry shortenings.Digital Object Identifier http://dx.doi.org/10.1007/s11746-013-2319-8