Unsaturated Emulsifier-Mediated Modification of the Mechanical Strength and Oil Binding Capacity of a Model Edible Fat Crystallized under Shear

摘要

The effects of processing using a scraped surfacenheat exchanger (SSHE) before and after adding unsaturatednmonoglyceride (UM) on blends of fully hydrogenated soybeannoil (FHSO) and soybean oil (SO) were studied. Mixtures of 40:60nand 45:55 FHSO:SO were melted at 80 °C for 30 min andncrystallized statically or in the SSHE (shear rate of 25 s−1) at ancooling rate of 9 °C/min. Upon shearing and UM addition,npolymorphic transformations toward more (β) or less (β′) stablenforms were governed by the combination between systemnconcentration, composition, and crystallization conditions, asndetermined by differential scanning calorimetry and powder X-rayndiffraction. Nuclear magnetic resonance was used to measure thensolid fat content (SFC) development which showed to increasenwith processing conditions due to the high nucleation rate induced.nProcessing conditions greatly affected the nano- and microcrystalline structures which were characterized by polarized lightnmicroscopy (PLM), cryogenic transmission electron microscopy (Cryo- TEM), and Scherrer analysis of the powder X-rayndiffraction data. Crystallization under shear promoted the longitudinal growth of the nanoplatelets; nevertheless, meso structuralnelements showed a decrease in their dimensions under the same crystallization conditions. The relative oil loss determinedngravimetrically was inversely related to the elastic modulus and yield stress of the sheared fat blends, and values were closer to thendesirable usability ranges for bakery applications. Our results suggest that fully hydrogenated fats can be functionalized byncrystallization in a SSHE and/or by judicious addition of an unsaturated emulsifier.