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Effect of high cooling and shear rate on the microstructural development of hybrid systems containing diacylglycerols and triacylglycerols of palm origin

Tavernier, Iris, Norton, Ian T., Rimaux, Tom, Lazidis, Aris, Dewettinck, Koen
Journal of food engineering 2019 v.246 pp. 141-152
X-ray diffraction, cooling, crystallization, diacylglycerols, differential scanning calorimetry, heat exchangers, processing technology, shortenings, texture, triacylglycerols
This research explores the potential of diacylglycerol (DAG) and triacylglycerol (TAG) combinations in shortenings. An alternative formulation of a fat blend alters the crystallization behavior, which was investigated with differential scanning calorimetry (DSC) and synchrotron X-ray diffraction. DSC experiments demonstrated that by replacing TAGs with DAGs, crystallization had an earlier onset. However, the lower concentrations of TAGs require more undercooling to fully crystallize, which resulted in more crystallization events during the isothermal step for samples with a higher DAG and lower TAG concentration. A higher DAG concentration also resulted in a more dominant presence of the β polymorphic form. As both DAG and TAG structuring are based on crystal network formation, processing conditions (cooling and shear) will play an important role. Considering processing is essential to understand the behavior of newly formulated fats on an industrial processing line. Samples were prepared both statically, without shear or rapid cooling, and dynamically, under high shear and fast cooling using a bench-top scraped surface heat exchanger. Dynamically crystallized samples containing DAGs were more brittle than samples without DAGs, which can be related to the slower crystallization kinetics of lower TAG concentrations at higher DAG concentrations. The final textural properties of the statically crystallized samples could not predict the properties of the dynamic values. As such, it was demonstrated that preparing crystalline samples using processing conditions similar to those used in an industrial setting is essential to assess applicability of alternatively structured crystalline fat phases.