The phase behavior of fully hydrogenated canola oil in soybean oil was investigated using iso-solid lines from temperature-controlled pulse-NMR along with DSC data, with the rate of cooling of crystallized samples kept constant. The molecular diversity within the fat system was investigated using HPLC and GC. The microstructure of the fats was determined using a temperature-controlled polarized light microscope, and the polymorphism of the solidified fat structures was determined via a temperature-controlled X-ray diffractometer. Hardness was measured by a temperature-controlled Instron mechanical analyzer with a penetration cone. The phase behavior predicted by the DSC and iso-solid lines did not account for the hardness trends observed, as the microstructure and polymorphism of the fat also played a significant role. The addition of hard fat to a system did not consistently increase the hardness of the fat system. Furthermore, the solution behavior demonstrated by the iso-solid line diagram did not account for all trends in melting behavior, as both intersolubility and polymorphic changes occurred simultaneously. It was found that variations in hardness can be inferred from structural changes, although the structural level causing variation differs.A phase is a domain, homogenous with respect to chemical composition and physical state (1). A natural fat is an example of a system of coexisting homogeneous domains in equilibrium. The relationship and occurrence of phase change in a fat system is referred to as the phase behavior of the fat. Phase behavior, characterized by the study of the solid fat content (SFC), is important in optimizing production processes and maintaining production quality, and has been used to predict important attributes such as mouthfeel and hardness in fat-containing food products. Studies on phase behavior also lead to a better understanding of the ways in which fat blends interact-an important understanding, because the large-scale industrial production of shortenings and other fat-containing products often requires blending of lipids from many different sources.The use of iso-solid lines to characterize phase behavior is important in illustrating some aspects of intersolubility but is ultimately limited in scope. In many instances, iso-solid line behavior may not indicate changes in polymorphism of the samples and certainly does not impart information beyond the prediction of hardness by SFC, a method that has been shown to be imperfect (2-4). On the other hand, DSC phase measurements can reflect changes in polymorphism as well as intersolubility. However, such changes are not attributable to either polymorphic or intersolubility effects alone when utilizing purely DSC data. Therefore, it is important to study phase behavior by using a number of different techniques, such as X-ray diffraction (XRD; 5), microstructure analysis, GC, and cone penetrometry.The fat systems used in this study are mixtures of fully hydrogenated canola and soybean oils. These two lipids were selected for stu...
Production of MAG by glycerolysis is important for food, pharmaceutical, and cosmetic industries. Conducting glycerolysis in supercritical carbon dioxide (SC‐CO2) media has advantages over conventional alkali‐catalyzed glycerolysis. However, kinetic data are lacking for such conversions in the presence of SC‐CO2. The objectives of this study were to estimate the rate constants and elucidate the mechanism for the glycerolysis of soybean oil in SC‐CO2 using previously reported data. The data were taken from experiments using soybean oil, glycerol (glycerol/oil molar ratios of 15–25) and water (3–8% w/w) in SC‐CO2 at 20.7–62.1 MPa and 250°C for a 4 h period. Rate constants for the parallel glycerolysis and hydrolysis reactions were estimated for each processing parameter (glycerol/oil, water content, pressure) by minimizing the summed squared error between the values calculated from the experimental data and those obtained from the kinetic model. The results suggested that water and pressure had an effect on rate constants but the glycerol/oil ratio did not. Findings provide the kinetic modeling data necessary for the optimization of supercritical processes involving glycerolysis reactions for the production of MAG from vegetable oils.
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