Kinetics of Melt Crystallization of a Sunflower Oil‐Based Polyunsaturated Fatty Acid Mixture

Abstract

Important parameters like supercooling and cooling rates affecting the melt crystallization of a polyunsaturated fatty acid (PUFA) mixture obtained from sunflower oil were investigated and compared via high-resolution polarized-light microscopy. PUFA was thermally characterized in a differential scanning calorimeter and the significant liquid-solid-phase transition temperatures determined were then implemented in the development of specific temperature profiles. Analyzed between two glass slides, induction times were found to decrease with low crystallization temperatures and the number of nuclei per unit area increased with higher supercooling and cooling rates. A comparison between the linear crystal growth rates of pure standards of each of the main fatty acids present in the PUFA mixture and the PUFA mixture itself indicated that the latter is much slower than that of each of its pure components.

Nucleation Kinetics during Melt Crystallization of Plant Based High Oleic and Linoleic Polyunsaturated Fatty Acid Mixtures

“…This is very good agreement with theory unlike previous investigations. 4 Activation energies of nucleation, ΔG c ′, were determined by means of the Fisher Turnbull equation. According to the plot, ΔG c ′ decreases exponentially with increasing supercooling.…”

“…7,10 The time required for the first crystal nucleus to appear in the sample once the crystallization or the observed temperature is reached is defined as the induction time. 4 Factors like the degree of supercooling and the rate of cooling greatly influence the speed and behavior of the nucleation. In our work, the sample's induction time has been calculated as the difference between the time at which the probe reaches the crystallization temperature and when the first sign of the presence of nuclei is noted by the FBRM sensor.…”

“…In our work, the sample's induction time has been calculated as the difference between the time at which the probe reaches the crystallization temperature and when the first sign of the presence of nuclei is noted by the FBRM sensor. 4,11,12 Furthermore, the Gibbs free energy of crystallization can be correlated to the crystallization temperature T, with the help of the eq 3 taking into account of the Gibbs− Thomson effect. (3)…”

“…In the case of melt crystallization, the desired product can be crystallized from the feed simply by following a predetermined temperature regime. Parameters like induction time, nucleation rate, and crystal growth rate influence the efficiency of the separation of the desired product with respect to time, quality, and quantity. , Therefore, an attempt to experimentally quantify the induction time of nucleation during the melt crystallization of high linoleic sunflower oil PUFA mixture and thereby correlate the Gibbs free energy involved with the rate of nucleation is made in this paper.…”

Determination and Comparison of Equilibrium Data of Various Plant‐Based Fatty Acid Mixtures

“…Crystallization temperatures of the unsaturated fatty acids are much lower than those of the saturated ones, which is an important and desirable property for raw materials in biodiesel production 9. Furthermore, multiple double bonds in the unsaturated fatty acid structures provide more cross‐linking opportunities required for the production of a variety of epoxy resins 8, 10. Significant fundamental research is still to be done to create an overview of the melt crystallization behaviors of various naturally occurring fatty acid mixtures in order to study the prospects and effectiveness of this separation process.…”