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Investigation of the crystallization and melting of the tripalmitin/triolein system via hot stage microscopy, differential scanning calorimetry, and pulsed NMR
journal contribution
posted on 2017-06-15, 15:09 authored by David I. Stewart, Peng Siong Chong, Andy StapleyAndy StapleyThe isothermal crystallization kinetics and melting behavior of mixtures of tripalmitin (PPP) and triolein (OOO) were investigated using hot stage microscopy (HSM), with supporting differential scanning calorimetry (DSC) and NMR measurements. Some melting points determined via HSM and DSC were higher than predicted by the Hildebrand equation, but solid fat content melting profiles from NMR were close to ideal predictions. The observed deviations from
ideal behavior with HSM/DSC could be attributed to
concentration gradients in the liquid phase, rather than from nonideality. Sufficient time should therefore be allowed in melting experiments for diffusional equilibration to occurthe remelting time should generally be longer than the crystallization time. When crystallizing mixed PPP/OOO samples, two distinct polymorphs could be seen in the same “crystal”, with an outer ring of β′ surrounding an inner circle of β. Polymorphic transformation from β′ to β could be seen to occur via dissolution through a narrow liquid interface region between the two crystals. Growth rate data for β′ were proportional to the reduced saturation (or supercooling) calculated assuming ideal behavior. Growth rates of β via the solvent/melt mediated transformation of the β′ form could be related to driving forces based on the difference in solubility of the β′ and β forms.
Funding
D.I.S. would like to thank Nestle and the Biotechnology and Biological Sciences Research Council (BBSRC) for their financial support.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Chemical Engineering
Published in
Crystal Growth and DesignVolume
17Issue
6Pages
3005 - 3016Citation
STEWART, D.I., CHONG, P.S. and STAPLEY, A.G.F., 2017. Investigation of the crystallization and melting of the tripalmitin/triolein system via hot stage microscopy, differential scanning calorimetry, and pulsed NMR. Crystal Growth and Design, 17 (6), pp. 3005-3016.Publisher
American Chemical SocietyVersion
- VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/Acceptance date
2017-03-27Publication date
2017-03-27Copyright date
2017Notes
This is an Open Access article published by ACS and published under a Creative Commons Attribution (CC-BY) License, https://creativecommons.org/licenses/by/4.0/ISSN
1528-7483eISSN
1528-7505Publisher version
Language
- en