A DSC determination of phase transitions and liquid fraction in fish oils and mixtures of triacylglycerides

The thermal phase transitions of 18 pure triacylglycerides (TAGs) and four fish oils were investigated using differential scanning calorimetry (DSC) and modulated DSC (MDSC) in the temperature range from −150 to 80°C. The dependence between the heat of fusions and the melting temperatures was determ...

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Bibliographic Details
Published in:Food research international 2014-04, Vol.58, p.132-140
Main Authors: Tolstorebrov, I., Eikevik, T.M., Bantle, M.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Differential scanning calorimetry
DSC
Fish oil
Fish oils
Food industries
Fundamental and applied biological sciences. Psychology
Glass transitions
Liquid fraction
Liquids
Mathematical analysis
Melting
Phase transformations
Regression
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Triacylglycerides
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Summary:The thermal phase transitions of 18 pure triacylglycerides (TAGs) and four fish oils were investigated using differential scanning calorimetry (DSC) and modulated DSC (MDSC) in the temperature range from −150 to 80°C. The dependence between the heat of fusions and the melting temperatures was determined for pure TAGs, and a regression equation was obtained. A liquid fraction in TAG mixtures and fish oils was determined by the partial integration of melting peaks enhanced by the regression equation. The method was considered to be beneficial for fish oils, because several pure TAGs did not show crystallization. These “unfreezable” TAGs were composited by polyunsaturated fatty acids with three or more double bonds. They showed a glass transition in the temperature range between −113.9 and −105.6°C. The fish oils melted in the range between −92.6 and 23°C. The heat of melting was measured to be between 31.5 and 41.8Jg−1. The oils had a significant share of liquid fraction (between 40.0 and 58.0%) at temperatures down to −110.0°C when the glass transition appeared. •The thermal properties of 18 TAGs and their mixtures were investigated.•The glass transition was found for several TAGs.•The relationship between melting enthalpy and temperature was found.•The DSC method for liquid fraction calculation was verified.
ISSN:0963-9969
1873-7145
DOI:10.1016/j.foodres.2014.01.064