Title

Effect of Cooling Rate on Crystallization Behavior of Milk Fat Fraction/Sunflower Oil Blends

Document Type

Article

Journal/Book Title/Conference

Journal of the American Oil Chemists' Society

Volume

79

Issue

11

Publisher

Springer Verlag

Publication Date

11-1-2001

First Page

1055

Last Page

1062

DOI

10.1007/s11746-002-0603-6

Abstract

The effect of cooling rate (slow: 0.1°C/min; fast: 5.5°C/min) on the crystallization kinetics of blends of a highmelting milk fat fraction and sunflower oil (SFO) was investigated by pulsed NMR and DSC. For slow cooling rate, the majority of crystallization had already occurred by the time the set crystallization temperature had been reached. For fast cooling rate, crystallization started after the samples reached the selected crystallization temperature, and the solid fat content curves were hyperbolic. DSC scans showed that at slow cooling rates, molecular organization took place as the sample was being cooled to crystallization temperature and there was fractionation of solid solutions. For fast cooling rates, more compound crystal formation occurred and no fractionation was observed in many cases. The Avrami kinetic model was used to obtain the parameters k n and n for the samples that were rapidly cooled. The parameter k n decreased as supercooling decreased (higher crystallization temperature) and decreased with increasing SFO content. The Avrami exponent n was less than 1 for high supercoolings and close to 2 for low supercoolings, but was not affected by SFO content.

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