Crystallization kinetics of palm oil of different geographic origins and blends thereof by the application of the Avrami model

• Published in: Food science & technology 2018-07, Vol.93, p.189-196
• Main Authors: Hubbes, Stephen-Sven, Danzl, Wolfgang, Foerst, Petra
• Format: Article
• Language: English
• Subjects: Avrami model; Crystallization kinetics; Fat crystallization; Palm oil; Tripalmitin
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2018.03.022

There is still ambiguity surrounding the application of the Avrami model to estimate kinetic parameters and growth dimension of crystallizing fats. In order to overcome this ambiguity, adjustments to the Avrami model are proposed. This research shows that isothermal palm oil (PO) crystallization is a stepwise process characterized by different consecutive kinetic segments, when dividing the Avrami equation into sub-domains following the study by Narine, Humphrey, and Bouzidi (2006) for an extended Avrami model. Thus, the Avrami model needs to be applied to each step separately. These sub-domains were merged to derive an average global rate constant that demonstrates the crystallization rates of fats follow bell-shaped curves depending on temperature, corroborating the fundamental crystallization literature. Applying this extended Avrami model to three different geographic origins of PO (Ghana, Colombia and Ecuador), the progression and maximum of these bell-shaped curves were found to be highly correlated with the tripalmitin to triolein (PPP/OOO) ratio of PO. Thus, we were able to advance the findings of Narine et al. (2006) and show the applicability of the Avrami model to describe the crystallization process of POs of different geographic origins and its blends with palm stearin. •Adjustments to the Avrami model for palm oil crystallization are proposed.•Proposals show that isothermal crystallization is a stepwise process.•Merging kinetic steps gives bell-shaped curves of rate constants over temperature.