Influence of Chemical Composition on the Isothermal Cocoa Butter Crystallization

Abstract

The influence of chemical composition on the isothermal cocoa butter crystallization was investigated quantitatively. Apart from the fatty acid and triacylglycerol profile, the amounts of some minor components (diacylglycerols, free fatty acids, phospholipids, soap, unsaponifiable matter, iron, and primary oxidation products) were determined. With the forward model selection technique, a multiple linear regression model was established, showing the influence of chemical characteristics on the different crystallization parameters of the new model to describe the fat crystallization kinetics as developed by Foubert and others (2002). The ratios of saturated to unsaturated fatty acids and monounsaturated to diunsaturated triacylglycerols have the most important effect on the amount of crystallization, the induction time of the 2nd step of the crystallization process, and the order of the reverse reaction. The more unsaturated fatty acids and the more diunsaturated triacylglycerols, the lower the amount of crystallization; the higher the induction time for the 2nd step of crystallization, the lower the order of the reverse reaction. The amount of diacylglycerols has the most important (negative) influence on the rate constant. Other minor components with a rather pronounced influence on different crystallization parameters are the free fatty acids, phospholipids, and traces of soap. saturated triacylglycerols. Loisel and others (1998) found that during crystallization of cocoa butter in a lab-scale scraped surface heat exchanger, which leads to formation of ␤Ј and ␤ polymorphs, tristearoylglycerol (SSS) crystallizes 1st as a separate fraction due to its limited solubility in monounsaturated and diunsaturated triacylglycerols. Adding extra SSS consequently shortens the induction time of the 1st crystallization step but does not affect the crystallization of the remaining triacylglycerols. Hachiya and others (1989) studied the effect of seeding on the crystallization kinetics (isothermal, agitated crystallization at 30 °C) of cocoa butter and dark chocolate. They concluded that SSS in the ␤ form does not remarkably accelerate the crystallization despite its high melting point, whereas SOS in the b form does enhance the crystallization rate.Pontillon (1998) observed that free fatty acids increase the crystallization time of cocoa butter but only at concentrations above 2%. Shukla (1995) and Ziegleder (1988) (isothermal crystallization at temperatures between 19 °C and 23 °C leading to crystallization in the ␤Ј polymorph) noticed that cocoa butters with a higher diacylglycerol level exhibit a slower crystallization. Gutshall-Zakis and Dimick (1993) showed that slow nucleating (when crystallizing dynamically at 26.5 °C in the ␤ polymorph) cocoa butters contain higher amounts of phospholipids. However, Savage and Dimick (1995) and Chaiseri and Dimick (1995) (isothermal crystallization at 26.5 °C under mild agitation leading to crystallization in polymorphs ␤Ј and ␤) only found a correlation between the nucleation times an...

Impacts of Bleaching and Packed Column Steam Refining on Cocoa Butter Properties

“…When the above results were compared to values obtained by Foubert et al [24], the qualitative effect of FFA removal (increase or decrease of the parameter) was quite similar in both studies. However, it must be noted that the respective impacts (regression slope) in the present study were substantially larger, especially when the butters with \1% FFA are taken into account in calculating the linear regression slope.…”

“…However, it must be noted that the respective impacts (regression slope) in the present study were substantially larger, especially when the butters with \1% FFA are taken into account in calculating the linear regression slope. This can be explained by the fact that in the study of Foubert et al [24] the lowest FFA content was 1.16%, and, therefore, the proposed regression coefficients of Foubert et al [24] might not necessarily be valid for cocoa butters with \1% FFA.…”

“…Similar DSC-experiments of isothermal crystallization of cocoa butter at 20°C in the given time span of 4 h have shown that the cocoa butter does not crystallize in or recrystallize to its more stable b-polymorph, but crystallization occurs in two steps at which a and b 0 crystals, respectively, are formed [24]. The parameter a gives a proper estimation of the amount of metastable b 0 -polymorphs formed (direct or through a-mediation) in the experiment.…”

“…Consequently, if the link between FFA removal and the crystallization properties can be quantified, it might serve as a tool to estimate the repercussions of the refining process on the physical properties. The results can then also be compared with the results of Foubert et al [24], in which the impact of the FFA on cocoa butter kinetics was quantified as a linear regression slope.…”

Modified soybean lecithins as inducers of the acceleration of cocoa butter crystallization

“…The content of trisatured (S 3 ) TAG was lower and monounsaturated (S 2 U) was similar or slightly lower than the majority of cocoa butter composition disclosed in the literature [23,25,26]. The di-(U 2 S) and tri-unsaturated (U 3 ) TAG had higher values than those presented by Ribeiro et al [23] and Foubert et al [26]. Thus, based to this compositional profile, one can anticipate that the cocoa butter used in this study has a lower melting point, a slower crystallization kinetic and lower SFC at high temperatures than those reported in the literature.…”