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

Abstract

Natural and alkalized cocoa butters were bleached and subsequently steam refined in a continuous packed column at temperatures ranging between 160 and 220°C. None of the processes evaluated gave rise to any detectable formation of trans fatty acids, interesterification or polymerization. For the pressures and steam injection rates used, packed-column steam refining required a minimum temperature of 170°C to achieve acceptable taste. Bleaching was highly effective in preventing darkening at high steam-refining temperatures, as well as in removing alkaloids, such as theobromine and caffeine, before steam refining. The impacts on the crystallization properties of cocoa butter were studied using DSC and P-NMR. The more significant changes in crystallization kinetics and equilibrium values can be reliably predicted on the basis of FFA removal from the butter.

Models for FFA-removal and changes in phase behavior of cocoa butter by packed column steam refining

“…The present study summarized in this paper aimed to build further on these insights: the experimental conditions were varied over a wider temperature and steam range to validate and extend the conclusions drawn by Vila Ayala et al (2007) for more extreme conditions. Secondly, the relationships between the process conditions, FFA-removal and crystallization behavior were verified in quantitative models, starting from Eqs.…”

“…The fatty acid methyl esters of the acylglycerols and FFA were prepared as described in Official Method Ce 2-66 (Firestone, 1997). Mono, di-and triacylglycerol-distribution of the butter was determined by HPLC, according to the AOCS Official Method Ce 5b-89 (Firestone, 1997), and further described in Vila Ayala et al (2007).…”

“…Calibration, sample preparation, isothermal crystallization procedures and the fitting of the Foubert-model to the data have been previously described in Vila Ayala et al (2007). A concise overview of this model and how it is employed will be given in Section 5.…”

“…According to Foubert, the heat release during a single-step isothermal crystallization can be best described by the following algebraic function as function of time t: f ðtÞ ¼ a F 1 À ð1 þ ð0:99 ð1ÀnÞ À 1Þe ððnÀ1ÞKðtÀt indÞÞ Þ It should be remarked that often parameter n, representing the order of the reverse reaction, can only be estimated with high standard deviations. Hence, it does not add to the mechanistic interpretation of the kinetics and becomes a redundant parameter (Vila Ayala et al, 2007). This value of n is also shown to be correlated with parameter K and it was therefore decided to fix n to the value 7 (Sichien, 2007).…”

“…In comparison to this kind of batch process however, the average residence time at high temperatures in a continuous packed column deodorizer is substantially shorter. Vila Ayala et al (2007) have recently shown that temperatures up to 220°C in packed column steam refining of cocoa butter did not invoke any changes in the TAG profile. It was also observed that changes in physical properties of cocoa butter after steam refining were highly correlated with the removal of FFA.…”