Crystallization Behavior Of Cocoa Butter Research Articles

Determination of the process effect on cocoa butter crystallization by rheometer: Kinetic modeling by Gompertz equation.

In this study, the effects of temperature (22, 24, 26, 28, and 30°C) and strain (0.1%, 1%, and 5%) on cocoa butter (CB) crystallization were investigated by oscillatory test, and the four-parameter Gompertz model was used to interpret the effect of parameters on pre-crystallization, nucleation, and crystal growth stages of CB. Lag time and growth rate were calculated using the Gompertz model using time-dependent storage modulus (G') data. According to the results, CB crystallization at 26°C with a 1% strain value had the highest growth rate value, the shortest lag time, and the formation of βv polymorph type. Followingly, polymorphic types of the CB crystals were determined based on the melting points of polymorphs via the temperature ramp step, and the results obtained were correlated with a polarized light microscope. In conclusion, using a rheometer in both the observation of the pre-crystallization process and the determination of polymorph types is very important for research and development studies in the chocolate industry for process and formulation optimization. PRACTICAL APPLICATION: This study demonstrates the feasibility of a novel approach for investigating crystallization and oscillatory shear of CB using a rheometer, both for observing crystallization kinetics and determining polymorph type, accompanied by the Gompertz equation to model the crystallization kinetics. According to the results, the effect of process parameters (temperature and shear) on the crystallization behavior of CB can be observed by rheometer, which can provide a detailed perspective for chocolate manufacturers and researchers in research and development studies.

Engineering effect of oleogels with different structuring mechanisms on the crystallization behavior of cocoa butter.

As promising cocoa butter (CB) alternatives, oleogels have the potential to prevent fat blooms of chocolate. We aimed to explore possible reasons for the bloom resistance of oleogels by investigating the crystallization behavior of CB-oleogel blends, including crystallization kinetics, thermodynamic properties, crystal polymorphism, and oil distribution. Oleogels structured by monoglyceric stearate (MO), β-sitosterol/lecithin (SLO), and ethylcellulose (EO) were selected as representative oleogels with various structuring-mechanisms. Crystallization kinetic results showed that the crystallization dimension of CB-oleogel increased with the oleogel proportion (from one-dimensional to multi-dimensional), confirming that CB crystallization was inhibited. The presence of liquid oil and oleogelators in oleogels may increase the free energy barrier for CB crystallization. The proton mobility of liquid oil in CB-MO was lower because MO was more tightly bound to CB. The crystallization mechanism of the CB-oleogel suggested that the inhibitory effect of oleogels on CB crystallization delayed the polymorphic transition, thereby improving the bloom stability of chocolate.

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The purpose of this study was to determine the effects of shear and cooling-heating rates on the rheological behavior of cocoa butter. Three different shear rates (25, 50 and 100 s-1) and two different cooling rates (1 and 10 °C.min-1) were applied for crystallization of cocoa butter at 20, 22 and 24°C. Also, effects of shear and heating-cooling rates were monitored during the cooling and heating cycle between 70-20°C. When the cooling rate was 1 °C.min-1, viscosity reached the highest value of 0.6 Pa.s with a shear rate of 25 s-1. A rapid rate of cooling generally led to nucleation at a lower temperature compared to slow cooling. It was observed that crystallization of Form V was improved by shear and induction time of crystallization decreased as the rate of shear increased. The longest induction period was obtained at 24°C. Effect of cooling rate was more significant at low temperatures (P < 0.05). It was also concluded that the crystallization behavior of cocoa butter was dependent on both shear and cooling rates under isothermal conditions.

Dynamic changes in the triacylglycerol composition and crystallization behavior of cocoa butter

Dynamic changes in triacylglycerol composition during complete crystallization were investigated by separating crystals from molten cocoa butter (CB) over different lengths of crystallization time. The dynamic crystallization behavior of CB was described by solid fat content (SFC), crystal morphology, and microstructure. The crystallization process was divided into stages, based on the growth mode of crystals: the induction, primary crystallization, and secondary crystallization stages. As crystallization progressed, the relative content of 1,3-dipalmitoyl-2-oleoylglycerol (POP) increased from 12.1% to 29.8%; that of 1,3-distearoyl-2-oleoylglycerol (StOSt) decreased from 37.1% to 20.2%; and that of tristearin (StStSt) decreased from 4.9% to 0.2%. Circular crystals were formed at the induction and primary crystallization stages, and β′-III form and β′-IV form polymorphisms were exhibited. When crystallization entered the secondary crystallization stage, the crystal morphology changed from circular to acicular, and polymorphic transformation from the β′-III form and β′-IV form to the β-form was observed.

The Effect of Hard Lauric Fats on the Crystallization Behavior of Cocoa Butter Substitute.

This work investigated the crystallization and melting behavior of cocoa butter substitute (CBS) blended with two hard lauric fats: fully hydrogenated palm kernel oil (FHPKO) and krabok seed fat (KSF). The aim was to find a way to increase the heat resistance of CBS for the production of heat-resistant compound chocolate (HRCC). Adding FHPKO to CBS increased the crystallization rate with a decrease in crystallization induction time but did not increase the heat resistance. In contrast, all KSF-CBS blends exhibited higher heat resistance than CBS and crystallized into β' form, a preferred polymorph for fats used in compound chocolate. Only the blends with 10-60% KSF melted completely at the body temperature, indicating that they would leave no waxy mouthfeel, but the blends with 30 and 40% KSF exhibited a significant decrease in the crystallization rate compared to the original CBS. Therefore, the KSF-CBS blends with 10, 20 and 60% KSF are recommended for future use as fats for HRCC production.

Isothermal Crystallization Behavior of Cocoa Butter at 17 and 20 °C with and without Limonene

Differential scanning calorimetry and real-time X-ray diffraction using synchrotron radiation were used to elucidate isothermal cocoa butter crystallization at 17 and 20 °C in the absence and presence of different limonene concentrations. At 17 °C, a three-step crystallization process was visible for pure cocoa butter, whereby first an unknown structure with long spacings between a 2L and 3L structure was formed that rapidly transformed into the more stable α structure, which in turn was converted into more stable β' crystals. At 20 °C, an α-mediated β' crystallization was observed. The addition of limonene resulted in a reduction of the amount of unstable crystals and an acceleration of polymorphic transitions. At 17 °C, the crystallization process was accelerated due to the acceleration of the formation of more stable polymorphic forms, whereas there were insufficient α crystals for an α-mediated β' nucleation at 20 °C, resulting in a slower crystallization process.

Lecithin influences cocoa butter crystallization depending on concentration and matrix

The isothermal crystallization at 20°C of cocoa butter (CB) or milk chocolate (MC) with addition of two different sunflower lecithins and one soy lecithin in different concentrations was investigated by differential scanning calorimetry (DSC), oscillatory rheology and a dynamic experiment. A two‐step crystallization process was observed with first formation of an unstable α polymorph followed by a polymorphic transition to β′. In the CB matrix, different measuring techniques led to distinct observations by addition of 1.5% lecithin on a fat base. DSC showed a faster α crystallization with addition of lecithin, while rheology measurements demonstrated the reverse effect. However, both measuring techniques evidenced a faster polymorphic transition to the β′ polymorph in lecithin enriched samples. Between the different lecithins no large differences could be detected by the static measuring techniques, while the dynamic experiment exhibited a clearly lower crystallization rate for lecithin B, which was even lower than the pure CB. A remarkable concentration effect was visible in the CB matrix with in general a reduced effect at higher lecithin concentrations. Finally, a different behavior was observed in the MC matrix compared to the CB matrix, presumably by the interaction of lecithin with sugar.Practical applications: Lecithin is added to chocolate formulations to control the flow properties. The handling and processability of the chocolate is improved by a proper viscosity and the perception of flavor by the consumer is also affected by the viscosity (Beckett, 2009, Industrial chocolate manufacture and use, Blackwell Publishing Ltd, Oxford, United Kingdom, pp. 224–246). The effect of lecithin on the rheology of chocolate has been extensively studied, but the effect of lecithin on the crystallization behavior has received much less attention in literature. This is true despite the fact that the crystallization process determines to a large extent the quality of the end product and the addition of minor components such as lecithin can modify the crystallization behavior. As lecithin is a natural product, different lecithins could demonstrate different effects and even different concentrations could show different behaviors (Smith et al., 2011, J. Am. Oil Chem. Soc. 88, 1085–1101). As such, the addition of lecithin should be optimized in chocolate recipes to compromise between flow properties and crystallization behavior.In this work two sunflower lecithins and one soy lecithin were chemically characterized and subsequently their effect (by addition of 1.5%) on the crystallization behavior of cocoa butter was studied by DSC. Thereafter, the concentration effect was examined by varying the added concentration of lecithin between 1, 1.5, and 2%. By using a cocoa butter and milk chocolate matrix, the matrix effect was investigated. Finally, addition of 1.5% lecithin to cocoa butter was also studied with rheology and a dynamic experiment. In general, we can state that the observed effect depends on the concentration, matrix, and measurement technique used, which explains contradictory results in the literature.

Effects of Sorbitan Monostearate and Monooleate on the Crystallization and Consistency Behaviors of Cocoa Butter

AbstractThe crystallization behavior of cocoa butter (CB) is the essential structuration issue in the development of chocolate products. An alternative to modify and control the crystallization patterns of CB in chocolate production is the incorporation of specific emulsifiers in their formulations. In this work, the effects of sorbitan monostearate (SMS) and sorbitan monooleate (SMO) in the crystallization and consistency behaviors as well as on the microstructure of CB were evaluated. CB samples at three different concentrations (0.5, 1.0 and 1.5 % w/w) of SMS and SMO were prepared and their main physical–chemical attributes determined. CB added with 1.5 % of SMS showed the largest effects with a sharp increase in the onset of the crystallization temperature (from 19.3 to 23.8 °C) and doubling the yield value (consistency) of pure cocoa butter. The classic two‐step isothermal crystallization behavior and morphology of CB were also modified with the addition of SMS. A possible explanation based on the solubility of SMS in an organic medium and its ability of self‐assembling was suggested as a mechanism for SMS performance in CB. SMS was considered as a potential crystal modifier for CB by changing its crystal structure and enhancing its thermal resistance—factors that favor the use of this emulsifier in the production of improved thermally stable chocolates.

Polymorphism and solidification kinetics of the binary system POS‐SOS

AbstractAs a first approach to modeling the crystallization behavior of cocoa butter, the binary system of its two major components, 1‐palmitoyl‐2‐oleoyl‐3‐stearoyl‐s n‐glycerol (POS) and 1,3‐distearoyl‐2‐oleoyl‐s n‐glycerol (SOS), was studied. Differential scanning calorimetry, coupled with polarized light microscopy, was used to determine the phase diagrams of the various polymorphic forms (the most metastable sub‐α and α, intermediate δ and β′, and stable β). Associated theoretical phase diagrams were also built. The presence of a solid solution for β and the ideal behavior of α were confirmed. Kinetics of isothermal solidification as a function of temperature were studied for three compositions of the POS‐SOS system. Results were displayed as time‐temperature‐transformation (TTT) diagrams and crystal morphology maps. Dependence of the crystallization kinetics on composition of the binary system was interpreted in terms of nucleation and growth mechanisms. The asymmetry of the POS molecule induces a slower growth rate of the mixture when the concentration of this triacylglycerol is increased. Solidification kinetics during continuous cooling were studied at various cooling rates for the system POS‐SOS 25:75. Experimental results were compared with numerical predictions of a solidification model based upon TTT data and an additivity principle. The calculated and measured volume fractions of the different phases formed and times of onset and finish of the solidification were in good agreement.

Real‐time X‐ray powder diffraction investigations on cocoa butter. I. temperature‐dependent crystallization behavior

AbstractThe crystallization behavior of cocoa butter has been investigated by means of real‐time X‐ray powder diffraction. Two procedures have been followed: cooling from 60°C at a constant rate until maximum solidification has taken place; and cooling from 60°C in 2 min to a constant solidification temperature. It appears that all polymorphic forms of cocoa butter, with the exception of the β form, can be formed from liquid. The solidification temperature appears to be the most important crystallization parameter.

Seeding Effects on Crystallization Behavior of Cocoa Butter

Seeding Effects on Crystallization Behavior of Cocoa Butter

Seeding effects on crystallization behavior of cocoa butter.

The crystallization rates of cocoa butter with and without seeding were measured at 25 and 30°C with a viscometer to examine seeding eifects on the solidification kinetics of cocoa butter. Three polymorphic forms of cocoa buffer were used as the seed crystals to examine the influence of polymorphism. We found that the crystallization was greatly accelerated by the addition of the seed powders of Forms III, V, and VI; Form VI was most effective. However, the polymorphic form of the crystallized cocoa butter was primarily set by the temperature of crystallization irrespective of the polymorphism of the seed crystal: Forms IV and V at 25°C, and Forms V and VI at 30°C.