Heterogeneous Nucleation Effects of Talc Particles on Polymorphic Crystallization of Cocoa Butter

Laura Bayés-García,Satoru Ueno,Teresa Calvet,Chinami Ishibashi,Mercedes Aguilar-Jiménez,Shinichi Yoshikawa

doi:10.1021/acs.cgd.1c00859

Abstract

Polymorphic crystallization of cocoa butter (CB) in a bulk system was examined for the influence of adding talc particles at different concentrations (0.1–5%). While the system was cooled from the melt and subsequently heated, changes in the heat flow and crystal structure of CB were analyzed using differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (SR-XRD). Synchrotron radiation microbeam X-ray diffraction (SR-μ-XRD) was employed to determine lamellar-plane directions of CB crystals occurring with talc addition. At any cooling rates (0.1–15 °C/min) applied, talc promoted CB crystallization to elevate the onset crystallization temperature logarithmically with the increasing concentration of talc; this effect became more prominent at higher cooling rates. Talc also acted as a polymorphic stabilizer so that CB crystallized in more stable forms even when cooled at highest rate of 15 °C/min. Moreover, a highly ordered lamellar-plane direction was extensively observed for CB crystals occurring with 0.1% talc addition, which was disturbed by 0.5% talc addition probably due to the spatial dispersion of densely populated talc particles in their randomized orientation. These heterogeneous nucleation effects indicate the potential of talc particles to be used for the quality and productivity control of CB-based products.

Highlights

Cocoa butter (CB) is a pale-yellow edible fat with multiple usages in the food, cosmetic, and pharmaceutical industries.[1]
We report on the heterogeneous nucleation effects of talc particles on polymorphic crystallization of multicomponent CB in a bulk system and the dependency on concentrations of talc and crystallization conditions, using measurement techniques of differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (SR-XRD)
Complementary SR-XRD data are detailed for CB in bulk (Figure 1b) and CB + 0.5% (Figure 1c) and 1% (Figure 1d) talc

Summary

Introduction

Cocoa butter (CB) is a pale-yellow edible fat with multiple usages in the food, cosmetic, and pharmaceutical industries.[1] When crystallized in chocolate products, CB constitutes the main body in which sugar crystals, cocoa particles, and other ingredients are embedded. Being composed of three main triacylglycerols (TAGs), 1(3)-palmitoyl-2-oleoyl-3(1)-stearoylglycerol (POS), 1,3-distearoyl-2-oleoyl-glycerol (SOS), and 1,3-dipalmitoyl-2-oleoyl-glycerol (POP), CB presents unique crystal polymorphism responsible for the excellent sensory properties of sharp melting and quick flavor release provided by chocolate.[2] Among the six polymorphs (Forms I−VI) of CB crystals, Form V is intentionally developed in chocolate products through the tempering process to achieve desired texture and mouthfeel. Additives have been mostly employed in chocolate products to retard the occurrence of CB Form-VI crystals, a cause of fat blooming that deteriorates the product quality.[10−17] For this purpose, some of the additives employed have been fatty acid esters, acylglycerols, glycerolglycolipids, lipid (e.g., milk fat) fractions, or emulsifiers, among others

Results

Discussion

Conclusion