Impact of triacylglycerol composition on shear-induced textural changes in highly saturated fats

• Effect of shear rate on the microstructure on texture of highly saturated fats.
• Results show a strong interaction between shear rate and TAG-composition.
• Blends based on symmetric monounsaturated TAGs are strongly influenced by shear rate.
• Only small effects of shear rate on blends based on asymmetric monounsaturated TAGs.
• Stearic acid rich blends are harder and more brittle than palmitic acid rich blends.

This study demonstrates a strong interaction between triacylglycerol (TAG) composition and effects of shear rate on the microstructure and texture of fats. Cocoa butter alternatives with similar saturated fat content, but different major TAGs (PPO-, PSO-, SSO-, POP- and SOS-rich blends) were evaluated. Results show how shear can create a harder texture in fat blends based on symmetric monounsaturated TAGs (up to ∼200%), primarily due to reduction in crystal size, whereas shear has little effect on hardness of asymmetric monounsaturated TAGs. Such differences could not be ascribed to differences in the degree of supercooling, but was found to be a consequence of differences in the crystallisation behaviour of different TAGs. The fractal dimension was evaluated by dimensional detrended fluctuation analysis and Fourier transformation of microscopy images. However, the concept of fractal patterns was found to be insufficient to describe microstructural changes of fat blends with high solid fat content.