Texture and microstructure of cocoa butter replacers: Influence of composition and cooling rate

• The influence of composition and cooling rate on texture of fats was studied.
• A strong interaction between composition and cooling rate was found.
• Inter- and intraparticle links in the fat crystal network was important.
• Formation of solid bridges plays an important role for brittleness of fat.

In this study, the effect of cooling rate on cocoa butter replacers with similar content of saturated fat but different types of saturated fatty acids was evaluated. Two fats with a high content of monounsaturated asymmetric triacylglycerol were studied (62.1% and 70.9%, respectively); one with a high content of palmitic acid (P-rich) and one with a high content of stearic acid (S-rich). Different cooling rates (0.1, 0.5 and 2 °C/min) were applied during crystallization and samples were stored at different times (0 h, 1 day and 7 days) prior to analysis by pNMR, texture analysis, oscillatory rheometry and microscopy. For the S-rich fat, cooling rate influenced brittleness to a higher extent compared with storage modulus and hardness whereas for the P-rich fat cooling rate influenced hardness and storage modulus to a higher extent compared with brittleness. For the S-rich fat, an increase in brittleness around 75% and an increase in storage modulus around 25% were observed for faster cooling whereas no significant effect of cooling rate on hardness was observed after 1 week of storage. An increase in hardness and storage modulus around 30% and 50%, respective, and no significant increase in brittleness was observed for faster cooling of the P-rich fat.The different behaviour depended on the relative inter- and intraparticle links in the fat crystal network. For the S-rich fat, faster cooling provided stronger interparticle links, most likely as a result of formation of solid bridges, which lead to a more brittle texture. For the P-rich fat, faster cooling provided stronger intraparticle links and an increase in the sum of weak interparticle links resulting in a harder but not brittle texture. The results contribute to clarify the mechanisms behind effects of cooling rate on different textural characteristics of fat and show the importance of understanding effects on the relative strength of inter- and intraparticle links in the fat crystal network to be able to tailor the textural properties of fats.

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