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Quantifying the differences in structure and mechanical response of confectionery products resulting from the baking and extrusion processes

Butt, Saba S., Mohammed, Idris K., Raghavan, Vivek, Osborne, James, Powell, Hugh, Charalambides, Maria N.
Journal of food engineering 2018 v.238 pp. 112-121
assets, baking, computed tomography, extrusion, geometry, image analysis, manufacturing, mechanical properties, microstructure, porosity, scanning electron microscopy, sensation, sweets, texture, water content
Extrusion has potential advantages over baking in terms of throughput, asset cost and flexibility. However, it is challenging to achieve through extrusion the “light, crispy” texture of a more traditional baked confectionery. This study compares and contrasts for the first time confectionery products produced through these two processes, i.e. baking and extrusion. The microstructural differences are measured using imaging techniques, i.e. Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT) whereas mechanical characterisation is used to highlight differences in the resulting mechanical properties. Crucial information is presented which shows that the two technologies result in different mechanical properties and microstructures, even if the level of porosity in the two products is kept constant. In addition, confectionery products whether they are produced through baking or extrusion, have irregular geometries. The latter makes mechanical characterisation a real challenge. Therefore this study also presents rigorous methods for measuring true mechanical properties such that meaningful and valid comparisons may be made. The accuracy of the chosen methodologies is verified through experiments using flat and tubular extruded geometries as well as testing the products in various directions. It was concluded that the manufacturing method and, in the case of extrusion, the initial moisture content influences the microstructure and mechanics of confectionery products, both of which have an impact on consumer sensory perception.