Structure design of 3D printed cookies in relation to texture

In order to develop a model that allows for a better understanding of the interaction between the properties of the solid matrix, the structure and the mechanical behaviour of the cookie, both mechanical and structural properties need to be taken into account. To this end, a finite element model (FEM) was developed that predicts the mechanical properties of the structured product based on the material properties of the solid material used. The solid material mechanical properties were measured using compression tests with a universal testing machine. A larger variation of structures was analysed by means of FEM simulations, varying the size and shape of the air spaces and wall thickness of the structure. Structural parameters such as porosity, pore size and wall thickness were correlated to the mechanical properties such as Young’s modulus. In a next step these structures validated by means of mechanical compression tests on actual printed structures (by means of fused deposition modelling) with different air space distributions based on the 3D FE design files. The structure of the printed cookies will also be verified by means of 3D micro-CT imaging. Using this final correlation model, microstructure of the products can be engineered to achieve desirable texture properties in silico and create dedicated print files for additive manufacturing of cookies.status: publishe

Structural-mechanical analysis of cookies produced by conventional and 3D printing techniques

Little knowledge exists of the relationship between mechanical properties and microstructure of cookies. A cookie can be described as a solid matrix in which gas spaces of different sizes and shapes are embedded. Additive manufacturing or 3D printing has emerged as a novel method to produce cookies. The process of 3D printing is, however, significantly different from a conventional baking process. In order to assess the texture of 3D printed cookies relative to that of traditional cookies, in this study the mechanical and structural properties of cookies of different compositions and production methods were measured and analysed. Three-point bending tests were performed to determine Young’s modulus, failure stress and strain. X-ray micro-CT imaging at 5 µm pixel size was applied to characterise the 3D microstructure of the cookie samples used in mechanical testing. Of the microstructure properties, structure thickness distribution appeared to change Young’s modulus of cookies; which could be affected by the sugar and fat composition in traditional cookies. The structure of printed cookies strongly depended on both the printing method and the composition. Both particle size of the flour and the binder composition were significant. The structure: binder ratio was less effective to change structure. The final aims of this study are to combine knowledge to understand structure-property relationships of cookies incorporating observed structural properties and to construct a model capable of computing mechanical properties of foods from the microstructure and composition.status: publishe

Characterization and model-based design validation of 3D printed cookies

Additive manufacturing is revolutionizing processing in many applications including 3D food printing. A Fused Deposition Modelling printing method was developed to produce cookies. In order to design food of particular texture, a fine element model was established to predict the mechanical properties of structured products. Cookie structures were engineered to achieve desirable texture properties in silico and dedicated print files were created for 3D printing. In order to validate the model, the properties of the printed cookies were measured and analysed. Compression tests were performed to determine Young’s modulus. X-ray micro-CT imaging was applied to characterize the 3D microstructure of the printed cookies samples. Micro-CT imaging provided a better understanding about the effects of the 3D printing process on cookie structure. Finally, a better fit of the prediction model was obtained by adjusting the model geometry to the scanned printed structure, which indicates the importance of structure integrity for mechanical properties of printed cookies.status: publishe