3D printing is a unique manufacturing method that enables food customization. The development of a modeling framework to predict mechanical properties of food products is an invaluable tool in such a customization process. To set up this framework, 3D printed samples are mechanically characterized by means of compression testing. The observed phenomena are captured in a constitutive model that describes the large deformation behavior and the brittle failure of the material. Due to the rough contact surface of 3D printed samples, spatial homogeneity is lost and parameter identification is rendered not straightforward. To incorporate this non-uniformity, the model is implemented in a finite element package. Simulations reveal the influence of this geometrical effect, allowing to identify the model parameters by which the mechanical behavior of the material is adequately described.