Strain Dependence of the Uniaxial Compression Response of Vegetable Shortening

Abstract

Many soft food materials, including vegetable shortening, exhibit complex rheological behavior. For shortening, a precise determination of rheological behavior is necessary to understand its functionality as a food ingredient. Commercial vegetable shortening was subjected to monotonic and cyclic uniaxial compression tests at a wide range of loading rates. The elastic modulus determined from unloading was a function of strain, varying between 740 kPa in the shortening's strain hardening region to 220 kPa at large strain where perfect plasticity had developed. Visual analysis of shortening specimens during the compression process showed that a rate‐dependent stress overshoot was attributable to the development of a shear band following strain hardening. An elastoviscoplastic constitutive model was developed to define the complex rate‐dependent compression response of vegetable shortening. Using the fundamental parameters obtained from the different types of compression tests, the proposed model accurately predicted the uniaxial compression response of vegetable shortening over a wide range (three decades) of compression rates. A model with predictive capabilities of large strain properties is desirable because shortening is subject to large strain in essentially all applications.

Physicochemical and Rheological Characterization of Roll‐in Shortenings

“…Likewise, two other regions including stress overshoot and plastic flow were distinguished. These phenomena have been associated with localized deformation or shear banding-inducing strain hardening, and stress unloading from the low strain adjacent zones promoting softening of the fat crystal network [52]. However, considerable differences are observed among the shortenings.…”

“…At ε h > 0.3, a stress build-up ensued as deformation progressively increased until it reached its peak value at ε h = 1.2. Such behavior appeared to occur faster for roll-in shortenings, which might be attributed to continuous development and propagation of shear bands [52]. Large deformation properties of fat crystal networks such as yield stress (σ * ) stress, apparent Young modulus (E app ), and yield values (C) provide valuable information related to the hardness, spreadability and overall functionality of shortenings.…”

Puff pastry with low saturated fat contents: The role of fat and dough physical interactions in the development of a layered structure

“…The application of large deformations, i.e. sheeting, induces structural changes to the particle network of fat, resulting in decreased elasticity of the fat (Gonzalez-Gutierrez and Scanlon, 2013;Kloek et al, 2005). Therefore, the product consistency during sheeting changes from brittle to spreadable.…”