Elastic reinforcement and yielding of starch-filled lipid gels

Many foods involve complex suspensions of assorted particles in a Newtonian liquid or viscoelastic medium. In this work, we study the case of suspensions of non-Brownian non-interacting rigid particles: starch, embedded in a soft solid: a colloidal lipid gel. We relate the macroscopic properties of the suspensions to the mechanics of the colloidal gel and the particle volume fraction. As particle volume fraction increases, the suspension gradually stiffens and becomes brittle as the system approaches its maximum packing fraction. The latter is independently determined from a geometric theory of random close packing for polydisperse hard spheres based on the log normal distribution of starch particles dispersed in oil. The elastic modulus, yield stress and yield strain are interrelated through simple scaling laws from a micromechanical homogenization analysis of hard spheres isotropically-distributed in yield stress fluids

Elastic reinforcement and yielding of starch-filled lipid gels

Many foods involve complex suspensions of assorted particles in a Newtonian liquid or viscoelastic medium. In this work, we study the case of suspensions of non-Brownian non-interacting rigid particles: starch, embedded in a soft solid: a colloidal lipid gel. We relate the macroscopic properties of the suspensions to the mechanics of the colloidal gel and the particle volume fraction. As particle volume fraction increases, the suspension gradually stiffens and becomes brittle as the system approaches its maximum packing fraction. The latter is independently determined from a geometric theory of random close packing for polydisperse hard spheres based on the log normal distribution of starch particles dispersed in oil. The elastic modulus, yield stress and yield strain are interrelated through simple scaling laws from a micromechanical homogenization analysis of hard spheres isotropically-distributed in yield stress fluids

Thermoresponsive oil-continuous gels based on double-interpenetrating colloidal-particle networks

Gels composed of multicomponent building blocks offer promising opportunities for the development of novel soft materials with unique and useful structures. While interpenetrating polymer networks have been extensively studied and applied in the creation of these gels, equivalent strategies utilizing colloidal particles have received limited scientific and technological attention. This study presents a novel class of thermo-responsive apolar double gels from interpenetrating networks of attractive colloidal silica and lipid particles. These double gels are easily assembled and suitable for the fabrication of 3D-printed edible soft constructs. Emphasis is focused on the rheological properties and structure emerging on the dilute regime (ϕ ≲ 0.1). Rheological investigations demonstrate that double gels exhibit greater stiffness and resilience to yielding compared to their single lipid gel counterparts. The scaling behavior of the oscillatory linear shear moduli and the critical strain for yielding with volume fraction remain comparable between single and double gels. Creep yielding in double gels exhibits two exponential decay regimes, suggesting the presence of thicker gel strands undergoing flow. Visualization and quantification of the quiescent microstructure confirms the existence of such denser aggregates devoid of larger clusters due to steric hindrance of interpenetrating networks in double gels. This is in stark contrast to lipid single gels where aggregates grow unrestrictedly into larger clusters. Our study constitutes the first demonstration on the assembly of apolar double gel networks as a promising avenue for the design of novel soft materials and foods with tailored structure and mechanics

Elastic reinforcement and yielding of starch-filled lipid gels

Many foods involve complex suspensions of assorted particles in a Newtonian liquid or viscoelastic medium. In this work, we study the case of suspensions of non-Brownian non-interacting rigid particles: starch, embedded in a soft solid: a colloidal lipid gel. We relate the macroscopic properties of the suspensions to the mechanics of the colloidal gel and the particle volume fraction. As particle volume fraction increases, the suspension gradually stiffens and becomes brittle as the system approaches its maximum packing fraction. The latter is independently determined from a geometric theory of random close packing for polydisperse hard spheres based on the log normal distribution of starch particles dispersed in oil. The elastic modulus, yield stress and yield strain are interrelated through simple scaling laws from a micromechanical homogenization analysis of hard spheres isotropically-distributed in yield stress fluids