In Situ Mechanical Testing of Dry and Hydrated Cellular Materials in the Environmental Scanning Electron Microscope (ESEM)

Extract

We present a method for directly observing and quantifying the mechanical deformation of cellular foods, such as breadcrumb and Chinese water chestnut, with the aim of identifying the key differences in the nature of cell wall failure and crack propagation. These factors are of importance to the food industry, and this work may enhance our understanding of the changes in behaviour of crisp cellular foods when subjected to a moist environment.

Breadcrumb coatings are commonly applied to a core substrate such as meat, poultry, fish and vegetables. After flash-frying the product is often frozen, but during storage there is a tendency for the coating to absorb water from the substrate. The driving force for this process is the large difference in water activity level a_w between the two materials. Incorrect reconstitution of the product, for example by microwave cooking, leads to a significant loss of crispness.