Numerical simulation of stress distribution in heterogeneous solids during high pressure processing

• Stress gradients can develop inside a solid food with hard inclusions during HPP.
• This contradicting the current assumption that pressure is uniform.
• The gradients are dependent on the mechanical properties of the material.
• Stress non-uniformity could lead to non-uniformity in microbial inactivation.

It is generally assumed that the internal stress distribution in foods under high pressure processing (HPP) is uniform, which may not be true for solid foods with hard inclusions, like meats with bones or for particulate foods. Our objective was to simulate the internal stress distribution during HPP of a model heterogeneous solid food made with a gel and a wood inclusion and determine how mechanical properties affect the internal stress distribution. It was determined that hydrostatic pressure decreased and shear stress was generated at the interface between the soft solid and the hard inclusion. The differences in pressure and shear stresses increased as the shear modulus of the soft solid increased. Our studies suggest that a better understanding of the mechanical properties that affect the development of the internal stress field is needed, since they could affect the achieved microbial inactivation levels at different locations in HPP solid foods.

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