Abstract Microwave reheating of ready-to-eat surimi-based shrimp-imitation product may produce undesired textural changes. Uniaxial compression tests indicated that a significant increase in toughness was observed during microwave heating but only if water boiling took place. Boiling under microwave was accompanied by a considerable product shrinkage and thus by an increase in density. The increase in toughness and density, which were highly correlated, was proven not to be the result of moisture-loss, but of partial volume collapse and the compaction of the product due to loss of internal pores volume. This change in volume seems to be the result of driving the air out from these pores by steam followed by shrinkage of the product elastic matrix.