Understanding osmotic dehydration of tissue structured foods by means of a cellular approach

This contribution presents a study on osmotic dehydration of tissue structured foods based on a microstructural approach in which simplified systems such as isolated apple cells and protoplasts have been used. An appropriate description of the microstructure of the raw material and its evolution during processing has been evidenced as critical in order to better understand and describe osmotic dehydration processes; as a direct consequence, it is stated that predictive models should incorporate this microstructural information so as to be more reliable. Microstructural changes observed by examining the isolated cells under the microscope along the treatments have been used to identify critical points that separate the stages that a cell undergoes, and which depend also on its particular response to the osmotic treatment (lysis, shrinkage or complete plasmolysis). Irreversible thermodynamics has been used to mathematically describe the process by distinguishing two main stages: one at which significant deformation–relaxation phenomena are coupled with mass transfer, and another one at which the former may be neglected.

► A comprehensive study on osmotic dehydration of isolated cells is presented.
► Microstructure and its evolution during processing are critical for better understanding and describing the process.
► Specific microstructural changes constitute critical points that make differences in the mechanisms involved in the process.
► Mass transfer is coupled with deformation–relaxation phenomena of the viscoelastic structures.
► Equations based on irreversible thermodynamics have been used to describe the different stages.