Assessment of two different rapid compression tests for the evaluation of texture differences in osmo-air-dried apple rings Original Research Article

Mechanical properties of dried apples rings were studied through two different rapid compression tests. A bending–snapping test and a modified compression–relaxation test were performed in order to differentiate between osmo-air-dried apple rings as a function of variety (Golden Delicious and Pink Lady®) and drying temperature (70 °C, 80 °C, 90 °C). Elastic modulus during bending, fracturability indices, peaks density, and relaxation coefficient during compression were taken into consideration. The obtained results reflect primarily the effect of the drying process on the moisture content of both varieties, but also the different changes in the tissues structure related to both the different solid–liquid exchanges during the osmotic pre-treatment and the drying process. Undergoing the same drying treatment, Pink Lady® rings showed a more rigid and stiff texture than Golden Delicious, which in contrast had a more brittle texture. The obtained results described satisfactorily structural changes of apple tissues, giving the possibility to discriminate, in a rapid way, between different categories of dried apples.