Micromechanical behaviour of apple tissue in tensile and compression tests: Storage conditions and cultivar effect

The micromechanical behaviour of apple tissue was studied using a miniature tensile stage positioned underneath a microscope that allowed for simultaneous acquisition of force–displacement curves while the deformation of the individual cells was followed and recorded. Tensile and compression tests were performed on small samples of apple parenchyma of two different cultivars (Jonagored and Braeburn) and two storage conditions (control and shelf-life). Tests on the repeatability of the methods has provided satisfactory results and will allow the reduction of samples in further experiments. Under tensile loading, no differences for any of the mechanical parameters were found between cultivars, while a significant storage effect was observed for both cultivars. This opens the possibility of developing new sensors for quality assessment. Differences were found when studying the relationship of mechanical properties at the micro- and macro-level, which requires further investigation. The insights gained in this research will be useful when developing mathematical models based upon the mechanical behaviour of apple tissue.