X-ray micro-computed tomography analysis of apple texture and structure

Texture is an important component of apple quality and is a key driver of consumer acceptability. Texture in fruits and vegetables is particularly dependent on the type of cells within a tissue, their turgor, cell wall strength, adhesion between cells and the way cells pack together. Here the textural aspects of two genotypes (402 and 495) from a 'Royal Gala' × 'Braeburn' mapping population with extremes in cortical tissue density were assessed using X-ray micro-computed tomography in combination with conventional textural assessments to evaluate tissue packing and air space volume and configuration. One of these genotypes (402) is less dense (0.78 g mL^-1) and has a lower flesh firmness (28.74 N) while the other (495) is considerably denser (0.93 g mL^-1) and firmer (90.37 N). Samples of cortex tissue from the less dense Genotype 402 was dominated a single very large airspace averaging over five million voxels, while Genotype 495 had more smaller airspaces and one airspace that averaged just over 200,000 voxels. These preliminary findings demonstrate the value of a combined approach to understanding the factors contributing to apple texture.