Is cell structure and composition linked to perception of taste in kiwifruit?

A multidisciplinary research approach has been undertaken to gain more understanding of the impact of cell structure and composition on taste perception. Sensory studies have been undertaken to determine the influence of fruit firmness and size on taste perception of kiwifruit. In parallel, the tissue structure, cell structure and cell acidity have been determined for fruit associated with these firmness and size attributes. The internal tissue zones could be divided into outer pericarp (63%), inner pericarp (35%) and core (2%). The relative proportions of these zones were not influenced by fruit size. The outer pericarp tissue was composed of two cell types: large cells, ellipsoidal in shape with a maximum dimension up to 1 mm, dispersed in a matrix of more isodiametric smaller cells with a maximum diameter <200 µm. In soft fruit, the large cells tended to maintain membrane integrity during mastication, while the small cells lost membrane integrity. In firm fruit, both the large and small cells were likely to lose membrane integrity during mastication. In soft fruit, the contents of large cells had a lower pH than juice expressed primarily from smaller cells. Thus the differential disruption of these cells in soft vs. firm fruit could be responsible for the increased perception of acidity in firmer fruit.