general method for the instrumental assessment of the colour of tomato fruit during ripening

The colour of subjectively‐chosen tomato fruit of three contrasting cultivars at each of five stages of ripeness were measured on a tri‐stimulus colour difference meter. The values were introduced into a formula previously developed for calculating objective limits for each ripening stage, but satisfactory separations were not achieved. When the colour components for areas on the side‐walls of tomatoes were introduced into a revised formula, good discrimination was achieved between classes of fruit from fairly ripe to fully ripe. Similar measurements carried out on areas near the stylar scar and used with an alternative formula led to efficient separation of less ripe fruit into distinct classes. It is suggested that the revised formula can be applied to any cultivated tomato line except colour mutants.