A method for measuring tomato fruit firmness using a modified shear press

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Abstract
Summary: Tomato fruit firmness was measured with a modified shear press by compressing individual fruit by 5 mm between two flat surfaces. the system was calibrated with a spring balance and the relationship between applied force and proving ring deformation was linear over the range tested.The correlation coefficient between tomato fruit firmness as measured by a finger feel panel and the shear press was 0.988. Minimum shear press firmness values for acceptability of fruit for sale at retail level and use in the home were obtained by matching the panel and shear press data.Tests showed that from fifteen to twenty‐five fruit should be tested per 12‐lb box to get a good estimate of the average firmness of the lot. the spread of firmness values on either side of the mean was considerable in the nineteen lots tested and it is important to quantify this and quote it, in addition to the mean firmness value, to give a complete picture of tomato fruit firmness.The system described is useful for carrying out firmness tests on tomato fruit cultivars at time of picking and during storage in order to obtain an estimate of potential shelf‐life during wholesaling and retailing.