Portable Instrument for Measuring Firmness of Cherries and Berries

A portable data-acquisition instrument was designed and built to rapidly and automatically measure firmness of cherries and berries. The firmness is measured by slightly compressing the fruit between two parallel surfaces and recording the force versus deformation data. Tests were conducted on sweet and tart cherries, blueberries, and strawberries. Results show the system is capable of distinguishing between bruise treatments, harvest treatments, and fruit maturity levels. Mean chord stiffness (MCS) was the best indicator of fruit firmness. A description of the instrument is given along with the measurement techniques and results.