Development and Evaluation of a Portable Apparatus for Bioyield Detection: A Case Study with Apple and Peach Fruits

Abstract

The objectives of the present study were to design and fabricate an apparatus for measuring the bioyield force of fruits as a potential replacement for Magness-Taylor tester. For this purpose an apparatus consisting of force measuring, motion control, and electronic control units was developed. Thirty-nine probes having various diameters and rubber tip designs at three loading rates were evaluated to select the most appropriate probes for detecting bioyield force of peach and apple fruits. For selecting appropriate probes two sets of tests (on bioyield force and Magness-Taylor firmness measurements) were conducted by Instron equipped with either of fabricated probes and Magness-Taylor probe. A probe with 4.8 mm diameter and 4.8 mm thickness of rubber tip with elastic modulus of 2.5 MPa and similar probe but with 1MPa elastic modulus could establish good correlation between bioyield force and Magness-Taylor firmness at 6 and 9 mm min−1 loading rates, thus these were selected as suitable probes for apple and peach fruits, respectively. In the second stage both Instron and newly developed apparatuses were equipped with two selected probes and bioyield tests were carried out. The results showed that the newly developed apparatus was able to measure apple bioyield force with a correlation (0.996) with data output from control (Instron). For peach fruit, similar correlation (0.991) was obtained. The root mean square error indices for apple and peach fruits were 0.77 and 0.11 N, respectively. Since bioyield measurements do not degrade the quality of a tested fruit, this device could be used to measure the firmness of fruits in the orchard, during postharvest handling.