In this study, the textural thermo-mechanical properties of three sweet cherry varieties were systematically investigated by the puncture test of whole fruit, uniaxial tension of the exocarp, and uniaxial compression test of mesocarp. It was found that the puncture test can not only reflect the shear mechanics of the exocarp in vivo at the tissue level, but it can also characterize the resistance level of fruit to puncture damage at the macroscopic level, particularly when the puncture failure stress is used. The environmental temperature had negative and positive significant effects on the puncture failure stress and the puncture failure deformation of the sweet cherry (p < .05), respectively. The environmental temperature showed a negative significant effect on the failure stress and elastic modulus of the sweet cherry exocarp under tension and mesocarp under compression (p < .05). As the environmental temperature increased from 5 to 40°C, the elastic modulus of the Black pearl, Summit, and Tieton sweet cherry exocarp ranged from 2.28 to 1.72, 2.57 to 1.47, and 1.98 to 1.24 MPa, respectively; and that of mesocarp ranged from 0.33 to 0.21, 0.27 to 0.19, and 0.43 to 0.23 MPa, respectively. The obtained exponential function relationships between environmental temperature and each mechanical parameter are useful for predicting the thermo-mechanical properties of sweet cherry across a 5-40°C continuous temperature range. This study provided systematical thermo-mechanical data for predicting the mechanical damage of sweet cherry in postharvest handling using the thermo-mechanical coupling numerical simulation.
Keywords: mechanical damage; postharvest handling; sweet cherry; texture; thermo-mechanical properties.
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