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Stress relaxation in cherry fruit
1Czech University of Agriculture, Prague Suchdol, Czech Republic. blahovec@tech.vsz.cz
Biorheology
|November 1, 1996
Summary
This study investigated cherry firmness using stress relaxation tests. Cherry skin significantly impacts elasticity measurements, but a thermal activation model accurately predicts fruit firmness from relaxation data.
Area of Science:
- Food science
- Materials science
- Biophysics
Background:
- Cherry skin significantly affects the apparent modulus of elasticity, potentially masking true fruit properties.
- Understanding cherry firmness is crucial for quality assessment and post-harvest handling.
Purpose of the Study:
- To analyze stress relaxation in three cherry varieties.
- To evaluate the influence of cherry skin on mechanical properties.
- To apply thermal activation theory to model cherry stress relaxation.
Main Methods:
- Utilized a penetration test with a 4 mm cylindrical pin and flat tip.
- Compared intact cherries with those partially skinned to isolate skin effects.
- Applied thermal activation theory to analyze stress relaxation data.
Main Results:
- Cherry skin approximately doubles the apparent modulus of elasticity.
- Thermal activation theory provided results comparable to those for vegetable flesh.
- Residual stress and activation volume were key indicators of real consistency.
- The relationship between parameters (Ct, log bt) and the initial slope of the relaxation curve correlates with fruit firmness.
Conclusions:
- Cherry skin significantly influences mechanical measurements and should be considered in firmness assessments.
- Thermal activation theory is a viable model for understanding stress relaxation in cherries.
- Specific parameters derived from stress relaxation curves can quantitatively assess cherry firmness.