Basic conditions required to obtain accuracy on the values of forces for collapse of coffee fruits under compression tests were investigated. The requirements of force, strain and energy up to the collapse point of the material were also determined. The independent variables investigated were: presence of peduncle; compression velocity; product maturation stage and fruit orientation during the compression. The fruits tested were at three maturation stages (classified by color): 'cherry', 'green' and one named 'verdoengo' (stage somewhere between cherry and green). Analysis of the results showed a sample size requirement of, at least, fifty fruits to estimate the collapse forces with an error less than 10%. The values of forces, strains and energies up to the collapse of 'cherry' fruits were not influenced by the presence of peduncle on their surfaces. Also the compression velocity seems to have no influence on the collapse parameters investigated. On the other hand, fruit orientation and product maturation stage were found to affect the values of force, strain and energy up to the fruit collapse.
Coffea arabica L; force, strain; collapse
