Abstract

As different tomatoes have different locular cavities and a particular tomato materialis inhomogeneous, the effect of tomato internal structure on its mechanical properties and degree of mechanical damage may be significant during the gripping process with robot fingers. This was studied using the loading-unloading experiment as well as the observation of shelf life. The results showed that the plastic strain energy, E_p, peak force, F_max and degree of elasticity, r_c, were not significantly affected by the internal structure of three-locular tomato before its failure, but loading slope, r_k, was. The degree of elasticity, r_c and loading slope, r_k, were significantly affected by the internal structure of four-locular tomato before its failure, but the plastic strain energy, E_p, and peak force, F_max, were not. The compressibility e was the most important explanatory variable in the model of the degree of mechanical damage to tomato. The internal structure of four-locular tomato had a significant effect on its degree of mechanical damage, but the internal structure of three-locular tomato does not. Excluding the covariates, at the same compressibility, the degree of mechanical damage was greatest under the condition of F*CW and lowest for F*L their difference was 21.3%. The discrepancy of the medium degree of mechanical damage was slight under the condition of T*CW andT*L, respectively.

Key words: Tomato, internal structure, mechanical properties, degree of mechanical damage, analysis of covariance.

Abbreviation

F*CW, Four-locular tomatoes at cross wall tissue; F*L, four-locular tomatoes at locular tissue; T*CW,  three-locular tomatoes being loaded at the cross wall tissue; T*L, three-locular tomatoes at locular tissue; GLM, generalized linear modeling; ANCOVA, analysis of covariance; RGB, red, green, blue; NMR, nuclear magnetic resonance.