TOMATO PERICARP TISSUE RESONANCE AND ITS USE IN TEXTURE EVALUATION

Abstract

ABSTRACTThe use of resonance properties, measured by dynamic oscillation using a constant stress rheometer, as textural parameters for excised pericarp tissue of tomato (Lycopersicon esculentum Mill cv Trust) fruit during 21 days of ambient temperature ripening was assessed relative to the large‐deformation behavior measured by flat‐plate compression. The resonance frequency (fr) of excised tissue discs decreased significantly (P < 0.05) over the first 9–12 days, and then approached a relatively low and constant value with subsequent ripening. A significant (P < 0.05) increase in associated resonance strain amplitude (ymax) became apparent after the first 9–12 days of tomato fruit ripening. Ripening‐associated changes in bioyield and failure strengths, toughness, and apparent elastic and failure deformability moduli derived from flat‐plate compression tests were similar to those observed for tissue fr. Results were consistent with a change in the dominant mode of tissue failure from cell relaxation and rupture to debonding after 9–12 days of fruit ripening. A significant (P < 0.05) semilogarithmic relationship was observed between fr, but not ymax, and compression parameters, allowing for reasonable prediction of large‐deformation behavior on the basis of measurement of only fr. The results demonstrate that resonance frequency may provide a useful parameter in the evaluation of tomato pericarp tissue texture.