Zhiguo Li
University of Birmingham
UK
Title: Mechanical behaviour of single tomato fruit cells under compression at high speed
Biography
Biography: Zhiguo Li
Abstract
Mechanical characterization of single cells is vital to the macro-scale modelling and simulation of mechanical damage to fruits and vegetables. The mechanical behaviour of single cells in the tomato mesocarp tissue was characterized by micro-compression testing. Single cells of Elegance tomatoes were novel isolated by mechanical brushing from a mesocarp block into water in a beaker and then transferred into a chamber for micro-compression. In order minimise the effect of viscoelasticity and possible loss of water under compression, 20 single cells were compressed to a final deformation of 15% at 4900 μm/s which was much higher than the previous loading speed. The cells were treated as a solid sphere in order to model their elastic behaviour using the Hertz model. The cell geometry was characterized by the initial height, geometric mean diameter and sphericity and the elastic-plastic mechanics of cell were characterized by peak force Fmax, elastic modulus E and yield stress σy deduced by Kogut & Etsion (2002). There was a strong correlation between the initial height and geometric mean diameter, and a significant difference in the geometric mean diameter of cells before and after compression (P<0.05). Fmax increased with the cell diameter GMD1, but E and σy were independent of the cell geometric parameters as expected. The Fmax, E and σy of single cells in the mesocarp were 2.5±0.6 mN, 0.8±0.2 MPa and 0.03±0.01 MPa respectively. These cell mechanical parameters are intended to be used to model the relationship between macro-scale and micro-scale mechanics of tomato fruits.