shape and strength of red haven peaches at the different stages of their maturity

Global shape of the peaches of the Red Haven variety (harvested on different days during July, 2007) has been characterized by calculating the H/Ds, H/Dc and Dc/Ds ratios. There is no, or nearly no, differences between peaches harvested at the different days. The shape of the all tested peaches was very close to round one. The more detailed description of the peach shape is based on the Elliptic Fourier analysis (EFDs) of the digital photos. The knowledge of the parameters (curvature etc.) is very useful e.g. for the evaluation of the results of the strength tests. Compression tests have been also perforemd – the whole peaches have been compressed between two plates at the constant cross–head velocity 20 mm/min. The force–displacement curves are characterised by certain monotonic increase and the point called bioyield, where force exhibits a drop. The bioyield significantly decreases with the date of the harvesting. There is no evidence of the dependence of this parameter on the direction of loading. The same result is approximatively valid for apparent modulus of elasticity E. The force–displacement curves have been successfully modelled by non-linear mathematical models.