Ripe plums (Prunus salicina L., cv. ‘Sapphire’) with an average
weight of approx. 75 g were bought at the nearby wholesale centre,
tested for external defects and finally graded according to uniform
outer appearance. To determine the fruit volume and the surface
area the main dimensions of produce items were measured
(3 times the diameter displaced at perimeter, 2 times height) using
an electronic calibre. Both the volume and the surface area of the
fruits were approximately calculated via the measured average
diameter applying the corresponding known formulas of a sphere.
For the trials, 5 or 7 fruits per film packaging unit were used to give
different volume relations between air and produce.