The firmness of 13 loose tomato cultivars was followed during a 2-week storage experiment
using a non-destructive commercial acoustic firmness sensor. The same experiment was later repeated
for a second harvest. The firmness change was modelled using a linear mixed model for repeated
measurements showing a significant difference in firmness change among cultivars. Harvest had a
significant effect on firmness change, with summer tomatoes being less firm at harvest, but showing a
less pronounced firmness decline than autumn tomatoes. The linear mixed model parameters were
used to group the different tomato cultivars according to their firmness change, their shelf life and
their variance within a cultivar. Ordering of initial firmness across harvest remained more or less the
same, indicating that the acoustic firmness tester was suitable for determining differences among
tomato cultivars.