De Kock, V.A., 2019, ‘Comparison of standard 11-mm penetrometer plungers against 8-mm plungers to establish the optimum harvest maturity of late season nectarines using flesh firmness as indices’, SA Fruit Journal, Feb – March, 62 – 68.
The aim was to establish if 8-mm plungers rather than 11-mm plungers can assist to determine the harvest maturity of late season nectarines more accurately. These cultivars are typically firm at harvest and may crack when the larger plunger penetrates the fruit, thus rendering the reading inaccurate. The 8-mm plunger gave good results and it was found that a division factor of 1.8 can be used to convert existing 11-mm standards to 8-mm. An industry wide dispensation was granted to use penetrometers fitted with 8-mm plungers for a range of listed cultivars.