Lately, we’ve had some problems with the Fuyu persimmons we are buying from various vendors. They are stored in a 34-36 degree cooler, but we are having some problems with them becoming soft within 5- 10 days of arrival.
We thought that maybe we were storing them too cold and they were getting chilled, so we looked up persimmons on the UC Davis Postharvest Technology website, but we are a bit confused about the information: it says 32 degree storage is optimal storage temp, but that chilling damage happens between 36 and 59 degrees. How does chilling damage occur at a higher temp than optimal storage temp? Is this the same as what happens with stonefruit when stored at 36 – 50 degrees? (C.B.)
Your analogy between persimmon and stone fruits is correct, but the mechanism (biochemical and physiological basis) is different. Persimmons are extremely sensitive to ethylene and if you want to keep Fuyu persimmons firm, do not store them with other fruits like apples that produce ethylene unless they are packaged in plastic bags that maintain the optimal range of oxygen (3-5%) and carbon dioxide (5-8%) which protects the persimmons from ethylene action. The photographs linked to Produce Facts on our website (see link) illustrate the effects of temperature and ethylene on Fuyu persimmons. The recommended storage temperature for Fuyu persimmon is 32 F beginning soon after harvest and until placed on display at retail. If modified atmosphere packaging is used, it should be done soon after harvest of firm fruits and before exposure to ethylene that initiates softening. Some marketers of Fuyu persimmons who follow these recommendations continue selling firm fruit that were harvested in November until February or March of the following year.
-Adel A. Kader