Q. I did what you told me to do to ripen the plums and it worked but they were mostly still very tart. Why did you tell me to put them in cold water after I picked them?
A. When you harvest fruit in the heat of the summer, the fruit will have a lot of excessive warmth or heat. The heat is from the environment as well as the fruit's respiration. We call this heat, field heat.
This heat can be very destructive to fruit harvested in the field and cause poor keeping quality. For this reason we want to remove this heat from the fruit as quickly as possible very soon after harvesting.One way to do this is just plunge the fruit into icy water for a few minutes and get it closer to room temperature. After it cools to room temperature, you can let it continue to ripen at room temperature.