Persimmons, a late-season fruit, are often picked when still firm, leading many to wonder if they will ever become palatable after leaving the tree. The good news is that persimmons are indeed climacteric fruit, meaning they continue to ripen post-harvest, a process that is often necessary for optimal flavor. The method and speed of this at-home ripening, however, depends entirely on the specific variety you are holding. Some types will simply soften on a countertop, while others require intervention to transform from an unpleasantly mouth-puckering state to a sweet, edible treat.
The Astringent and Non-Astringent Distinction
Persimmons are broadly categorized into two groups based on their tannin content: astringent and non-astringent. Astringency is the dry, furry sensation caused by water-soluble tannins in the unripe fruit, making them inedible until fully ripe. The classic heart-shaped Hachiya persimmon is a well-known example of an astringent variety that must be fully softened before eating.
Non-astringent persimmons, such as the flat, tomato-shaped Fuyu variety, contain much lower levels of these soluble tannins. This difference means the non-astringent types can be eaten while they are still crisp and firm, much like an apple. For astringent varieties, the goal of ripening is to convert the soluble tannins into an insoluble form, which neutralizes the unpleasant mouthfeel and allows the fruit’s natural sweetness to emerge.
Methods for Ripening Persimmons Off the Tree
Since non-astringent persimmons are ready to eat when firm, the methods for accelerated ripening are primarily aimed at neutralizing the tannins in hard, unripe astringent varieties. The simplest and most common technique uses ethylene gas, a natural plant hormone that promotes softening and the polymerization of tannins.
This is easily achieved by placing three or four firm persimmons in a clean paper bag with a high-ethylene-producing fruit, such as a ripe banana or apple, before sealing the bag. The enclosed space traps the gas, and the persimmons should soften in two to five days at room temperature. Check them daily to prevent over-ripening, which can lead to spoilage.
Another effective method involves the use of alcohol vapor, which accelerates the production of acetaldehyde inside the fruit. Acetaldehyde then binds with the soluble tannins, rendering them non-astringent. To use the alcohol method, place the hard persimmons in a sealed container with a small amount of high-proof spirit, like vodka or rum, ensuring the liquid does not directly touch the fruit. The alcohol vapor will permeate the fruit, and they should be ready in about a week at cool room temperature, emerging firm but sweet.
Freezing and thawing is a third, quick method that physically alters the fruit structure, neutralizing the tannins. Simply place the firm, astringent persimmons in the freezer for 24 hours. When thawed, they will be very soft and non-astringent. This technique results in a very soft, almost jam-like texture, making the fruit best suited for baking or pureeing.
Knowing When the Fruit is Ready
Determining readiness depends on the type of persimmon you have. Non-astringent varieties, like Fuyu, are ready to eat when they have developed a deep orange color but still feel firm to the touch, similar to a ripe plum.
For astringent varieties such as Hachiya, readiness is signaled by a dramatic change in texture. The fruit must be completely soft, feeling almost like a water balloon or an over-ripe tomato when gently squeezed. If any firm spots remain, the fruit still contains active tannins and should be allowed to ripen further.