How to make astringent persimmons non-astringent


In recent years persimmons are often seen in the US food markets in late autumn. There are two kinds of persimmons, one is a flat kind, in other words the length in the axial direction is shorter than diameter, another is in the bullet shape with the axial length longer than the diameter.


Japanese Persimmon


Flat shaped persimmon



Bullet-shaped persimmon



The former called fuyu gaki is non-astringent persimmon edible all the time.The latter called shibu gaki is astringent persimmon which has very unpleasantly bitter taste (shibu means astringent).Even when the fruit is well ripened, the unpleasant taste often remains.The good news is, however, if the bitterness is removed in some way, the astringent kind is sweeter than the non-astringent.


Why the astringent persimmons taste bitter first of all?The astringent persimmons contain large amounts of bitter substances such as catechin, gallocatechin, betulinic acid, and shibuol which are soluble in water.Eating astringent persimmons without removing the bitterness is not only extremely unpleasant but can cause a severe health hazard. For example shibuol may polymerize when it is mixed with acid in stomach producing indigestible balls that could be removed only by surgery. (Recently, coca cola was found to resolve the polymerized chunk.)


In Japan where persimmons have been eaten for centuries, a few different wisdoms are known to treat astringent persimmons. First is to dry making dried persimmons.When dried, the bitter substances become insolvable in water. Second is to expose astringent persimmons to alcoholic vapor for a few days. In practice, the persimmons are stored in the wood barrels used to make sake.This method is called tarunuki where taru means barrel and nuki removal.The third way, according to the authorís friend in Japan, is to soak astringent persimmons in lukewarm water for a few days.


We can, however, easily mimic tarunuki without using any sake barrel.Namely, put astringent persimmons in a plastic containment with a tight lid, or alternatively in a zip lock plastic bug.Before sealing the lid, pour a small amount (1/2 teaspoon) of white liquor, rum, brandy or whiskey.Keep the persimmons in the containment for 2~3 days.Voila, astringent persimmons then become only very sweet with no taste of bitterness.


What happens is the materials of bitterness become insolvable in water after chemically combining with alcohol.The persimmons do not get any alcoholic flavor because the alcohol is consumed in the chemical reactions.


Author: Sho Nakamura††† 2011