blet

c. 1835, B. Maund, The Botanic Garden, Or, Magazine of Flowering Plants, Volume 6, Simpkin & Marshall, page 115, Bletting is in particular a special alteration; it appears that the more austere a fruit is before this is brought on, the more it is capable of bletting regularly.

You can also hasten the bletting process by giving firm medlars a night in the freezer. I usually pick some medlars early to blet a little indoors, as this is perfect for making jelly, whereas fully soft fruit is ideal for any other use.

For example, you wouldn't be happy if you bit into a medlar. They need to be bletted (left to go over-ripe) before you can eat them but, once bletted, medlars taste sweet – a little bit like dates.[…]To be frank, bletting is a more polite word for "rotting".