Quince? How can I tell when it's ready to use?
When ripe, they will smell like heaven - if heaven is filled with flowers - , but will still be rather hard. If they are green, they will turn yellower. Quince are generally cooked, no need to peel, but do remove the cores. You can cook them as soft as you like.
Quince contain a lot of natural pectin, and are thus quite helpful in preserves.
You can tell when they are ripe when they are very fragrant, almost floral like. You can't eat them raw, at least most people can't. too puckery and astringent. Most recipes will have you peel them and core them too. They will be very hard, harder than an apple, but worth the work. They should turn a beautiful rosy pink when they are finished and will turn your apple dish pink too. the longer you cook them, the darker pink they will get.