As apples ripen the starches in the apple turn to the fruit sugars which are crucial for good flavours.
Whether eating an apple, making juice or making cider, apples are best when at the peak of their ripeness – but before starting rot.
It is important not to think apples are ready for picking just because some have fallen from the tree.
It is also important to appreciate that taste is not a good way to know if an apple if fully ripe – whilst it is easy to tell by taste that an apple is nowhere near being ripe, once there is a reasonable amount of sugar in the apple, taste is not sensitive to how much starch remains to be turned into sugar.
There are several simple clues that together are a very good guide to apple ripeness.
Knowing when your tree usually ripens
Different apple varieties ripen at different times during the growing season.
For example, Discovery apples are ready in late August whereas Kingston Black apples are ripen in early November.
Knowing your tree variety helps you to know when to expect ripeness and know the likely order in which different tress will be ready to pick.
Each year there are variations of ripeness timing according to the weather during the growing season.
Ease of apple picking/ dropping
The ease with which apples drop off the tree is a good guide to ripeness.
Coming off the stem easily indicates ripeness. This can be tasted either by gentle shaking of a branch or by cupping an apple in your hand and gently twisting it to see if it comes off.
However, if strong shaking or twisting is needed, the apple is not yet ripe.
Early windfalls from high winds or the natural shedding by the tree of excess crop do not indicate ripeness and it is important not to pick a tree simply because some apples are on the ground. Such apples do not make good juice, cider or eaters.
Darkness of the apple pip
For most apple varieties the darkness of the pip is a good indication of ripeness.
A light coloured pip (white, yellow or light brown) indicates lack of ripeness.
A dark brown or black pip occurs at ripeness.
This does not work for the very early ripening apples, such as Discovery, where the pips usually do not darken even when ripe.
Iodine Test – the best method
The Iodine Test uses the fact that a solution of the chemical Iodine reacts with starch to turn it dark blue/ black in colour.
This provides a simple means to check the amount of remaining starch in apples as they develop.
An apple is cut in half and the cut surface dipped into a solution of Iodine for a second or two. After a few seconds any starch present will cause blackening.
If an apple is far from being ripe (eg. a month or more away) the cut surface is likely to go fully black. As ripeness approaches there will be less and less darkening.
When all the starch has been turned to sugars there will be no colour change to the apple’s cut surface (other than the usual slow browning of cut apples that occurs when left exposed to the air).
Whilst this is the best method – and we use it at Vale Cider – a combination of the more simple methods is sufficient for most purposes.