As apples ripen the starches in the apple turn to the sugars which crucial for good flavours.
Whether eating an apple, making juice or cider, apples are best when at the peak of ripeness – but before starting rot.
There are several simple clues that together are a very good guide to 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 but there are variations according to the local climate and also the particular 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. 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.
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 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 monitor more away) the cut surface is likely to go fully black. As ripeness approaches there will be less and less darkening. Whilst this is the best method, a combination of the more simple methods is sufficient for most purposes.