Sonic the Hedgehog (2006)
In Sonic the Hedgehog (2006), apples can be found around Castle Town, usually inside barrels. They can be pushed by walking into them or attacked to be kicked away. Silver the Hedgehog can also use Psychokinesis to pick them up and throw them as projectiles.
In the Xbox 360/PlayStation 3 version of Sonic Unleashed, the apple is a consumable that can be purchased for thirty Rings at various Shops such as Counter of Dreams 2, Treeshade and Wang's Emporium. It can be given to Chip to contribute to the "BFF's" or to Sonic for the "Hungry Hungry Hedgehog" Achievements/Trophies. When consumed by Sonic, it gives him twenty Exp.
Sonic and the Black Knight
In Sonic and the Black Knight, apples appear during the Special Challenge Missions in Misty Lake. They are collected like Pearls, even making the same chime sounds when picked up. Unlike Pearls though, apples do not serve any purpose when collected other than help the player practice the Wii-mote controls.
Apple trees can also be seen in Faraway Avalon.
Sonic Lost World
In the Wii U version and PC version of Sonic Lost World, gigantic apples can be found in Tropical Coast. These fruits roll around on their own and will actively seek out Sonic to flatten him, causing damage upon impact. By luring the apples into giant fans, they will get shredded and form cords of juice for Sonic to use to reach new areas. Master Zik balances on top of these apples in his battle to attack Sonic.