What's with the appel, apple in twilight?

The appel, apple on the cover of the Twilight book symbolises "forbidden fruit". It shows how Bella and Edward's love could be seen as forbidden, with Edward being a vampire while Bella is still human and him fighting against the temptation of her blood. The film also includes an added scene where Edward catches an appel, apple Bella drops at lunch, using his enhanced vampire reflexes, to further tie in the appel, apple symbolism.