Was the forbidden fruit really an apple?
In reality, we do not know what type of fruit the forbidden fruit was. Could it have been an apple? Perhaps, just as it could have been any other fruit, including perhaps a fruit that does not currently exist on the earth! More important than the type of fruit, is understanding the effects of the fruit, and what we can learn from Adam and Eve’s experience in partaking.
In lieu of the typical discussion of spiritual and physical death, I would like to direct your attention to a statement made by a modern Apostle, Elder James E. Talmage:
A modern revelation given to the Church in 1833 (D&C 89), prescribes rules for right living, particularly as regards the uses of stimulants, narcotics, and foods unsuited to the body. Concerning the physical causes by which the fall was brought about, and the close relation between those causes and current violations of the Word of Wisdom embodied in the revelation referred to above, the following is in point. “This, [the Word of Wisdom] like other revelations that have come in the present dispensation, is not wholly new. It is as old as the human race. The principle of the Word of Wisdom was revealed unto Adam. All the essentials of the Word of Wisdom were made known unto him in his immortal state, before he had taken into his body those things that made of it a thing of earth. He was warned against that very practice. He was not told to treat his body as something to be tortured. He was not told to look upon it as the fakir of India has come to look upon his body, or professes to look upon it, as a thing to be utterly condemned; but he was told that he must not take into that body certain things which were there at hand. He was warned that, if he did, his body would lose the power which it then held of living for ever, and that he would become subject to death. It was pointed out to him, as it has been pointed out to you, that there are many good fruits to be plucked, to be eaten, to be enjoyed. We believe in enjoying good food. We think that these good things are given us of God. We believe in getting all the enjoyment out of eating that we can; and, therefore, we should avoid gluttony, and we should avoid extremes in all our habits of eating; and as was told unto Adam, so is it told unto us: Touch not these things, for in the day that thou doest it thy life shall be shortened and thou shalt die.”
“Here let me say that therein consisted the fall—the eating of things unfit, the taking into the body of the things that made of that body a thing of earth . . .”
(Jesus the Christ: Chapter 3 – Footnote 3)
Ultimately, the type of fruit is unimportant; what is important is to understand that Adam and Eve partook of something that was harmful to their bodies and resulted in the loss of immortality, and subjected themselves, their offspring and the world to mortality.