The first one does nothing in particular, except be oddly dark-fleshed and juicy for an apple, that he can detect.

At the second, he feels cold, when he first bites it - and colder as he goes on - and at the end of the apple he is so much so that "cold" has ceased to have meaning; he can no more feel cold than a snowflake can.

At the third apple, he may notice the color of his hands changing, as though he is a snowflake, or a human-shaped tracery of frost on the landscape.