John Calvin Commentary Leviticus 2:14

"And if thou offer a meal-offering of first-fruits unto Jehovah, thou shalt offer for the meal-offering of thy first-fruits grain in the ear parched with fire, bruised grain of the fresh ear." — Leviticus 2:14 (ASV)

And if you offer a meat-offering. This offering is different from that of the first-fruits, since it was voluntary, whereas the first-fruits were paid in obedience to the enactment of the Law.

But if anyone chose to add anything to the first-fruits of his new corn, Moses lays down the rule that the ears should be dried in the fire, so that they might be more easily pounded and subsequently burned, mixed with oil and frankincense. For this is how I interpret his words: that he means the same thing by “ears of corn dried by the fire” and “corn beaten out of full ears.” He requires full ears, so that the people may select them and not offer anything poor or stunted.