The spokesman confirmed her carry-on luggage was overweight but the woman had declined to pay the excess and had gone to the gate assuming she would board.
She had discarded some cherries immediately before this, but her baggage was still overweight, the spokesman said.
"It was time to board and staff again offered to upgrade her luggage for a discount, at the online rate. She declined to pay that also."
A staff member stepped in to take the cherries and keep them until other arrangements could be made, the spokesman said.
The box was closed and never opened by staff. Cromwell orchardist Martin Milne had investigated the following day and a wrong assumption was made that cherries had been eaten by airline staff. The woman had actually removed some from the box herself, the Jetstar spokesman said.
The staff member had done the woman a favour. "We probably should have just disposed of them."
Cherry grower Milne said he had been contacted by the passenger to arrange the fruit to be sent on to her Auckland address, when he discovered the half-eaten box.
"We picked those cherries with love and that is what hurt."