When evaluating carton boxes, the most critical factor is the bursting strength and edge crush test (ECT) rating. For heavy fruits like apples or citrus, a double-wall corrugated board (5-layer) is recommended to prevent collapsing during stacking. Ensure the material is moisture-resistant or wax-coated, as fruits release moisture (respiration) which can soften standard cardboard. Additionally, ventilation holes must be strategically placed to allow airflow and prevent premature ripening or molding.