Cell wall-modifying enzymes and firmness loss in ripening 'Golden Reinders' apples: A comparison between calcium dips and ULO storage

► ULO and calcium effects on cell wall metabolism of 'Golden' apples were explored. ► ULO and calcium dips delayed pectin solubilisation by different mechanisms. ► Calcium inhibited some cell-wall degrading enzymes and enhanced pectin cross-links. ► Softening was well related to PL, β-Gal and AFase activities.