Cell wall changes in untreated and calcium-treated ‘Fuji Kiku-8’ apples harvested at commercial maturity were examined after cold storage during 19 and 31 weeks under either air or ultra-low oxygen atmosphere (ULO), followed by 7 d at 20 ºC to simulate commercial shelf life. Postharvest calcium treatment was applied by immersion in a 2 % (w/v) CaCl2 solution prior to cold storage. Both ULO storage and calcium dips attenuated firmness loss in comparison with untreated fruit stored in air, particularly for the shorter period, in parallel to higher retention of both chelator- and sodium carbonate-soluble fractions. After hydrolysis, the analysis of these fractions revealed higher retention of arabinose and uronic acids in response to ULO storage and calcium treatment. Results indicate that the contents of uronic acids and arabinose in pectin-containing fractions were strongly correlated, suggesting that removal of arabinosyl residues from pectin sidechains be a key event in the process of postharvest pectin solubilization.