Effect of Short-Term High-CO₂ Treatments on the Quality of Highbush and Rabbiteye Blueberries During Cold Storage

The global demand for blueberries has increased due to their health benefits, but postharvest losses, particularly firmness loss and decay, present significant challenges. This study evaluated the effects of high CO₂ concentrations (15% and 20%) applied for 3 d at 1.0 °C on highbush (cv. 'Duke') and rabbiteye (cv. 'Ochlockonee') blueberries, with a focus on quality maintenance during cold storage. The quality parameters evaluated included titratable acidity, pH, total soluble solids, weight loss, and decay. The effect of gaseous treatments on firmness was analyzed using mechanical parameters and the expression of genes related to cell wall integrity (XTH23, PL8, PG, PM3, EXP4, and VcGH5). Treatment efficacy varied between species. High CO₂ levels reduced decay in both cultivars, but only the highbush cultivar ('Duke') showed improvements in firmness. In 'Duke', CO₂ treatments affected the expression of XTH23, PL8, and GH5, while the role of PG and PME in maintaining firmness was minimal, with no significant differences between treatments. In 'Ochlockonee', CO₂ effectively reduced weight loss but did not improve firmness. In conclusion, these results highlight the need for tailored postharvest strategies for different blueberry cultivars and suggest that short-term high CO₂ treatments may effectively prolong the postharvest life of highbush blueberries.