Are Fruit Surface Differences in Two Blueberry Cultivars Major Drivers of Contrasting Postharvest Dynamics?

Fresh blueberries are prone to softening and dehydration during postharvest, which limits their competitiveness when reaching the final markets. Commercial cultivars 'Duke' and 'Brigitta' exhibit contrasting softening patterns. Although 'Duke' berries usually show higher firmness levels at harvest as compared to 'Brigitta', they display higher softening and weight loss rates after cold storage. The aim of this study was to evaluate the physicochemical changes and modifications in cuticle composition of 'Duke' and 'Brigitta' blueberries across five developmental stages: green (G), 25 and 50% pink (25P, 50P), and 75 and 100% blue (75B, 100B), to determine those characters with the most influence on their postharvest behavior. For each developmental stage, maturity parameters, respiration, and ethylene production rates were assessed, and cuticular wax and cutin were analyzed. Principal component analysis (PCA) revealed that 'Duke' berries were characterized by higher respiration and ethylene production rates, while 'Brigitta' showed higher contents of oleanolic acid and alpha-amyrin over total waxes. The results suggest that larger surface/volume ratios and higher amounts of ursolic acid and lupeol in ripe fruit may underlie higher weight and firmness loss rates of 'Duke' berries as compared to 'Brigitta'.