Postharvest quality of a thorny Andean blackberry (Rubus glaucus Benth) cultivar

Andean blackberries (Rubus glaucus Benth) are highly perishable due to their susceptibility to water loss, softening, mechanical injuries, and postharvest diseases. They are considered non-climacteric, and thus, sold at an advanced maturity stage when the fruit is more sensitive to mechanical damage and spoilage. Harvesting at the proper maturity stage and temperature control are two critical factors in reducing postharvest losses, maintaining quality and extending shelf-life of fruit and vegetables. In this study, the effects of harvest maturity and storage temperature on physicochemical quality of Andean blackberries were evaluated. Blackberries were harvested at maturity stages 3 (light red) and 5 (dark purple), packed in polyethylene terephthalate (PET) clamshells (200±10 g) and stored under room temperature (18±2°C) and cold storage (8±1°C) until visual symptoms of decay were detected. Weight loss was determined daily. Fruit diameter, length and weight were determined on day 1 and colour (L and °hue), firmness, total soluble solids (TSS), pH titratable acidity (TA) and maturity index (TSS/TA) were evaluated on day 1 and every 3 d during storage. The more immature fruit were classified as small and presented lower pH, TSS and maturity index together with higher TA, luminosity, °hue and firmness than the blackberries harvested at maturity stage 5, both at harvest and during storage. Weight loss gradually increased during the storage period in the fruit of both maturity stages with around 9 and 5% after 10 d under refrigeration and 4 d at room temperature, respectively. Refrigeration was effective in maintaining fruit quality and delaying softening and weight loss, with a shelf-life of 3 d at 18°C and up to 8 d in cold storage. The main limiting factors were microbial growth and softening and weight loss at 18 and 8°C, respectively.