Shelf life and changes in phenolic compounds of organically grown blackberries during refrigerated storage

Fruit of organically grown fresh market blackberry cultivars 'Natchez', 'Ouachita', and 'Navaho' harvested at shiny black and dull black ripeness stages were stored at 1 °C for 15 d or at 1 °C for 13 d plus 20 °C for 2 d. Berries were subjectively rated and anthocyanins and phenolic compounds were analyzed by high performance liquid chromatography (HPLC) to determine storage effects on berry postharvest quality and phenolic compounds. Berries harvested at the shiny black ripeness stage or those stored constantly at 1 °C had lower leakage, decay, and softness and a higher overall rating. 'Navaho' fruit had generally better storability compared to the other cultivars. Total anthocyanin content was generally higher in 'Natchez' and 'Navaho' than in 'Ouachita', and increased with storage at 20 °C for 2 d, while shiny black and dull black fruit were similar in anthocyanin content. Cyanidin 3-glucoside was found to represent 87-96% of the total anthocyanin content, and cyanidin 3-rutinoside, cyanidin 3-xyloside, and pelargonidin 3-glucoside were also detected. Total phenolic content increased during storage for all cultivars, especially when berries were stored at 20 °C for 2 d. Hydroxybenzoic acids were the primary phenolic compounds identified in fruit tissues of the three cultivars. Content and proportion of cyanidin 3-xyloside and vanillic acid in 'Natchez' were significantly lower than in 'Ouachita' or 'Navaho' fruit. Results indicate that the fruit of blackberry fruit of these cultivars, when grown organically, could be held with acceptable results when harvested at the shiny black stage of ripeness and stored at 1 °C. Transferring fruit to room temperature for as little as 2 d, even after cold storage, decreased marketability. In contrast, phenolic composition differed among cultivars and generally increased with storage.