Evaluation of Harvest Time on Postharvest Incidence of Red Drupelet Reversion Development and Firmness of Blackberry Cultivars

Blackberry (Rubus  subgenus Rubus Watson) is an increasingly important fruit for fresh-market worldwide. Developing improved cultivars to be shipped and stored is crucial to expand the fruit shipping industry. The University of Arkansas Fruit Breeding Program has been working to resolve major postharvest disorders, with several cultivars released that show good storage potential. A major limitation for shipping blackberry is its ability to maintain firmness in storage. Another important postharvest disorder is incidence of red drupelet reversion, or simply referred to as reversion. Reversion is a disorder in which drupelets change from black to red during storage. It is thought to occur as a result of rapid changes in temperature from harvest to storage. Fruit is often harvested at high temperatures and moved quickly to storage especially in the southern U.S, this is thought to contribute to increased reversion. In this study, five cultivars were evaluated for firmness and incidence of reversion when harvested at 7:00 am, 10:00 am, 1:00 pm, or 4:00 pm which represented increasing temperatures during the day. Fruit were harvested on two dates, and moved immediately to cold storage (5 ^◦C), and stored for 7 d prior to evaluations. Firmness was evaluated by berry compression and drupelet skin penetration measurements and reversion by absence or presence of reversion of berries. Data analysis indicated significance for main effects of cultivar for penetration, and time of harvest for compression and reversion. No interactions were significant. Compression showed significant differences for harvest time with the 4:00 pm harvest having significantly higher mean firmness across cultivars than the other harvest times. Penetration results indicated ‘Prime-Ark^® Traveler’ had significantly higher skin firmness compared to other cultivars. Incidence of reversion was lowest at the 7:00 AM harvest time but not different among other times. Further research is necessary on this topic, but evaluation of the influence of harvest time for postharvest evaluations should continue to be examined.