|Authors: ||A. Salgado, J.R. Clark|
|Keywords: ||Rubus, postharvest, fruit firmness, breeding, small fruits|
The University of Arkansas blackberry breeding program was begun in 1964 and the program has released cultivars with the aim to provide high-quality fruit to the fresh-market industry.
One of the critical traits for successful postharvest handling is flesh firmness, so developing cultivars with high firmness is a top priority for the majority of breeding programs around the world.
In particular, the Arkansas blackberry program has a wide range of genotypes with exceptional firmness characteristics, including fruit with a unique crispy texture and firmness.
During 2013 and 2014, fruit firmness measurements were done on six crispy and non-crispy Arkansas selections.
Firmness measurements consisted of fruit compression, skin drupelet penetration, and receptacle penetration.
Compression force values differentiated crispy and non-crispy genotypes, with average values of 11.9 and 8.4 N, respectively.
Drupelet penetration force was also higher for crispy genotypes (0.17 N) compared to non-crispy genotypes (0.15 N). Receptacle penetration force averaged 0.20 N for crispy genotypes and 0.15 N for non-crispy genotypes.
However, penetration values were more variable than compression values.
In 2014 confocal images were taken on sectioned berries from a subset of crispy and non-crispy genotypes.
Drupelet and receptacle cells of crispy genotypes maintained their structure when sectioned and did not break apart, while non-crispy genotypes did not maintain the same tissue and cellular integrity.
Finally, color reversion was evaluated among these genotypes after storage.
Color reversion is a postharvest disorder in which some drupelets of blackberry fruits turn from black to red after harvest and has a negative impact for growers, shippers, and consumers.
After storage at 5°C for 7 d, crispy genotypes expressed low levels of reversion.
An average of 94% of the berries from crispy genotypes had no drupelet showing reversion after cold storage in contrast to non-crispy genotypes where low-mid to high levels of reversion were found.
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