Sensory and postharvest attributes of four Blackberry varieties

Zilfina Rubio Ames and Taylor Ibibofori, Department of Horticulture, University of Georgia – Tifton

Blackberry production and consumption has increased in the United States in the last ten years. Similarly, blackberry production acreage in Georgia has increased from 300 acres in 2009 to 818 acres in 2017 (USDA-NASSA, 2021). Blackberries are harvested in Georgia from June to mid-July, and the main production area is South Georgia. The most common varieties cultivated in South Georgia were developed by the University of Arkansas blackberry breeding program. Thus, physicochemical attributes of the fruit under Arkansas conditions were previously evaluated by Threlfall et al., 2021. However, no information on fruit quality characteristics of Arkansas cultivars grown under Georgia conditions was previously reported. During the 2022 blackberry season in Georgia, the small fruit program at the University of Georgia evaluated physical and compositional attributes as well as sensory characteristics of the cultivars ‘Caddo’, ‘Osage’, ‘Ponca’, and ‘Ouachita.’ (Fig.1)

**Figure 1.** Arkansas cultivars grown under South Georgia conditions. Each cultivar was evaluated for physical, compositional and sensory attributes.

The four cultivars were harvested from a commercial farm in South Georgia. The fruits were harvested fully ripe, and free of damage or deterioration on June 23^rdand 29^th. There were two sensory evaluations conducted, one for each harvest. A non-trained panel (n=16) evaluated the four cultivars on appearance, texture, sweetness, overall liking, and flavor. The panelist rated each characteristic using a 9-point hedonic scale, in which 1= dislike extremely, 2= dislike very much, 3=dislike moderately, 4= dislike slightly, 5 = neither like nor dislike, 6= like slightly, 7= like moderately, 8= like very much, and 9 =like extremely. Compositional attributes like total soluble solids and titratable acidity were measured using a refractometer and automated titrator respectively. Berry firmness and berry size were measured using a Fruitfirm 1000.

The cultivar with the biggest berry size was ‘Caddo,’ while the cultivars ‘Osage’ and ‘Ouachita’ had a smaller berry (Table 1). Firmness was inconsistent between the two harvests. However, there were no significant differences in firmness between ‘Caddo’ and ‘Ouachita.’ Panelists rated ‘Ouachita’ as less sweet. The results obtained in the sensory evaluations resemble the total soluble solids content and titratable acidity of ‘Ouachita’ in the first harvest (Fig. 2 and Fig. 3). ‘Ouachita’ flavor was liked slightly by the panelist and ‘Caddo,’ ‘Osage,’ and ‘Ponca’ were liked moderately. ‘Caddo,’ ‘Osage,’ and ‘Ponca’ were rated higher by the panelist on sweetness and flavor. Total soluble solids (TSS), which are expressed as degree brix, are related to the sugar content of the fruit. Thus, it could imply that the higher TSS content the sweeter the fruit. ‘Caddo,’ ‘Osage,’ and ‘Ponca’ had higher TSS than ‘Ouachita.’ Acid content and volatile aroma compounds also have an important role in overall liking. Citric acid is the acid found in higher quantities in blackberries. However, cultivars differ in the amount of citric acid. ‘Caddo,’ ‘Osage,’ and ‘Ponca’ had a lower content of citric acid in the first sensory evaluation (first harvest) (Figure 2). In the second sensory evaluation (second harvest), ‘Ouachita’ and ‘Ponca’ were not significantly different in citric acid content. However, ‘Ponca’ had higher TSS than ‘Ouachita.’ The higher acid content and lower TSS of ‘Ouachita’ could be the reason the panelist like ‘Ouachita’ less when compared to the other cultivars.

In conclusion, participants liked the sweetness of ‘Ponca’, ‘Caddo’, and ‘Osage’ more than ‘Ouachita’. In addition, the overall liking of ‘Ouachita’ was less compared to ‘Ponca’, ‘Caddo’, and ‘Osage.’ Low scores from the taste panel regarding sweetness and overall liking of ‘Ouachita’ correlates with this cultivar’s low amount of total soluble solids and high titratable acidity value. ‘Caddo’ had bigger berries compared to the other varieties.

References

Threlfall, R. T., Clark, J. R., Dunteman, A. N., & Worthington, M. L. (2021). Identifying marketable attributes of fresh-market blackberries through consumer sensory evaluations. HortScience, 56(1), 30-35.

Noncitrus Fruits and Nuts, National Agricultural Statistics Service (NASS), USDA, 2021.

**Figure 2.** Total soluble solids expressed as degree brix. Blue bars represented the fruit harvested on June 23^rd and red bars represent the fruit harvested on June 29^th.

**Figure 3.** Titratable acidity expressed as % of citric acid. Blue bars represented the fruit harvested on June 23^rd and red bars represent the fruit harvested on June 29^th.

Table 1. Berry size and firmness of fruits harvested on June 23^rd and June 29^th.

Table 2. Sensory attributes of the four blackberry varieties evaluated using a 9-point hedonic scale.
1= dislike extremely, 9 =like extremely, and 5 = neither like nor dislike

Table 3. Sensory attributes of the four blackberry varieties evaluated using a 9-point hedonic scale.
1= dislike extremely, 9 =like extremely, and 5 = neither like nor dislike

Acknowledgments
We would like to thank Paulk Farms for donating the fruit for this experiment and Phillip Edwards for helping us coordinate the experiment.