Characterization of cuticular waxes in six blueberry cultivars reveals their role in influencing berry surface color

Y. Yan, M. Dossett, S.D. Castellarin
Blueberry surface color is one of the most important quality traits affecting consumers’ choices. While popularity of blueberries has been driven, in part, by news of the health benefits of their intense pigments leading one to expect consumers to prefer fruits with a darker color, blueberries with a light blue color covered by thick wax bloom on their surface have long been considered to be more attractive to consumers. However, knowledge about the influence of cuticular waxes on fruit surface color is limited in blueberries. In this study, six blueberry cultivars, including two northern highbush, two southern highbush, and two hybrid cultivars, were selected for characterizing the cuticular waxes; fruit surface color was measured in the same fruits before and after wax removal. Total cuticular wax content ranged from 31.96 (‘Pearl River’) to 82.35 (‘Misty’) μg cm‑2 among the six cultivars. Cyclic triterpenoids were the most abundant group in ‘Reka’, ‘Chandler’, ‘Misty’ and ‘Pearl River’, representing for approximately 70% of their total cuticular waxes. In ‘Legacy’ and ‘Chippewa’, around 50% of total cuticular waxes consisted of aliphatic compounds such as alkanes and β-diketones. Fruit surface color measured by CIELAB Color Space indicated the highest lightness (L*) in ‘Legacy’ and the lowest in ‘Pearl River’ before cuticular wax removal. The wax removal resulted in greatly reduced L* and a much darker surface color in all cultivars. A greater difference in L* before and after wax removal was correlated with a higher total β-diketone content, indicating an important role of β-diketones in influencing the fruit surface color. This study provides new insights on the role of cuticular wax composition in affecting blueberry surface color. Further studies should examine the potential roles of other aspects of cuticular waxes (e.g., the structure and appearance), as well as the synergistic effects of cuticular waxes and pigments, in influencing the blueberry surface color.
Yan, Y., Dossett, M. and Castellarin, S.D. (2023). Characterization of cuticular waxes in six blueberry cultivars reveals their role in influencing berry surface color. Acta Hortic. 1381, 181-190
DOI: 10.17660/ActaHortic.2023.1381.25
highbush blueberry, wax composition, β-diketones, lightness, delta color

Acta Horticulturae