Examining Various Phytochemical Attributes of Southern Highbush and Rabbiteye Blueberry Genotypes

Georgia was first in the nation for highbush blueberry production in 2014 with 96 million pounds produced. The production includes both rabbiteye (V. virgatum Aiton), sold as fresh and frozen, and southern highbush (species complex between Vaccinium corymbosum L. and V. darrowii Camp) sold primarily as fresh earlier in the season. The main objective of this study was to examine various phytochemical attributes of highbush and rabbiteye varieties grown in Georgia. Fruit harvested from nine southern highbush and seven rabbiteye blueberry genotypes at ca. 50% ripe at the University of Georgia Blueberry Research Farm near Alapaha, GA, were examined during 2014.  Early, mid-, and late-season material was selected for both types to represent the Georgia blueberry market. Highbush genotypes included ‘Camillia’, ‘Emerald’, ‘Farthing’, ‘Legacy’, ‘Meadowlark’, ‘Rebel’, and ‘Star’, and two advanced breeding selections: TH-1111 and TH-1125.  Rabbiteye genotypes included ‘Alapaha’, ‘Brightwell’, ‘Ochlockonee’, ‘Powderblue’, ‘Premier’, ‘Tifblue’, and ‘Vernon’.  Fruit were frozen for approximately 7 to 8 months before chemical analyses. Measurements included total titratable acids (TTA), soluble solids content (°brix), total monomeric anthocyanin concentration (mg/L cyanidin-3-glucoside equivalents), sugars, organic acids, antioxidants, and sugar acid ratio (°brix /TTA and total sugars/total acids).  Total sugar, organic acid, and antioxidant content were also determined. Overall, highbush genotypes were significantly higher (P < .05) for total titratable acids (0.69% vs. 0.43%), and rabbiteye genotypes were significantly higher for soluble solids (13.4% vs. 11.6%) and sugar acid ratio (°brix /TTA) (34.5 vs. 23.3). Sucrose was significantly higher in rabbiteyes (2.54 mg/g vs. 0.10 mg/g) and total sugar content and sugar acid ratio (total sugar/total acid) were not significantly different between types. Rabbiteyes were significantly higher for three of the six organic acids (oxalic, succinic, and malic acid) and were over 60% higher for total acids (12.2 mg/g vs. 7.5 mg/g).  For antioxidants, rabbiteyes were 23% higher for catechin (39.7µg/g vs. 32.3µg/g), two times higher for caffeic acid (108.6 µg/g vs. 52.7 µg/g), over four times higher for quercetin (7,831 µg/g vs. 1,743 µg/g), 50% higher for ferulic acid (33.0 µg/g vs. 22.0 µg/g) and 37% higher for total antioxidants (20,482 µg/g vs. 14,934 µg/g).  Results from this study show variation within genotypes for fruit quality and suggest that rabbiteye varieties are quite high in many important compounds. Future studies will be conducted to determine the effect of fruit quality across years and in consumer perception.