Volatile Compounds In Southern Rabbiteye Blueberry Varieties Commonly Grown In Mississippi and Louisiana, Harvested At Various Maturities

Recently, superfruits such as blueberries have received much attention as scientists, marketers and consumers push forward knowledge and demand for high antioxidant, healthier diets.  Blueberries are rich in nutritional value, contain high levels of anthocyanins and antioxidants with beneficial health attributes yet, studies are lacking in regard to bitterness and astringency and sensory attributes and volatiles.  Several years have passed since aroma volatiles have been assessed in rabbiteye blueberries, and only a few varieties were assayed.  Volatile composition of five commonly grown rabbiteye varieties (‘Brightwell’, ‘Climax’, ‘Premier’, ‘Powder blue’ and ‘Tifblue’) from two locations (Clinton, LA and Bush, LA), harvested at 4 maturities (white, pink, firm-blue and soft-blue) were evaluated by SPME GC-MS.  Fifty five volatiles were identified, including 14 aldehydes, 7 alcohols, 12 esters, 4 ketones, 15 terpenoids, and 3 furans.  Order of abundance in soft-ripe fruit was generally aldehydes (51.4%) > esters (33.7 %) > alcohols (7.9 %) > terpenoids (5.1 %) > ketones (1.5 %) > furans (0.4 %).  An exception was noted in ‘Climax’ where esters (51.3%) topped aldehydes (35.9%), although this variety was past peak harvest time.  In all varieties, aldehydes were highest in the pink stage and decreased with maturity.  Esters were very low at white and pink stages and increased ca. 5 to 10-fold at soft-blue.  Alcohols decreased with increasing maturity whereas terpenoids increased.  The five most abundant compounds in most soft-blue varieties were ethyl acetate, (E) 2-hexenal, acetaldehyde, hexanal and (E,E) 2,4-hexadienal.  These 5 compounds comprised 79.0, 78.8, 75.6, 72.7, and 69.6% of the total compounds in ‘Tifblue’ ‘Brightwell’, ‘Premier’, ‘Powder blue’ and ‘Climax’, respectively.  In total, the most prevalent 10 compounds recovered by our method comprised 90.7% of the total compounds recovered.  Determining actual concentrations and ascribing the importance of these volatiles in regard to overall berry and juice astringency and bitterness, as compared against polyphenolic attributes, is a long-range goal.