Blackberries have been enjoyed for their delicious flavor and high nutritional value for hundreds of years. In North America, blackberries were cultivated since 1850-1860. Blackberries have their characteristic and unique aromas depending on the cultivar and growing conditions. The objective of this study was to evaluate the impact of seasonal variation and growing environment on blackberry aroma. Volatile compositions of 'Marion' and 'Thornless Evergreen' blackberries from three growing seasons were analyzed using gas chromatography-flame ionization detection (GC-FED) and GC-mass spectrometry (GC-MS). Seasonal variations were observed for some volatile compounds in these two blackberry cultivars. In 'Marion', the compounds were mainly acids, while in 'Thornless Evergreen', they were mainly acids, alcohols, and a few terpenoids. Although seasonal variations were present, it was generally observed that the most abundant volatiles in 'Marion' blackberry were acetic, 2/3-methylbutanoic, hexanoic and decanoic acids and linalool, whereas the most abundant volatiles in 'Thornless Evergreen' were 2-heptanol, hexanol, octanol, α-pinene, nopol and/p-cymen-8-ol. Compared with 'Marion', 'Thornless Evergreen' contained significantly more total volatiles, especially in alcohols, terpenoids and phenols, whereas 'Marion' contained more organic acids. Odor Activity Values (OAVs) were used to determine the most potent odorants in each cultivar. The compounds with high odor activity values (OAV > 10) in 'Marion' were ethyl hexanoate, β-ionone, linalool, 2-heptanone, 2-undecanone, α-ionone and hexanal. The compounds with high odor activity values (OAV > 10) in 'Thornless Evergreen' were ethyl hexanoate, 2-heptanone, ethyl 2-methylbutanoate, 2-heptanol, 3-methylbutanal, α-pinene, limonene, p-cymene, linalool, t-2-hexenal, myrtenol, hexanal, 2- methylbutanal and sabinene. To investigate the influence of growing environment on blackberry aroma, aroma extraction dilution analysis (AEDA) was employed to characterize the aroma profile of 'Chickasaw' blackberries from two growing regions in United States: Oregon and Arkansas. Eighty-seven odorants were detected in the two berries, in which seventy-seven could be identified. Comparative AEDA analysis showed that the berries grown in these two regions had similar aroma compositions, however, those odorants had various aroma impacts in each region. The compounds with high FD factors in Oregon's 'Chickasaw' were ethyl butanoate, linalool, methional, trans,cis-2,6-nonadienal, cis-l,5-octadien-3-one, and 2,5-dimethyl-4-hydroxy- 3(2H)-furanone, whereas in the 'Chickasaw' grown in Arkansas, they were ethyl butanoate, linalool, methional, ethyl 2-niethylbutanoate, β-damascenone and geraniol. The flavor formation in 'Chickasaw' blackberries was largely influenced by their growing environment. / Graduation date: 2005