# Volatiles in Berries: Biosynthesis, Composition, Bioavailability, and Health Benefits
## 3 The Chemical Composition of Volatile Compounds in Berries
### Blueberry  
Blueberries (_Vaccinium_ spp.) are the second most popular berry fruit in the U.S. after strawberries [97]. The blueberry market has increased 10-20% annually over the last 5 years [98]. The increased blueberry consumption is due to its well-known health benefits and flavor [99]. Highbush blueberries mainly contained ethyl acetate, (E)-2-hexenal, (E)-2-hexenol, hexanol, (Z)-3-hexenol, linalool, and geraniol [68]. Others, including citronellol, \(\alpha\)-terpineol, 2-phenylethanol, and vanillin, were also considered to have the highbush blueberry aroma [81]. A total of 38 aroma volatiles were detected from southern highbush blueberry [74]. There were nine aldehydes, eight esters, seven terpenes, five ketones, two alcohols, two acids, two sulfurs, and three miscellaneous compounds. Aldehydes were the most abundant chemical group within southern highbush blueberry and a major volatile compound group to the blueberry aroma. Hexanal, (Z)-3-hexenal, (E)-2-hexenal, (E,Z)-2,6-nonadienal, and (E,E)-2,4-nondeional had \"fresh green\", \"grassy\", and \"fruity\" aroma characteristics, whereas pentanal, octanal, (E,E)-2,4-hexaional, and decanal had \"fatty\" and \"citrus\" [74]. Esters were the second most abundant in southern highbush blueberry, and they included ethyl propanoate, methyl 2-methylbutanoate, methyl 3-methylbutanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, (Z)-3-hexyl acetate, (E)-2-hexyl acetate, and geranyl acetate, with \"green\", \"sweet\", \"fruity\", \"apple\", \"banana\", \"pear\", and \"floral\" aromatic characteristics. Unlike strawberries, apples, and bananas, where esters are the main contributors to the aroma, fewer esters were found in highbush blueberry [66; 100]. Terpenes including linalool, citronellol, nerol, and geraniol showed \"sweet\", \"floral\", \"fruity\", \"citrus\", and \"berry-like\", while 1,8-cineo, dihydrolinalool oxide, and \(\alpha\)-terpineol had \"woody\", \"herbaceous\", and \"piney\" characteristics. Linalool was one of the major volatiles in southern highbush blueberry. Two alcohols, including (Z)-3-hexenol and 2-heptanol, were aroma active. Only three ketones, including 2-heptanone, 1-octen-3-one, and 2-nonanone with \"fruity\" \"mushroom\", \"earthy\", and \"cheese-like\", were found to have aroma activity. Furnael was found in southern highbush blueberries. Furaneol had \"sweet\", \"candy\", and \"caramel\" characteristics. In another study, five _Vaccinium_ cultivars (\"Bilox\", \"Brigitta Blue\", \"Centurion\", \"Chandler\", and \"Ozark Blue\") were found to have 106 volatile organic compounds [78]. Esters, 25 compounds, were the major compounds and were followed by 18 aldehydes, 16 alcohols, 14 monoterenes, 7 ketones, 4 acids, 4 hydrocarbons, 3 sesquiterpenenes, 1 lactone, and 1 norisopenroid. Aldehydes, including (E)-2-hexenal, hexanal, (Z)-3-hexenal, hexaional, or heptal, are the most abundant, accounting for almost half of the _Vaccinium_ volatile composition. Monoteprenes, including 1,8-cineo and linalool, were also important compounds in the volatile blueberry profile [78]. Even though esters had smaller content compared to others, esters had a unique aroma that characterizes the aroma of blueberry. Among seven ketones identified, 2-heptanone and 6-methyl-5-hepten-2-one were the ones with the highest contents. Octane, ethyl benzene, p-xylene, and mxylene were identified as hydrocarbons. Other volatile compounds in the blueberry aroma profile were hexanoic acid, octanoic acid, nonanoic acid, decanoic acid (acids), d-elemene, (E)-caryophyllene, and carryophyllene oxide (sesquierpenes), b-damasceno (norisopenroid), and butylactone (lactone). [PERSON] et al. conducted identification of volatile blueberry compounds, and alcohol (51.8%), ester (32.8%), and carboxylic acid (6.9%) were mainly detected [101]. Forty-six blueberry volatiles were identified by [PERSON] et al. by using GC-MS [69].