Differences in volatile ester composition between Fragaria x ananassa and F. vesca and implications for strawberry aroma patterns

Esters are a very important component of strawberry (Fragaria sp.) aroma. In this study, fruit volatiles were isolated by solid-phase microextraction and analyzed by gas chromatography-mass spectrometry (SPME/GC-MS). It was found that F. x ananassa had more esters than F. vesca, but there was no significant difference in average relative content of esters. Twenty five esters were selected as predominant esters, 16 of which were prevalent in F. x ananassa and another 16 in F. vesca. Among them, hexyl acetate, octyl acetate, ethyl butyrate, ethyl hexanoate, ethyl octanoate, methyl decanoate, and ethyl decanoate were found in both F. x ananassa and F. vesca, while 1-methyltridecyl acetate, myrtenyl acetate, transpinocarvyl acetate, and ethyl dodecanoate were only present in F. vesca. The numbers of carbons of the predominant esters in F. x ananassa were usually smaller than those of F. vesca. Ethyl hexanoate and octyl acetate were the esters with the highest average concentrations in F. x ananassa and F. vesca, respectively. It was found that hexyl acetate, methyl butyrate, hexyl butyrate, methyl hexanoate, and ethyl hexanoate were major contributors to the aroma of cultivated strawberry because their odor values were >= 1 in every cultivar, however, no ester was found to be so important like that for all of the F. vesca accessions. Most of the predominant esters of F. x ananassa were described as having only fruity odor. Unlike the case of F. x ananassa, nearly all of the predominant esters of F. vesca have a noticeable floral odor in addition to a fruity note. That may contribute to the variations in fruit aroma. The average number and proportion of acyl and alkyl esters differed between species. Acetate esters predominated in F. vesca, accounting for a significantly higher average proportion of total esters than in F. x ananassa. All the differences in volatile esters are likely to play a key role in the different aroma patterns of F. x ananassa and F. vesca. (C) 2012 Elsevier B.V. All rights reserved.