a-Terpineol and linalool have been identified as key aroma compounds in blueberries.  In this study, the (R/S)-enantiomer distributions of a-terpineol and linalool were further studied in different blueberry cultivars using headspace solid-phase microextraction (SPME) sampling techniques coupled with multidimensional gas chromatography-mass spectrometry. The results showed that linalool had a strong enantiomeric excess of the (S)-form over the (R)�form, in >50% for all of cultivars.  We found that linalool (S/R) isomeric ratio in 'Duke', 'Draper', 'Bluecrop', 'Liberty', 'Elliott', 'Aurora', 'ORUS 235-4', 'ORUS 10-1' varied from 53/47  to 76/24.  However, a-terpineol has an almost equal distribution of (S)- and (R)�form. The a-terpineol (S/R) isomeric ratio in these varieties varied from 45/55 to 49/51. Moreover, harvesting time had impact on the isomeric ratio of these chiral compounds. We found that ORUS 235.4 has a linalool (S/R) isomeric ratio of 76/24 and a-terpineol (S/R) isomeric ratio of 49/51. However, later harvested fruits of the same variety had a linalool (S/R) isomeric ratio of 54/46 and a-terpineol (S/R) isomeric ratio of 46/54.  Since different isomer has different aroma characteristics and sensory threshold, understanding the aroma isomer formation will provide useful knowledge about the aroma quality of agricultural products.

Isomeric ratio of linalool and a-terpineol in high bush blueberry fruit

248th National Meeting (2014)

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