A comparison of citrus blossom volatiles.

The objective of this study was to identify the major volatiles and their relative concentrations in intact grapefruit, sweet orange, sour orange, mandarin, lemon, lime and pummelo blossoms. Volatiles from freshly picked blossoms were collected and concentrated using static headspace solid-phase microextraction and then separated and identified using GC-MS. Seventy volatiles were detected, 66 identified, of which 29 were identified for the first time in citrus blossoms. Major volatiles consisted of linalool, beta-myrcene, alpha-myrcene, limonene, (E)-ocimene, methyl anthranilate and indole. In terms of total volatiles: pummelo >> grapefruit approximately = sweet orange > sour orange approximately = mandarin approximately = lemon-lime > Volkamer lemon > Kaffir lime. Principal component analysis of blossom volatiles demonstrated that there were three widely separated, tightly clustered groups which consisted of mandarin, lemon-lime and pummelo. Other cultivars of possible mixed parentage produced non-overlapping values within the boundaries of these three clustered groups. The first two Eigenvectors explained 83% of the total variance. Linalool, limonene and myrcene had the highest loading values. Those cultivars requiring insect pollination such as pummelo produced highest levels of total volatiles as well as highest levels of known honeybee stimulants such as 1-hexanol and linalool.