Volatile constituents of Asian pear (Pyrus serotina)

Abstract

The volatiles of Asian pear (Seuri cultivar) were studied by high-resolution gas chromatography and combined gas chromatography/mass spectrometry (GUMS) using vacuum simultaneous distillationextraction of blended fruit and dynamic headspace sampling of intact and enzymatically inhibited blended fruit. Esters were the dominant constituents in all of the samples. A total of 72 components were identified in the headspace of intact fruit, including 39 constituents reported for the first time in pear. Odor unit values calculated from concentration and odor threshold data indicate that the following compounds are important contributors to pear aroma: ethyl 2-methylbutanoate, ethyl hexanoate, ethyl butanoate, ethyl 2-methylpropanoate, hexyl acetate, ethyl heptanoate, hexanal, ethyl pentanoate, and ethyl propanoate. Asian pears (Pyrus serotina) are a completely distinct species from the more common European-type pears (Pyrus communis L.) such as Bartlett and La France and are not a cross between apples and pears. Though the volatile constituents of Bartlett pears have been extensively investigated (Maarse and Visscher, 1984), there has been, to our knowledge, only one publication on the flavor compounds of Asian pears (Shiota et al., 1981). These researchers studied four Asian pear cultivars [Nijisseiki (20th Century), Kosui, Hosui, and Kikusuil and found distinct compositional differences between the peel and pulp. The peel contained major amounts of nonanal, cy-farnesene, phenylacetaldehyde, and straight-chain hydrocarbons with 19-23 carbon atoms, while the pulp had ethyl butanoate, hexanol, hexyl acetate, butylbenzene, and