Abstract: To study the volatile composition changes of steamed bread during processing, the volatile components in wheat flours, fermented doughs and steamed breads from three representative wheat cultivars with different gluten strength, Pubing 143, Jinmai 47 and Xinong 9817, were extracted by headspace solid-phase microextraction (HSPME) and analyzed by GC-MS. A total 23 volatile compounds (mainly naphthalene, 1-methyl-naphthalene, (Z)-2-Butenedioic acid dimethyl ester, 1,7-dimethyl-naphthalene and 2-methyl-naphthalene) were found to be common to wheat flours from all investigated cultivars, accounting for 84.01%, 77.82% and 82.28% of the total volatile compounds in Pubing 143, Jinmai 47 and Xinong 9817, respectively. Eighteen volatile compounds (mainly ethanol, naphthalene, 1-methyl-naphthalene, butanedioic acid ethyl methyl ester and phenylethyl alcohol) were common to fermented doughs made with wheat flours from all investigated cultivars, accounting for 80.99%, 71.65% and 70.44% of the total volatile compounds in Pubing 143, Jinmai 47 and Xinong 9817, respectively. Twenty-six volatile compounds (mainly naphthalene, 1-methyl-naphthalene, 2-pentyl-furan, ethanol and nonanal) were common to steamed breads made with wheat flours from all investigated cultivars, accounting for 80.26%, 75.99% and 80.43% of the total compounds in Pubing 143, Jinmai 47 and Xinong 9817, respectively. The results obtained demonstrate that wheat flour, fermented dough and steamed bread vary in volatile composition among wheat cultivars with different gluten strength despite no difference in most of the main volatile components. During the processing of steamed bread from wheat flour; the relative content of hydrocarbons significantly decreases, whereas both the kinds and relative contents of alcohols increase, suggesting a significant change in the volatile composition.

Key words: wheat, steamed bread, solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) , volatile components