###### Abstract
At present, 93 types of volatile flavor substances have been identified, including aldehydes, alcohols, esters, furans, and others [2]. [PERSON] et al. [12] observed that the hydrocarbons, alcohols, aldehydes, esters, and heterocyclics were the main components in six kinds of Mantou (by different Aegel yeast, sourdough, and mixed starter), with some differences in the composition and amount, among which the relative contents of 1-phenylethanol and ethyl acetate were relatively higher in steamed breads fermented by sourdough. [PERSON] et al. [2] showed that the characteristic flavor compounds of Liaomian steamed bread were 3-methyl-1-butanol, phenylethylene, decanal, gamma-nonanolactone, ethyl caprate, geranylacetone, and \(\beta\)-lonone. [PERSON] et al. [13] identified 77 compounds in sourdough steamed bread, of which ethanol and 3-methyl-1-butanol had the highest content. [PERSON] et al. [14] identified 20 volatile compounds from five kinds of sourdough steamed breads from different regions of China, and the main aroma compounds were (E)-2-nonaldehyde, (E,E)-2,4-decenal, ethanol, and acetic acid. Similarly, [PERSON] et al. [15] found that the main aroma components of sourdough steamed bread were ethanol, 1-octene-3-ol, 1-butanol, 3-methyl-1-butanol, and 1-amyl alcohol determined using simultaneous distillation and extraction (SDE) and headspace solid-phase microextraction (HS-SPME) with GC-MS, and the aroma features included vegetation aroma, fat aroma, fermentation aroma, flower and fruit aroma, mushroom aroma, sweet aroma, and wine aroma. In addition, [PERSON] et al. [16] used near-infrared spectroscopy to monitor dough fermentation by instant dry yeast every 5 min, and found that near-infrared spectroscopy could accurately distinguish samples of different fermentation states. [PERSON] et al. [17] used SPME-GC-MS and high-throughput sequencing (HTS) to study the effect of yellow glutinous rice and Baijiu koji on the aroma properties of steamed bread, and found that the composition of the volatile compounds in dough at different fermentation stages had significant differences. The formation of flavor substances in steamed bread is influenced by many factors, such as the flour, processing technology, and starter. The existing research mainly studies the flavor substances in steamed bread fermented by single yeast (mainly _S. cerevisiae_) or sourdough;however, few studies focus on the effects of other strains on flavor substances, especially aroma components, during steamed bread making. In our previous work, the mixed fermentation of _S. cerevisiae_ SQJ20 and _W. anomalous_ GZJ2 at a ratio of 1:2, newly isolated from sourdough, significantly improved the quality of steamed bread than those by commercial yeast. Specifically, the addition of _W. anomalous_ GZJ2 increased the content of total protein and free amino acids in steamed bread [9]; however, their volatile flavor substances, especially aroma components, were not studied in detail. Therefore, in this study, the headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined E-nose technology was used to analyze the dynamic changes in the volatile flavor compounds during the process of making steamed bread fermented by _S. cerevisiae_ SQJ20 and _W. anomalous_ GZJ2, especially focusing on the effect of _W. anomalous_ GZJ2 on the volatile aroma substances in steamed bread, which will lay a theoretical and application foundation for the industrial production of mixed-starter steamed bread.