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Pediococcus pentosaceus has a promising potential to improve the quality and flavor of Chinese steamed bread (CSB), but its synergistic effect with Saccharomyces cerevisiae is still unclear. In this study, P. pentosaceus was cocultured with three S. cerevisiae isolates separately, which had different leavening ability. The times required for the fermentation of dough by 2 times the volume of S. cerevisiae isolates ACX 0089, ACX 0490 and ACX 0078 were 46, 88 and 120 min, respectively. The results showed that the leavening ability of S. cerevisiae had a significant impact on the quality of CSBs. Compared other S. cerevisiae isolates, the ACX 0490 cocultured with P. pentosaceus increased the contents of bound water and free water in CSB, decreased the content of semibound water, and produced larger and regular porosity, thus endowed a greater specific volume and softer texture. A total of 36 volatile organic compounds (VOCs) were found in CSBs, with alcohols accounting for the main component. The coculture of P. pentosaceus with the intermediate leavening ability of S. cerevisiae ACX 0490 produced the highest proportion of esters among all CSBs. Moreover, S. cerevisiae ACX 0490 endowed the CSB unique VOCs, including cyclodecanol, ethylacetate, and 3,5-dimethylbenzaldehyde. The results of sensory evaluation also showed that S. cerevisiae ACX0490 cocultured CSB obtained the highest scores among all the test samples. The results provided a reference for selecting S. cerevisiae isolates with different leavening ability and the combination of P. pentosaceus to achieve the best quality and flavor of CSB. [Display omitted] • The quality and flavor of CSB cocultured by P. pentosaceus and S. cerevisiae with different leavening ability were compared. • The hardness of CSB cocultured by S. cerevisiae ACX0490 was the lowest. • The contents of volatile esters in CSBs cocultured by S. cerevisiae ACX 0490 were the highest. • CSB cocultured by S. cerevisiae ACX 0490 and P. pentosaceus had the best sensory quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cinnamaldehyde will not affect the physical and chemical indicators of ready-to-eat beef but can effectively inhibit the growth of microorganisms. • Cinnamaldehyde inhibits spore germination due to downregulation of the smc and mreB genes. • Cinnamaldehyde inhibits the osmotic pressure regulation by downregulating kdp family and opuE genes in spores. • Cinnamaldehyde cannot interfere with the regulation of the resistance regulatory system. The purpose of this study was to investigate the antibacterial effect and mechanism of cinnamaldehyde on Bacillus cereus spores in ready-to-eat beef. The colour difference and texture of the ready-to-eat beef supplemented with cinnamaldehyde did not differ greatly from the colour and texture of the blank beef. However, cinnamaldehyde has an effective antibacterial effect on the total number of bacterial colonies and B. cereus spores in ready-to-eat beef. Transmission electron microscopy (TEM) analysis revealed that the cell membrane of B. cereus was disrupted by cinnamaldehyde, leading to leakage of intracellular components. Transcriptome sequencing (RNA-seq) indicated that the B. cereus spore resistance regulation system (sigB , sigW , rsbW , rsbV , yfkM and yflT) and phosphoenolpyruvate phosphotransferase system (PTS) (ptsH , ptsI and ptsG) respond positively to cinnamaldehyde in an adverse environment. Intracellular disorders due to damage to the cell membrane involve some transporters (copA , opuBA and opuD) and some oxidative stress systems (ywrO, scdA and katE) in the regulation of the body. However, downregulation of K+ transport channels (kdpD and kdpB), osmotic pressure regulation (opuE) and some oxidative stress (norR and srrA)-related genes may accelerate spore apoptosis. In addition, cinnamaldehyde also effectively inhibits the spore germination-related genes (smc , mreB and gerE). This study provides new insights into the molecular mechanism of the antibacterial effect of cinnamaldehyde on B. cereus spores in ready-to-eat beef. [ABSTRACT FROM AUTHOR]