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This study was to investigate the succession of the bacterial community in Harbin dry sausages during fermentation and its correlation to the sausage flavour. The results showed that Staphylococcus count increased but the moisture content and water activity decreased (P < 0.05). The lactic acid bacteria count first increased and then decreased, while the pH showed an opposite trend during a twelve-day fermentation (P < 0.05). According to a single molecule real time sequencing analysis, Lactobacillus sakei and Staphylococcus xylosus were the predominant bacterial species over the entire fermentation period. A total of 79 volatile compounds were detected using the headspace solid phase microextraction gas chromatography-mass spectrometry. Furthermore, the correlation between the core bacteria (top 30) and the major volatile compounds was explored, which highlighted that three bacterial species (Lb. sakei , S. xylosus and Weissella hellenica) were significantly correlated with the major volatile compounds, such as 2,3-butanediol, ethanol, 3-hydroxy-2-butanone, ethyl hexanoate and ethyl lactate. The results may provide a theoretical basis for improving the flavour and overall quality of dry sausage. • Lactobacillus sakei and Staphylococcus xylosus were the dominant bacterial species. • Seventy-nine volatile compounds were detected in Harbin dry sausages. • L. sakei , S. xylosus and W. hellenica were correlated with the volatile compounds. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of NaCl reduction (2.5% 2.0%, 1.5% and 1.0%) on the bacterial growth, physicochemical characteristics, flavour profile and sensory traits of fermented dry sausage. The moisture content, water activity and lactic acid bacteria count increased as the NaCl level decreased (P < 0.05), contributing to decreases in pH (P < 0.05). A total of 50 volatile compounds were identified, and increases in volatile compounds, such as acetone, 3-hydroxy-2-butanone, with high odour activity values derived from carbohydrate metabolism and lipid oxidation may contribute to flavour development (P < 0.05). Additionally, the increased Staphylococcus spp. counts in sausages with 2.0% and 2.5% NaCl contributed to the increased contents of ethyl octanoate, ethyl butyrate and ethyl acetate (P < 0.05). Sensory evaluation showed higher scores for taste, chewiness and aroma in sausages with 2.0% and 2.5% NaCl. Therefore, it can be concluded that 2.0% NaCl can be employed as the desired addition level in fermented sausage to achieve better quality and flavour. • Sausages with reduction in NaCl level had higher moisture content and water activity. • The reduction of NaCl level increased lactic acid bacteria population. • Volatile compounds in fermented sausage during fermentation were identified. • 2.0% NaCl can be employed as the desired addition level in fermented sausage. [ABSTRACT FROM AUTHOR]

Pediococcus pentosaceus (Pp) , Lactobacillus curvatus (Lc) , Lactobacillus sakei (Ls) and Staphylococcus xylosus (Sx) were evaluated to determine their roles in the quality characteristics and flavor formation in Harbin dry sausage. The inoculation of dry sausages with bacterial strains, especially mixed strains (Pp + Sx + Lc and Pp + Sx + Ls), significantly decreased the moisture content and water activity. Compared with the sausages inoculated with a single strain and non-inoculated, those inoculated with mixed strains had shorter transverse relaxation time T 21 that represents the immobilized water (P < 0.05) after a nine-day fermentation. The texture profile analysis showed that inoculation with bacterial strains increased the hardness and springiness of sausages. The sausages inoculated with mixed strains showed higher a *-values (P < 0.05). Furthermore, the percentages of some aldehydes, ketones, alcohols, acids and esters in the sausage inoculated with Pp + Sx + Lc were significant higher than that in control sausages (P < 0.05), which may be derived from carbohydrate catabolism (such as 3-hydroxy-2-butanone), amino acid metabolism (such as 3-phenylpropanol, 2,3-butanediol, phenylethyl alcohol, 2-methyl-propanal, 2-methyl-butanal and 3-methyl-butanal), β-lipid oxidation (such as 2-pentanone, 2-heptanone and 2-nonanone) and esterification (such as ethyl esters). • Bacterial fermentation promoted the decrease in moisture content and water activity. • Bacterial fermentation improved the hardness and springiness of sausage. • The fermentation with multiple bacterial strains had higher percentages of favorable volatile compounds. [ABSTRACT FROM AUTHOR]