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Thirty-seven lactic acid bacteria (LAB) strains were isolated from traditional dry sausages collected from Northeast China, including Latilactobacillus sakei (29 strains), Lactiplantibacillus plantarum (4 strains), Latilactobacillus curvatus (2 strains), Weissella hellenica (1 strain), and Lactococcus lactis (1 strain). Some LAB strains had tolerance to high concentrations of sodium chloride (6%), sodium nitrite (150 mg/L NaNO 2), and acid (pH 4.0). They showed good growth and acidification properties and antimicrobial activity. Among them, five LAB strains that exhibited the best technological properties were selected and inoculated in the sausage model to explore their roles in flavor development. The contents of total free amino acids (FAAs) decreased ranging from 109.11 mg/g to 58.06 mg/g. A total of 46 volatile compounds were identified and the contents of volatile compounds increased in the sausage model during fermentation. Partial least squares regression analysis showed that Lb. sakei HRB10, Lb. plantarum MDJ2, W. hellenica HRB6, and Lc. lactis HRB0 promoted the generation of FAAs and volatile compounds in the sausage model. These findings demonstrated that the autochthonous LAB species are promising for the production of sausage with better flavor and fermentation performance. [Display omitted] • Thirty-seven LAB strains were isolated from traditional dry fermented sausages. • The selected strains exhibited high tolerance to salt, sodium nitrite, and acid. • LAB inoculation promoted free amino acid (FAA) and flavor generation. • The FAAs were responsible for the differences in the flavor of sausage models. [ABSTRACT FROM AUTHOR]

The traditional dry sausage is highly appreciated in China because of its unique quality characteristics, but it contains high salt content. Hence, this study aimed to evaluate the effects of lactic acid bacteria (LAB) comprising Lactobacillus sakei (LS), Lactobacillus curvatus (LC), Lactobacillus plantarum (LP), and Weissella hellenica (WH) on the quality attributes of the reduced-salt dry fermented sausages. The results indicated that the LP sausage showed higher (P < 0.05) shear force value compared to the other sausages, while the LP, LC, and WH sausages had higher (P < 0.05) lightness values than the control sausages. Seventy-six volatile compounds were detected, and nine compounds were identified as the key differential volatile compounds among the sausages based on partial least squares discriminant analysis. Clustering analysis of electronic nose results corresponded well to the volatile compound results. The sensory evaluation confirmed that the inoculation with LC and LP had a positive impact on the aroma, color, and hardness attributes of the reduced-salt sausages. Besides, partial least squares regression analysis further indicated that L. curvatus and L. plantarum could be used as the potential starter cultures to manufacture reduced-salt dry fermented sausage having improved texture, color, and flavor. [Display omitted] • The LP sausage shows higher shear force value compared to the other sausages. • The LP, LC, and WH sausages have higher lightness values than the control sausages. • Seventy-six volatile compounds are detected in dry fermented sausage. • Sensory attributes correlate with the key volatile compounds using PLSR analysis. • L. curvatus and L. plantarum can improve the quality of reduced-salt dry sausage. [ABSTRACT FROM AUTHOR]

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 explore the correlation between bacterial communities and volatile compounds in traditional dry sausages from different regions in Northeast China. The bacterial community structure of dry sausages from five different regions as determined by high-throughput sequencing technology demonstrated that Firmicutes and Proteobacteria were the predominant phyla; Lactobacillus , Staphylococcus , Leuconostoc , Lactococcus and Weissella were the predominant genera; and Staphylococcus xylosus , Lactobacillus sakei , Weissella hellenica , Leuconostoc citreum , Lactococcus raffinolactis and Lactobacillus plantarum were the predominant species. Meanwhile, a total of 120 volatile compounds were detected in sausages from five different regions and mainly included alcohols, acids, aldehydes, ketones, esters and terpenes. Furthermore, the potential correlations between the core bacteria and major volatile compounds (64) were explored based on Spearman's correlation analysis. Positive correlations were found between W. hellenica , Lb. sakei , Lactococcus lactis , Lactobacillus alimentarius , Lb. plantarum and carboxylic acids and alcohols. Lc. lactis , Lb. alimentarius and Lb. plantarum were associated with the production of most esters, aldehydes and ketones. This study provides a deep insight into the relationship between the bacterial community and the volatile flavour profile of dry sausages, which may be helpful for the production of fermented dry sausages. Image 1 • The pdredominant phyla were Firmicutes and Proteobacteria in traditional dry sausage. • A total of 120 volatile compounds were detected in the five traditional sausages. • Five core bacteria improved the formation of volatile compounds in dry sausage. [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]

The technological properties and flavour formation potential of yeast strains isolated from traditional dry fermented sausages were evaluated. A total of 46 yeast strains were isolated and characterized at the strain level by genotyping. Among them, 34 strains were selected for evaluation of technological properties (tolerance to acid, salt, and sodium nitrite stresses; proteolytic and lipolytic activities; and biogenic amine formation capacity) based on their genetic profiles. Then, seven strains (Debaryomyces hansenii HRB2, SH4, and HG2; Torulaspora delbrueckii DQ3 and HG7; Pichia kudriavzevii MDJ1; and Candida zeylanoides DQ7) were selected to investigate their flavour formation potential in a fermented sausage model. A total of 56 volatile compounds were detected in all models, of which 17 volatile compounds were the most important flavour contributors with an odour activity value (OAV) > 1. The most remarkable result was the significant production of acid, alcohol, and esters in the inoculated models, such as acetic acid, hexanoic acid, ethanol, phenethyl alcohol, ethyl acetate, and ethyl hexanoate. Of all the strains, D. hansenii SH4 was considered to be the best flavour producer because it produced multiple compounds with the highest OAVs, which are associated with the development of desirable sensory characteristics in dry sausages. • A total of 46 yeast strains were isolated from traditional dry fermented sausages. • Intraspecific genetic diversity of yeast strains was explored using ISSR-PCR. • Eight strains exhibited high tolerance to acid, salt, and sodium nitrite stresses. • Seven strains showed specific capacities to produce acids, alcohols, and esters. • Debaryomyces hansenii SH4 produced multiple compounds with high odour activity value. [ABSTRACT FROM AUTHOR]