Effect of inoculation of selected Staphylococcus xylosus and Lactobacillus plantarum strains on biochemical, microbiological and textural characteristics of a Tunisian dry fermented sausage

Insight into the autochthonous bacterial strains as starter cultures for improving the flavor profiles of dry-cured duck: Changes in microbial diversity and metabolic profiles

The purpose of this study was to reveal the effect of inoculating autochthonous bacterial strains (Lactobacillus and Staphylococcus simulans) on the flavor profiles, microbial community, and metabolites, and to elucidate the potential mechanism of flavor formation in dry-cured duck. The results indicated that the inoculation of bacterial strains could improve the amount of lactic acid bacteria and Staphylococcus and reduce the counts of Enterobacteria. There was a significant difference in flavor profiles between samples inoculated with different strains. Hexanal-D, acetone, 3-methyl-1-butanol-D, thiophene, hexanal-M, propanal, pentanal, (Z)-2-penten-1-ol and ethanol-D were the potential biomarkers. A total of 70 differential metabolites were screened and identified. Amino acid metabolism and lipid metabolism were the key pathways for the production of flavor and metabolites in dry-cured duck. The results of this study will improve our understanding of the mechanism of flavor formation regarding the inoculation of autochthonous starter cultures.

Study on the Correlations between Quality Indicators of Dry-Aged Beef and Microbial Succession during Fermentation

Dry-aged beef has been long favored by people due to its unique flavor and taste. However, the inner relationship between its overall quality formation and microbial changes during dry aging has not yet received much attention and research. To deeply reveal the forming mechanism of the unique flavor and taste of dry-aged beef, correlations between its three main quality indicators, i.e., texture, free amino acids (FAAs), volatile flavor compounds (VFCs), and microbial succession were analyzed in this study. The results showed that Staphylococcus spp. and Macrococcus spp. were key strains that influenced the total quality of dry-aged beef and strongly correlated with chewiness, hardness, and sweet FAAs (Ala), providing beef with unique palatability and taste. Additionally, among VFCs, Staphylococcus spp. and Macrococcus spp. showed a strong correlation with octanal and heptanal, and meanwhile, those highly correlated with nonanal, pentanol, and oct-1-en-3-ol were Debaryomyces spp., Psychrobacter spp., and Brochothrix spp., respectively, providing beef with a unique flavor. Staphylococcus spp. was proposed to be the dominant genus for dry-aged beef. This study provides valuable reference for the understanding of the role of microorganisms involved in dry aging.

Effects of different mixed starter cultures on microbial communities, taste and aroma compounds of traditional Chinese fermented sausages

The aim of this study was to investigate and compare the effects of different mixed starter cultures (Lactiplantibacillus plantarum and Staphylococcus simulans) on the bacterial communities and flavor of fermented sausages. The results indicated that native starters grew well in fermented sausages and became dominant at the end of ripening. Among them, Lactobacillus spp. had the highest relative abundance, followed by Staphylococcus spp. In addition, the inoculation of the mixed starters promoted the formation of taste and aroma compounds that contribute to the overall flavor of the fermented sausages. Among them, the L. plantarum CQ01107 + S. simulans CD207 (CCA) treatment was found to have the highest umami amino acid, nucleotide, lactic acid, fatty acid and ketone contents (P < 0.05), as well as excellent sensory properties. In conclusion, the CCA starter may be a desirable starter culture to enhance the flavor of fermented sausages.

High-Hydrostatic-Pressure-Stabilized White Grape Pomace to Improve the Oxidative Stability of Dry-Cured Sausages ("Salchichón")

White grape pomace (winery by-product) stabilized by blanching and high hydrostatic pressure has recently been successful at delaying lipid oxidation in burgers. The aim of this study was to investigate whether it can also delay lipid oxidation in dry-cured sausages, and to compare its effect when added at 0.5 and 3% with those of synthetic additives (sodium nitrite and ascorbic acid) and no additives (Control) in lipid and protein oxidation, the instrumental color, the sensory characteristics, and the volatile compounds. The pomace (68.7 ± 7.4 mmol Trolox g-1) was as effective as the additives at preventing lipid oxidation, resulting in values 3.2-3.8 times lower than the Control sausages. However, the pomace was not effective at decreasing the microbial counts, improving the instrumental and sensory color and the volatile compound profile, and decreasing the off-odor and off-flavor developed in the Control sausages. The lack of a detrimental effect of the pomace at 0.5% on the volatile compounds and the sensory characteristics and its benefits to delay lipid oxidation suggest that it might be useful to improve the oxidative stability. Conversely, at 3%, with a detrimental effect on some sensory characteristics and no benefits over the lower dosage, is not advisable.

Improving quality of poultry and its meat products with probiotics, prebiotics, and phytoextracts

Remarkable changes have occurred in poultry farming and meat processing in recent years, driven by advancements in breeding technology, feed processing technology, farming conditions, and management practices. The incorporation of probiotics, prebiotics, and phytoextracts has made significant contributions to the development of poultry meat products that promote both health and functionality throughout the growth phase and during meat processing. Poultry fed with these substances improve meat quality, while incorporating probiotics, prebiotics, and phytoextracts in poultry processing, as additives or supplements, inhibits pathogens and offers health benefits to consumers. However, it is vital to assess the safety of functional fermented meat products containing these compounds and their potential effects on consumer health. Currently, there's still uncertainty in these aspects. Additionally, research on utilizing next-generation probiotic strains and synergistic combinations of probiotics and prebiotics in poultry meat products is in its early stages. Therefore, further investigation is required to gain a comprehensive understanding of the beneficial effects and safety considerations of these substances in poultry meat products in the future. This review offered a comprehensive overview of the applications of probiotics and prebiotics in poultry farming, focusing on their effects on nutrient utilization, growth efficiency, and gut health. Furthermore, potential of probiotics, prebiotics, and phytoextracts in enhancing poultry meat production was explored for improved health benefits and functionality, and possible issues associated with the use of these substances were discussed. Moreover, the conclusions drawn from this review and potential future perspectives in this field are presented.

Characteristics of Lactic Acid Bacteria as Potential Probiotic Starters and Their Effects on the Quality of Fermented Sausages

The aim of this study was to explore the potential of commercial lactic acid bacteria (LAB) as probiotic starters in fermented sausages. We initially investigated the growth activity, acid production capability, and tolerance to fermentation conditions of Lactobacillus sakei, Lactiplantibacillus plantarum, and Pediococcus pentosaceus. All three LAB strains proved viable as starters for fermented sausages. Subsequently, we explored their potential as probiotics based on their antibacterial and antioxidant capabilities. L. plantarum exhibited stronger inhibition against Escherichia coli and Staphylococcus aureus. All three strains displayed antioxidant abilities, with cell-free supernatants showing a higher antioxidant activity compared to intact cells and cell-free extracts. Moreover, the activities of superoxide dismutase, glutathione peroxidase, and catalase were stronger in the cell-free supernatant, cell-free extract, and intact cell, respectively. Finally, we individually and collectively inoculated these three LAB strains into sausages to investigate their impact on quality during the fermentation process. External starters significantly reduced pH, thiobarbituric acid reactive substances, and sodium nitrite levels. The improvements in color and texture had positive effects, with the L. plantarum inoculation achieving higher sensory scores. Overall, all three LAB strains show promise as probiotic fermentation starters in sausage production.

Characterization of the physicochemical Properties, bacterial community and non-volatile profiles of fermented Yu jiangsuan by Weissella cibaria and Lactobacillus plantarum

Yu jiangsuan (YJS) is a unique traditional fermented condiment in China. Physicochemical, bacterial communities, and non-volatile properties were examined in inoculation Autochthonous Weissella cibaria and Lactobacillus plantarum. The results indicated that inoculation samples did well in shortening fermentation time; amino acid nitrogen (AN) and TCA-soluble peptide contents of fermented YJS were 10.8% and 17.4% higher than those of naturally fermented YJS, respectively. However, its total volatile base nitrogen (TVB-N), thiobarbituric acid (TBARS), and nitrite were only 74.3%, 87.2% and 83.6% of those of naturally fermented YJS. In addition, the dominant bacterial genera were Lactobacillus, Weissella and Pectobacterium, whose contributions were 41.2%, 20.3% and 5.5%, respectively. Moreover, 26 significantly differential metabolites were identified, and involved in 10 metabolic pathways. The decomposition of substrates and the formation of differential metabolites in YJS were primarily centered on the TCA cycle and the metabolism of carbohydrates. Therefore, this study is conducive to discovering the bacterial community structure and metabolite composition of probiotic inoculated YJS fermentation, as well as the potential value of core functional bacteria genera in controlling YJS production in industry.

Effects of lactic acid bacteria and coagulase-negative staphylococci on dry-fermented sausage quality and safety: Systematic review and meta-analysis

The meta-analysis aim was to confirm and quantifying the influence of starter cultures on microbiological and physical-chemical parameters of dry-fermented sausages at the end fermentation stage. The literature search yielded 1194 citations, and 77 studies with 178 experiments were eligible and included in the meta-analysis, a random-effects model was used to estimate the pooled weighted mean difference (MD) with 95% confidence interval (CI).The use of starter culture in dry-fermented sausages significantly reduced pH (MD: -0.364; CI: -0.414; -0.319), moisture (MD: -1.443; CI: -1.931; -0.955), aw (MD: -0.011; CI: -0.017; -0.006), Enterobacteriaceae count (MD: -1.119; CI: -1.293; -0.945), yeasts and molds count (MD: -0.351; CI: -0.691; -0.084), and increased color component a* (MD: 0.859; CI: 0.266;1.452), color component L* (MD: 1.288; CI: 0.433; 2.143), LAB count (MD: 0.981; CI: 0.696;1.267), Staphylococci count (MD: 0.484; CI: 0.293; 0.675) and TVC (MD: 0.529; CI: 0.098; 0.959). The results of the sub-analysis suggest that the addition of LAB and LAB/CNS inocula have a greater effect on the physico-chemical and microbiological parameters studied in this work. In the meta-regression analysis, a positive linear relationship was found in starter culture sausages in comparison with control batch between LAB count and the dose of starter culture added, and in the pH and Enterobacteriaceae count with the passage of fermentation days. In contrast, a negative linear relationship was found between redness and increased casing diameter of the sausages. Therefore, our work shows impact that addition of starter cultures has on safety and quality of dry-fermented sausages.

Lactiplantibacillus paraplantarum BPF2 and Pediococcus acidilactici ST6, Two Bacteriocinogenic Isolated Strains from Andalusian Spontaneous Fermented Sausages

Traditional spontaneously fermented foods are well known for their sensory and safety properties, which is mainly due to their indigenous microflora. Within this group of food, Mediterranean dry-cured sausages stand out as a significant source of lactic-acid bacterial strains (LAB) with biotechnological properties, such as their antimicrobial activity. The aim of this study was to investigate the biodiversity of antagonistic LAB strains from different Andalusian traditional sausages, such as salchichón and chorizo. First, a screening was carried out focusing on the antimicrobial activity against foodborne pathogens, such as Listeria monocytogenes, Escherichia coli, Clostridium perfringens, and Staphylococcus aureus, selecting two strains due to their higher antibiosis properties, both in agar and liquid media. These bacteria were identified as Lactiplantibacillus paraplantarum BPF2 and Pediococcus acidilactici ST6. In addition, genomic studies confirmed the presence of certain structural genes related to the production of bacteriocins. Finally, the culture supernatants of both strains were purified and analyzed by LC-MS/MS, obtaining the relative molecular mass and the amino acid sequence and identifying the peptides as the bacteriocins Pediocin-PA and Leucocin K. In conclusion, genomes and antimicrobial substances of P. acidilactici ST6, a Pediocin-PA producer, and Lpb. paraplantarum BPF2, a Leucocin K producer, isolated from Andalusian salchichón and chorizo, respectively, are presented in this work. Although further studies are required, these strains could be used alone or in combination as starters or protective cultures for the food industry.

Effect of Limosilactobacillus fermentum 332 on physicochemical characteristics, volatile flavor components, and Quorum sensing in fermented sausage

The effects of Limosilactobacillus fermentum 332 on quality characteristics in fermented sausage were explored in terms of physicochemical characteristics, volatile flavor components, and Quorum sensing (QS). The results showed that the pH of fermented sausage decreased from 5.20 to 4.54 within 24 h with the inoculation of L. fermentum 332. Lightness and redness were significantly improved, and hardness and chewiness were significantly increased after the addition of L. fermentum 332. With the inoculation of L. fermentum 332, the thiobarbituric acid reactive substance content decreased from 0.26 to 0.19 mg/100 g and total volatile basic nitrogen content decreased from 2.16 to 1.61 mg/100 g. In total, 95 and 104 types of volatile flavor components were detected in the control and fermented sausage inoculated with starter culture, respectively. The AI-2 activity of fermented sausage inoculated with L. fermentum 332 was significantly higher than that of the control and positively correlated with viable count and quality characteristics. These results provide support for further research on the effect of microorganisms on the quality of fermented food.

Effects of the addition of leucine on flavor and quality of sausage fermented by Lactobacillus fermentum YZU-06 and Staphylococcus saprophyticus CGMCC 3475

Methyl-branched aldehydes, especially 3-methylbutanal, have been reported to be perceived either as a malty or as a nutty/chocolate-like aroma and were considered an important flavor contributor in fermented meat products. Decomposition of leucine (Leu) by branched-chain amino acid transaminase (BACT) is a crucial step in the metabolism of Leu to 3-methylbutanal. This study was conducted to explore the effects of mixed-starter culture (Lactobacillus fermentum YZU-06 and Staphylococcus saprophyticus CGMCC 3475) and addition of Leu (0, 1, and 3 mM) on the flavor and quality of fermented sausages. The pH, water activity, texture profile analysis, color, counts of lactic acid bacteria (LAB) and staphylococci, peptide, and flavor compounds were detected during fermentation. The results showed that the starter culture group increased hardness, elasticity, the counts of LAB and staphylococci, peptide content, volatile flavor compounds, as well as the sensorial scores of sausage, while decreasing pH, a _w , and L* and b* values compared with the non-inoculation group. The mixed starter of adding with 3 mM Leu enhanced the content of 3-methylbutanal and overall flavor of fermented sausages. It is applicable to directionally produce methyl-branched aldehydes and improve the overall quality of fermented sausage by the addition of Leu and using starter of L. fermentum YZU-06 and S. saprophyticus CGMCC 3475.

Bifidobacterium animalis A12, a Probiotic Strain That Promotes Glucose and Lipid Metabolism, Improved the Texture and Aroma of the Fermented Sausage

Bifidobacterium animalis A12 was used for the development of fermented sausage. The growth activity, tolerance, and enzyme activity of B. animalis A12 and its contribution to the texture and flavour of fermented sausages were evaluated. Additionally, the sensory texture, flavour components, and amino acid nutrients during the fermentation process were assessed. B. animalis had high tolerance to NaCl and nitrite, and B. animalis A12 had protease and lipase activities. The pH value of sausage fermented with B. animalis A12 was lower than that of sausage fermented without any fermentation strain. Hexanal, heptanal, decanal, cis-2-decanal, and 4-methoxy-benzaldehyde are the unique aldehydes flavour components of fermented sausages in the A12 group. The highest content of volatile flavour substances and amino acids, and the color and texture characteristics of fermented sausage in the experimental group at 18 h were better than those at other times. These results suggest that B. animalis A12 has the potential to be used as a starter culture for im-proving flavour and texture in fermented sausage.

Influence of Lactobacillus helveticus ZF22 and TR1-1-3 strains on the aromatic flavor of fermented sausages

In this study, five strains isolated from traditional Inner Mongolian air-dried meat products were used, two Lactobacillus helveticus strains, ZF22 and TR1-1-3, with potent antibacterial activity, acid, salt, and nitrite tolerance, were selected for this study. Lactic acid bacteria (LAB) (Lactobacillus helveticus ZF22 and TR1-1-3) were inoculated into fermented sausages at 10⁷ CFU/g and their volatiles were studied during fermentation and storage. Clustering heat map and principal component analysis (PCA) were used to identify differentiating flavor components in uninoculated and inoculated sausages. The results showed that 72 volatile flavor substances were identified during the fermentation of the fermented sausages and that inoculation with Lactobacillus helveticus ZF22 and TR1-1-3 increased the proportion of acids, ketones and alkanes. Moreover, the clustering heat map demonstrated that esters such as ethyl isobutyrate, ethyl acetate, and ethyl valerate were more abundant in TR1-1-3 and ZF22 than ZR. The PCA analysis showed that the volatile compounds of the three fermented sausages were distributed in separate quadrants, suggesting that the volatile compound compositions of the three fermented sausages differed significantly. Our findings suggest that inoculating fermented sausages with Lactobacillus helveticus TR1-1-3 and ZF22 can improve flavor by enhancing the type and amount of flavor compounds.

Effect of Starter Cultures on Quality of Fermented Sausages

The expansion and advancement of the meat product market have increased the demand for fermented sausages. A typical method for manufacturing high-quality fermented sausages is using a starter culture, which improves the taste, aroma, and texture. Currently, the starter culture for manufacturing fermented sausages is mainly composed of microorganisms such as lactic acid bacteria, yeast, and fungi, which generate volatile compounds by the oxidation of fatty acids. In addition, protein decomposition and changes in pH occur during the fermentation period. It can positively change the texture of the fermented sausage. In this review, we discuss the requirements (improving food safety, the safety of starter culture, enzyme activity, and color) of microorganisms used in starter cultures and the generation of flavor compounds (heptanal, octanal, nonanal, hexanal, 2-pentylfuran, 1-penten-3-ol, and 2-pentanone) from lipids. Furthermore, quality improvement (hardness and chewiness) due to texture changes after starter culture application during the manufacturing process are discussed.

Screening and identification of biogenic amine oxidase producing strains in Sanchuan Ham and their effect on biogenic amine accumulation

Sanchuan ham is a kind of popular fermented meat product in China. To understand the role of microorganisms in reducing the accumulation of Biogenic amine (BA) during ham fermentation. Biogenic amine oxidase-producing strains were screened and identified using color development method on double-layered plate, oxidase test, high-performance liquid chromatography (HPLC), physiological, biochemical methods, and 16 S rDNA. And then a model for simulated fermentation of Sanchuan ham was developed using the strains as single or mixed starter cultures. The results showed that two biogenic amine oxidase-producing strains were identified as Enterococcus faecium and Enterococcus faecalis from Sanchuan ham by compared to the NCBI database. And the mixed starter cultures showed a more remarkable effect on the decreased production of BA compared to single starter cultures, especially cadaverine and tyramine. The cadaverine was decreased from 92.74 ± 2.44 mg/Kg to 53.95 ± 2.69 mg/Kg and tyramine was decreased from 94.23 ± 3.42 mg/kg to 57.24 ± 3.51 mg/kg in mixed starter cultures than the control group. These results indicate exist biogenic amine oxidase-producing strains could decrease the accumulation of BA in Sanchuan ham. This study reveals important findings for improving the safety and health of Sanchuan ham and other fermented meat products.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-022-05419-y.

Improving the Flavor of Fermented Sausage by Increasing Its Bacterial Quality via Inoculation with Lactobacillus plantarum MSZ2 and Staphylococcus xylosus YCC3

This research aims to investigate the effects of Staphylococcus xylosus YCC3 (Sx YCC3) and Lactobacillus plantarum MSZ2 (Lp MSZ2) on lipid hydrolysis and oxidation, the bacterial community’s composition, and the volatile flavor compounds in fermented sausage. The bacterial community was examined by plate counting and high-throughput sequencing. Differential flavor compounds in non-inoculated and inoculated sausages were identified by principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA). The results showed that the free fatty acid (FFA) content was increased after inoculating with Sx YCC3 or Lp MSZ2. The pH, peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value, lipoxygenase activity, and the counts of Enterobacteriaceae were lower in the inoculated sausage than in the non-inoculated sausage. The bacterial inoculation enhanced the competitiveness of Staphylococcus and Lactobacillus and restricted the growth of unwanted bacteria. The OPLS-DA revealed that (Z)-hept-2-enal, (E)-2-octenal, 1-nonanal, octanal, and 1-octen-3-ol were common differential flavor compounds that were found in the inoculated sausages but were not found in the non-inoculated sausages. A positive correlation was observed between the differential flavor compounds and the relative abundance of Staphylococcus or Lactobacillus, or the FFA content. Our results indicated that inoculation with Sx YCC3 or Lp MSZ2 can improve fermented sausages’ flavor by enhancing their bacterial quality and increasing their FFA content.

Staphylococcus spp. and Lactobacillus sakei Starters with High Level of Inoculation and an Extended Fermentation Step Improve Safety of Fermented Sausages

Paio do Alentejo (PA) is one of the most popular dry-fermented sausages in Portugal. The aim of the present work was to evaluate the effect of a high concentration of starter cultures with an extended fermentation step on the safety and quality of PA. Physicochemical parameters, microbiological parameters, biogenic amines, colour, texture profile, and sensory attributes were assessed. Five starters were selected based on our previous works. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056, and a yeast strain (2RB4) were co-inoculated in meat batters at a concentration of 108 cfu/g for bacteria and 106 cfu/g for yeast strain, and 0.25% dextrose was added. Inoculated starters significantly reduced pH, Listeria monocytogenes counts, and total content in biogenic amines. The studied starter cultures did not compromise the sensory characteristics of PA, and thus, their use can be considered to protect these sausages and contribute to their safety.

Inoculation of Lactobacillus sakei on Quality Traits of Dry Fermented Sausages

In this study, fermented sausage prepared by inoculating different strains of Lactobacillus sakei was assessed for their physiochemical, microbiological, and textural characteristics during fermentation and ripening. Five treatments were prepared: Control (commercial starter culture, C), L. sakei Korean Collection for Type Cultures (KCTC)-3802 (S1), L. sakei KCTC-3598 (S2), L. sakei KCTC-5053 (S3), and L. sakei KCTC-3603 (S4). The different strains of L. sakei did not show substantial differences (P>0.05) in pH values for dry fermented sausages at the end of the ripening period. Water activity (aw) values for all treatments were below 0.85 (P<0.05). Total viable count at the end of the study decreased in all L. sakei starter culture inoculated fermented sausages as S3> S2> S1> S4. High values of lactic acid bacteria (LAB) count and hardness were observed in the S2 batch as compared to other L. sakei inoculated treatments at the end of ripening (21st day). S3 inoculated with L. sakei strain exhibited significantly (P<0.05) higher value of a* (redness). A significant difference (P<0.05) in thiobarbituric acid reactive substances was exhibited in the following order: S4> S2> S1> S3> C. This study suggests that inoculation of S3 (L. sakei KCTC-5053) strain can improve the red color and reduce lipid oxidation while S2 enhances better microbiological quality as LAB. Incorporation of S3 and S2 strains accordingly can be helpful to enhance the quality of dry fermented sausages.

Effects of Lactobacillus plantarum C7 and Staphylococcus warneri S6 on flavor quality and bacterial diversity of fermented meat rice, a traditional Chinese food

Fermented meat rice (FMR) is a traditional Chinese fermented food with special flavor and abundant microorganisms. Lactobacillus and Staphylococcus species have been found to be excellent strains in FMR during fermentation. However, their roles in FMR flavor formation remain yet to be elucidated. Here, we investigated the correlation between physicochemical properties and volatile flavor components, as well as the microbial community during FMR fermentation. First, we determined pH, total titratable acids (TTA), proteins, total lipids, organic acids, free amino acids (FAAs), and volatile flavor compounds (VFCs). With increasing fermentation time, inoculation with Lactobacillus plantarum C7+ Staphylococcus warneri S6 (LP + SW) accelerated the decrease in pH, increased TTA, and reduced protein and total lipid content of FMR. In addition, LP + SW inoculation resulted in significantly (P < 0.05) higher contents of β-eudesmol, nerolidol, ethyl caproate, citronellal, lactic acid, and most FAAs (aspartic acid, glutamic acid, alanine, and lysine) in FMR compared to natural fermentation. Second, inoculated fermentation promoted the growth of Lactobacillus plantarum and/or Staphylococcus warneri and inhibited the growth of some potentially pathogenic microorganisms such as Acinetobacter and Enhydrobacter. Lactobacillus and Staphylococcus were found to be highly correlated with the physicochemical properties and VFCs (P < 0.05) of FMR as indicated by redundancy analysis (RDA) and partial least squares (PLS, VIP > 1.0) analysis. Finally, Spearman's correlation (| r | ≥ 0.7, P < 0.05) analysis of SPSS was visualized by the Cytoscape software. The findings suggest that inoculation with L. plantarum C7 and/or S. warneri S6 can significantly improve the flavor quality of FMR.

Effect of Mixed Starters on Proteolysis and Formation of Biogenic Amines in Dry Fermented Mutton Sausages

In this study, by comparing the four groups of sausages, namely, CO (without starter culture), LB (with Lactobacillus sakei), LS (with L. sakei 3X-2B + Staphylococcus xylosus SZ-8), and LSS (with L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2), the effects of mixed starter cultures on physical-chemical quality, proteolysis, and biogenic amines (BAs) during fermentation and ripening were investigated. Inoculation of the mixed starter cultures increased the number of lactic acid bacteria and staphylococci in sausages during fermentation and ripening for 0 to 5 days. The L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2 mixed starter accelerated the rate of acid production and water activity reduction of sausages and improved the redness value. Compared with CO, the mixed starter effectively inhibited Enterobacteriaceae. At the end of ripening, the LSS group was approximately 1.25 CFU/g, which was less than the CO group, thereby reducing the total volatile basic nitrogen (TVB-N) in the LSS group. The free amino acids in the LS and LSS groups (224.97 and 235.53 mg/kg dry sausage, respectively) were significantly (p < 0.001) higher than that in the CO group (170.93 mg/kg dry sausage). The level of histamine, cadaverine, putrescine, and common BAs showed an opposite trend to the increase of the corresponding precursor amino acid content, which were significantly lower (p < 0.001) in the LS and LSS sausages than in CO. This study showed that L. sakei 3X-2B + S. xylosus SZ-8 + S. carnosus SZ-2 is a potential mixed starter for fermented meat products.

Incorporation of Selected Strains of Pediococcus spp. on Quality Characteristics of Dry Fermented Sausage during Fermentation and Ripening

This research investigated the physio-chemical and microbial quality characteristics of dry fermented sausage from selected Pediococcus strains: P. acidiliactici (PE1) and P. pentosaceus (PE2) as compared to commercial starter culture (COS) during fermentation and ripening. Treatments showed no substantial variation (p<0.05) in water activity (a_w) values across the study period. PE1 and PE2 treatments exhibited similar (p>0.05) pH values and presented remarkable (p<0.05) lower volatile basic nitrogen (VBN) and thiobarbituric acid reactive (TBARS) content than COS treatment throughout the ripening period. However, the pH values in COS batch were considerably lower than others. PE1 samples presented a significant highest (p<0.05) counts both in lactic acid bacteria (LAB) and total plate count (TPC) than COS and PE2 treatments at 7 days fermentation, and it resulted in a similar and higher TPC count as COS after the ripening period. After the ripening process, treatments are ordered based on LAB counts as follows: COS>PE1>PE2. All batches presented similar redness and yellowness attributes since the 7 days of fermentation and in lightness across the study period. Treatments were similar (p>0.05) in springiness and chewiness traits across the study period and in hardness characteristics in the ripened products. Cohesiveness was higher in PE1 and COS batches. No variation (p>0.05) in aroma and sourness sensory attributes of treatments. The color attribute was highest (p<0.05) in PE1 and PE2 treatments and PE1 had the highest overall acceptability. The overall outstanding merit exhibited by PE1 can be utilized in the commercial production of high-quality dry fermented sausage.

Effect of Different Pediococcus pentosaceus and Lactobacillus plantarum Strains on Quality Characteristics of Dry Fermented Sausage after Completion of Ripening Period

The aim of this study was to evaluate the effect of three different strains of lactic acid bacteria (LAB) starter cultures: Pediococcus pentosaceus (KC-13100) (PP), Lactobacillus plantarum (KCTC-21004) (LP1), and L. plantarum (KCTC-13093) (LP2) on the physicochemical and microbiological characteristics, and sensory quality of dry fermented sausages after 21 days of drying and ripening period. Treatments added with PP and LP2 strains showed a significant higher (p<0.05) LAB and total plat counts, and water activity (a_w) of all three treatments was below 0.85 after the completion of the ripening process. A significant variation (p<0.05) in pH values of treatments was exhibited due to the difference in acidification capacity of the LAB strains: LP2<PP<LP1. Treatments had significant difference (p<0.05) in the thiobarbituric acid reactive substances (TBARS) content, in the following order: LP1>PP>LP2. Substantial variations (p<0.05) in shear force values were detected amongst three batches (LP2>LP1>PP). In sensory attributes, PP treated samples had significantly higher (p<0.05) color and overall acceptability scores. The current findings proved how important the optimal assortment of starter culture. Inoculation with PP produced importantly beneficial effects on sensory quality improvement of dry fermented sausage.

Co-Inoculation with Staphylococcus equorum and Lactobacillus sakei Reduces Vasoactive Biogenic Amines in Traditional Dry-Cured Sausages

Dry-cured sausages are traditional in Mediterranean countries, and Paio do Alentejo (PA) is one of the most popular in South Portugal. The aim of the present work was to evaluate the effect of combined starters on the safety and quality of PA preserving its sensory quality. Physicochemical parameters, namely pH and water activity (aW), microbiological parameters, biogenic amines, color, texture, and sensory attributes were assessed. Three starter cultures were used, namely Staphylococcus equorum S2M7 and Lactobacillus sakei CV3C2, both separate and combined with the 2RB4 yeast strain at a concentration of 106 cfu/g. Dextrose 0.25% was added to the meat batter. Starters had a significant effect on the reduction of aW values (0.845 to 0.823). The treatment with L. sakei as well as the co-inoculation of L. sakei with S. equorum effectively reduced the L. monocytogenes counts to undetectable levels. Sausages co-inoculated with S. equorum S2M7/L. sakei CV3C2 showed a significant reduction in the content of vasoactive amines, namely tryptamine (26.21 to 15.70) and β-phenylethylamine (4.80 to 3.69). Regarding texture, control PA showed higher hardness values, and the starters promoted the cohesiveness of the batter while reducing chewiness. The studied starters did not compromise the sensory characteristics of PA.

Screening and optimization of a nitrate reductase-producing Staphylococcus simulans UV-11 and its application

A strain of Staphylococcus simulans D14 (S. simulans D14) showed the highest nitrate reductase activity (NRA) of 4.52 mM NO₂⁻/mg dry weight by the spectrophotometric method, which was screened from traditional Chinese sausage. When the UV mutagenesis time was 25 s, the positive mutation rate was the highest at 26.60%. The NRA of the obtained positive mutant UV-11 was 9.21 mM NO₂⁻/mg dry weight, and the activity was found to be 1.04-fold higher than that of the original strain S. simulans D14. A Plackett–Burman design (PBD) was employed to screen the significant variables pH, KNO₃ (%) and incubation time (h), and response surface methodology (RSM) was used to optimize the significant variables using a Box–Behnken design (BBD). The results showed that the NRA of S. simulans UV-11 was 15.22 mM NO₂⁻/mg dry weight under optimum conditions of 37 °C, pH 6.5, incubation time 15 h, KNO₃ 0.045%, NaCl 5%, NaNO₂ 0.015%, peptone 1%, and D–mannitol 1%, which increased by 65.2% compared with the unoptimized medium. Natural curing agents (containing 10⁷ CFU/g S. simulans UV-11 under optimal conditions and 1.40% celery powder, T2) were added to the cured meat model. T2 produced significantly lighter and redder signals than the control group (C) and the addition of 150 ppm NaNO₂ group (T1). The thiobarbituric acid reactive substance (TBARS) of T2 was 2.30 mg malonaldehyde/kg product and residual nitrite of T2 was 7.1 ppm after 14 days of storage,which were lower than those groups of C and T1. Taking into account the results of cured meat models, S. simulans UV-11 could be selected as a potential starter culture for the processing of natural meat products.

Antimicrobial and Preservative Effects of the Combinations of Nisin, Tea Polyphenols, Rosemary Extract, and Chitosan on Pasteurized Chicken Sausage

ABSTRACT

This study was conducted to evaluate the antimicrobial and preservative effects of the combinations of nisin (NS), tea polyphenols (TP), rosemary extract (RE), and chitosan (CS) on pasteurized chicken sausage. An orthogonal test revealed that the most effective preservative was a mixture of 0.05% NS plus 0.05% TP plus 0.03% RE plus 0.55% CS (weight by sausage weight). This mixture had antimicrobial and antioxidant effects in pasteurized chicken sausage and extended the shelf life to >30 days at 4°C. The inhibitory effects of NS, TP, RE, and CS were also evaluated against Pseudomonas aeruginosa, lactic acid bacteria (LAB), and Staphylococcus aureus, the dominant spoilage and pathogenic bacteria in pasteurized chicken sausage. NS had the greatest inhibitory effect on LAB and S. aureus, with inhibitory zone diameters of 19.7 and 17.8 mm, respectively. TP had the largest inhibitory effect on P. aeruginosa, with a clear zone diameter of 18.2 mm. These results indicate that the combination of NS, TP, RE, and CS could be used as a natural preservative to efficiently inhibit the growth of microorganisms in pasteurized chicken sausage and improve its safety and shelf life.

HIGHLIGHTS

Biochemical Changes during the Manufacture of Galician Chorizo Sausage as Affected by the Addition of Autochthonous Starter Cultures

In this work, the effect of the use of two autochthonous starter cultures (Lactobacillus sakei LS131 + Staphylococcus equorum SA25 (EQU), or L. sakei LS131 + Staphylococcus saprophyticus SB12 (SAP)) on the physicochemical, microbiological, proteolytic and lipolytic changes taking place during the manufacture of Galician chorizo, a traditional Spanish sausage, was studied. Three different batches (control (CNT), EQU and SAP) were manufactured in triplicate and analysed during the manufacturing process (samples were taken and analysed at 0, 2, 5, 9, 14, 21 and 30 days of ripening) for proximate composition, pH, aw, colour parameters, nitrogen fractions, free amino acids, biogenic amines, fat parameters and free fatty acids. The use of either of these two starter cultures slightly but significantly reduced the pH values during the fermentation and increased the percentage of transformation to nitrosyl-heme pigments as well as the a* and b* values in the final products. The two starters significantly decreased the Enterobacteriaceae counts in the final product, but without this microbial group completely disappearing. Both starter cultures significantly increased the α-amino acidic nitrogen and the total basic volatile nitrogen fractions during manufacturing, also increasing the free amino acid content and reducing the total biogenic amine content by approximately 20%. The SAP starter enhanced the lipolytic processes, increasing the free fatty acid content. Due to their performances, these two starter cultures seem to be suitable for increasing the quality and safety of the Galician chorizo sausage.

Application of isolated Lactobacillus sakei and Staphylococcus xylosus strains as a probiotic starter culture during the industrial manufacture of Tunisian dry-fermented sausages

For decades, lactic acid bacteria has been isolated and selected to be used as starter cultures in meat fermentation for standardization and management of quality of dry-fermented sausage which constitute a considerable challenge. The aim of this study was to evaluate the effect of Lactobacillus sakei strains, isolated from different origins, on qualities of dry-fermented sausages. These last, manufactured with different combinations of starter cultures (L. sakei + Staphylococcus xylosus), were ripened, using the same raw materials and conditions, for 45 days. Samples were collected during this period, and microbiological, physicochemical, fatty acid profile, and sensorial analyses determined. Lactic acid bacteria were the dominant flora during ripening. A desirable PUFA/SFA ratio, corresponding to 1:1.7 (0.6), was detected after 24 days of maturation in sausages inoculated by L. sakei BMG 95 and S. xylosus. Sensory analysis showed that fermented sausages manufactured with L. sakei and S. xylosus had a more desirable odor, flavor, and texture and consequently were preferred overall. In particular, sensory panellists preferred sausages produced with either L. sakei 23K or L. sakei BMG 95 when compared to fermented sausage produced with a commercial starter or no starter at all.

Factors affecting the viability of Staphylococcus aureus and production of enterotoxin during processing and storage of white-brined cheese

Staphylococcus aureus is a major foodborne pathogen that causes severe disease in humans. It is commonly found in milk and dairy products, particularly in fresh brined cheese. Our aim was to investigate the behavior of Staph. aureus and enterotoxin production during the storage of white-brined cheese prepared with or without a starter culture and stored in a 10 or 15% NaCl brine at 10°C and 25°C for 28 d. NaCl concentration, water activity, pH, and number of Staph. aureus and lactic acid bacteria were determined in cheese and brine. Only 1 of 4 Staph. aureus strains (ATCC 439) was positive for enterotoxin production, and its production was detected in unsalted UHT milk, but not in salted milk or in any of the cheese treatments held at 37°C for 1, 3, or 7 d. Staphylococcus aureus grew in the cheese stored in both brines at 10°C and 25°C, regardless of the presence of a starter culture, although the latter significantly reduced Staph. aureus growth in cheese or its brine at 10°C. Staphylococcus aureus numbers were increased by 2.26 and 0.47 log₁₀ cfu/g in cheese stored in 10 and 15% NaCl brine, respectively, in the presence of starter culture, and by 2.78 and 2.96 log₁₀ cfu/g, respectively, in the absence of starter culture at 10°C. Nonetheless, the pathogen grew, but at a lower number in the brines. The salt concentration of cheese stored in 10% brine remained at approximately 5% during storage; however, in 15% brine, the salt concentration increased to almost 8% (wt/wt) by 28 d. The addition of a starter culture, high salt concentration, low temperature, and pH (∼5.2) had inhibitory effects on the growth of Staph. aureus. Moreover, lactic acid bacterial numbers increased considerably in cheese and brine by d 28. The use of starter cultures, salt (15%), and low storage temperature (10°C) reduced the growth of Staph. aureus, and salt may have prevented enterotoxin production in white-brined cheese.

Improvement of oxidative stability and textural properties of fermented sausage via addition of pistachio hull extract

The purpose of this study was to evaluate the effectiveness of pistachio hull extract (PHE) as an antioxidant and antimicrobial agent for preservation of dry fermented sausages during fermentation and storage period. Sausages were prepared using starter culture (Biobak K) and treated with three levels of PHE (500, 750 and 1,000 ppm). The results showed that PHE at concentrations of 500 ppm and 750 ppm decreased significantly (p < .05) the TBARS content of the sausage samples compared to control (without PHE). Moreover, PHE increased L* and a* value of samples during fermentation period but did not affect the color of samples during storage period. The PHE was also able to improve the chewiness and gumminess of the fermented sausage. Evaluation of microbial properties (total viable count, yeast and molds, lactic acid bacteria, staphylococci and Enterobacteriaceae) also showed that antimicrobial activity of PHE in fermented sausage.

Autochthonous Starter Cultures Are Able to Reduce Biogenic Amines in a Traditional Portuguese Smoked Fermented Sausage

Traditional smoked fermented sausages are highly appreciated in Portugal and are mostly manufactured according to traditional procedures. The aim of the present work was to evaluate the effect of autochthonous starter cultures on the safety and quality of a smoked fermented sausage, Painho da Beira Baixa (PBB), preserving its sensory quality. Physicochemical parameters, namely pH and water activity (a_W), microbiological parameters, biogenic amines, colour, texture profile and sensory attributes were assessed. Different starters were selected based on our previous work. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056 and a yeast strain (2RB4) were co-inoculated in meat batters at defined concentrations. Starters had a significant effect on the reduction of pH. Enterobacteria and Listeria monocytogenes were not detected in inoculated end-product sausages. Moreover, sausages inoculated with S. equorum S2M7/L. sakei CV3C2/yeast 2RB4 showed a significant reduction in the total content of biogenic amines. No significant differences between treatments were observed for colour and texture parameters, except for adhesiveness. The studied starters did not compromise the sensory characteristics of PBB. To our knowledge, this is the first comprehensive study on the quality and safety of this type of smoked fermented sausage from the central region of Portugal.

Effect of Lactobacillus plantarum and Staphylococcus xylosus on flavour development and bacterial communities in Chinese dry fermented sausages

The use of starter cultures helps to improve the quality and safety of traditional meat products. In this study, the effects of Lactobacillus plantarum R2 and Staphylococcus xylosus A2 inoculation on microbial community, lipolysis, proteolysis, and volatile compounds in Chinese dry fermented sausages were investigated. Culture-dependent and culture-independent high-throughput sequencing) methods were employed to evaluate the bacterial communities. Results showed that the total contents of free fatty acids (FFAs) and free amino acids (FAAs) were increased by inoculating the starter cultures, especially a mixed culture. A significant decrease in pH and water activity was observed in the inoculated sausages (p < 0.05). Moreover, the inoculation treatment enhanced the competitiveness of dominant bacteria and inhibited the growth of unwanted bacteria. This was beneficial to promote the release of FFAs and FAAs and to prevent the formation of off-flavours and rancidity. Thus, the flavour development in the inoculated dry fermented sausages was attributed to the improvements in microbiological quality.

Use of pomegranate peel and artichoke leaf extracts to improve the quality of marinated sardine (Sardinella aurita) fillets

Effects of pomegranate peel and artichoke leaf aqueous extracts on biochemical, microbiological and sensorial quality of sardine fillets was investigated during marination and storage for 90 days. Sardine fillets were marinated with 4% acetic acid, 10% NaCl and either 5% pomegranate peel extracts or 5% artichoke leaf extracts. The control sample was marinated with only 4% acetic acid and 10% NaCl. The antimicrobial activity of pomegranate peel and artichoke leaf extracts led to reduce total viable counts and total coliform during marination and storage. Samples marinated with pomegranate peel and artichoke leaves showed better oxidative stability and higher content of polyunsaturated fatty acids. Higher values of free fatty acids and histamine were found in control samples, whereas adding extracts of pomegranate peel or artichoke leaves significantly decreased total volatile basic nitrogen and trimethylamine during storage. Greater color and appearance scores were found for samples marinated with pomegranate peel and artichoke leaf extracts than the control samples.

Impact of fructooligosaccharides and probiotic strains on the quality parameters of low-fat Spanish Salchichón

The substitution of dietary fiber and probiotic strains to reduce fat content of fermented sausages has been used for the development of innovative and healthier meat products. For this study, pork back fat was partially replaced by fructooligosaccharides (FOS) and the probiotic strains Lactobacillus paracasei and Lactobacillus rhamanosus. The fat replacement resulted in a significant decrease (P ≤ .05) in fat content (29%) compared with the control formulation (no fat substitution). The addition of FOS did not have a significant effect on microbial counts; however, reductions in Enterobacteriaceae and yeast were observed when Lactobacillus strains were also incorporated. The inclusion of FOS and probiotic strains did not show any significant effect on lipid oxidation and proteolysis. The partial fat replacement and the addition of Lactobacillus rhamanosus GG as probiotic strain in Spanish Salchichón can be considered a successful reformulation strategy for the meat product market.

Unraveling microbial community diversity and succession of Chinese Sichuan sausages during spontaneous fermentation by high-throughput sequencing

The microbial community diversity and succession of Chinese Sichuan sausages during the spontaneous fermentation were demonstrated using high-throughput sequencing technology. The bacterial diversity was abundant and the succession of bacterial community along the direction of Lactobacillus spp. increased and Weissella spp. decreased. While fungal diversity was single and trace fungal population was detected. The core functional microbiota were lactic acid bacteria, including Lactobacillus spp., Weissella spp. and Pediococcus spp. In initial fermentation, Weissella spp. was the dominant bacteria and its relative abundance was 49.84%, but then its relative abundance decreased to 11.96% during fermentation before recovering to 26.74% at the end of fermentation. Meanwhile, Lactobacillus spp. rose from 24.70 to 55.74% and became the dominant genus. Moreover, Pediococcus spp. increased from 0.06 to 18.05% on day 20 but then decreased to 1.89% on day 30. These results revealed that the primary microorganisms contributing to spontaneous fermentation of Chinese Sichuan sausages were bacteria, while eukaryotic microorganisms such as yeast scarcely contributed to fermentation.