Two efficient nitrite-reducing Lactobacillus strains isolated from traditional fermented pork (Nanx Wudl) as competitive starter cultures for Chinese fermented dry sausage

Enhancement of fermented sausage quality driven by mixed starter cultures: Elucidating the perspective of flavor profile and microbial communities

The metabolic activities of microorganisms play a crucial role in the quality development of fermented sausage. This study investigated the effect of inoculation with different combinations of starter cultures (Lactiplantibacillus plantarum YR07, Latilactobacillus sakei L.48, Staphylococcus xylosus S.14, and Mammaliicoccus sciuri S.18) on the quality of sausages. Inoculation with mixed starter cultures promoted protein degradation to generate amino acids and the conversion to volatile compounds, which enhanced the flavor development in fermented sausages. The bacterial community analyses demonstrated that the inoculation of mixed starter cultures could inhibit the growth of spoilage and pathogenic bacteria, thereby reducing the total content of biogenic amines. The correlation analysis between the core bacteria and characteristic volatile compounds revealed that fermented sausages inoculated with Lactobacillus and coagulase negative staphylococci exhibited significant positive correlations with the majority of key characteristic volatile compounds. In four treatments, inoculation with L. plantarum YR07 and M. sciuri S.18 greatly promoted the formation of characteristic volatile compounds (3-hydroxy-2-butanone, hexanal, and 1- octen-3ol). Therefore, the combined inoculation of L. plantarum YR07 and M. sciuri S.18 is promising to enhance fermented sausage's flavor profile and safety.

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.

Microbiota Succession and Chemical Composition Involved in Lactic Acid Bacteria-Fermented Pickles

Pickles are a type of traditional fermented vegetables in China. To ascertain the effect of different lactic acid bacteria on pickles, the chemical composition characteristics, flavor substances, and bacterial diversity of the pickles fermented by natural bacteria, Lactobacillus plantarum R5, Lactobacillus pentosus R8, and L. plantarum R5 plus L. pentosus R8 were investigated in this study. The results showed that Lactobacillus enhanced the decrease in pH, increase in total acid content, degradation of nitrite, and production of organic acid (lactic acid and malic acid) of fermented pickles. A total of 80 flavors were detected in the pickles fermented for 14 days, and esters in pickles fermented by Lactobacillus were more plentiful. Firmicutes emerged as the predominant microbial phyla. Amongst these, the commonly encountered microorganisms were Lactobacillus, unclassified Enterobacteriaceae, Pantoea, and Weissella. The multivariate statistical analysis further showed that Lactobacillus had a strong negative correlation with pH and a strong positive correlation with malic acid and lactic acid, and the microorganisms in pickles could acclimate to the changing fermentation environment. The insights gained from this study may be of assistance to us in obtaining new insights into the microbiota succession and chemical compounds involved in the pickles fermented by Lactobacillus.

Combined Effect of Acid Whey Addition and Ultrasonic Treatment on the Chemical and Microbiological Stability of Lamb Stuffing

The microbiological and chemical stability of stuffing is crucial in meat processing. Small ruminant (lamb) meat has many nutritional advantages (fatty acid composition and ratio, high biological value of protein, source of zinc, and selenium) but is poorly utilized in processing. In this experiment, we determined the effects of physical (sonication), chemical (salt, curing salt, and air access), and microbiological (acid whey) factors on the microbiological and chemical stability of lamb meat stuffing. Proximate composition and fatty acids profile, pH, water activity, lipid oxidation, color parameters, and microbiology examinations were performed in fresh meat stuffing and on the fifth day of refrigerated storage. Ultrasound treatment of the meat with whey reduced its acidity and increased the oxidative stability of fats but did not modify the water activity and color of the stuffing. Stuffing sonication did not affect the growth of LAB but reduced the number of Entereobacteriace, especially in the presence of whey and salt. The treatment of lamb meat stuffing with low-frequency and medium-intensity ultrasound assisted by the addition of acid whey and salt is a technique conducive to reducing the use of nitrates in meat technology and their consumption by consumers.

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.

Applicability of the probiotic Lactiplantibacillus plantarum BFL as an adjunct culture in a dry fermented sausage

The addition of probiotic bacteria to a meat batter allows the development of functional fermented sausages. The aim of this work was to study the effect of microencapsulated Lactiplantibacillus plantarum BFL (EP) and as free cells (FP) on microbiological, physicochemical, and sensory parameters of fermented sausages during the drying stage and on the product ready for consumption. The microencapsulation of L. plantarum BFL did not improve its viability during the drying stage. In addition, sausages inoculated with L. plantarum BFL (FP and EP) caused lower residual nitrites values, pH values and Escherichia coli counts than the Control (C). However, only the presence of free cells of L. plantarum BFL (FP) caused a decrease in the Enterobacteriaceae and mannitol salt-positive Staphylococcus counts. In the sensory analysis, no significant differences were found in the acceptability of the different sausages. However, the acidity in probiotic sausages (FP and EP) was an attribute that consumers highlighted. The probiotic L. plantarum BFL could adapt and survive at high doses in the matrix of an industrial fermented sausage. Therefore, its use could represent a strategy both for biocontrol of pathogens and for the development of functional meat products.

A Review on the Role of Lactic Acid Bacteria in the Formation and Reduction of Volatile Nitrosamines in Fermented Sausages

Nitrosamines are N-nitroso compounds with carcinogenic, mutagenic and teratogenic properties. These compounds could be found at certain levels in fermented sausages. Fermented sausages are considered to be a suitable environment for nitrosamine formation due to acid formation and reactions such as proteolysis and lipolysis during ripening. However, lactic acid bacteria (spontaneous or starter culture), which constitute the dominant microbiota, contribute significantly to nitrosamine reduction by reducing the amount of residual nitrite through nitrite degradation, and pH decrease has an important effect on the residual nitrite amount as well. These bacteria also play an indirect role in nitrosamine reduction by suppressing the growth of bacteria that form precursors such as biogenic amines. In recent years, research interest has focused on the degradation or metabolization of nitrosamines by lactic acid bacteria. The mechanism by which these effects are seen has not been fully understood yet. In this study, the roles of lactic acid bacteria on nitrosamine formation and their indirect or direct effects on reduction of volatile nitrosamines are discussed.

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.

Investigating the effect on biogenic amines, nitrite, and N-nitrosamine degradation in cultured sausage ripening through inoculation of Staphylococcus xylosus and lactic acid bacteria

Introduction

Microbial inoculants can reinvent the value and edible security of cultured sausages. Various studies have demonstrated that starter cultures made up of Lactic acid bacteria (LAB) and Staphylococcus xylosus (known as L-S) isolated from traditional fermented foods were used in fermented sausage manufacturing.

Methods

This study evaluated the impact of the mixed inoculation cultures on limiting biogenic amines, nitrite depletion, N-nitrosamine reduction, and quality metrics. Inoculation of sausages with the commercial starter culture (SBM-52) was evaluated for comparison.

Results and discussion

Results showed that the L-S strains could rapidly decrease the water activity (Aw) and pH of fermented sausages. The ability of the L-S strains to delay lipid oxidation was equivalent to the SBM-52 strains. The non-protein nitrogen (NPN) contents of L-S-inoculated sausages (0.31%) were higher than that of SBM-52-inoculated sausages (0.28%). After the ripening process, the nitrite residues in the L-S sausages were 1.47 mg/kg lower than in the SBM-52 sausages. Compared to the SBM-52 sausages, there was a 4.88 mg/kg reduction in the biogenic amines' concentrations in L-S sausage, especially for histamine and phenylethylamine concentrations. The N-nitrosamine accumulations of the L-S sausages (3.40 ug/kg) were lower than that of the SBM-52 sausages (3.70 ug/kg), and the NDPhA accumulations of the L-S sausages were 0.64 ug/kg lower than that of the SBM-52 sausages. Due to their significant contributions to nitrite depletion, biogenic amine reduction, and N-nitrosamine depletion in fermented sausages, the L-S strains have the potential to serve as an initial inoculant in the process of manufacturing fermented sausages.

Nitrite and nitrate in meat processing: Functions and alternatives

Meat and meat products are important foods in the human diet, but there are concerns about their quality and safety. The discovery of carcinogenic and genotoxic N-nitroso compounds (NOCs) in processed meat products has had serious negative impacts on the meat industry. In order to clarify the relationship between the use of nitrite or nitrate and the safety of meat or meat products, we reviewed NOCs in meat and meat products, the origin and safety implications of NOCs, effects of nitrite and nitrate on meat quality, national regulations, recent publications concerning the using of nitrite and nitrate in meat or meat products, and reduction methods. By comparing and analyzing references, (1) we found antioxidant, flavor improvement and shelf-life extension effects were recently proposed functions of nitrite and nitrate on meat quality, (2) the multiple functions of nitrite and nitrate in meat and meat products couldn't be fully replaced by other food additives at present, (3) we observed that the residual nitrite in raw meat and fried meat products was not well monitored, (4) alternative additives seem to be the most successful methods of replacing nitrite in meat processing, currently. The health risks of consuming processed meat products should be further evaluated, and more effective methods or additives for replacing nitrite or nitrate are needed.

Microbiological Composition and Sensory Characterization Analysis of Fermented Sausage Using Strains Isolated from Korean Fermented Foods

This study aimed to analyze the microbiological composition and sensory characterization of fermented sausage using strains isolated from Kimchi (GK1, Pediococcus pentosaceus SMFM2016-GK1; NK3, P. pentosaceus SMFM2016-NK3), Doenjang (D1, Debaryomyces hansenii SMFM2021-D1), and spontaneously fermented sausage (S8, D. hansenii SMFM2021-S8; S6, Penicillium nalgiovense SMFM2021-S6). The control was commercial starter culture. Nine treatments were applied [GD (GK1+D1), GS (GK1+S8), GDS (GK1+D1+S8), ND (NK3+D1), NS (NK3+S8), NDS (NK3+D1+S8), GND (GK1+NK3+D1), GNS (GK1+NK3+S8), and GNDS (GK1+NK3+D1+S8)] by mixing lactic acid bacteria and yeast, and S6 was sprayed. The microbial composition of fermented sausage was analyzed [aerobic bacteria (AC), Lactobacillus spp. (LABC), Staphylococcus spp. (STPC), and yeast and mold (YMC)], and pH and electronic nose and tongue measurements were taken. The AC, LABC, STPC, and YMC values of the control and treatment groups tended to increase during fermentation (p>0.05). The STPC values of the GD, GS, ND, and GDS groups were similar to that of the control on day 3. The pH of the control on day 3 was significantly lower than that of the GD, ND, and GND groups (p<0.05). Higher levels of 4-methylpentanol, 2-furanmethanol, and propyl nonanoate, which provide a "fermented" flavor, were detected in the GD group compared to in the control and other treatment groups. GD and ND groups showed higher umami values than the control and other treatment groups. Therefore, it is expected that GD can be valuable as a starter culture unique to Korea when manufacturing fermented sausage.

Development of Healthier and Functional Dry Fermented Sausages: Present and Future

In recent years, consumer perception about the healthiness of meat products has changed. In this scenario, the meat industry and the scientific and technological areas have put their efforts into improving meat products and achieving healthier and functional formulations that meet the demands of today’s market and consumers. This article aims to review the current functional fermented meat products, especially on sausage development. Firstly, an emphasis is given to reducing and replacing traditional ingredients associated with increased risk to consumer’s health (sodium, fat, and nitrites), adding functional components (prebiotics, probiotics, symbiotics, and polyphenols), and inducing health benefits. Secondly, a look at future fermented sausages is provided by mentioning emerging strategies to produce innovative healthier and functional meat products. Additional recommendations were also included to assist researchers in further development of healthier and functional sausages.

The investigation on the characteristic metabolites of Lactobacillus plantarum RLL68 during fermentation of beverage from by-products of black tea manufacture

At present, lactic acid bacteria (LAB) fermentation is commonly considered as an effective strategy to remarkably drive the improvement of flavor and nutritional value, and extend shelf-life of fermented foods. In this study, the by-product of tea manufacture, including broken tea segments and tea stalk, was used to produce fermented tea beverages. In addition, the residual components of matrices and bacterial metabolites were measured, as well as the sensory quality of the beverage was evaluated. Subsequently, the determination of monosaccharides, volatile aroma profile, free amino acids, biogenic amines and organic acids, and several functional substances involving γ-aminobutyric acid (GABA), polyphenols, caffeine and L-theanine were carried out. The results revealed that glucose, fructose, mannose and xylose are principal carbon source of Lactobacillus plantarum RLL68 during the fermentation; moreover, the abundance of aromatic substances is varied dramatically and the characteristic flavors of the beverages, particularly fermentation for 48 h and 72 h, are imparted with sweet and fruity odor on the basis of initial nutty and floral odor; Meanwhile, the organoleptic qualities of fermented beverages is also enhanced. Furthermore, the levels of organic acids and GABA are elevated, while the bitter amino acids, as well as some bioactive substances including tea polyphenols and L-theanine are declined; Besides, the caffeine level almost remains constant, and quite low levels of various biogenic amines are also observed. The results of this study will provide the theoretical basis to steer and control the flavor and quality of the fermented tea beverages in the future.

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The dynamic variation of characteristic metabolites of the beverage was elucidated.

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The characteristic flavors changed from nutty and floral to sweet and fruity.

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L. plantarum fermentation bring both beneficial and adverse impacts.

The Influence of Acid Whey on the Lipid Composition and Oxidative Stability of Organic Uncured Fermented Bacon after Production and during Chilling Storage

The aim of this research was to evaluate the effect of acid whey on changes in the fatty acid profile, oxidative stability, physico-chemical parameters, and microbiological and sensory quality of traditional organic uncured fermented Polish bacon after production and during chilling storage. Three different treatments of fermented bacon were produced: C—control bacon with a nitrite curing mixture; T—bacon with a nitrate curing mixture; and AW—bacon with acid whey and NaCl. The acid whey used in the production of uncured fermented pork bacon positively changed the sensorial characteristics, directly after the ripening process, and had a positive effect in terms of a decrease in the pH of the product. All of the fermented bacon treatments in general were of good microbiological quality. A higher lactic acid bacteria (LAB) level was observed in the AW treatment after the fermentation process, and the bacteria number did not change during storage, whereas in the C and T treatments, the LAB level increased during storage (p < 0.05). The application of acid whey did not limit the formation of secondary oxidation products (TBARS) during bacon ripening (1.68 mg MDA kg⁻¹), but had a reduced value during storage time (0.73 mg MDA kg⁻¹). The highest polyunsaturated fatty acid (PUFA) levels, after ripening and after four weeks of refrigerated storage, were found in the C treatment. In the AW treatment, it was found that the PUFA level increased; likewise, the content of n-3 and n-6 fatty acids increased, while saturated fatty acids (SFAs) decreased during storage (p < 0.05). The opposite tendency was observed in the C treatment. After four weeks of storage, the PUFA/SFA ratio was the lowest in the nitrate treatment, and higher values of the PUFA/SFA ratio were obtained in the acid whey and nitrite treatment (p < 0.05).

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

This study investigated the positive effects of complete replacement of nitrite with a Lactobacillus fermentum on the quality and safety of Chinese fermented sausages, and evaluated the risk of this strain. The effects of the strain on pH, color, nitrite, thiobarbituric acid reactive substances (TBARS), total volatile basenitrogen (TVB-N), metmyoglobin (Met-Mb), biological amines, free amino acid content, and sensory index have been studied. The results revealed that the strain reduced the pH of the sausages, which reduced the risk of food-borne pathogens, and accelerated the acidification and gelation process. The inoculation of the strain produced pink color similar to 50 mg/kg nitrite, significantly reducing the residual risk of nitrite in the sausages. In addition, the strain effectively improved quality and nutrition of the sausages through preventing fat oxidation, protein decomposition, and myoglobin oxidation and increasing free amino acid content. The harmful biogenic amines species of the treated sample were reduced, although the tyramine contents were higher than the control, and the contents of the two groups were all far below the specified limit (800 mg/kg). The sensory analysis showed that the strain enhanced the taste, flavor, sourness, and overall acceptability of the sample sausages. Therefore, replacing nitrite completely with the strain L. fermentum could be a potential strategy to produce healthier and safer acceptable sausages through decreasing the risk of nitrite and improving nutrition and quality of the sausages.

Effect of Lactobacillus plantarum on antioxidant activity in fermented sausage

This study investigated in vitro antioxidant activity of Lactobacillus plantarum CD101 and its effect on antioxidant peptides formation in fermented sausage. The antioxidant substances of L. plantarum CD101 were mainly distributed on the cell surface and extracellular secretions. L. plantarum CD101 affected the acidification and proteolysis during the fermentation. Combined with electrophoresis and peptide content analysis, these results indicated the effectiveness of the starters in promoting peptide formation, accompanied by a small change in antioxidant activities. Forty-four effective peptides were identified by LC-MS/MS. The masses of the peptides were less than 3 kDa, and their amino acid sequences were between 5 and 27 amino acids in length. Thus, L. plantarum CD101 may be beneficial to inhibit the oxidative rancidity of fermented sausage through its in vitro antioxidant activity, while effectively promoting protein degradation with a weak effect on antioxidant peptides promotion.

Use of Starter Cultures in Foods from Animal Origin to Improve Their Safety

Starter cultures can be defined as preparations with a large number of cells that include a single type or a mixture of two or more microorganisms that are added to foods in order to take advantage of the compounds or products derived from their metabolism or enzymatic activity. In foods from animal origin, starter cultures are widely used in the dairy industry for cheese, yogurt and other fermented dairy products, in the meat industry, mainly for sausage manufacture, and in the fishery industry for fermented fish products. Usually, microorganisms selected as starter culture are isolated from the native microbiota of traditional products since they are well adapted to the environmental conditions of food processing and are responsible to confer specific appearance, texture, aroma and flavour characteristics. The main function of starter cultures used in food from animal origin, mainly represented by lactic acid bacteria, consists in the rapid production of lactic acid, which causes a reduction in pH, inhibiting the growth of pathogenic and spoilage microorganisms, increasing the shelf-life of fermented foods. Also, production of other metabolites (e.g., lactic acid, acetic acid, propionic acid, benzoic acid, hydrogen peroxide or bacteriocins) improves the safety of foods. Since starter cultures have become the predominant microbiota, it allows food processors to control the fermentation processes, excluding the undesirable flora and decreasing hygienic and manufacturing risks due to deficiencies of microbial origin. Also, stater cultures play an important role in the chemical safety of fermented foods by reduction of biogenic amine and polycyclic aromatic hydrocarbons contents. The present review discusses how starter cultures contribute to improve the microbiological and chemical safety in products of animal origin, namely meat, dairy and fishery products.

Indigenous Microbiota to Leverage Traditional Dry Sausage Production

The main issue addressed in this review is the need for innovation in the artisanal production of dry fermented sausages—leveraging rather than discarding tradition, together with some practical strategies available to achieve it. Throughout the text, emphasis is placed on the autochthonous microbiota responsible for the identity and unique sensory characteristics of these products. The available strategies to introduce innovation in this manufacturing process rely on metabolic flexibility of microbial strains. In this sense, this review evaluates the application of several tools aimed at improving the quality and safety of artisanal dry fermented sausages focusing on the microbial community role. The most studied alternatives to enhance dry sausage production comprise the use of autochthonous starter cultures—including functional and/or probiotic strains, the production of bacteriocins, and the generation of bioactive peptides, which have been thoroughly covered herein. The purpose of this work is to review recent research about novel different strategies available for food technologists to improve safety and quality in the manufacture of dry fermented sausages. Additional support strategies—quality product registers and innovation through tradition—have been suggested as complementary actions towards a successful introduction of indigenous microbial communities into traditional dry sausage production.

The Use of the Mixed Bacteria Limosilactobacillus fermentum and Staphylococcus carnosus in the Meat Curing Process with a Reduced Amount of Sodium Nitrite

The aim of the research was to estimate the possibility of using mixed bacteria cultures consisting of Lactobacillus fermentum S8 and Staphylococcus carnosus ATCC 51365 in the meat curing process with a reduced amount of sodium nitrite and to study the effect of bacteria on residual nitrites and nitrates, nitrosyl pigments content, colour, pH, redox potential, microbiologic, and the sensory quality of a cooked meat product. The study was performed on heat treated three-model meat treatments in cans: (C) a control treatment with NaNO2 at 100 mg/kg, (M) a treatment with NaNO2 at 50 mg/kg and (SL) a treatment with NaNO2 at 50 mg/kg and L. fermentum S8 at about 107 cfu/g and S. carnosus ATCC 51365 at about of 107 cfu/g. The research was performed after production and after cold storage. It was shown that using a mixed bacteria culture for meat curing had an influence (p < 0.05) on reducing nitrite and nitrate levels and increasing the amount of nitrosyl pigments in the SL treatment compared to the M treatment. Applying mixed bacteria in curing meat with NaNO2 at 50 mg/kg allowed for obtaining a higher redness in the cooked meat product after production, storage and exposure to light than in the product cured with NaNO2 at 100 mg/kg, with similar sensory and microbiological quality in both products.

Beneficial effects of Jerusalem artichoke powder and olive oil as animal fat replacers and natural healthy compound sources in Harbin dry sausages

This study aimed to improve the nutritional quality of Harbin dry sausages using natural plant-based Jerusalem artichoke powder (JAP) and olive oil as animal fat replacers. Low-fat Harbin dry sausages were manufactured with 2 different formulations containing JAP and olive oil as pork fat replacers. The texture, rheological properties, microstructure, water holding capacity, muscle protein structure, physicochemical indices, microbiological characteristics, and sensory evaluation of the sausages were analyzed. The result showed that Harbin dry sausages with JAP and olive oil were healthier than control sausages based on the lower fat content and improved fatty acid composition. Scanning electron microscopy showed gel network formation in sausages with a high JAP content. Low-field nuclear magnetic resonance illustrated that the water-holding capacity of the modified sausages was improved, suggesting that the replacers enhanced protein gel formation by changes in C-H stretching and bending vibrations, a reduction in α-helixes, and increases in β-sheets and random coils accompanying the exposure of reactive groups and microenvironment of the tertiary structure. Dynamic rheological and texture tests indicated that the replacers improved the elasticity of sausages. The reduction of fat and addition of replacers significantly enhanced lipid oxidative resistance. Overall, JAP and olive oil improved the fatty acid composition, gel structure, lipid oxidative resistance, and sensory quality of the sausages. These results may contribute to the development of healthy meat products to further reduce animal fat.

Selection of nitrite-degrading and biogenic amine-degrading strains and its involved genes

Objectives

Accumulation of nitrite and biogenic amines (BAs) in fermented meat products is a matter of public health concern. The study aimed to screen nitrite-degrading and BA-degrading strains from sour porridges and sausages and bacon products in China.

Materials and Methods

After screening out 12 strains, the degradation of nitrite, the degradation of BAs, the activities of nitrite-reducing enzymes, and the detection of genes involved in the BAs were assessed by spectrophotometry method with hydrochloric acid naphthalene ethylenediamine, high-performance liquid chromatography, GENMED kit, and polymerase chain reaction, respectively.

Results

Pediococcus pentosaceus labelled M SZ1 2 and M GC 2, Lactobacillus plantarum labelled M SZ2 2, and Staphylococcus xylosus labelled Y CC 3 were selected. The activity of nitrite-reducing enzyme in M SZ2 2 was 2.663 units/mg. The degradation rate of total BAs of M SZ2 2 was 93.24%. The degradation rates of nitrite and BAs of M SZ1 2 were 86.49% and 37.87%, respectively. The activity of nitrite-reducing enzyme in M SZ1 2 was up to 1.962 units/mg. M GC 2 showed higher degradation rates of nitrite (89.19%) and Y CC 3 showed higher degradation rates of BAs (36.16%). The genes encoding the multicopper oxidases (suf I/D2EK17) were detected in the four strains, which also did not contain BAs (histidine decarboxylase (hdc), tyrosine decarboxylase (tdc), ornithine decarboxylase (odc), lysine decarboxylase (ldc)) formation encoding genes.

Conclusion

These four strains (M SZ1 2, M GC 2, M SZ2 2, and Y CC 3) are promising candidates to use as starter cultures for nitrite and BAs in fermented sausages.

Microbial diversity of representative traditional fermented sausages in different regions of China

AIMS

The purpose of this experiment was to study the bacterial diversity of traditional fermented sausages from four typical regions of China (Chengdu, Shenzhen, Changsha and Harbin) and to further evaluate their microbiological safety.

METHODS AND RESULTS

The diversity of the microbiota of the sausages was studied using the Illumina HiSeq platform. The results showed that compared with the highest diversity of fermented bacteria in Guangdong, the bacterial diversity of fermented sausage was the lowest in Sichuan. The percentage of dominant phylum (Firmicutes, Cyanophyta, Proteobacter) were 78·39, 13·13 and 7·14% in SC, 35·47, 30·36 and 28·04% in GD, 54·81, 28·91 and 14·00% in HN, 20·20, 58·16 and 17·31% in HB respectively. The main genus distribution of fermented sausages in different regions is varied, but lactic acid bacteria and cyanobacteria are generally the main ones. Traditional fermented sausages using natural fermentation methods have poor microbiological safety, and pathogenic and spoilage micro-organisms such as Acinetobacter, Brochothrix and Pseudomonas have been detected in all four regions.

CONCLUSIONS

The results in this paper provide a microbiota profile of four typical fermented sausages in China. There is a big difference in the microbiota of sausages in different regions, and the good flavour of traditional Chinese fermented sausage is related closely with the abundant microbial resources, however, the natural fermentation method also expose to the product security threats, including spoilage, pathogenic micro-organisms and biogenic amines, etc. SIGNIFICANCE AND IMPACT OF THE STUDY: The results would offer guidance for industrial fermented sausage production with certain flavour and also improve the microbial resource utilization, and contribute to the control of harmful micro-organisms in traditional fermented sausage.

Application of Weissella cibaria X31 or Weissella confusa L2 as a starter in low nitrite dry-fermented sausages

Effects of Weissella strains (Weissella cibaria X31 or Weissella confusa L2) as starters on the physicochemical, volatile, proteolytic, microbiological, and sensory properties of low-nitrite dry-fermented sausages were evaluated for 20 d. Results showed that the addition of 8 log CFU/g of Weissella strains increased the redness, hardness, adhesiveness, and chewiness, but decreased the pH, water activity, and nitrite content of sausages during processing. Morover, Weissella strains inhibited the growth of Salmonella enterica. Weissella strains also could hydrolyze myofibrillar proteins in sausages. The sausage inoculated with W. confusa L2 was more abundant in ester compared with the control. Sausages inoculated with W. cibaria X31 and W. confusa L2 and sodium nitrite (0.05 g) had more desirable characteristics, compared with other groups. W. cibaria X31 and W. confusa L2 show potential as multifunctional starters in low-nitrite fermented sausage, which is uniqueness and addressed the gap of Weissella in low nitrite sausages. This study is distinct in that Weissella strains were found to improve the redness of dry-fermented sausages and was effective at partly replacing nitrite in dry-fermented sausages, addressing the research gap regarding the application of Weissella in low-nitrite sausages.

Isolation of Antibacterial, Nitrosylmyoglobin Forming Lactic Acid Bacteria and Their Potential Use in Meat Processing

The use of nitrite as a colorant and preservative in meat processing is associated with health risks. This study aimed to isolate nitrite-substituting lactic acid bacteria for use as natural biological colorants and preservatives. Among the 106 strains isolated from fermented foods, two strains with excellent ability to convert myoglobin and metmyoglobin (Met-Mb) to red nitrosylmyoglobin (Mb-NO) were selected. The superior ability to form Mb-NO was confirmed through UV-visible spectrophotometry, Fourier transform infrared spectrometry, electron spin resonance analysis, nitric oxide synthase activity assay, and Met-Mb reductase activity assay. The potent antibacterial activity was confirmed through biofilm and cytomembrane breakage of the indicator bacteria. Though performing 16S rDNA sequencing, they were identified as two different strains of Lactobacillus plantarum. Based on their favorable characteristics, their applications in the meat industry were further evaluated. This study identified a novel dual-function natural biological colorant and preservative to substitute nitrite in meat products. The application of the two strains would decrease the hazardous of nitrite to health.

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.

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.

Purification and biochemical characteristics of the extracellular protease from Pediococcus pentosaceus isolated from Harbin dry sausages

This study investigated the purification and biochemical characteristics of the protease produced by Pediococcus pentosaceus isolated from Harbin dry sausages. The optimized fermented conditions were as follows: fermentation time 36 h, initial pH 5 and fermentation temperature 30 °C. A 29.6 kDa extracellular protease was purified using ammonium sulphate deposition, ion exchange layer system and gel filtration. The protease produced by P. pentosaceus had a certain pH and thermal stability at pH 6 and 30 °C. The microbial protease activity could be inhibited by ethylene diamine tetraacetic acid disodium salt (EDTA). V_max and K_m of the protease were 43.9 mg/min and 8.3 mg/mL, respectively. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) reflected the ability of the protease to hydrolyse sarcoplasmic and myofibrillar proteins, particularly those of myosin heavy chain, paramyosin, actin, phosphorylase and creatine kinase-M types. 3D structure modelling of the P. pentosaceus protease found two domains in the protease protein and the correlation of the active sites with protease properties and substrate specificity. In conclusion, P. pentosaceus can be used as a starter culture or enzyme producing strain for inoculation in Harbin dry sausages.

Evaluation of the Biogenic Amines and Microbial Contribution in Traditional Chinese Sausages

Biogenic amines (BAs) in sausages represent a health risk for consumers, and thus investigating the BAs accumulation mechanism is important to control the BAs. In this study, the BAs profiles of 16 typical Chinese sausage samples were evaluated, and 8 kinds of common BAs were detected from different samples. As a whole, the BAs contents of the majority of Chinese sausage samples were within the safe dosage range, except that the total BAs and histamine concentrations of sample HBBD were above the toxic dosage levels. Furthermore, the bacterial and fungal communities of the Chinese sausage samples were investigated by high-throughput sequencing analysis, and Staphylococcus, Bacillus, Lactococcus, Lactobacillus, Debaryomyces, and Aspergillus were identified as the predominant genera. Accordingly, 13 representative strains were selected from the dominant genera, and their BAs formation and degradation properties were evaluated. Finally, the results of fermented meats model experiment indicated that the Staphylococcus isolates including Staphylococcus pasteuri Sp, Staphylococcus epidermidis Se, Staphylococcus carnosus Sc1, Staphylococcus carnosus Sc2, and Staphylococcus simulans Ss could significantly reduce BAs, possessing the potential as the starter cultures to control the BAs in fermented meat products. The present study not only helped to explain the BAs accumulation mechanism in Chinese sausage, but also developed the candidates for potential BAs control in fermented meat products.