Partial replacement of nitrite with a novel probiotic Lactobacillus plantarum on nitrate, color, biogenic amines and gel properties of Chinese fermented sausages

Screening and evaluating microorganisms with broad-spectrum biogenic amine-degrading ability from naturally fermented dry sausage collected from Northeast China

This study aimed to screen autochthonous strains with broad-spectrum biogenic amine (BA) degradation ability from traditional dry sausages and to evaluate their BA-degrading ability in dry sausages. A total of 120 strains were isolated from dry sausages collected from various regions in Northeast China, and 35 of 120 isolates were identified as non-BA producing strains by the in vitro agar method. The random amplified polymorphic DNA polymerase chain reaction technique genotyped these 35 isolates into 18 biotypes. Moreover, high performance liquid chromatography (HPLC) quantification showed that six strains (Latilactobacillus sakei MDJ6; Lactiplantibacillus plantarum SH7; Weissella hellenica DQ9; Staphylococcus saprophyticus JX18 and SYS8; and Macrococcus caseolyticus SYS11) of the 18 biotypes exhibited broad-spectrum BA-degrading ability, all of which had various levels of amine oxidase activity with monoamine oxidase and diamine oxidase activities ranged of 6.60-619.04 and 26.32-352.81 U/mg protein, respectively. These six strains were subsequently inoculated into dry sausages and the results showed that they exhibited varying degrees of BA-degrading ability, of which strain Lat. sakei MDJ6 allowed to have less BA production on dry sausage with a final concentration of 61.33 mg/kg.

The Contribution of Microorganisms to the Quality and Flavor Formation of Chinese Traditional Fermented Meat and Fish Products

Guizhou sour meat and sour fish, Chaoshan fish sauce, Sichuan sausage and bacon, Cantonese sausage, Jinhua ham, and Xinjiang air-dried beef are eight representatives of Chinese traditional fermented meat and fish products (FMFPs), which are favored by Chinese consumers due to their high nutritional value and quality. The quality of the spontaneously fermented Chinese traditional FMFP is closely correlated with microorganisms. Moreover, the dominant microorganisms are significantly different due to regional differences. The effects of microorganisms on the texture, color, flavor, nutrition, functional properties, and safety of Chinese traditional FMFPs have not been not fully described. Additionally, metabolic pathways for flavor formation of Chinese traditional FMFPs have not well been summarized. This article describes the seven characteristic Chinese traditional FMFPs and correlated dominant microorganisms in different regions of China. The effects of microorganisms on the texture, color, and flavor of Chinese traditional FMFPs are discussed. Furthermore, the metabolic pathways of microbial regulation of flavor formation in Chinese traditional FMFPs are proposed. This work provides a theoretical basis for improvement of Chinese traditional FMFPs by inoculating functional microorganisms isolated from Chinese traditional fermented foods.

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.

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.

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.

Zinc protoporphyrin IX generation by Leuconostoc strains isolated from bulged pasteurized vacuum sliced hams

The colour of meat typically fades as it decays. However, it has been observed that certain vacuum-packaged spoiled hams can maintain a pink colour even when the packaging is bulged. A large amount of Zinc protoporphyrin IX (ZnPP) was found in these hams, compared to fresh red hams or spoiled and grey hams. Combined with high-throughput sequencing and cultural isolation, the potential cultures of Leuconostoc mesenteroides S-13 (LM), Leuconostoc citreum OCLC11 (LC), and Leuconostoc mesenteroides subsp. IMAU:80679 (LS) were selected based on their ability to produce ZnPP. Subsequently, these cultures were introduced into a fermented sausage model to assess their effect on colour conversion. The analysis of absorption and fluorescent spectra showed that Nitrite sausages contained nitrosyl heme pigment, while bacteria-inoculated sausages were predominantly composed of ZnPP. In addition, the a* value of the LS sausage was close to the Nitrite group at the end of fermentation, significantly higher than control, indicating the effect of bacterial metabolism on the redness. Meanwhile, the Ferrochelatase (FECH) activity of LM, LC and LS groups were 140 ± 13, 113 ± 16 and 201 ± 20 U/g sausage, respectively, providing a potential method on compensating for nitrite/nitrate substitution based on the presence of ZnPP in meat products.

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.

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.

Antibiofilm activity and NMR-based metabolomic characterization of cell-free supernatant of Limosilactobacillus reuteri DSM 17938

The microbial biofilm has been defined as a "key virulence factor" for a multitude of microorganisms associated with chronic infections. Its multifactorial nature and variability, as well as an increase in antimicrobial resistance, suggest the need to identify new compounds as alternatives to the commonly used antimicrobials. The aim of this study was to assess the antibiofilm activity of cell-free supernatant (CFS) and its sub-fractions (SurE 10 K with a molecular weight <10 kDa and SurE with a molecular weight <30 kDa), produced by Limosilactobacillus reuteri DSM 17938, vs. biofilm-producing bacterial species. The minimum inhibitory biofilm concentration (MBIC) and the minimum biofilm eradication concentration (MBEC) were determined via three different methods and an NMR metabolomic analysis of CFS and SurE 10K was performed to identify and quantify several compounds. Finally, the storage stability of these postbiotics was evaluated by a colorimetric assay by analyzing changes in the CIEL*a*b parameters. The CFS showed a promising antibiofilm activity against the biofilm developed by clinically relevant microorganisms. The NMR of CFS and SurE 10K identifies and quantifies several compounds, mainly organic acids and amino acids, with lactate being the most abundant metabolite in all the analyzed samples. The CFS and SurE 10 K were characterized by a similar qualitative profile, with the exception of formate and glycine detected only in the CFS. Finally, the CIEL*a*b parameters assess the better conditions to analyze and use these matrices for the correct preservation of bioactive compounds.

Effect of Autochthonous Lactic Acid Bacteria-Enhanced Fermentation on the Quality of Suancai

The lactic acid bacteria (LABs) used for fermentation have an extremely vital impact on the quality of Suancai, a fermented vegetable. The bacterial diversity and metabolites of inoculated Suancai with LABs, including Lactiplantibacillus plantarum (Lb. plantarum), Levilactabacillus brevis (Lb. brevis), and Leuconostoc mesenteroides (Leu. mesenteroides), were investigated. The inoculation of LABs significantly decreased the pH and the content of nitrite. The Suancai inoculated with LABs had a higher content of the total titratable acidity (TTA) and organic acids than spontaneous fermentation. The LABs inoculation significantly influenced the bacterial community structures, which directly or indirectly caused changes of metabolites. The bacterial community profiles of Suancai inoculated with Lb. plantarum were more similar to spontaneous fermentation. The inoculation of Lb. plantarum, Lb. brevis, and Leu. mesenteroides could increase its abundance in Suancai. Whatever the species inoculated, Lb. plantarum was always the predominant bacterium in Suancai after fermentation. The inoculated LABs were positively correlated with most volatile compounds and amino acids. The inoculated LABs significantly improved the volatile compounds and amino acid content of Suancai. This study could contribute to understanding the function of starters in Suancai fermentation and promote the selection of applicable starters for high-quality Suancai production.

Application progress of intelligent flavor sensing system in the production process of fermented foods based on the flavor properties

Fermented foods are sensitive to the production conditions because of microbial and enzymatic activities, which requires intelligent flavor sensing system (IFSS) to monitor and optimize the production process based on the flavor properties. As the simulation system of human olfaction and gustation, IFSS has been widely used in the field of food with the characteristics of nondestructive, pollution-free, and real-time detection. This paper reviews the application of IFSS in the control of fermentation, ripening, and shelf life, and the potential in the identification of quality differences and flavor-producing microbes in fermented foods. The survey found that electronic nose (tongue) is suitable to monitor fermentation process and identify food authenticity in real time based on the changes of flavor profile. Gas chromatography-ion mobility spectrometry and nuclear magnetic resonance technology can be used to analyze the flavor metabolism of fermented foods at various production stages and explore the correlation between flavor substances and microorganisms.

Assessment of the safety and probiotic properties of Roseburia intestinalis: A potential “Next Generation Probiotic”

Roseburia intestinalis is an anaerobic bacterium that produces butyric acid and belongs to the phylum Firmicutes. There is increasing evidence that this bacterium has positive effects on several diseases, including inflammatory bowel disease, atherosclerosis, alcoholic fatty liver, colorectal cancer, and metabolic syndrome, making it a potential “Next Generation Probiotic.” We investigated the genomic characteristics, probiotic properties, cytotoxicity, oral toxicity, colonization characteristics of the bacterium, and its effect on the gut microbiota. The genome contains few genes encoding virulence factors, three clustered regularly interspaced short palindromic repeat (CRISPR) sequences, two Cas genes, no toxic biogenic amine synthesis genes, and several essential amino acid and vitamin synthesis genes. Seven prophages and 41 genomic islands were predicted. In addition to a bacteriocin (Zoocin A), the bacterium encodes four metabolic gene clusters that synthesize short-chain fatty acids and 222 carbohydrate-active enzyme modules. This bacterium is sensitive to antibiotics specified by the European Food Safety Authority, does not exhibit hemolytic or gelatinase activity, and exhibits some acid resistance. R. intestinalis adheres to intestinal epithelial cells and inhibits the invasion of certain pathogens. In vitro experiments showed that the bacterium was not cytotoxic. R. intestinalis did not affect the diversity or abundance of the gut flora. Using the fluorescent labelling method, we discovered that R. intestinalis colonizes the cecum and mucus of the colon. An oral toxicity study did not reveal any obvious adverse effects. The lethal dose (LD)50 of R. intestinalis exceeded 1.9 × 10⁹ colony forming units (CFU)/kg, whereas the no observed adverse effect level (NOAEL) derived from this study was 1.32 × 10⁹ CFU/kg/day for 28 days. The current research shows that, R. intestinalis is a suitable next-generation probiotic considering its probiotic properties and safety.

Bacterial community diversity and its potential contributions to the flavor components of traditional smoked horsemeat sausage in Xinjiang, China

Smoked horsemeat sausage is a famous fermented traditional food in Xinjiang, China. However, the microbial diversity and its potential contributions to the flavor components of smoked horsemeat sausage are unclear. In this study, the microbial community and flavor components of smoked horsemeat sausage from six regions of Xinjiang were measured by using amplicon sequencing and headspace solid-phase microextraction combined with gas chromatography–mass spectrometry (HS-SPME-GC–MS) technology, respectively. Relations among microbial communities, flavor components and environmental factors were subsequently predicted based on redundancy analysis (RDA) and Monte Carlo permutation tests. Although smoked horsemeat sausage samples from different regions possessed distinct microbial communities, lactic acid bacteria (LAB) were identified as the dominant consortium in smoked horsemeat sausage. Lactobacillus, Vagococcus, Lactococcus, and Carnobacterium were detected at high abundance in different sausages. The moisture content, nitrite content, and pH of the sausage might be important factors influencing the dominant bacterial community, according to the RDA. Among the dominant consortia, the eight core bacterial genera showed considerable correlations with the formation of sixteen volatile compounds in smoked horsemeat sausage based on multivariate statistical analysis. For example, the levels of Leuconostoc and Lactobacillus were positively correlated with those of 1-hexadecanol, hexyl acetate, 2-methyl-phenol, 1-pentanol, d-limonene, and 2-heptanone, and the levels of Leuconostoc, Lactobacillus, and Weissella were negatively correlated with those of 1-octanol, acetic acid, octanal, heptanal, and 1-hexanol. This study will provide a theoretical basis for understanding the microbial metabolic modes of Xinjiang smoked horsemeat sausages.

Research Update on the Impact of Lactic Acid Bacteria on the Substance Metabolism, Flavor, and Quality Characteristics of Fermented Meat Products

This paper reviews the effects of domestic and foreign influences on the substance metabolism pathways and the flavor and flora of LAB in fermented meat products to provide a new theoretical basis for developing new products for the industrial application of lactic acid bacteria (LAB) in fermented meat products. LAB are extensively used among commonly fermented ingredients, such as fermented meat products and yogurt. As fermenting agents, LAB metabolize proteins, lipids, and glycogen in meat products through their enzyme system, which affects the tricarboxylic acid cycle, fatty acid metabolism, amino acid decomposition, and other metabolic processes, and decompose biological macromolecules into small molecules, adding a special flavor with a certain functionality to the final product. Metabolites of LAB in the fermentation process also exert nitrite degradation, as well as antibacterial and antioxidant functions, which improve the physical and chemical qualities of fermented meat products. While fermenting meat products, LAB not only add unique flavor substances to the products, but also improve the safety profile of fermented foods.

The effect of nitric oxide synthase and arginine on the color of cooked meat

In previous studies, it has been suggested that the NO-synthase enzyme may be responsible for color formation in fermented sausages. Thus, this is the first study in which the aim was to analyze the effects of direct NO-synthase and arginine application to meat on its color after heating. Myoglobin forms as well as the presence of NO-myoglobin were investigated. The color of the meat and myoglobin forms present in the samples were mainly affected by pH differences, caused by a HEPES buffer or arginine. None of the variants demonstrated a bright pink color as in the case of the heated nitrite-cured sample. Based on analysis of the absorption spectra, it can be concluded that there is some evidence of nitroso-complex formation. Therefore, it is probable that optimizing the pH/time/temperature conditions for NO-synthase activity would allow to obtain a desirable color effect. NO-synthase could be used as an alternative curing ingredient.

Evaluation and monitoring of the quality of sausages by different analytical techniques over the last five years

Sausages are among the most vulnerable and perishable products, although those products are an important source of essential nutrients for human organisms. The evaluation of the quality of sausages becomes more and more required by consumers, producers, and authorities to thwarter falsification. Numerous analytical techniques including chemical, sensory, chromatography, and so on, are employed for the determination of the quality and authenticity of sausages. These methods are expensive and time consuming, and are often sensitive to significant sources of variation. Therefore, rapid analytical techniques such as fluorescence spectroscopy, near infrared (NIR), mid infrared (MIR), nuclear magnetic resonance (NMR), among others were considered helpful tools in this domain. This review will identify current gaps related to different analytical techniques in assessing and monitoring the quality of sausages and discuss the drawbacks of existing analytical methods regarding the quality and authenticity of sausages from 2015 up to now.

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.

Fermentation characteristics and bacterial dynamics during Chinese sauerkraut fermentation by Lactobacillus curvatus LC-20 under varied salt concentrations reveal its potential in low-salt suan cai production

Salt profoundly affects the physicochemical properties and microbial abundance of fermented foods such as suan cai, a popular traditional fermented food in China. It is vital to systematically investigate the effects of salt concentrations on fermented suan cai for high fermentation quality and large-scale production. We elucidated the effects of salt concentrations on Lactobacillus curvatus (LC-20) and suan cai during fermentation, and found that salt (0-1%) favoured an increase in LC-20 growth and a decrease in pH (salt: 0-2%). For suan cai fermentation, the results from sensory scoring judged 1% salt treatment the highest. Salt concentration also affected the nitrite content of the fermentation system with peak nitrite values in low salt treatments being significantly higher on the first day, and gradually decreasing to similar levels. After fermentation, the total titratable acid and lactic acid concentrations in the 0-1% treatments were higher (p < 0.05) than those in 2-5% treatments. The colony forming units of lactic acid bacteria increased initially and then decreased after 6 d of fermentation. At the phylum level, Firmicutes and Proteobacteria were predominant in all treatments, and at the genus level, Lactobacillus dominated the fermentation. Other lactic acid bacteria such as Lactococcus and Weissella were also detected. Quantitative PCR showed DNA concentration of LC-20 at 0.5-2% salt treatments were higher than that in other treatments and L. curvatus was the dominant microorganism during fermentation. Hence, we conclude that L. curvatus could be used for suan cai product at low salt concentrations.

Sage (Salvia officinalis L.) Essential Oil as a Potential Replacement for Sodium Nitrite in Dry Fermented Sausages

This study investigates the effects of sodium nitrite replacement by the sage essential oil (SEO), on the physico-chemical, microbiological and sensory quality of dry fermented sausages (DFS) during 225 days of storage. The SEO (0.00, 0.05 and 0.10 µL/g) was added in DFS batters formulated with different levels of pork back fat (15% and 25%) and sodium nitrite (0, 75 and 150 mg/kg). The inclusion of SEO had no negative impact on pH, color (instrumental and sensory) and texture parameters. Total plate counts were lower than 6 log CFU (colony forming units)/g in all samples throughout the storage. Furthermore, the addition of SEO at concentration of 0.05 µL/g provided acceptable TBARS (2-Thiobarbituric acid reactive substances) values (<0.3 mg MDA (malondialdehyde)/kg) in the samples produced with reduced levels of sodium nitrite (0 and 75 mg/kg) without negative alternations on sensory attributes of odor and flavor. Generally, our findings confirmed that the usage of SEO could be a good solution to produce healthier DFS with reduced levels of sodium nitrite.

Evaluation and Application of Different Cholesterol-Lowering Lactic Acid Bacteria as Potential Meat Starters

ABSTRACT

A total of 115 isolates of lactic acid bacteria were screened from traditional fermented foods in Guizhou Province, People's Republic of China. The cholesterol removal rates of 86 isolates ranged from 7.29 to 25.66%, and 18 isolates showed a cholesterol removal rate of more than 15%. According to the results of physiological and biological tests, 13 isolates were selected to determine the fermentation performance; 9 isolates-MT-4, MT-2, PJ-15, SR2-2, SQ-4, SQ-7, ST2-2, ST2-6, and NR1-7-had high tolerance of bile salt and acid and had a survival rate of more than 96% under pH 3.0 and 0.3% bile salt. ST2-2, SR2-2, NR1-7, SQ-4, and MT-4 had high survival rate in different concentrations of NaCl and NaNO2 under different temperatures. According to BLAST comparison results of the 16S rRNA sequence in the GenBank database and the genetic distance of the 16S rRNA sequence with an ortho-connected algorithm, SR2-2, NR1-7, and ST2-2 were identified as Lactobacillus plantarum, MT-4 was identified as Lactobacillus pentosus, and SQ-4 was identified as Lactobacillus paraplantarum. Moreover, strains SQ-4 and MT-4 were added to fermented beef. Results showed that the fermented beef had delicious taste and was popular to consumers because of its proper pH, pleasant colors, high viable cell count, and suitable content of bound and immobilized water. These results provide a basis for the development of new starter formulation for the production of high-quality fermented meat products.

HIGHLIGHTS

Evaluation of microbiological, chemical, and sensory properties of cooked probiotic sausages containing different concentrations of astaxanthin, thymol, and nitrite

In this study, the effects of different concentrations of thymol and astaxanthin on control of Clostridium perfringenes and also microbial, chemical, and organoleptic properties of common and probiotic beef cooked sausages containing two levels of nitrite during storage at refrigerated condition during 45 days were evaluated. Based on findings, control group had significantly higher total volatile base nitrogen (TVB-N) than nitrite-, thymol-, and astaxanthin-treated samples. At the end of the storage time in control, thiobarbituric acid reactive substances (TBARS) value reached 1.96 mg/kg, while the values for treated samples remained lower than 1.63 mg/kg. Final count of lactic acid bacteria decreased approximately 1.67-3.79 log CFU/g in treated samples compared with the control group (p < .05). A reduction between 1.46 and 2.46 log CFU/g in C. perfringenes count was recorded for the treated samples in comparison with control group after 45 days of storage.

Antibacterial Activity and Mechanism of Lacidophilin From Lactobacillus pentosus Against Staphylococcus aureus and Escherichia coli

The main purpose of this study was to explore the antibacterial activity and mechanism of lacidophilin from Lactobacillus pentosus against Staphylococcus aureus and Escherichia coli. The effects of temperature, enzyme, metal ions, and pH on the antibacterial activity of L. pentosus were evaluated. The result showed that lacidophilin had good thermal stability and could be decomposed by trypsin completely. The antibacterial ability was affected by high concentration of metal ions, and the best antibacterial ability was acquired under acidic conditions. The antibacterial mechanism of lacidophilin was explored through studying cytomembrane injury, phosphorus metabolism, protein changes, and oxidative stress response of the indicator bacteria. It was shown that lacidophilin destroyed the cytomembrane of the bacteria and increased the cytomembrane permeability, which resulted in the leak of proteins, nucleic acids, and electrolytes. In addition, it further restrained phosphorus metabolism, caused changes of some protein contents, and increased cytomembrane lipid peroxidation and cell oxidative damage. All these might inhibit the growth of bacteria and even cause their death. This study identified a natural biological preservative with strong antibacterial activity against both Gram-positive and Gram-negative foodborne pathogens. The high antibacterial activity against the two types of bacteria reflected its potential in food preservation used as a natural food preservative.

Towards More Sustainable Meat Products: Extenders as a Way of Reducing Meat Content

The low efficiency of animal protein (meat products) production is one of the main concerns for sustainable food production. However, meat provides high-quality protein among other compounds such as minerals or vitamins. The use of meat extenders, non-meat substances with high protein content, to partially replace meat, offers interesting opportunities towards the reformulation of healthier and more sustainable meat products. The objective of this review is to give a general point of view on what type of compounds are used as meat extenders and how they affect the physicochemical and sensory properties of reformulated products. Plant-based ingredients (pulses, cereals, tubers and fruits) have been widely used to replace up to 50% of meat. Mushrooms allow for higher proportions of meat substitution, with adequate results in reduced-sodium reformulated products. Insects and by-products from the food industry are novel approaches that present an opportunity to develop more sustainable meat products. In general, the use of meat extenders improves the yield of the products, with slight sensory modifications. These multiple possibilities make meat extenders' use the most viable and interesting approach towards the production of healthier meat products with less environmental impact.