Physicochemical and structural characterisation of a branched dextran type exopolysaccharide (EPS) from Weissella confusa S6 isolated from fermented sausage (Sucuk)

Exopolysaccharide (EPS) producing Lactic Acid Bacteria (LAB) species can be presented in distinct environments. In this study, Turkish fermented sausage (sucuk) was tested for the presence of EPS producer LAB strains and slimy-mucoid colonies were selected for further tests. Among the isolates, Weissella confusa strain S6 was identified and tested for the physicochemical characterisation of its EPS. This strain was found to produce 0.74 g L-1 of EPS in modified BHI medium conditions. Structural characterisation of EPS S6 by 1H and 13C NMR demonstrated that EPS S6 was a highly branched dextran type glucan formed by mainly (1 → 2)-linked α-d-glucose units together with low levels of (1 → 3)-linked α-d-glucose units as branching points. This structure was further confirmed by methylation analysis detected by GC-MS. An average molecular weight of 8 × 106 Da was detected for dextran S6. The FTIR analysis supported the dextran structure and revealed the presence of distinct functional groups within dextran S6 structure. A strong thermal profile was observed for dextran S6 detected by DSC and TGA analysis and dextran S6 revealed a degradation temperature of 289 °C. In terms of physical status, dextran S6 showed amorphous nature detected by XRD analysis. SEM analysis of dextran S6 demonstrated its rough, compact and porous morphology whereas AFM analysis of dextran S6 detected in its water solution showed the irregularity with no clear cross-link within the dextran chains. These technological features of dextran S6 suggests its potential to be used for in situ or ex situ application during meat fermentations.

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.

Effect of Lactobacillus helveticus IMAUJBH1 on fat and volatile flavor substances in fermented mutton sausages

The decomposition and oxidation of fat is essential for the formation and quality of the unique flavor of sausage. To explore the effect of lactic acid bacteria on fat decomposition and oxidation in fermented sausage, free fatty acids and volatile flavor compounds were determined by gas chromatography (GC) and headspace solid-phase microextraction (HS-SPME)-GC-MS, respectively. The results showed that the addition of Lactobacillus helveticus IMAUJBH1 inhibited fat peroxidation and relatively increased the proportion of monounsaturated fatty acids. A total of 47 volatile flavor compounds were detected, including aldehydes, esters, alcohols, and ketones. The content of substances such as hexanal, heptanal, nonanal and 1-octene-3-ol related to lipid oxidation was significantly reduced. The results obtained in this study show that the strain can further affect the flavor of the product by inhibiting the formation of lipid oxidation or peroxide flavor substances to a certain extent.

Genome-Based Identification and Characterization of Bacteriocins Selectively Inhibiting Staphylococcus aureus in Fermented Sausages

The bacteriocin-producing Lactiplantibacillus plantarum SL47 was isolated from conventional fermented sausages, and the bacteriocin SL47 was purified using ethyl acetate, Sephadex G-25 gel chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC). Bacteriocin SL47 was identified by HPLC-MS/MS combined with whole-genome sequencing, and the results showed it consisted of plantaricin A, J, K, and N. Further characterization analysis showed that the bacteriocin SL47 was highly thermostable (30 min, 121 °C), pH stable (2-10), sensitive to protease and exhibited broad-spectrum antibacterial ability against Gram-positive and Gram-negative bacteria. The mechanism of action showed that the bacteriocin SL47 increased cell membrane permeability, and 2 × minimum inhibitory concentration (MIC) treatment for 40 min caused apoptosis of Staphylococcus aureus F2. The count of S. aureus in the sausage that was inoculated with L. plantarum SL47 and bacteriocin SL47 decreased by about 64% and 53% of that in the initial stage, respectively. These results indicated the potential of L. plantarum SL47 and bacteriocin SL47 as a bio-preservative in meat products.

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.

Effect of fat concentration on protein digestibility of Chinese sausage

Chinese sausage is a popular traditional Chinese meat product, but its high-fat content makes consumers hesitant. The purpose of this study is to compare the nutritional differences of Chinese sausages with different fermentation times (0, 10, 20, 30 d) and fat content (the initial content was 11.59% and 20.14%) during digestion. The comparison of digestion degree, protein structure, and peptide composition between different sausages were studied through in vitro simulated digestion. Chinese sausages with high-fat content had higher α-helix, β-turn, and random coil, making them easier to digest. The fermentation process made this phenomenon more pronounced. The high-fat sausage fermented for 10 d showed the highest release of primary amino acids (about 9.5%), which was about 3.5% higher than the low-fat sausage under the same conditions. The results of peptidomics confirmed the relevant conclusions. After gastric digestion, the types of peptides in the digestive fluid of high-fat sausages were generally more than those in low-fat sausages, while after intestinal digestion, the opposite results were observed. The type of peptide reached its peak after fermentation for 20 d. These findings are of obvious significance for selecting the appropriate fermentation time and fat content of Chinese sausages.

Effect of probiotic Bacillus cereus DM423 on the flavor formation of fermented sausage

Insufficient protein and fat hydrolysis capacity of lactic acid bacteria (LAB) limit the flavor formation of fermented sausage. Bacillus is known for its substantial expression of proteases and lipases. However, its application in meat fermentation remains underexplored. In this study, a strain of probiotic Bacillus cereus (B. cereus DM423) was employed as a co-starter to improve the quality of Lactiplantibacillus plantarum (L. plantarum HH-LP56) fermented sausage. The addition of DM423 did not interfere with regular fermentation, but it significantly improved the flavor, as measured by electronic tongue and electronic nose. Further analyses using SDS-PAGE and thin-layer chromatography observed enhanced hydrolysis of protein and fat in sausages in which DM423 was involved in fermentation. GC-IMS identified DM423 mediated upregulation of various flavor compounds, including esters, ketones, furans, and branched-chain fatty acids. In addition, genomic de novo sequencing revealed that DM423 carried an abundance of genes associated with proteolysis, lipolysis, and the production of flavor substances, whereas HH-LP56 lacked these genes. Overall, this study finds that B. cereus DM423 can promote flavor formation in fermented sausages. It may illuminate a promising direction for the development of sausage co-starters from a wider microbial pool.

Microbiota dynamics and volatile metabolite generation during sausage fermentation

Microorganism metabolic activity is critical for the formation of unique flavors in fermented meat products. To clarify the relationship between the formation of the special flavor of fermented meat and microorganisms, high-throughput sequencing and gas chromatography-ion mobility spectrometry were used to analyze microorganisms and volatile compounds in naturally fermented sausage. The findings revealed 91 volatile compounds and 4 key microorganisms, including Lactobacillus, Weissella, Leuconostoc, and Staphylococcus. The key microorganisms were positively correlated with the formation of 21 volatile compounds. The validation results showed that the contents of volatile compounds such as heptanal, octanal, 2-pentanone, and 1-octen-3-ol increased significantly after inoculation with Lb. sakei M2 and S. xylosus Y4. These two bacteria are the key microorganisms that produce the special flavor of fermented sausage. The present study can provide a theoretical basis for the directional development of fermented meat products, the preparation of special flavor enhancers, and expedited fermentation processes.

Effects of natural nitrite sources from arugula and barberry extract on quality characteristic of heat-treated fermented sausages

This study was designed to compare the effects of natural nitrite sources from the arugula leaves (arugula extract and pre-converted arugula extract) and the use of barberry extract (BE) in heat-treated fermented sausage formulations. Eight different sausages were manufactured as follows: pre-converted arugula extract (PA), arugula extract (A), pre-converted arugula extract + BE (PAB), arugula extract + BE (AB), nitrite +BE (POB), no nitrite+ BE (NEB), also positive and negative control groups were prepared with (POC) or without nitrite (NEC). The addition of arugula and barberry extracts reduced the residual nitrite content, in fact PAB had the lowest value with a reduction ratio of 47%. The addition of BE lowered the lipid oxidation compared to other counterparts. The use of arugula extract or pre-converted arugula extract resulted in a lower carbonylation than nitrite free samples. The use of natural extracts lowered the a* and b* values compared to control. At the end of the storage, no differences were observed on the overall acceptability of all samples. Combined use of barberry extract with arugula and pre-converted arugula extracts could be used as alternative novel curing agent in heat-treated fermented sausages.

Effect of fermentation by Pediococcus pentosaceus and Staphylococcus carnosus on the metabolite profile of sausages

A multi-omics approach was applied to investigate the differences and correlations between characteristic volatile flavor substances and non-volatile metabolites in sausages fermented by Pediococcus pentosaceus (P. pentosaceus) and Staphylococcus carnosus (S. carnosus) alone and in a mixture. Twenty-seven volatile metabolites were identified by headspace solid-phase microextraction/gas chromatography-mass. According to orthogonal projections to latent structures-differential analysis, 17 characteristic volatile metabolites were detected in the sausages of different treatments. Utilizing ultra-high-performance liquid chromatography coupled with a mass spectrometer to analyze metabolite profiles, 42.03% of the non-volatile metabolites were classified as lipids and lipid-like molecules, 25.00% of organic acids and derivatives, and others. Seventeen characteristic flavor substances were significantly correlated with twenty differential non-volatile metabolites, and the non-volatile metabolites changed significantly. Differences in the characteristics and combinations of microorganisms themselves have a decisive role in the development of flavor substances and non-volatile metabolites in sausages.

Sensory attributes and characterization of aroma profiles of fermented sausages based on fibrous-like meat substitute from soybean protein and Coprinus comatus

Plant-based meat substitutes are emerging as healthy, balanced, and sustainable non-animal alternatives to alleviate stress from the increased demand for meat products. In this study, fibrous-like extrudates acting as meat substitutes were manufactured from soybean protein and Coprinus comatus by thermos-extrusion and fermentation processing improved the meat-like physicochemical and textural properties, taste, and flavor of products. The fermentation period was greatly shortened than animal meat-based fermented sausage. For comparison reasons, the aroma profiles of meat substitute fermented sausages (MS-FS), fermented sausages without curing (MS-NCFS) and natural fermented sausages (MS-NFS) were systemically analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 156 volatile compounds were identified, and the curing and fermenting process contributed to the increased contents of volatile compounds greatly. Moreover, the MS-FS without curing evaded undesired off-flavors like grass and bean flavor from 1-octen-3-ol. Sensory evaluation was also showed higher scores for MS-FS than other processing.

Interspecies assertiveness of Lactobacillus curvatus and Lactobacillus sakei in sausage fermentations

Lactobacillus (L.) curvatus and L. sakei contain strains, which are assertive in sausage fermentation. Previous work has demonstrated differences in assertiveness at strain level within one species, and revealed either exclusion of competitors by complementary partner strains or their inhibition by single strains. This work addresses interspecies differences in the assertiveness of L. curvatus and L. sakei. Strain sets of L. curvatus and L. sakei were employed as starters in a fermented sausage model and their abundancy upon fermentation was determined by strain-specific MALDI-TOF MS identification. Generally, single or groups of L. sakei strains outcompeted L. curvatus strains. In multiple growth tests employing mMRS and mMSM it could be shown that assertive L. sakei strains can be predicted along their μ max in mMSM. Still, L. curvatus TMW 1.624 could suppress all L. curvatus and most L. sakei strains in competitive settings. This could be referred to its expression of several bacteriocins, which are active against all of the L. curvatus strains. Strain specific differences could be demonstrated in the susceptibility of L. sakei to bacteriocins, and in oxidative stress tolerance, which is higher in co-existing L. sakei strains than in the bacteriocin producer. This suggests that tolerance to bacteriocins and oxidative stress represent additional determinants for assertiveness, above previously reported bacteriocin production versus metabolic complementarism of partner strains.

Evaluation of the physicochemical, biochemical and microbiological characteristics of three Serbian traditional dry-fermented sausages

Three Serbian traditional dry-fermented sausages, Sremski kulen (S), Lemeški kulen (L) and Petrovačka kobasica (P), were compared for physicochemical, biochemical and microbiological properties, in order to provide complex overview of their quality and safety. The sausages were produced and analyzed within two production seasons in traditional practice. Water activity, color, texture and proximate composition varied significantly (P < 0.05), particularly due to moisture, protein and fat content, what indicated differences in basic formulation of raw sausage mixture, type of casing and some technological procedures. Based on the fatty acid profile the most favorable PUFA/SFA ratio was obtained in sausage P (0.68), while the obtained results for acid value (15.2-22.4 mg KOH/g lipid) and TBARS value (0.27-0.55 mg malondialdyde/kg) indicated low level of lipid degradation and oxidation in all samples. Regarding the microbial and biogenic amines (BA) analysis, positive outcome of this research is the total absence of all pathogenic microorganisms examined, while the registered levels of BA showed a great variability among the sausages. In particular, total BA content in L attained level that is approx. 50% higher than the recommended one. Hence, special care should be implemented regarding the future production and consumption of this type of sausage. Overall results of this study may be useful to define complete distinctive features of these sausages, to determine relations among them, as well as to improve some phases of traditional manufacturing process.

Detection and quantification of hepatitis E virus RNA in ready to eat raw pork sausages in the Netherlands

The aim of the present study was to assess raw pork sausages collected on the Dutch market for the presence of hepatitis E virus (HEV) RNA. 46 of 316 (14.6%) products sampled from Dutch retail stores in 2017-2019 were positive for HEV RNA. HEV RNA was detected in 10.8% of "cervelaat" (n = 74), 18.5% of salami (n = 92), 26.1% of "metworst" (n = 46), 16.3% of "snijworst" (n = 43) samples. This was significantly more often than in other raw pork sausages like dried sausages, fuet or chorizo (3.3%, n = 61). The percentage of HEV RNA positive products was not significantly different for products sold as either sliced or unsliced deli meat. The average viral load in positive tested products was 2.76 log₁₀ genome copies per 5 g, incidentally reaching up to 4.5 log₁₀ genome copies per 5 g. The average HEV RNA level was significantly higher in samples collected in 2017 than those in samples collected in 2018, and most of the samples in 2019. Typing by sequence analysis was successful for 33 samples, all revealing genotype 3c. The results support recent epidemiological studies that identified specific raw pork sausages as risk factor for hepatitis E virus infection in the Netherlands. Persons at risk, including Dutch transplant recipients, have been advised to avoid the consumption of raw pork sausages. The study warrants a continuation of monitoring to follow the HEV RNA levels in pork products for use in risk assessments and risk management.

Applicability of potentially probiotic Lactobacillus casei in low-fat Italian type salami with added fructooligosaccharides: in vitro screening and technological evaluation

The aim was to evaluate the use of Lactobacillus casei strains in the fermentation process of low-fat Italian type salami with fructooligosaccharides (FOS). A screening using probiotic strains was performed at pH 5.5, 5.0 and 4.5 and incubation temperatures of 15 and 25 °C. Lactobacillus casei SJRP66 and Lactobacillus casei SJRP169 were selected and added to the low-fat fermented sausage - C (control), FOS (25% reduced fat with 2% FOS), FOS_66 (25% reduced fat with 2% FOS and L.casei SJRP 66) and FOS_169 (25% reduced fat with 2% FOS and L.casei SJRP 169). The evaluation included pH, moisture, lactic acid bacteria count, probiotic count, weight loss, instrumental color, TBARS and texture parameters. FOS_66 and FOS_169 presented a good probiotic count (8 log CFU/g) and similar technological behavior to the control. The addition of the probiotic showed no effect on lipid oxidation and * value. These strains of probiotic showed promising properties for applications in low-fat Italian type salami with healthier appeal.

Technological properties of autochthonous Lactobacillus plantarum strains isolated from sucuk (Turkish dry-fermented sausage)

PURPOSE

Five Lactobacillus strains isolated from sucuk (Turkish dry-fermented sausage) were studied for their genetic and technological properties.

METHODS

For genotypic identification, strains 16S rRNA gene sequences were used. To determine the antimicrobial activity of strains, seven foodborne pathogens were tested. Strains technological properties were characterized.

RESULTS

These strains were identified as Lactobacillus plantarum by 16S rRNA gene sequence analysis and the phylogenetic tree obtained by neighbor-joining method allowed grouping of these strains into three subgroups. L. plantarum strains showed antagonistic activities against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Micrococcus luteus strains. PCR assay, using specific primers, showed the presence of bacteriocin (plantaricin) encoding genes in all L. plantarum strains tested. Antimicrobial metabolite production of these strains started at log phase and reached the maximum level at the end of the stationary phase. Regarding their technological properties, better growth was observed at 25 °C compared with 15 °C and 45 °C. The isolates which grown well within the pH scale pH 4.5-6.5 range additionally showed a decent growth at 6.5% salt concentration. It has been found that strains do not exhibit lipolytic and proteolytic activities nor have lysine, ornithine, and arginine decarboxylase activity. On the other hand, one strain showed weak nitrate reductase activity, and four strains produced acetoin from glucose. In addition, all strains were DL-lactic acid producers. Consequently, L. plantarum strains isolated exhibited some biochemical properties required for a starter culture in sucuk and similar products.

CONCLUSIONS

All identified strains may be a protective culture in the production of fermented meat products. In particular, L. plantarum S51 was distinguished from other isolates due to the inability to form acetoin from glucose. Further work will be needed to characterize L. plantarum strains as starter culture.

Assessment of safety aspect and probiotic potential of autochthonous Enterococcus faecium strains isolated from spontaneous fermented sausage

OBJECTIVE

The objectives of this research project were isolation, identification, and evaluation of the safety aspect and probiotics properties of 21 Enterococcus faecium strains isolated from sausages originated from southeastern Serbia.

RESULTS

Analyzed E. faecium isolates showed tolerance to simulated gastrointestinal conditions. All the examined isolates grew well on media with 0.1% and 0.2% of phenol. None of the tested isolates were histamine-producers, while the synthesis of tyramine was observed for E. faecium sk8-1 and sk8-17. Full resistance to antibiotics was not observed for any examined isolate of E. faecium (penicillin, amoxicillin, and ofloxacin showed the effect on all tested isolates). An inhibition zone against examined pathogens was exhibited by all strains, with the largest inhibition zone against Pseudomonas spp., Proteus spp. and E. coli (12-30 mm/MIC values ranged from 0.5 to 12 mg mL^-1).

CONCLUSION

The results indicated that E. faecium isolates from spontaneously fermented sausage showed a potential for further investigation and possible application as probiotics.

Isolation, identification, and potential probiotic characterization of isolated lactic acid bacteria and in vitro investigation of the cytotoxicity, antioxidant, and antidiabetic activities in fermented sausage

BACKGROUND

Probiotic bacteria can provide health benefits when delivered in functional foods. This study involved isolation of lactic acid bacteria (LAB) from traditionally dried and salted anchovy fish and characterization of their survival in simulated gastrointestinal digestion. Promising strains were used to prepare fermented fish sausages which were then evaluated for cytotoxicity activity against two cancer cell-lines, antidiabetic activity as determined by α-amylase and α-glucosidase inhibition, and antioxidant and proteolytic activities in vitro, as compared to non-fermented control sausages.

RESULTS

Out of 85 LAB obtained, 13 isolates with high tolerance to simulated gastrointestinal digestion were obtained, which were identified as Enterococcus spp. Four E. faecium strains, one E. faecalis, and one E. durans were used separately to make fermented fish sausages. The α-amylase and α-glucosidase inhibition from fish sausages fermented by Enterococcus spp. ranged from 29.2 to 68.7% and 23.9 to 41.4%, respectively, during 21 days of storage. The cytotoxicity activities against Caco₂ and MCF-7 cells of fish sausages fermented with Enterococcus spp. ranged from 18.0 to 24% and 13.9 to 27.9%, respectively. Cytotoxicity activities correlated positively with proteolysis and antioxidant activities, α-amylase and α-glucosidase inhibition activities, but negatively with the pH in fermented fish sausages. Strains also exhibited antimicrobial activity against foodborne pathogens and presented no significant concerns with regards to antibiotic resistance or virulence gene content.

CONCLUSIONS

Fish sausages fermented by potential probiotic isolates of Enterococcus spp. from dried fish had valuable health-promoting benefits compared with non-fermented control sausages.

Can dietary fiber improve the technological characteristics and sensory acceptance of low-fat Italian type salami?

To meet the needs of new consumers, meat researchers need to develop healthier products. Dietary fibers can be added for structural purposes, to present functional characteristics or to change the composition of the final product. In this study, mixture design was used to investigate the effects of partial substitution of pork fat by inulin, fructooligosaccharides and α-cyclodextrin on the technological and sensory quality characteristics of low-fat Italian type salami. The partial substitution of fat using dietary fibers shows no effect on weight loss, Aw and pH during ripening time. However, the addition of up to 2% α-cyclodextrin increased lightness and reduced redness and yellowness. Up to 2% of inulin or fructooligosaccharides added improved the sensory acceptance, texture parameters and redness. Healthier low-fat Italian type salami can be produced using inulin or fructooligosaccharides as fat substitute for pork fat and still obtain good technological and sensorial results.

Analysis for change in microbial contents in five mixed Kimchi starter culture and commercial lactic acid bacterial-fermented sausages and biological hazard in manufacturing facilities

The purpose of this study was to compare change in microbial contents between sausages with five mixed Kimchi starter culture (T1) and commercial lactic acid bacterial (LAB) (T2) during fermentation, and to screen manufacturing facilities for microbial condition. For T1 and T2, pH levels decreased at 7 days and increased at 14 days. For color, the lightness of T1 decreased at 7 days (36.50 ± 6.04) and slightly increased at 14 days (38.40 ± 4.35). In addition, T1 and T2 were observed decrement of redness and increment of yellowness during ripening. Mold, yeast, and LAB were detected, whereas pathogenic bacteria were not detected in both sausages (T1 and T2) and screening manufacturing facilities. Taken together, five mixed Kimchi starter culture fermented sausage was similar to commercial LAB-fermented sausage, and this study could be used to information as basic data biological hazard for HACCP system in fermented sausage.

The investigation of the use of beetroot powder in Turkish fermented beef sausage (sucuk) as nitrite alternative

The objective of this study was to examine the effects of reformulation of Turkish dry fermented beef sausage (sucuk) by replacing nitrite with beetroot powder (BP), which has high nitrate content, on some quality characteristics of the product during storage at 4 °C for 84 days. Four different sausage formulations were produced containing C:150 mg/kg sodium nitrite; BS1:100 mg/kg sodium nitrite and 0.12% BP; BS2:50 mg/kg sodium nitrite and 0.24% BP and BS3: 0.35% BP. The inclusion of BP increased a* value of samples and resulted in the protection of the desired red color during storage. There was no significant difference between the residual nitrite contents of the samples at the end of the storage period. The lactic acid bacteria count was highest in BS3. Suggested storage periods for BS2 and BS3 samples were 56 days by taking into consideration the TBARS value. Sensory evaluation scores of samples with BP were comparable to those of C during storage.

Effect of In Vitro Human Digestion on Biogenic Amine (Tyramine) Formation in Various Fermented Sausages

Biogenic amines are formed in various fermented foods by microbial amino acid decarboxylation activities, and ingestion of these amines may cause human illness. However, the effect of digestion on the biogenic amines in fermented sausages has not been studied. This study was conducted to determine the effect of in vitro human digestion with the enterobacteria Escherichia coli and Lactobacillus casei on concentrations of the biogenic amine tyramine in six types of fermented sausages. Tyramine concentration was not significantly changed until simulated digestion in the small intestine. However, tyramine concentration for all sausage samples was increased after simulated digestion in the large intestine. Addition of E. coli and L. casei dramatically increased the tyramine concentrations ( P < 0.05). This result indicates that enterobacteria increase biogenic amine concentrations during human digestion.

Potential of a lactic acid bacterial starter culture with gamma-aminobutyric acid (GABA) activity for production of fermented sausage

The ability of lactic acid bacterial starter cultures to produce gamma-aminobutyric acid (GABA) during sausage fermentation was studied. Among 305 strains of lactic acid bacteria isolated from kimchi samples, 11 strains were selected as starter candidates based on the following criteria: growth speed, pH lowering ability, and biogenic amine productivity including GABA-producing activity. During in vitro tests, the Y8 (Lactobacillus brevis), O52, and KA20 strains produced 39.00 ± 1.36, 49.73 ± 3.80, and 64.59 ± 0.61 mg/kg of GABA, respectively. Interestingly, although isolate Y8 showed low productivity in vitro, the GABA content it produced during in situ tests (61.30 ± 2.61 mg/kg) was similar to that produced by isolate PM3 (L. brevis) used as positive control (69.64 ± 2.20 mg/kg). Therefore, isolate Y8 was selected as the best functional starter culture for the production of fermented sausage because it exhibited rapid growth, safety, and abundant GABA productivity.

Lactic acid bacterial population dynamics during fermentation and storage of Thai fermented sausage according to restriction fragment length polymorphism analysis

This study applied restriction fragment length polymorphism (RFLP) analysis to identify the lactic acid bacteria (LAB) isolated from "mum" Thai fermented sausages during fermentation and storage. A total of 630 lactic acid bacteria were isolated from the sausages prepared using 2 methods. In Method 1, after stuffing, the sausages were stored at 30 °C for 14 days. In Method 2, after stuffing and storage at 30 °C for 3 days, the sausages were vacuum-packed and stored at 4 °C until Day 28. The sausages were sampled on Days 0, 3, 14, and 28 for analyses. The 16S rDNA was amplified and digested using restriction enzymes. Of the restriction enzymes evaluated, Dde I displayed the highest discrimination capacity. The LAB were classified and 7 species were identified For Methods 1 and 2, during fermentation, the Lactobacillus sakei and Lactobacillus plantarum species were dominant. For Method 2, the proportion of Leuconostoc mesenteroides markedly increased during storage, until L. sakei and Ln. mesenteroides represented the dominant species. The identification of LAB in the sausage samples could facilitate the selection of appropriate microorganisms for candidate starter cultures for future controlled mum production.

Investigation of reduction and tolerance capability of lactic acid bacteria isolated from kimchi against nitrate and nitrite in fermented sausage condition

Lactobacillus brevis KGR3111, Lactobacillus curvatus KGR 2103, Lactobacillus plantarum KGR 5105, and Lactobacillus sakei KGR 4108 isolated from kimchi were investigated for their potential to be used as starter culture for fermented sausages with the capability to reduce and tolerate nitrate/nitrite. The reduction capability of tested strains for nitrate was not dramatic. All tested strains, however, showed the capability to produce nitrite reductase with the reduction amount of 58.46-75.80 mg/l of NO(2)(-). L. brevis and L. plantarum showed nitrate tolerance with the highest number of 8.71 log cfu/ml and 8.81 log cfu/ml, and L. brevis and L. sakei exhibited nitrite tolerance with the highest number of 8.24 log cfu/ml and 8.25 log cfu/ml, respectively. As a result, L. brevis, L. plantarum, and L. sakei isolated from kimchi showed a tolerance against nitrate or nitrite with a good nitrite reduction capability, indicating the satisfaction of one of the selection criteria to be used as starter culture for fermented sausages.

Effect of reducing and replacing pork fat on the physicochemical, instrumental and sensory characteristics throughout storage time of small caliber non-acid fermented sausages with reduced sodium content

The effect of pork fat reduction (from 44% to 20% final fat content) and its partial substitution by sunflower oil (3% addition) on the physicochemical, instrumental and sensory properties throughout storage time of small caliber non-acid fermented sausages (fuet type) with reduced sodium content (with partial substitution of NaCl by KCl and K-lactate) and without direct addition of nitrate and nitrite (natural nitrate source used instead) was studied. Results showed that sausages with reduced fat (10% initial fat content) and with acceptable sensory characteristics can be obtained by adding to the shoulder lean (8% fat content) during the grinding, either 3.3% backfat (3% fat content) or 3% sunflower oil, both previously finely comminuted with lean. Furthermore, sunflower oil showed to be suitable for partial pork backfat substitution in very lean fermented sausages, conferring desirable sensory properties similar to those of sausages with standard fat content. The sensory quality of the sausages was maintained after three-month cold storage in modified atmosphere.

Evolution of amino acids and biogenic amines throughout storage in sausages made of horse, beef and turkey meats

The changes in concentration of free amino acids and biogenic amines, along 28 d of storage at 4°C, were monitored in a wide range of European ripened sausages manufactured from horse, beef and turkey meats. Generally speaking, both chemical families became more concentrated with elapsing time--but rather distinct patterns were followed in each meat type: total free amino acids increased by 13-fold in the case of horse sausages, and 5-fold in the case of beef sausages, but decreased to one third in the case of turkey sausages; and total biogenic amines attained 730 mg/kg in turkey sausages, 500 mg/kg in beef sausages and 130 mg/kg in horse sausages by 28 d of refrigerated storage. For putrescine, maximum levels of 285 mg/kg were attained in turkey and 278 mg/kg in beef sausages; for cadaverine, maximum levels of 6 mg/kg in turkey and 9 mg/kg in beef; and for histamine, maximum levels of 263 mg/kg in turkey and 26 mg/kg in beef. Hence, public safety concerns may be raised in the case of turkey sausages.

Inhibition of Listeria monocytogenes and Escherichia coli O157:H7 in liquid broth medium and during processing of fermented sausage using autochthonous starter cultures

The antimicrobial effect of two autochthonous starter cultures of Lactobacillus sakei was evaluated in vitro (in liquid broth medium) and in situ assays. The inactivation of foodborne pathogens Listeria monocytogenes (serotype 4ab No 10) and Escherichia coli O157:H7 ATCC 43888 was investigated during the production of fermented sausage according to a typical Greek recipe using L. sakei strains as starter cultures. The inactivation kinetics were modeled using GInaFiT, a freeware tool to assess microbial survival curves. By the end of the ripening period, the inhibition of L. monocytogenes was significant in treatments with L. sakei 8416 and L. sakei 4413 compared to the control treatment. A 2.2-log reduction of the population of E. coli O157:H7 resulted from the autochthonous starter culture L. sakei 4413 during sausage processing. The use of the autochthonous starter cultures constitutes an additional improvement to the microbial safety by reducing foodborne pathogens.