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High incidences of the foodborne pathogen Listeria monocytogenes have been reported on smear cheeses, and despite increased hygiene efforts, this incidence has remained stable in recent years. Applying antilisterial strains may increase the safety of smear cheeses. To find and test antilisterial strains, we inoculated fresh soft cheeses from nine dairies with the surrogate species Listeria innocua and assessed its growth under standardized ripening conditions. Acetic acid at day 23 (r = −0.66), lactose in fresh cheese (r = −0.63), and glucose at day 10 (r = −0.62), as well as seven amplicon sequence variants (ASVs), were negatively correlated with L. innocua growth. Two of these ASVs were assigned to the genus Leuconostoc of Lactobacillaceae (r = −0.82 and −0.71). Isolates from this family, from Aerococcaceae, and Carnobacteriaceae were characterized according to their inhibitory properties, and those showing antilisterial properties were applied as protective cultures in challenge tests. The combined application of strains of Leuconostoc mesenteroides, Aerococcaceae, and Carnobacteriaceae successfully eliminated low levels of L. innocua in the final products. This is likely explained by antimicrobial compounds, including mesentericin Y105 and acetate, and competition for carbon sources and iron. This study shows a promising way to improve the safety of soft smear cheeses by applying defined protective cultures. [ABSTRACT FROM AUTHOR]

Alcohol-related hangovers impact both physical and mental wellness, largely due to acetaldehyde levels produced through alcohol metabolism. The present study investigated the efficacy and safety of the Wilac L probiotic complex (Levilactobacillus brevis WiKim0168 and Leuconostoc mesenteroides WiKim0172 isolated from kimchi) in improving hangovers post-alcohol consumption. This study was conducted as a randomized, double-blind, crossover placebo-controlled clinical trial from August 2023 to February 2024. Subjects (n = 26) were randomized into six test groups consuming three products, the Wilac L probiotic complex, Wilac L35 (Wilac L probiotic complex with Pyrus pyrifolia Nakai), or placebo, in different orders with crossover after a wash-out interval of 7–10 days. Blood alcohol and acetaldehyde concentrations were measured 0, 0.25, 0.5, 1, 2, 4, 6, and 15 h after alcohol consumption. The blood acetaldehyde levels measured with Wilac L probiotic complex supplementation were significantly lower than the control at 0.25 (p = 0.0381), 0.5 (p = 0.0498), and 1 h (p = 0.0260) post-consumption. The blood acetaldehyde levels after Wilac L35 consumption compared to the control are significant at 0.25 (p = 0.0115), 0.5 (p = 0.0054), 1 (p = 0.0285), 2 (p = 0.0113), and 6 h (p = 0.0287) post-consumption. No significant adverse events were reported. The Wilac L probiotic complex is associated with decreased blood acetaldehyde levels and improved subjective hangover symptoms. [ABSTRACT FROM AUTHOR]

This study investigated the impact of a transglycosylated product (ACOD) catalyzed by Leuconostoc mesenteroides MKSR dextransucrase using sucrose as a glucosyl donor and both maltose and Artemisia capillaris as acceptors on gut microbiota through fecal fermentation. ACOD promoted the growth of probiotics such as Lactiplantibacillus plantarum, Lacticaseibacillus casei, Lacticaseibacillus rhamnosus GG, and Leuconostoc mesenteroides MKSR, while inhibiting the growth of pathogenic bacteria such as Escherichia coli, E. coli O157:H7, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, Shigella flexneri, Streptococcus mutans, Pseudomonas aeruginosa, and Bacillus cereus during independent cultivation. Fecal fermentation for 24 h revealed that ACOD significantly increased the production of short-chain fatty acids (SCFAs) compared to the blank and fructoooligosaccharide (FOS) groups. Specifically, ACOD led to a 4.5-fold increase in acetic acid production compared to FOSs and a 3.3-fold increase in propionic acid production. Both the ACOD and FOS groups exhibited higher levels of butyric acid than the blank. Notably, ACOD significantly modulated the composition of the gut microbiota by increasing the relative abundances of Lactobacillus and decreasing Escherichia/Shigella and Salmonella. In contrast, FOSs remarkably promoted the growth of Salmonella. These findings suggest that ACOD is a potential candidate for prebiotics that improve the intestinal environment by being actively used by beneficial bacteria. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the biological activity and probiotic properties of lactic acid bacteria (LAB) isolated from sweet potato stalk kimchi (SPK). Various LAB and Bacillus spp. are active in the early stages of the fermentation of kimchi made from sweet potato stalk. Four strains of LAB were identified, including SPK2 (Levilactobacillus brevis ATCC 14869), SPK3 (Latilactobacillus sakei NBRC 15893), SPK8 and SPK9 (Leuconostoc mesenteroides subsp. dextranicum NCFB 529). SPK2, SPK3, SPK8, and SPK9 showed 64.64–94.23% bile acid resistance and 78.66–82.61% pH resistance. We identified over 106 CFU/mL after heat treatment at 75 °C. Four strains showed high antimicrobial activity to Escherichia coli and Salmonella Typhimurium with a clear zone of >11 mm. SPK2 had the highest antioxidative potentials, higher than the other three bacteria, with 44.96 μg of gallic acid equivalent/mg and 63.57% DPPH scavenging activity. These results demonstrate that the four strains isolated from sweet potato kimchi stalk show potential as probiotics with excellent antibacterial effects and may be useful in developing health-promoting products. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an innovative sourdough using dehydrated okra (Abelmoschus esculentus L.) pod flour and to use it in the production of bread. Three different flours (sun-dried S, freeze-dried F, oven-dried O) were individually mixed at 9% with wheat flour (Dough Yield 300) and fermented (N0: 8.0 log10 CFU/g) for 14 h, using Lactiplantibacillus plantarum ITM21B, Weissella cibaria C43-11 or Leuconostoc mesenteroides C43-2M. The results showed that after fermentation, the content of organic acids (lactic, acetic and propionic), exopolysaccharides (EPS), l-glutamic acid and total free amino acids (TFAA) increased and the high molecular weight proteins were converted into smaller proteins. Sourdough based on Leuc. mesenteroides and O flour (O_LeuMes) was selected to evaluate its applicability in bread making. It was included in the yeast-leavened bread formulation at 20 or 40% (0.6% and 1.21% w/w O flour replacement). The results showed that fermentation limited the negative effects of unfermented O flour on bread quality attributes, mainly the specific volume and firmness. Bread with O_LeuMes at 40% was improved in TFAA, EPS and l-glutamic acid content and showed a higher specific volume and lower moisture and firmness compared to bread with the unfermented O flour. [ABSTRACT FROM AUTHOR]

Isolation of new plant-derived lactic acid bacteria (LAB) is highly prioritized in developing novel starter cultures for plant-based fermentation. This study explores the diversity of LAB in Danish flowers and their potential use for plant-based food fermentation. A total of 46 flower samples under 34 genera were collected for LAB isolation. By introducing an enrichment step, a total of 61 LAB strains were isolated and identified using MALDI-TOF and 16S rRNA sequencing. These strains represent 24 species across 9 genera, predominantly Leuconostoc mesenteroides, Fructobacillus fructosus, Apilactobacillus ozensis, and Apilactobacillus kunkeei. Phenotypic screening for exo-cellular polysaccharide production revealed that 40 strains exhibited sliminess or ropiness on sucrose-containing agar plates. HPLC analysis confirmed that all isolates produced exo-cellular polysaccharides containing glucose, fructose, or galactose as sugar monomers. Therefore, the strains were glucan, fructan, and galactan producers. The suitability of these strains for plant-based fermentation was characterized by using almond, oat, and soy milk. The results showed successful acidification in all three types of plant-based matrices but only observed texture development in soy by Leuconostoc, Weissella, Lactococcus, Apilactobacillus, and Fructobacillus. The findings highlight the potential of flower-derived LAB strains for texture development in soy-based dairy alternatives. [ABSTRACT FROM AUTHOR]

The anti-inflammatory effects of supernatants produced from sprouted barley inoculated with Lactiplantibacillus plantarum KCTC3104 (Lp), Leuconostoc mesenteroides KCTC3530 (Lm), Latilactobacillus curvatus KCTC3767 (Lc), or a mixture of these lactic acid bacteria were investigated using RAW264.7 macrophages. BLp and BLc, the lyophilized supernatants of fermented sprouted barley inoculated with Lp and Lc, respectively, effectively reduced the nitric oxide (NO) levels hypersecreted by lipopolysaccharide (LPS)-stimulated RAW264.7 and LPS-stimulated Caco-2 cells. BLp and BLc effectively reduced the NO levels in LPS-stimulated RAW264.7 macrophages, and these effects tended to be concentration-dependent. BLc and BLp also exhibited strong DPPH radical scavenging activity and immunostimulatory effects. BLp and BLc significantly suppressed the levels of NO and pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 in LPS-stimulated RAW264.7 macrophages and LPS-stimulated Caco-2 cells, indicating their anti-inflammatory effects. These effects were greater than those of unfermented barley sprout (Bs). The functional components of Bs, BLp, and BLc were analyzed by HPLC, and it was found that lutonarin and saponarin were significantly increased in the fermented sprouted barley sample inoculated with Lp and Lc (BLp and BLc). [ABSTRACT FROM AUTHOR]

This study aimed to isolate lactic acid bacteria (LAB) from a traditional Ethiopian fermented product, Tella, and evaluate their functional properties. Of forty-three isolates, seven LAB were screened and identified as Pediococcus pentosaceus, Latilactobacillus curvatus, Leuconostoc mesenteroides, and Lactiplantibacillus plantarum species. The isolates were tested for their alcohol tolerance, acid and bile resistance, auto-aggregation, co-aggregation, hydrophobicity, antibacterial activity, and antibiotic susceptibility. LAB isolates, specifically P. pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41, showed a higher degree of alcohol tolerance in 8% and 10% (w/v) ethanol concentrations. Additionally, these three isolates displayed survival rates >85% in both acidic pH and bile environments. Among the isolates, L. plantarum TDM41 demonstrated the highest auto-aggregation, co-aggregation, and hydrophobicity with (44.9 ± 1.7)%, (41.4 ± 0.2)%, and (52.1 ± 0.1)% values, respectively. The cell-free supernatant of the isolates exhibited antibacterial activity against foodborne pathogens of Escherichia coli, Salmonella Enteritidis, and Staphylococcus aureus. Each isolate exhibited various levels of resistance and susceptibility to seven antibiotics and resistance was observed against four of the antibiotics tested. After performing a principal component analysis, Pediococcus pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41 were selected as the most promising ethanol-tolerant probiotic isolates. [ABSTRACT FROM AUTHOR]

As one of the typical representatives of Chinese rice wine (Huangjiu), Hongqu rice wine is produced with glutinous rice as the main raw material and Hongqu as the fermentation starter. The complex microbial flora in the brewing process may have a great influence on the formation of the flavor quality and drinking safety of Hongqu rice wine. Previous studies have shown that high biogenic amine (BA) content in rice wine has potential physiological toxicity and has become a bottleneck problem restricting the development of the rice wine industry. This study aimed to evaluate the regulatory effects of the microbial community on the formation of BAs and volatile flavor components during the brewing of Hongqu rice wine. The results demonstrated that histamine, putrescine, cadaverine, tyramine, tryptamine, spermine, and spermidine were the main BAs in Hongqu rice wine. The contents of putrescine, cadaverine, histamine, tyramine, and spermidine in Hongqu rice wine of HBAs (with higher BAs content) were significantly higher than those in LBAs (with lower BAs content). GC-MS testing results showed that there were significant differences in the composition of volatile organic compounds (VOCs) between HBAs and LBAs. Among them, VOCs such as 2-methoxy-4-vinylphenol, ethyl caprate, phenethyl acetate, ethyl lactate, ethyl myristate, ethyl palmitate, ethyl n-octadecanoate, ethyl oleate, and ethyl linoleate were identified as the characteristic volatile components with significant differences between HBAs and LBAs. Microbiome analysis based on metagenomic sequencing revealed that unclassified_g_Pantoea, Klebsiella pneumoniae, Panobacter disperse, unclassified_f_Enterobacteriaceae, Leuconostoc mesenteroides, and Saccharomyces cerevisiae were the dominant microbial species in the HBA brewing process, while Weissella confuse, Pediococcus acidilactici, Saccharomyces cerevisiae, and Aspergillus niger were the dominant microbial species in the LBA brewing process. Furthermore, correlation heatmap analysis demonstrated that BAs were positively related to Lactobacillus curvatus, Lactococcus lactis, and Leuconostoc mesenteroides. Bioinformatical analysis based on the KEGG database revealed that the microbial genes encoding enzymes involved in BAs' synthesis were more abundant in HBAs, and the abundances of microbial genes encoding enzymes related to BAs' degradation and the metabolism of characteristic volatile components were higher in LBAs. Overall, this work provides important scientific data for enhancing the flavor quality of Hongqu rice wine and lays a solid foundation for the healthy development of the Hongqu rice wine industry. [ABSTRACT FROM AUTHOR]

Leuconostoc mesenteroides strains are common contributors in fermented foods producing a wide variety of polysaccharides from sucrose through glycosyltransferases (GTFs). These polymers have been proposed as protective barriers against acidity, dehydration, heat, and oxidative stress. Despite its presence in many traditional fermented products and their association with food functional properties, regulation of GTFs expression in Ln. mesenteroides is still poorly understood. The strain Ln. mesenteroides ATCC 8293 contains three glucansucrases genes not found in operons, and three fructansucrases genes arranged in two operons, levLX and levC-scrB, a Glycoside-hydrolase. We described the first differential gene expression analysis of this strain when cultivated in different carbon sources. We observed that while GTFs are expressed in the presence of most sugars, they are down-regulated in xylose. We ruled out the regulatory effect of CcpA over GTFs and did not find regulatory elements with a direct effect on glucansucrases in the condition assayed. Our findings suggest that only operon levLX is repressed in xylose by LexA and that both fructansucrases operons can be regulated by the VicK/VicR system and PerR. It is essential to further explore the effect of environmental conditions in Ln. mesenteroides bacteria to better understand GTFs regulation and polymer function. [ABSTRACT FROM AUTHOR]

Texture and flavour are the key attributes determining sensory quality and are highly affected by starter cultures. A selection of phenotypic strains is needed to create diverse texture and flavour to meet consumers' preferences. In this study, the use of five lactic acid bacteria strains in the production of fermented milk, along with the metabolite profiles, microstructure, and rheological properties of the fermented milk samples, was investigated. Our results showed that Lactobacillus helveticus (LH) and Streptococcus thermophilus (ST) had a stronger acidification during fermentation but resulted in products with a coarser protein network compared to Lactococcus lactis (BL1) and Leuconostoc mesenteroides (CL3). Milk fermented by LH had the highest viscosity and exopolysaccharide concentration, while milk fermented by ST had the highest concentration of diacetyl. Although Leuconostoc pseudomesenteroides (CL3ST) had a minimal acidification capability, it produced high levels of ethyl-derived compounds associated with sweet, fruity, and floral fragrances. The results demonstrated that LH and ST could be used as starter cultures targeting fermented milks with different viscosities, while BL1, CL3, and CL3ST are suitable as adjunct cultures to impact different acidic sharpness and flavour notes. [ABSTRACT FROM AUTHOR]

Ulcerative colitis (UC) is caused by inflammation only in the mucosa of the colon, and its incidence is increasing worldwide. The intake of probiotics is known to have a beneficial effect on the development of UC. In this study, we investigated the alleviating effects of kimchi (KC), a fermented food rich in probiotics, and Leuconostoc mesenteroides DRC 1506 (DRC) isolated from kimchi on UC. A freeze-dried kimchi suspension and DRC were orally given to mice at a dose of 1 × 109 CFU/day for 3 weeks. Furthermore, 3% dextran sulfate sodium (DSS) in drinking water was given to induce UC. The KC and DRC groups reduced symptoms of colitis, such as disease activity index, decrease in colon length, colon weight-to-length ratio, and pathological damage to the colon caused by DSS treatment. The KC and DRC groups decreased the levels of pro-inflammatory cytokine (TNF-α) and increased anti-inflammatory cytokine (IL-10) in the colon tissues. At the mRNA and protein expression levels in the colon tissue, KC and DRC groups downregulated inflammatory factors and upregulated tight junction-related factors. Therefore, DRC, as well as KC supplementation, are potent in alleviating UC by improving the inflammatory response and mucosal barrier function in the colon. [ABSTRACT FROM AUTHOR]

Litchi polysaccharides are a kind of macromolecular polymers with various biological activities and a wide range of molecular weights. In this study, two separate fractions, with average molecular weights of 378.67 kDa (67.33%) and 16.96 kDa (6.95%), which were referred to as LP1 and LP2, respectively, were separated using an ultrafiltration membrane. Their physicochemical properties, and immunomodulatory and prebiotic activity were compared. The results revealed that LP2 contained more neutral sugar, arabinose, galactose and rhamnose, but less uronic acid, protein, mannose and glucose than LP1. Compared with LP1, LP2 possessed higher solubility and lower apparent viscosity. LP2 exhibited stronger stimulation on macrophage secretion of NO, TNF-α and IL-6, as well as better proliferation of Lactobacillus plantarum, Leuconostoc mesenteroides, Lactobacillus casei and Bifidobacterium adolescentis. These results suggest that an ultrafiltration membrane might be used to prepare a highly-active polysaccharide fraction from litchi pulp that may be used for food or drug development. [ABSTRACT FROM AUTHOR]

Queijo Serra da Estrela is a PDO Portuguese cheese produced through coagulation of raw ewe's milk using cardoon (Cynara cardunculus L.) flowers. The present research was aimed at depicting an up-to-date and comprehensive overview of the microbiota of Queijo Serra da Estrela cheese. To this end, viable counting and metataxonomic analysis were carried out on cheeses sampled from four Portuguese artisan producers. Physico-chemical and morpho-textural analyses were also performed, together with the analysis of volatile organic compounds (VOCs). Finally, non-starter lactic acid bacteria (NSLAB) isolated from the cheeses were characterized for their enzymatic activities using a semi-quantitative method. According to the metataxonomic analysis, Lactococcus lactis and Lactococcus piscium were the species occurring at the highest relative abundance. The isolates collected from the cheeses were assigned to Enterococcus durans, Enterococcus faecalis, Enterococcus faecium, Enterococcus lactis, Levilactobacillus brevis, Latilactobacillus graminis, Leuconostoc mesenteroides, and the Lacticaseibacillus casei group. The enzymatic characterization of these cultures highlighted esterase, aminopeptidase, acid phosphatase, beta-galactosidase, alpha-glucosidase, and beta-glucosidase among the major enzymatic activities. Fungal populations were dominated by Debaryomyces hansenii and Kurtzmaniella zeylanoides; however, species rarely found in cheese (e.g., Candida boidinii, Vishniacozyma victoriae, and Starmerella) were also detected. The volatile compounds characterizing the analyzed cheeses were carboxylic acids and esters, followed by carbonyl compounds and alcohols. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The European culinary culture relies on a wide range of fermented products of plant origin, produced mostly through spontaneous fermentation. Unfortunately, this kind of fermentations is difficult to standardize. Therefore, the use of commercial starter cultures is becoming common to achieve more stable, reproducible, and predictable results. Among plant-based fermentation processes, that of the red beet (Beta vulgaris L. var. conditiva) is scarcely described in the scientific literature. In this work, we compared different types of fermentation methods of beetroot and evaluated the processes' micro-biological, physico-chemical, structural, and volatilome features. A multi-variate analysis was used to match the production of specific VOCs to each starter and to define the correlations between the process variables and volatilome. Overall, the results showed a successful lactic acid fermentation. The analysis of the volatilome clearly discriminated the metabolic profiles of the different fermentations. Among them, the sample fermented with the mixture was the one with the most complex and diversified volatilome. Furthermore, samples did not appear softened after fermentation. Although this work had its weaknesses, such as the limited number of samples and variety, it may pave the way for the standardization of artisanal fermentation procedures of red beetroot in order to improve the quality and safety of the derived food products. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the antimicrobial potential of different extracts of Simira ecuadorensis, a characteristic plant of Ecuador, and to validate its potential as a food preservative. Four extracts referred to as ethanol, ethanol-water (50:50 v/v), spray-dried, and freeze-dried were obtained under different processes. Initially, their antimicrobial activities were evaluated against a wide group of microorganisms consisting of 20 pathogenic and spoilage microbial strains found in foods through the agar diffusion method. Then, the extracts with the best yields and antimicrobial properties against microorganisms of greatest interest were selected to determine their effect on model foods preserved under normal commercial conditions through challenge tests. Spray-dried and ethanol-water extracts were tested for their ability to inhibit C. jejuni in chicken model products, where is a common pathogen and Shew. putrefaciens in fish model products as it is a spoilage microorganism frequently found in fish. One solid and one liquid were chosen as model foods: burger and broth, respectively. Campylobacter jejuni and Shewanella putrefaciens were effectively inhibited by the four extracts with minimum inhibitory concentration (MIC) of 80 mg/mL. Bacillus cereus, Yersinia enterocolitica, Clostridium perfringens, and Leuconostoc mesenteroides were also inhibited by ethanolic extract. The ethanol-water extract showed greater antimicrobial activity in fish products, whereas spray-dried extract had low growth inhibition of C. jejuni in chicken burgers; however, it was quite effective on C. jejuni in broth. The spray-dried extract significantly decreased the pH of the chicken burgers, while the ethanolic extract had a slight impact on the pH of the fish burgers. The presence of antibacterial effects revealed that the S. ecuadorensis extracts could be potentially used in food preservation and as a natural antimicrobial. [ABSTRACT FROM AUTHOR]

In this study, the fermentation of Artemisia capillaris by probiotic Leuconostoc mesenteroides MKJW (MKJW) was optimized to increase the acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory and antioxidant activities using the response surface method (RSM). The independent variables were the contents of A. capillaris, Gryllus bimaculatus, and yeast extract, while the dependent variables were AChE inhibitory activity, BuChE inhibitory activity, and antioxidant activities such as FRAP, reducing power, and DPPH radical scavenging ability. Seventeen experimental runs were designed with RSM and analyzed after fermentation with MKJW. Quadratic models were used to analyze the inhibition of AChE and BuChE, and a linear model was used to analyze the FRAP. The three models were significantly appropriate (p < 0.0001). The highest optimal condition of the AChE inhibitory activity was derived by a multiple regression equation. When the optimum fermentation conditions were A. capillaris 6.75%, G. bimaculatus 0.18%, and yeast extract 1.27%, 91.1% was reached for AChE inhibitory, 74.0% for BuChE inhibitory, and 34.1 mM FeSO4 for FRAP. The predicted dependent variables were not significantly different from the experimental values (p > 0.05). In conclusion, the A. capillaris fermented by MKJW might be used as a natural antidementia improving agent with AChE inhibitory, BuChE inhibitory, and antioxidant activities. [ABSTRACT FROM AUTHOR]

Leuconostoc mesenteroides strains are common contributors in fermented foods producing a wide variety of polysaccharides from sucrose through glycosyltransferases (GTFs). These polymers have been proposed as protective barriers against acidity, dehydration, heat, and oxidative stress. Despite its presence in many traditional fermented products and their association with food functional properties, regulation of GTFs expression in Ln. mesenteroides is still poorly understood. The strain Ln. mesenteroides ATCC 8293 contains three glucansucrases genes not found in operons, and three fructansucrases genes arranged in two operons, levLX and levC-scrB, a Glycoside-hydrolase. We described the first differential gene expression analysis of this strain when cultivated in different carbon sources. We observed that while GTFs are expressed in the presence of most sugars, they are down-regulated in xylose. We ruled out the regulatory effect of CcpA over GTFs and did not find regulatory elements with a direct effect on glucansucrases in the condition assayed. Our findings suggest that only operon levLX is repressed in xylose by LexA and that both fructansucrases operons can be regulated by the VicK/VicR system and PerR. It is essential to further explore the effect of environmental conditions in Ln. mesenteroides bacteria to better understand GTFs regulation and polymer function.

Ulcerative colitis (UC) is caused by inflammation only in the mucosa of the colon, and its incidence is increasing worldwide. The intake of probiotics is known to have a beneficial effect on the development of UC. In this study, we investigated the alleviating effects of kimchi (KC), a fermented food rich in probiotics, and Leuconostoc mesenteroides DRC 1506 (DRC) isolated from kimchi on UC. A freeze-dried kimchi suspension and DRC were orally given to mice at a dose of 1 × 109 CFU/day for 3 weeks. Furthermore, 3% dextran sulfate sodium (DSS) in drinking water was given to induce UC. The KC and DRC groups reduced symptoms of colitis, such as disease activity index, decrease in colon length, colon weight-to-length ratio, and pathological damage to the colon caused by DSS treatment. The KC and DRC groups decreased the levels of pro-inflammatory cytokine (TNF-α) and increased anti-inflammatory cytokine (IL-10) in the colon tissues. At the mRNA and protein expression levels in the colon tissue, KC and DRC groups downregulated inflammatory factors and upregulated tight junction-related factors. Therefore, DRC, as well as KC supplementation, are potent in alleviating UC by improving the inflammatory response and mucosal barrier function in the colon.

Plant-based foods with desirable texture and nutritional value have attracted considerable interest from consumers. In order to meet the growing demand for more sustainable and health-focused products, new sources for plant-based products are needed. In this study, we aimed to develop an innovative plant-based dessert based on the underutilized crop chufa tubers (Cyperus esculentus). The chufa extract was fermented with plant-adapted lactic acid bacteria and formulated with the purpose of imitating the Danish summer dessert “cold butter-milk soup”. The effect of various bacterial fermentations and formulations on steady and oscillatory rheology, stability, dry matter, pH, and sugar profile of the product were studied and compared to a commercial cold buttermilk soup sample. A strain of Leuconostoc mesenteroides was found to create the most similar taste to a commercial sample. By adding lemon juice, sucrose, xanthan gum, and vanilla to the fermented chufa drink, the drink was found to mimic the pH, texture, acid profile, and stability of a commercial dairy-based sample, while containing a lower concentration of carbohydrates. [ABSTRACT FROM AUTHOR]

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.

The European culinary culture relies on a wide range of fermented products of plant origin, produced mostly through spontaneous fermentation. Unfortunately, this kind of fermentations is difficult to standardize. Therefore, the use of commercial starter cultures is becoming common to achieve more stable, reproducible, and predictable results. Among plant-based fermentation processes, that of the red beet (Beta vulgaris L. var. conditiva) is scarcely described in the scientific literature. In this work, we compared different types of fermentation methods of beetroot and evaluated the processes’ micro-biological, physico-chemical, structural, and volatilome features. A multi-variate analysis was used to match the production of specific VOCs to each starter and to define the correlations between the process variables and volatilome. Overall, the results showed a successful lactic acid fermentation. The analysis of the volatilome clearly discriminated the metabolic profiles of the different fermentations. Among them, the sample fermented with the mixture was the one with the most complex and diversified volatilome. Furthermore, samples did not appear softened after fermentation. Although this work had its weaknesses, such as the limited number of samples and variety, it may pave the way for the standardization of artisanal fermentation procedures of red beetroot in order to improve the quality and safety of the derived food products.

Leuconostoc mesenteroides includes strains used as starter and/or adjunct cultures for the production of several fermented foods. In this study, the effect of anaerobic and respiratory cultivations, as well as of citrate supplementation and different pH values, was evaluated on growth, biomass, metabolite, and enzymatic activities (pyruvate oxidase, POX; NADH-dependent oxidase, NOX; NADH-dependent peroxidase, NPR) of Leuconostoc mesenteroides subsp. cremoris E30. We compared the respiration-increased growth rate and biomass production of Leuc. mesenteroides E30 to anaerobic cultivation. A supplementation of citrate impaired the growth rate of the respiratory cells. As expected, anaerobic cultures did not consume oxygen, and a similar trend in oxygen uptake was observed in respiratory cultures. The aerobic incubation caused changes in the metabolic pattern, reducing the production of ethanol in favour of acetic acid. Citrate was already exhausted in the exponential phase and did not affect the yields in acetic acid and ethanol. NOX activity increased in the presence of oxygen, while catalase was also detected in the absence of hemin. The absence of H2O2 suggested its degradation by NPR and catalase. Respiratory cultivation provided benefits (increase in growth rate, biomass, and activity in antioxidant enzymes) for Leuc. mesenteroides E30. Therefore, the exploitation of respiratory phenotypes may be useful for the formulation of competitive starter or adjunct cultures.

Effective biopreservation measures are needed to control the growth of postprocess Listeria monocytogenes contamination in fresh whey cheeses stored under refrigeration. This study assessed growth and biocontrol of inoculated (3 log10 CFU/g) L. monocytogenes in vacuum-packed, fresh (1-day-old) or ‘aged’ (15-day-old) Anthotyros whey cheeses, without or with 5% of a crude enterocin A-B-P extract (CEntE), during storage at 4 °C. Regardless of CEntE addition, the pathogen increased by an average of 2.0 log10 CFU/g in fresh cheeses on day 15. Gram-negative spoilage bacteria also increased by an average of 2.5 log10 CFU/g. However, from day 15 to the sell-by date (days 35–40), L. monocytogenes growth ceased, and progressively, the populations of the pathogen declined in most cheeses. This was due to an unmonitored, batch-dependent natural acidification by spoilage lactic acid bacteria, predominantly Leuconostoc mesenteroides, which reduced the cheese pH to 5.5, and finally to ≤5.0. The pH reductions and associated declines in pathogen viability were greater in the CEntE-treated samples within each batch. L. monocytogenes failed to grow in cheeses previously ‘aged’ in retail for 15 days. Overall, high population levels (>7.5 log10 CFU/g) of psychrotrophic Enterobacteriaceae, particularly Hafnia alvei, were associated with an extended growth and increased survival of L. monocytogenes during storage.

Although fresh whey cheeses are prone to rapid deterioration, mainly by psychrotrophic Gram-negative bacteria and lactic acid bacteria (LAB), data on the specific spoilage species in traditional Greek whey cheeses are scarce. Therefore, this study quantified growth and characterized the primary spoilage bacteria in fresh Anthotyros whey cheeses stored at 4 °C in a vacuum for 40 days, without or with an added 5% (v/w) of an enterocin A-B-P crude extract (CEntE). Psychrotrophic Pseudomonas spp., Aeromonas spp., Hafnia spp. and Serratia spp. grew faster than LAB during early storage. However, LAB outgrew the Gram-negative bacteria and prevailed by mid to late storage in all cheese batches, causing a strong or milder batch-dependent natural acidification. Two major non-slime-producing and two minor biotypes of Leuconostoc-like bacteria, all identified as Leuconostoc mesenteroides by 16S rRNA sequencing, dominated the LAB association (76.7%), which also included four subdominant Carnobacterium maltaromaticum biotypes (10.9%), one Leuconostoc lactis biotype (3.3%) and few Lactococcus (1.6%), mesophilic Lactobacillus (0.8%) and Enterococcus (0.8%). Growth and distribution of LAB and Gram-negative species were strongly batch-dependent and plant-dependent. The CEntE neither retarded growth nor altered the whey cheese spoilage association but enhanced LAB growth and the declines of Gram-negative bacteria by late storage.

The appropriate solution to the problem of quality variability and microbial stability of traditional non-alcoholic pearl millet fermented beverages (NAPMFB) is the use of starter cultures. However, potential starter cultures need to be tested in the production process. We aimed to identify and purify bioburden lactic acid bacteria from naturally fermented pearl millet slurry (PMS) and assess their effectiveness as cultures for the production of NAPMFB. Following the traditional Kunun-zaki process, the PMS was naturally fermented at 37 °C for 36 h. The pH, total titratable acidity (TTA), lactic acid bacteria (LAB), total viable count (TVC) and the soluble sugar were determined at 3 h interval. The presumptive LAB bacteria were characterized using a scanning electron microscope, biochemical tests and identified using the VITEK 2 Advanced Expert System for microbial identification. The changes in pH and TTA followed a non-linear exponential model with the rate of significant pH decrease of 0.071 h−1, and TTA was inversely proportional to the pH at the rate of 0.042 h−1. The Gompertz model with the mean relative deviation modulus, 0.7% for LAB and 2.01% for TVC explained the variability in microbial growth during fermentation. The LAB increased significantly from 6.97 to 7.68 log cfu/mL being dominated by Leuconostoc, Pediococcus, Streptococcus and Enterococcus with an optimum fermentation time of 18 h at 37 °C and 4.06 pH. L. mesenteroides and P. pentosaceus created an acidic environment while E. gallinarum increased the pH of the pearl millet extract (PME). Innovative NAPMFB was produced through assessment of LAB from PMS to PME fermented with L. mesentoroides (0.05%) and P. pentosaceus (0.025%) for 18 h, thereby reducing the production time from the traditional 24 h.

This study evaluated microbial growth in commercial frankfurters formulated with 1.8% sodium lactate (SL) singly or combined with 0.25% sodium diacetate (SDA), vacuum-packaged (VP) and stored at 4 °C and 12 °C. Standard frankfurters without SDA, containing 0.15% SL, served as controls (CN). Lactic acid bacteria (LAB) were the exclusive spoilers in all treatments at both storage temperatures. However, compared to the CN and SL treatments, SL + SDA delayed growth of LAB by an average of 5.1 and 3.1 log units, and 3.0 and 2.0 log units, respectively, after 30 and 60 days at 4 °C. On day 90, the SL + SDA frankfurters were unspoiled whereas the SL and CN frankfurters had spoiled on day 60 and day 30 to 60, respectively. At 12 °C, LAB growth was similar in all treatments after day 15, but strong defects developed in the CN and SL frankfurters only. Differential spoilage patterns were associated with a major reversal of the LAB biota from gas- and slime-producing Leuconostoc mesenteroides and Leuconostoc carnosum in the CN and SL frankfurters to Lactobacillus sakei/curvatus in the SL + SDA frankfurters. Thus, SL + SDA extends the retail shelf life of VP frankfurters by delaying total LAB growth and selecting for lactobacilli with a milder cured meat spoilage potential than leuconostocs, particularly under refrigeration.

Leuconostoc mesenteroides includes strains used as starter and/or adjunct cultures for the production of several fermented foods. In this study, the effect of anaerobic and respiratory cultivations, as well as of citrate supplementation and different pH values, was evaluated on growth, biomass, metabolite, and enzymatic activities (pyruvate oxidase, POX; NADH-dependent oxidase, NOX; NADH-dependent peroxidase, NPR) of Leuconostoc mesenteroides subsp. cremoris E30. We compared the respiration-increased growth rate and biomass production of Leuc. mesenteroides E30 to anaerobic cultivation. A supplementation of citrate impaired the growth rate of the respiratory cells. As expected, anaerobic cultures did not consume oxygen, and a similar trend in oxygen uptake was observed in respiratory cultures. The aerobic incubation caused changes in the metabolic pattern, reducing the production of ethanol in favour of acetic acid. Citrate was already exhausted in the exponential phase and did not affect the yields in acetic acid and ethanol. NOX activity increased in the presence of oxygen, while catalase was also detected in the absence of hemin. The absence of H2O2 suggested its degradation by NPR and catalase. Respiratory cultivation provided benefits (increase in growth rate, biomass, and activity in antioxidant enzymes) for Leuc. mesenteroides E30. Therefore, the exploitation of respiratory phenotypes may be useful for the formulation of competitive starter or adjunct cultures. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine 189 LAB strains belonging to the species Enterococcus faecium, E. faecalis, Lactococcus lactis, Pediococcus pentosaceus, Leuconostoc mesenteroides, Lactiplantibacillus pentosus, Latilactobacillus curvatus, Lp. plantarum, Levilactobacillus brevis, and Weissella paramesenteroides isolated form sheep milk, Feta and Kefalograviera cheeses at different ripening stages, for their technological compatibility with dairy products manufacturing, their activities that may compromise safety of the dairy products as well as their capacity to survive in the human gastrointestinal tract. For that purpose, milk acidification and coagulation capacity, caseinolytic, lipolytic, hemolytic, gelatinolytic, and bile salt hydrolase activity, production of exopolysaccharides, antimicrobial compounds, and biogenic amines, as well as acid and bile salt tolerance and antibiotic susceptibility were examined. The faster acidifying strains were Lc. lactis DRD 2658 and P. pentosaceus DRD 2657 that reduced the pH value of skim milk, within 6 h to 5.97 and 5.92, respectively. Strains able to perform weak caseinolysis were detected in all species assessed. On the contrary, lipolytic activity, production of exopolysaccharides, amino acid decarboxylation, hemolytic, gelatinase, and bile salt hydrolase activity were not detected. Variable susceptibility to the antibiotics examined was detected among LAB strains. However, in the majority of the cases, resistance was evident. None of the strains assessed, managed to survive to exposure at pH value 1. On the contrary, 25.9 and 88.9% of the strains survived after exposure at pH values 2 and 3, respectively; the reduction of the population was larger in the first case. The strains survived well after exposure to bile salts. The strain-dependent character of the properties examined was verified. Many strains, belonging to different species, have presented very interesting properties; however, further examination is needed before their potential use as starter or adjunct cultures. [ABSTRACT FROM AUTHOR]

Effective biopreservation measures are needed to control the growth of postprocess Listeria monocytogenes contamination in fresh whey cheeses stored under refrigeration. This study assessed growth and biocontrol of inoculated (3 log10 CFU/g) L. monocytogenes in vacuum-packed, fresh (1-day-old) or 'aged' (15-day-old) Anthotyros whey cheeses, without or with 5% of a crude enterocin A-B-P extract (CEntE), during storage at 4 °C. Regardless of CEntE addition, the pathogen increased by an average of 2.0 log10 CFU/g in fresh cheeses on day 15. Gram-negative spoilage bacteria also increased by an average of 2.5 log10 CFU/g. However, from day 15 to the sell-by date (days 35–40), L. monocytogenes growth ceased, and progressively, the populations of the pathogen declined in most cheeses. This was due to an unmonitored, batch-dependent natural acidification by spoilage lactic acid bacteria, predominantly Leuconostoc mesenteroides, which reduced the cheese pH to 5.5, and finally to ≤5.0. The pH reductions and associated declines in pathogen viability were greater in the CEntE-treated samples within each batch. L. monocytogenes failed to grow in cheeses previously 'aged' in retail for 15 days. Overall, high population levels (>7.5 log10 CFU/g) of psychrotrophic Enterobacteriaceae, particularly Hafnia alvei, were associated with an extended growth and increased survival of L. monocytogenes during storage. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria present in Kimchi, such as Leuconostoc mesenteroides (Lm), Latilactobacillus curvatus (Lc), and Lactiplantibacillus plantarum (Lp) produce extracellular vesicles (ECVs) that modulate immune responses. The ECVs of probiotic Kimchi bacteria are abbreviated as LmV, LcV, and LpV. Treatment of macrophages (RAW264.7) with ECVs (LmV, LcV, and LpV) increased the production of nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6). Immunostimulatory effects exerted on the RAW264.7 cells were stronger after treatments with LmV and LcV than with LpV. Treatment of mice with LcV (1 mg/kg, orally) induced splenocyte proliferation and subsequent production of both NO and cytokines (INF-γ, TNF-α, IL-4, and IL-10). Furthermore, pre-treatment of macrophages and microglial cells with ECVs prior to LPS stimulation significantly attenuated the production of NO and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Therefore, ECVs (LmV, LcV, and LpV) prevent inflammatory responses in the LPS-stimulated microglial cells by blocking the extracellular signal-regulated kinase (Erk) and p38 signaling pathways. These results showed that LmV, LcV, and LpV from Kimchi probiotic bacteria safely exert immunomodulatory effects. [ABSTRACT FROM AUTHOR]

Although fresh whey cheeses are prone to rapid deterioration, mainly by psychrotrophic Gram-negative bacteria and lactic acid bacteria (LAB), data on the specific spoilage species in traditional Greek whey cheeses are scarce. Therefore, this study quantified growth and characterized the primary spoilage bacteria in fresh Anthotyros whey cheeses stored at 4 °C in a vacuum for 40 days, without or with an added 5% (v/w) of an enterocin A-B-P crude extract (CEntE). Psychrotrophic Pseudomonas spp., Aeromonas spp., Hafnia spp. and Serratia spp. grew faster than LAB during early storage. However, LAB outgrew the Gram-negative bacteria and prevailed by mid to late storage in all cheese batches, causing a strong or milder batch-dependent natural acidification. Two major non-slime-producing and two minor biotypes of Leuconostoc-like bacteria, all identified as Leuconostoc mesenteroides by 16S rRNA sequencing, dominated the LAB association (76.7%), which also included four subdominant Carnobacterium maltaromaticum biotypes (10.9%), one Leuconostoc lactis biotype (3.3%) and few Lactococcus (1.6%), mesophilic Lactobacillus (0.8%) and Enterococcus (0.8%). Growth and distribution of LAB and Gram-negative species were strongly batch-dependent and plant-dependent. The CEntE neither retarded growth nor altered the whey cheese spoilage association but enhanced LAB growth and the declines of Gram-negative bacteria by late storage. [ABSTRACT FROM AUTHOR]

Many lactic acid bacteria (LAB) produce metabolites with applications in the food industry, such as dextran-type exopolysaccharides (EPS) and riboflavin (vitamin B2). Here, 72 bacteria were isolated from sourdoughs made by Spanish bread-makers. In the presence of sucrose, colonies of 22 isolates showed a ropy phenotype, and NMR analysis of their EPS supported that 21 of them were dextran producers. These isolates were identified by their random amplified polymorphic DNA (RAPD) patterns and their rrs and pheS gene sequences as LAB belonging to four species (Weissella cibaria, Leuconostoc citreum, Leuconostoc falkenbergense and Leuconostoc mesenteroides). Six selected strains from the Leuconostoc (3) and Weissella (3) genera grew in the absence of riboflavin and synthesized vitamin B2. The EPS produced by these strains were characterized as dextrans by physicochemical analysis, and the L. citreum polymer showed an unusually high degree of branching. Quantification of the riboflavin and the EPS productions showed that the W. cibaria strains produce the highest levels (585–685 μg/and 6.5–7.4 g/L, respectively). Therefore, these new LAB strains would be good candidates for the development of fermented foods bio-fortified with both dextrans and riboflavin. Moreover, this is the first report of riboflavin and dextran production by L. falkenbergense. [ABSTRACT FROM AUTHOR]

The appropriate solution to the problem of quality variability and microbial stability of traditional non-alcoholic pearl millet fermented beverages (NAPMFB) is the use of starter cultures. However, potential starter cultures need to be tested in the production process. We aimed to identify and purify bioburden lactic acid bacteria from naturally fermented pearl millet slurry (PMS) and assess their effectiveness as cultures for the production of NAPMFB. Following the traditional Kunun-zaki process, the PMS was naturally fermented at 37 °C for 36 h. The pH, total titratable acidity (TTA), lactic acid bacteria (LAB), total viable count (TVC) and the soluble sugar were determined at 3 h interval. The presumptive LAB bacteria were characterized using a scanning electron microscope, biochemical tests and identified using the VITEK 2 Advanced Expert System for microbial identification. The changes in pH and TTA followed a non-linear exponential model with the rate of significant pH decrease of 0.071 h−1, and TTA was inversely proportional to the pH at the rate of 0.042 h−1. The Gompertz model with the mean relative deviation modulus, 0.7% for LAB and 2.01% for TVC explained the variability in microbial growth during fermentation. The LAB increased significantly from 6.97 to 7.68 log cfu/mL being dominated by Leuconostoc, Pediococcus, Streptococcus and Enterococcus with an optimum fermentation time of 18 h at 37 °C and 4.06 pH. L. mesenteroides and P. pentosaceus created an acidic environment while E. gallinarum increased the pH of the pearl millet extract (PME). Innovative NAPMFB was produced through assessment of LAB from PMS to PME fermented with L. mesentoroides (0.05%) and P. pentosaceus (0.025%) for 18 h, thereby reducing the production time from the traditional 24 h. [ABSTRACT FROM AUTHOR]

This study evaluated microbial growth in commercial frankfurters formulated with 1.8% sodium lactate (SL) singly or combined with 0.25% sodium diacetate (SDA), vacuum-packaged (VP) and stored at 4 °C and 12 °C. Standard frankfurters without SDA, containing 0.15% SL, served as controls (CN). Lactic acid bacteria (LAB) were the exclusive spoilers in all treatments at both storage temperatures. However, compared to the CN and SL treatments, SL + SDA delayed growth of LAB by an average of 5.1 and 3.1 log units, and 3.0 and 2.0 log units, respectively, after 30 and 60 days at 4 °C. On day 90, the SL + SDA frankfurters were unspoiled whereas the SL and CN frankfurters had spoiled on day 60 and day 30 to 60, respectively. At 12 °C, LAB growth was similar in all treatments after day 15, but strong defects developed in the CN and SL frankfurters only. Differential spoilage patterns were associated with a major reversal of the LAB biota from gas- and slime-producing Leuconostoc mesenteroides and Leuconostoc carnosum in the CN and SL frankfurters to Lactobacillus sakei/curvatus in the SL + SDA frankfurters. Thus, SL + SDA extends the retail shelf life of VP frankfurters by delaying total LAB growth and selecting for lactobacilli with a milder cured meat spoilage potential than leuconostocs, particularly under refrigeration. [ABSTRACT FROM AUTHOR]

The aim of the investigation was the identification and initial study of lactic acid bacteria (LAB) isolated from spontaneously fermented (at 28 °C for 5 days) fruiting bodies of white button mushrooms (Agaricus bisporus). The isolated LAB were preliminarily characterized applying the MALDI-TOF Biotyper. Moreover, further phenotypical, genotypical characteristics as well as some functional and technological properties of the selected microorganisms (including the ability to produce exopolysaccharides, cell hydrophobicity, resistance to low pH, and bile salt) were also analyzed. Among autochthonous LAB (isolated from the tested mushroom raw material), Leuconostoc mesenteroides predominated in spontaneously fermented A. bisporus, while Lactiplantibacillus paraplantarum, Lactiplantibacillus plantarum, and Lactococcus lactis were less abundant. The highest dynamics of acidification of the mushroom material were exhibited by isolates EK55 and EK4 that, after 24 h of incubation, were able to decrease the pH of the raw material up to 5.06 ± 0.021 and 5.17 ± 0.015, respectively. Furthermore, the analysis of bacterial cell hydrophobicity indicated that the highest values of this parameter were noted for L. plantarum isolates EK12 (29.59 ± 0.7%), EK55 (28.75 ± 0.551%), and EK5 (27.33 ± 1.516%). It was revealed some of the analyzed LAB (especially isolates L. plantarum EK55 and L. paraplantarum EK4) exhibited functional and technological potential that might be used in the formulation of novel starter cultures. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the evolution of the volatile compounds of aerobically stored sterile pork meat as a consequence of the metabolic activities of inoculated specific spoilage microorganisms. Thus, Pseudomonas fragi, Pseudomonas putida, Lactobacillus sakei and Leuconostoc mesenteroides were inoculated in monocultures, dual cultures and a cocktail culture of all strains on sterile pork meat stored aerobically at 4 and 10 °C. Microbiological and sensory analyses, as well as pH measurements, were performed, along with headspace solid-phase microextraction gas chromatography/mass spectroscopy (headspace SPME–GC/MS) analysis. Data analytics were used to correlate the volatile compounds with the spoilage potential of each stain using multivariate data analysis. The results for the sensory discrimination showed that the volatiles that dominated in spoiled samples consisted mostly of alcohols, ketones and two esters (butyl acetate and ethyl acetate), while at fresh samples, dimethyl sulfide, furans, acetoin and ethyl lactate were detected. On the other hand, 2-butanone, diacetyl and acetaldehyde were among the volatile compounds that were mainly correlated with the inoculated meat during storage. In addition, P. fragi was positively correlated with a higher number of volatiles compared to the other strains, strengthening the hypothesis that volatile compound production is strain-dependent. [ABSTRACT FROM AUTHOR]

Changes in the ecology of the various lactic acid bacteria (LAB) species, which are involved in traditional fermented sausages, were investigated in the light of the use of different breeds of pork, each of which was raised in two different environments and processed using two different technologies. The semi-quantitative molecular method was applied in order to understand how the different species alternate over time, as well as their concentration ratios. A significant increase in LAB over the first days of fermentation characterized the trials where the starter culture wasn't added (T), reaching values of 107–108 cfu g−1. On the other hand, in the trials in which sausages were produced with starter addition, LAB counts had a less significant incremental jump from about 106 cfu g−1 (concentration of the inoculum) to 108 cfu g−1. Lactobacillus sakei and Lb. curvatus were detected as the prevalent population in all the observed fermentations. Pediococcus pentosaceus, Lb. casei, Leuconostoc mesenteroides, Lactococcus garviae, and Lb. graminis also appeared, but their concentration ratios varied depending on the diverse experimental settings. The results of cluster analysis showed that a plant- and breed-specific LAB ecology exists. In addition, it was also observed that the breeding system can influence the presence of certain LAB species. [ABSTRACT FROM AUTHOR]