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Sour bamboo shoots are a traditional fermented delicacy that has garnered appreciation both domestically and internationally. This study investigates the intricate dynamics of microbial communities and volatile flavor compounds primarily derived from salted and pickled bamboo shoots during the fermentation process of Phyllostachys purpurea (PP). The dynamics of microorganisms and volatile flavor compounds were thoroughly examined initially using conventional isolation and cultivation methods in conjunction with high-throughput sequencing (HTS), headspace solid-phase microextraction (HS-SPME), and gas chromatography-mass spectrometry (GC-MS). In addition, we analyzed the core microorganisms responsible for modulating the volatile flavor profile. Our findings revealed 60 volatile compounds, 14 of which were the predominant contributors to the aroma of fermented PP. This group primarily comprised alcohols, aldehydes, and olefins. Notably, our investigation identified Lactobacillus and Candida as the dominant microbial genera during the middle and late stages of fermentation. These two genera exert a significant influence on the formation of characteristic aromas. Furthermore, we discovered that acids, sugars, and proteins pivotally influence the succession of microorganisms. Specifically, acids and soluble sugars drove the transition of Lactococcus to Lactobacillus and Pediococcus, whereas soluble proteins facilitated fungal succession from Candida to Kazachstania and Issatchenkia. These insights shed light on the community structure and succession patterns of flavor compounds throughout the PP fermentation process. Ultimately, they provide a foundation for optimizing the fermentation process and ensuring quality control in the production of sour bamboo shoots., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Table olives are one of the most known fruit consumed as fermented food, being a fundamental component of the Mediterranean diet. Their production and consumption continue to increase globally and represent an important economic source for the producing countries. One of the most stimulating challenges for the future is the modernization of olive fermentation process. Besides the demand for more reproducible and safer production methods that could be able to reduce product losses and potential risks, producers and consumers are increasingly attracted by the final product characteristics and properties on human health. In this study, the contribution of microbial starters to table olives was fully described in terms of specific enzymatic and microbiological profiles, nutrient components, fermentation-derived compounds, and content of bioactive compounds. The use of microbial starters from different sources was tested considering their technological features and potential ability to improve the functional traits of fermented black table olives. For each fermentation assay, the effects of controlled temperature (kept at 20 °C constantly) versus not controlled environmental conditions (oscillating between 7 and 17 °C), as well as the consequences of the pasteurization treatment were tested on the final products. Starter-driven fermentation strategies seemed to increase both total phenolic content and total antioxidant activity. Herein, among all the tested microbial starters, we provide data indicating that two bacterial strains (Leuconostoc mesenteroides KT 5-1 and Lactiplantibacillus plantarum BC T3-35), and two yeast strains (Saccharomyces cerevisiae 10A and Debaryomyces hansenii A15-44) were the better ones related to enzyme activities, total phenolic content and antioxidant activity. We also demonstrated that the fermentation of black table olives under not controlled environmental temperature conditions was more promising than the controlled level of 20 °C constantly in terms of technological and functional properties considered in this study. Moreover, we confirmed that the pasteurization process had a role in enhancing the levels of antioxidant compounds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Kimchi is one of the primary sources of high sodium content in the Korean diet. Low-sodium kimchi is commercially manufactured to minimize the health effects of high salt. We investigated the influence of lactic acid bacteria (LAB) as starter culture in combination with 1% or 2.5% salt on the survival of pathogenic Escherichia coli and physicochemical properties of kimchi during fermentation at 10 °C and 25 °C. Among ten strains of LAB isolated from kimchi, Leuconostoc mesenteroides (KCTC 13374) and Lactobacillus plantarum (KCTC 33133) exhibited antimicrobial activities against pathogenic E. coli (EPEC, ETEC, and E. coli O157:H7) and strong tolerance to low pH (2 and 3) and 0.3% bile salts. Thus, L. mesenteroides and L. plantarum were used as starter cultures for kimchi that contained 1% and 2.5% salt. All pathogenic E. coli strains survived in kimchi regardless of starter cultures or salt concentration for over 15 days at 10 °C, but they died off within 4 days at 25 °C. Survival of pathogenic E. coli was better in naturally fermented kimchi (titratable acidity:0.65%) than kimchi fermented with starter cultures (titratable acidity:1.0%). At 10 °C, the average delta value of E. coli O157:H7 (16.15 d) was smaller than those of EPEC (20.76 d) and ETEC (20.20 d) in naturally fermented kimchi. Overall, survival ability of E. coli O157:H7 was lower than EPEC and ETEC, although differences were not significant. Reduced salt concentration from 2.5% to 1% in kimchi did not affect the growth of LAB and the fermentation period. Pathogenic E. coli died at a faster rate in kimchi fermented with starter cultures and 1% salt than in naturally fermented kimchi with 2.5% salt., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Sub-Saharan region is often characterized by food and nutrition insecurity especially "hidden hunger" which results from inadequate micronutrients in diets. African indigenous leafy vegetables (AILVs) can represent a valid food source of micronutrients, but they often go to waste resulting in post-harvest losses. In an attempt to prolong AILVs shelf-life while enhancing their nutritional quality, fermentation was studied from a microbiological and nutritional point of view. Pumpkin leaves (Cucurbita sp.) were spontaneously fermented using the submerged method with 3% NaCl and 3% sucrose. Controls were set up, consisting of leaves with no additions. During fermentation, samples of both treatments were taken at 0, 24, 48, 72 and 168 h to monitor pH and characterize the microbial population through culture-based and molecular-based analyses. Variations between fresh and treated leaves in B-group vitamins, carotenoids, polyphenols, and phytic acid were evaluated. Data revealed that the treatment with addition of NaCl and sucrose hindered the growth of undesired microorganisms; in controls, unwanted microorganisms dominated the bacterial community until 168 h, while in treated samples Lactobacillaceae predominated. Furthermore, the content in folate, β-carotene and lutein increased in treated leaves compared to the fresh ones, while phytic acid diminished indicating an amelioration in the nutritional value of the final product. Thus, fermentation could help in preserving Cucurbita sp. leaves, avoiding contamination of spoilage microorganisms and enhancing the nutritional values., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The fungal communities and volatile compounds of traditional dry sausages collected from five different regions in Northeast China, including Harbin (HRB), Daqing (DQ), Suihua (SH), Hegang (HG) and Mudanjiang (MDJ) were investigated in this study. The results revealed clear differences among the fungal community structures of the sausages. Aspergillus pseudoglaucus, Debaryomyces hansenii, and Trichosporon asahii were found to be the predominant species in the sausages from HRB, HG, and MDJ, respectively. Candida zeylanoides was the predominant species in the sausage from DQ and SH. Additionally, 88 volatile compounds were identified in all sausages, of which 31 volatile compounds were the most important flavor contributors (odor activity value > 1). Potential correlation analysis revealed that 8 fungi (D. hansenii, C. zeylanoides, T. asahii, A. pseudoglaucus, Aspergillus sydowii, Penicillium expansum, A. alternata, and Alternaria tenuissima) showed significant positive correlations with ≥3 key volatile compounds. Among these fungi, D. hansenii was regarded as a core functional fungus responsible for the formation of the volatile compounds, given its strong connection with the highest number of key volatile compounds. These results provide detailed insight into the fungal communities of traditional dry sausages and a deeper understanding of the contribution of these fungi to sausage flavor., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Table olives are considered the most widespread fermented food in the Mediterranean area and their consumption is expanding all over the world. This fermented vegetable can be considered as a natural functional food thanks to their high nutritional value and high content of bioactive compounds that contribute to the health and well-being of consumers. The presence of bioactive compounds is strongly influenced by a complex microbial consortium, traditionally exploited through culture-dependent approaches. Recently, the rapid spread of omics technologies has represented an important challenge to better understand the function, the adaptation and the exploitation of microbial diversity in different complex ecosystems, such as table olives. This review provides an overview of the potentiality of omics technologies to in depth investigate the microbial composition and the metabolic processes that drive the table olives fermentation, affecting both sensorial profile and safety properties of the final product. Finally, the review points out the role of omics approaches to raise at higher sophisticated level the investigations on microbial, gene, protein, and metabolite, with huge potential for the integration of table olives composition with functional assessments., (Copyright © 2020. Published by Elsevier Ltd.)

The fermentation of vegetables is a traditional preservation method, that experiences a renaissance even in domestic households. Table salt is added to the fermentation batches to favor the growth of lactic acid bacteria usually. On an industrial scale, the fermentation brine is typically prepared with non-iodized table salt. In our study, we investigated the microbiota of cucumber fermentations using culture-dependent and -independent methods. We could show that the fermentation process of cucumbers and the involved microbiota is influenced by the concentration of table salt and not by the use of iodized table salt. Therefore, we conclude that the use of iodized table salt does not negatively affect the fermentation process. We could verify that iodine permeates the cucumbers by diffusion, leading to satisfactory iodine concentrations in the final food product. The industrial use of iodized table salt in food fermentations could contribute to maintain a constant iodine supply to the general public., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, the microbiota of ready-to-eat surströmming from three Swedish producers were studied using a combined approach. The pH values of the samples ranged between 6.67 ± 0.01 and 6.98 ± 0.01, whereas their a w values were between 0.911 ± 0.001 and 0.940 ± 0.001. The acetic acid concentration was between 0.289 ± 0.009 g/100 g and 0.556 ± 0.036 g/100 g. Very low concentrations of lactic acid were measured. Viable counting revealed the presence of mesophilic aerobes, mesophilic lactobacilli and lactococci as well as halophilic lactobacilli and lactococci, coagulase-negative staphylococci, halophilic aerobes and anaerobes. Negligible counts for Enterobacteriaceae, Pseudomonadaceae and total eumycetes were observed, whereas no sulfite-reducing anaerobes were detected. Listeria monocytogenes and Salmonella spp. were absent in all samples. Multiplex real-time PCR revealed the absence of the bont/A, bont/B, bont/E, bont/F, and 4gyrB (CP) genes, which encode botulinic toxins, in all the samples analyzed. Metagenomic sequencing revealed the presence of a core microbiota dominated by Halanaerobium praevalens, Alkalibacterium gilvum, Carnobacterium spp., Tetragenococcus halophilus, Clostridiisalibacter spp. and Porphyromonadaceae. Psychrobacter celer, Ruminococcaceae, Marinilactibacillus psychrotolerans, Streptococcus infantis and Salinivibrio costicola were detected as minor OTUs. GC-MS analysis of volatile components revealed the massive presence of trimethylamine and sulphur compounds. Moreover, 1,2,4-trithiolane, phenols, ketones, aldehydes, alcohols, esters and long chain aliphatic hydrocarbons were also detected. The data obtained allowed pro-technological bacteria, which are well-adapted to saline environments, to be discovered for the first time. Further analyses are needed to better clarify the extent of the contribution of either the microbiota or autolytic enzymes of the fish flesh in the aroma definition., Competing Interests: Declaration of competing interest The authors declare no conflict of interests. Regarding the manuscript titled “Discovering microbiota and volatile compounds of surströmming, the traditional Swedish sour herring” submitted for publication in Food Microbiology, the authors declare that NO conflict of interest exists., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The objective of this study was to explore the correlation between bacterial communities and volatile compounds in traditional dry sausages from different regions in Northeast China. The bacterial community structure of dry sausages from five different regions as determined by high-throughput sequencing technology demonstrated that Firmicutes and Proteobacteria were the predominant phyla; Lactobacillus, Staphylococcus, Leuconostoc, Lactococcus and Weissella were the predominant genera; and Staphylococcus xylosus, Lactobacillus sakei, Weissella hellenica, Leuconostoc citreum, Lactococcus raffinolactis and Lactobacillus plantarum were the predominant species. Meanwhile, a total of 120 volatile compounds were detected in sausages from five different regions and mainly included alcohols, acids, aldehydes, ketones, esters and terpenes. Furthermore, the potential correlations between the core bacteria and major volatile compounds (64) were explored based on Spearman's correlation analysis. Positive correlations were found between W. hellenica, Lb. sakei, Lactococcus lactis, Lactobacillus alimentarius, Lb. plantarum and carboxylic acids and alcohols. Lc. lactis, Lb. alimentarius and Lb. plantarum were associated with the production of most esters, aldehydes and ketones. This study provides a deep insight into the relationship between the bacterial community and the volatile flavour profile of dry sausages, which may be helpful for the production of fermented dry sausages., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Suancai is a popular fermented product of Brassica vegetable in China. As important additive, salt concentration has crucial effects on the quality of suancai. To investigate the effects of salt concentration on suancai fermentation, the microbial diversity and volatile compounds (VCs) during fermentation were investigated by using Illumina HiSeq sequencing and GC-MS. Firmicutes, Proteobacteria and Ascomycota were detected as the main phylum during the fermentation with different salt concentrations. Lactobacillus, Lactococcus, Klebsiella, Weissella, Pediococcus, Candida, Cladosporium, Gibberella, Aspergillus, etc., were detected were observed during the fermentation with different concentrations. After fermentation, Lactobacillus predominated the fermentation of suancai and was not affected by salt concentration. Pediococcus, Leuconostoc, Weissella, Sporobolomyces, Azospirillum, Klebsiella, Acinetobacter and Cladosporium were significant affected by salt concentration. Salt addition could affect the VCs profiles and reduce the isothiocyanates after fermentation. Seventy-nine VCs were detected and strongly correlated with the dominant genus Lactobacillus during suancai fermentation. The inoculated fermentation of Lactobacillus could improve the VCs during fermentation. In conclusion, 6% salt addition could acquire a higher Lactobacillus abundance and a better taste quality. These results may facilitate the understanding of the effect of salt concentration on the fermentation ecology to improve suancai characteristics., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

High-throughput sequencing and gas chromatography-mass spectrometry (GC-MS) were used to investigate changes in bacterial and fungal communities and volatile flavor compounds during a 32-day fermentation process of red pepper (Capsicum annuum L.). Key odorants were identified by olfactometry combined with GC-MS. Sixteen volatile compounds differed significantly after fermentation, including seven odorants. After fermentation, 1-butanol, 3-methyl-, acetate, phenol, 4-ethyl-2-methoxy-, octanoic acid, ethyl ester, styrene and 2-methoxy-4-vinylphenol were the key odorants, producing a flavor described as peppery, fruity, sour, and spicy. The correlation between microorganisms and odorants in the fermentation was studied and 18 odorants significantly correlated with the core microbial communities in the fermented samples. For further analysis, strains of seven genera were isolated and correlation analysis by O2PLS indicated that Aspergillus, Bacillus, Brachybacterium, Microbacterium and Staphylococcus were highly correlated with the flavor formation. These findings would help to understand the fermentation mechanism of fermented red pepper flavor formation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this work, Lactobacillus pentosus LPG1, Lactobacillus pentosus Lp13, Lactobacillus plantarum Lpl15, and Wickerhanomyces anomalous Y12, all of them previously isolated from fermented table olive biofilms, were used (alone or in combination) as multifunctional starters for Manzanilla Spanish-style green table olive fermentations. Their performances were evaluated through the changes in the key physico-chemical and microbiological parameters, correlation between AI-2 production and biofilm formation, inoculum imposition, metataxonomic analysis and sensory characteristics of the finished products. Inoculation only with lactic acid bacteria (LAB) strains led to higher titratable acidities and lower pH values than the spontaneous fermentation (non-inoculated control), mainly during the first steps of processing. However, the sequential inoculation of the yeast and then the combination of the 3 LAB strains showed the most favourable evolution. LPG1 strain and, particularly Lp13, were excellent biofilms former and showed the major imposition on the fruit epidermis, as corroborated by rep-PCR analysis. Production of AI-2 was lower in the treatment inoculated exclusively with yeast Y12 but had the highest presence in the sequential yeast-LAB inoculum, with its maximum concentration and maximum LAB population on fruits (19th days) strongly related. Metataxonomic analysis of the biofilms at the end of the fermentation revealed, in addition to Lactobacillus, high proportions of sequences from genera Marinilactobacillus, Alkalibacterium, Halolactobacillus, and low levels of Halomonas and Aerococcus. Compositional data analysis of the omics data revealed that Lpl15 was scarcely efficient for controlling the spontaneous microbiota since its treatment presented the highest proportions of Aerococcus genus. Finally, the sensory analysis showed similar characteristics for the treatment inoculated with LPG1 and the spontaneous process, with olives inoculated with the yeast (alone or in combination with Lactobacillus strains) showing attractive scores. Then, inoculation of Spanish-style table olive fermentations with a sequential yeast and LAB combination could be an advisable practice., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Lactic acid bacteria (LAB) are commonly used in soymilk fermentation to improve health-related functionality, but their contribution to sensory qualities is less valued. We characterized Lactobacillus harbinensis M1, Lactobacillus mucosae M2, Lactobacillus fermentum M4, Lactobacillus casei M8 and Lactobacillus rhamnosus C1 from naturally-fermented tofu whey, along with Streptococcus thermophilus ST3 from kefir XPL-1 fermented soymilk, to investigate their potential as starter cultures of fermented soymilk. They were characterized for antibiotic susceptibility, probiotic potential and their performance as starter cultures. All the LABs showed sensitivity to the tested antibiotics. L. casei M8 had strongest tolerance to synthetic gastrointestinal juice (<1.0 log CFU/mL loss), as well as antagonistic effects towards five food-borne pathogens. GC/MS analysis showed that L. harbinensis M1 produced significantly higher abundance (P < 0.05) of 2,3-butanedione (2.45 ppm) and acetoin (44.30 ppm), thus improving the overall sensory acceptability of fermented soymilk. The coding genes for the synthesis of 2,3-butanedione/acetoin (alsS, alsD, butA) were predicted from the whole-genome. A co-culture of L. harbinensis M1 and L. casei M8 produced a fermented soymilk product with both markedly improved flavor and good probiotic potential. It appears that L. harbinensis M1 has much potential for improving the organoleptic properties of fermented soymilk., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The present work was carried out to evaluate the microbiological and physicochemical composition of salamis produced with the meat of beef, horse, wild boar and pork. Salami productions occurred under controlled laboratory conditions to exclude butchery environmental contaminations, without the addition of nitrate and nitrite. All trials were monitored during the ripening (13 °C and 90% relative humidity) extended until 45 d. The evolution of physicochemical parameters showed that beef and pork salamis were characterized by a higher content of branched chain fatty acids (FA) and rumenic acid than horse and wild boar salamis, whereas the last two productions showed higher values of secondary lipid oxidation. Plate counts showed that lactic acid bacteria (LAB), yeasts and coagulase-negative staphylococci (CNS) populations dominated the microbial community of all productions with Lactobacillus and Staphylococcus as most frequently isolated bacteria. The microbial diversity evaluated by MiSeq Illumina showed the presence of members of Gammaproteobacteria phylum, Moraxellaceae family, Acinetobacter, Pseudomonas, Carnobacterium and Enterococcus in all salamis. This study showed the natural evolution of indigenous fermented meat starter cultures and confirmed a higher suitability of horse and beef meat for nitrate/nitrite free salami production due to their hygienic quality at 30 d., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

As the spirit of Chinese Sichuan cuisine, Pixian Doubanjiang (DBJ) is an indispensable flavor condiment and has been widely used for centuries, which is made from red pepper (Capsicum annuum L.), meju and brine after open ripening fermentation. In this study, the physicochemical factors including pH value, titratable acidity, moisture, organic acids, free amino acids and volatile components etc., were identified; the compositions of microbial communities and representative microbiota were investigated; the correlations between physicochemical factors and representative microbial taxa were analyzed, at different ripening stages. The results indicated that the organic acids were all relatively stable starting from the 12th month; most of the free amino acids (17/20) reached the peak concentrations at the 6th month and 28 volatile components were considered as major odorant flavors in DBJ. Zygosaccharomyces rouxii could be the key microorganism associated with 10 volatile components to the maturing of DBJ flavor. The comprehensive analysis on the physicochemical changes related to the succession of microbiota is expected to help us understand the maturing of the taste and flavor in DBJ production., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Four sets of doenjang (traditional Korean fermented soybean paste) with 9%, 12%, 15%, and 18% solar salt concentrations were prepared and their pH, microbial abundances and communities, metabolites, and volatile compounds were analyzed periodically during the entire fermentation. The speeds of decrease in pH and increase in microbial abundances, representing microbial activity, were higher during early fermentation in lower (9% and 12%) salt doenjang. Microbial abundances in 15% and 18% salt doenjang were significantly lower than in the 9% and 12% salt doenjang, indicating low microbial activity. Community analysis revealed that Bacillus, Staphylococcus, and Clostridium and Aspergillus, Scopulariopsis, Fusarium, Mucor, and Penicillium, which might be derived from doenjang-meju used for preparing doenjang, were identified as major bacterial and fungal genera, respectively, in all doenjang samples. Weissella, Tetragenococcus, Oceanobacillus, and Debaryomyces, not dominant in doenjang-meju, were also identified as major groups in low salt doenjang. Metabolite analysis showed that amino acid profiles were relatively similar independent of salt concentrations and microbial growth, indicating important roles of indigenous proteases present in doenjang-meju, not microbial activity during doenjang fermentation, in amino acid production. The metabolism of free sugars to organic acids and biogenic amine production were greater in lower salt doenjang, which might be associated with the growth of microbes, particularly lactic acid bacteria. A higher level of and more diverse volatile compounds were identified in lower salt doenjang, indicating close association with microbial growth. This study provides a deeper understanding of doenjang fermentation and insight into the development of low salt doenjang., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This work aimed to study the phenolic acid metabolism of sourdough lactic acid bacteria (LAB) in laboratory media, and in sourdough fermentation with single cultures and in co-fermentations. Lactobacilli were selected from isolates obtained from 35 sourdough samples. Isolates (114 strains) were screened for phenolic acid decarboxylase gene pdc and EPS production. Ferulic acid metabolism of the 18 pdc positive strains was evaluated in mMRS; all pcd positive strains converted ferulic acid by decarboxylation and/or reduction. Single whole wheat and rye malt dough fermentation fermented with lactobacilli or yeasts were characterized with respect to free, conjugated, or bound phenolic acids. Concentrations of free, conjugated, or bound phenolic acids were not altered substantially in chemically acidified sourdoughs, or in yeast fermented doughs. L. plantarum metabolized free ferulic acid in wheat and rye malt sourdoughs; L. hammesii DSM 16381 metabolized syringic and vanillic acids and reduced levels of bound ferulic acid in wheat sourdoughs. Co-fermentation of L. hammesii and L. plantarum achieved release of bound ferulic acid and conversion of the resultant free ferulic acid to dihydroferulic acid and volatile metabolites. Phenolic acid metabolism in sourdoughs was enhanced by co-fermentation with strains exhibiting complementary metabolic activities. Results may enable improvement of bread quality by targeted conversion of phenolic acids during sourdough fermentation., (Copyright © 2018. Published by Elsevier Ltd.)

The effect of iodine present in 1.0% table salt in combination with the use of starter cultures in sauerkraut fermentations were investigated in order to determine whether iodine interferes with lactic acid bacteria responsible for the fermentation. The effect of iodine was tested in fermentations performed using selected starter cultures or without starters (spontaneous fermentation). Lactobacillus plantarum and Leuconostoc mesenteroides used as starters at levels of ca. 1 × 10 7  cfu ml -1 led to a quick establishment of lactic acid bacteria (LAB) as predominant microorganisms, reaching 1 × 10 9  cfu ml -1 after 24 h decreasing the pH to below 4.0. In contrast, LAB counts in control fermentations without starters increased slower from 1 × 10 5  cfu ml -1 to 1 × 10 9  cfu ml -1 and a pH reduction below 4.0 was achieved only after 3 days fermentation. A metagenomic investigation showed a more diverse bacterial community in fermentations without starters, consisting of enterobacteria and pseudomonads in the first days of fermentation, and of LAB such as lactococci in the later stages. In fermentations with starters, lactobacilli predominated. Leuconostocs also occurred, but at much lower sequence abundance than lactobacilli, and thus were not able to predominate. Determination of iodine in the fermentation with starter bacteria and with iodized salt showed that the fermentation did not affect iodine concentration. The use of iodized salt did not statistically significantly influence microbial populations in the fermentation. Thus, there is no basis for the popular held belief that the use of iodized salt inhibits the growth of the bacteria important for the sauerkraut fermentation. A statistically near significant effect (p = 0.06), however, was noted for the effect of iodine on yeasts and mould populations in the fermentations performed without starter cultures. As sauerkraut is usually produced without starters, this should be further investigated., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Lactococcus lactis, is extensively used as starter culture in dairy products. Nevertheless, it has recently been detected in cheese, as metabolically active cells, in advanced ripening stages. In this study, we assessed the viability of L. lactis subsp. lactis in model cheeses up to 180 days of ripening by both culture-dependent and -independent methods. In addition, we studied the expression of metC and als genes involved in the production of aroma compounds detected by Gas Chromatography-Mass Spectrometry (GC-MS). Three L. lactis subsp. lactis commercial starters were inoculated in pasteurized milk and model cheeses were manufactured and ripened for six months. Samples were analysed at manufacturing and ripening steps, in terms of viability of L. lactis by both traditional plating and direct analysis of RNA by reverse transcription quantitative PCR (RT-qPCR), and in terms of aroma profile by GC-MS. Relatively to RT-qPCR analysis, L. lactis was found viable throughout the whole process of cheesemaking and aging, with final average loads of 3-4 Log CFU/g at 180 days. On the contrary, the microorganism was not detected, in ripened samples, by traditional plating on M17 medium, suggesting its entering in a viable but not cultivable (VBNC) state. The aroma profiles of the cheeses highlighted the presence of volatile compounds related to cheese flavor as acetoin, diacetyl, 2,3-butanediol and dimethyl disulfide, whose presence was partially correlated to metC and als genes expression. These results add new insights on the capability of L. lactis to persist during late cheese ripening and suggest a potential contribution of the microorganism to cheese flavor formation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Pao cai is a spontaneously fermented cabbage where native bacteria may have an important influence on nitrite content during fermentation. In this research, we used metagenomic-based 16S rRNA gene amplicon sequencing to analyze differences in bacterial composition of pao cai from Hohhot City (northern China) and Guiyang City (southern China). Alongside this, metagenome functional features from the 16S rRNA genes of the microbiome were predicted and correlated with the nitrite content of pao cai. Nitrite-reducing bacterial genera were identified including Lactobacillus (73.37%), Pediococcus (0.93%), Acinetobacter (0.74%), Leuconostoc (0.31%), Weissella (0.14%), Streptococcus (0.09%), Megamonas (0.08%), Enterococcus (0.07%), and Alistipes (0.06%). Lactobacillus was the predominant genus in both the northern and the southern pao cai samples and was significantly negatively correlated with nitrite content; it was more abundant in southern samples than northern samples. Based on determination of alpha and beta diversities of the microbiome in samples, differences in the microbiome of northern and southern pao cai were demonstrated that may influence nitrogen metabolism. This research suggests that 16S rRNA gene amplicon sequencing is an effective way to comprehensively study the microbes with potential nitrite formation or decomposition ability instead of investigating the individual bacterial genera., (Copyright © 2017 Elsevier Ltd. All rights reserved.)