Fermented Pickles Research Articles

The relationships between microbiota and the amino acids and organic acids in commercial vegetable pickle fermented in rice-bran beds

The microbial community during fermented vegetable production has a large impact on the quality of the final products. Lactic acid bacteria have been well-studied in such processes, but knowledge about the roles of non-lactic acid bacteria is limited. This study aimed to provide useful knowledge about the relationships between the microbiota, including non-lactic acid bacteria, and metabolites in commercial pickle production by investigating Japanese pickles fermented in rice-bran. The samples were provided by six manufacturers, divided into two groups depending on the production conditions. The microbiological content of these samples was investigated by high-throughput sequencing, and metabolites were assessed by liquid chromatography-mass spectrometry and enzymatic assay. The data suggest that Halomonas, halophilic Gram-negative bacteria, can increase glutamic acid content during the pickling process under selective conditions for bacterial growth. In contrast, in less selective conditions, the microbiota consumed glutamic acid. Our results indicate that the glutamic acid content in fermented pickle is influenced by the microbiota, rather than by externally added glutamic acid. Our data suggest that both lactic acid bacteria and non-lactic acid bacteria are positive key factors in the mechanism of commercial vegetable fermentation and affect the quality of pickles.

Fermentasyonun Mantar Turşusunun Biyoaktivitesi ve Çeşitli Özelliklerine Etkisi

Fonksiyonel bileşenlerce zengin gıda arasında yer alan mantarlar, yapılarında yüksek oranda su, doğal mikrobiyota ve enzimatik aktivite sebebi ile çabuk bozulan gıdalar arasında değerlendirilmektedir. Bu yüzden raf ömrünü uzatmak amacı ile çeşitli muhafaza yöntemlerine başvurulmaktadır. Bu muhafaza yöntemlerinden biri olan fermentasyon sırasında ortamda baskın mikrobiyota olan laktik asit bakterilerinin (LAB) kendine has tat ve aroma bileşenleri oluşturmasıyla mantar turşusu uzun süreler sevilerek tüketilebilmektedir. Bu çalışmada Kastamonu ilinden taze olarak toplanan kanlıca mantarından (Lactarius deliciosus) turşu üretimi gerçekleştirilmiş ve fermentasyon süresince meydana gelen bazı biyoaktiviteleri, fizikokimyasal, mikrobiyolojik ve duyusal özellikleri belirlenmiştir. Turşu fermentasyonu sırasında LAB gelişimiyle birlikte pH değerinin düştüğü, tersine titrasyon asitliğin yükseldiği, duyusal özellikler açısından turşunun beğenildiği gözlenmiştir. Taze mantarın toplam fenolik madde miktarının 188.73 mg Gallik Asit Eşdeğeri (GAE) /100 g kuru madde (KM) olduğu, antioksidan aktivitesinin ise; DPPH yöntemiyle 14.80 μmol Troloks Eşdeğeri (TE) /g KM, CUPRAC yöntemiyle 22.31 μmol TE /g KM ve ABTS yöntemiyle 7.72 μmol TE /g KM olduğu saptanmıştır.

Metabolism of glutamic acid to alanine, proline, and γ-aminobutyric acid during takuan-zuke processing of radish root.

Takuan-zuke is a traditional Japanese fermented pickle, prepared by dehydration of radish root (daikon) by salt-pressing or sun-drying followed by aging with salt. We previously reported that alanine, proline, and γ-aminobutyric acid (GABA) accumulate during daikon dehydration, whereas the level of glutamic acid, their precursor, decreases. We have also reported that dehydration and salt-aging markedly influence the dynamics of free amino acids. In this study, we quantitatively analyzed free amino acid levels, enzyme activity, and gene expression to characterize takuan-zuke amino acid metabolism. Enzyme activities related to alanine, proline, GABA, and glutamic acid metabolism were sustained during dehydration. Moreover, genes encoding alanine, proline, and GABA synthases (ALT1, P5CS1, and GAD4) were significantly upregulated during dehydration. These effects may represent cellular stress responses to the dehydration process. The biological response of daikon contributes to the healthy functional aspects that characterize takuan-zuke. These findings could guide the selection of suitable vegetable varieties to produce pickled vegetables with health-promoting properties. PRACTICAL APPLICATION: The fermented pickle takuan-zuke, prepared by dehydration of radish root (daikon), accumulates amino acids, such as alanine, proline, and GABA, during preparation that provide taste and health benefits. In this study, the aforementioned amino acids were found to accumulate because of the stress response of daikon during the dehydration process and not because of the action of microorganisms during fermentation. Takuan-zuke processing is a method for improving the nutrition of daikon.

Lactobacillus fermentum CQPC08 protects rats from lead-induced oxidative damage by regulating the Keap1/Nrf2/ARE pathway.

In this experiment, Lactobacillus fermentum CQPC08 (LF-CQPC08) isolated from traditionally fermented pickles was used to study its mitigation effect on lead acetate-induced oxidative stress and lead ion adsorption capacity in rats. In vitro experiments showed that the survival rate in artificial gastric juice and the growth efficiency in artificial bile salt of LF-CQPC08 was 93.6% ± 2.2% and 77.2% ± 0.8%, and the surface hydrophobicity rate was 45.5% ± 0.3%. The scavenging rates of hydroxyl radical, superoxide anion, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 47.8% ± 0.9%, 63.9% ± 1.2%, and 83.6% ± 1.5%, respectively, and the reduction power was 107.3 ± 2.8 μmol L-1. LF-CQPC08 could not only adsorb 76.9% ± 1.0% lead ions in aqueous solution but also reduce the lead content in serum, liver, kidneys, and brain tissue of Sprague-Dawley (SD) rats, as well as maintain the cell structure and tissue state of the liver and kidneys. In addition, by examining the indicators of inflammation and oxidation in the serum, liver, and kidneys of SD rats, we found that LF-CQPC08 can reduce the proinflammatory factors interleukin (IL)-1 beta (1β), IL-6, tumor necrosis factor alpha, and interferon gamma in the body, increase the level of anti-inflammatory factor IL-10, enhance the activity of antioxidant enzymes such as superoxide dismutase and catalase and glutathione levels in serum and organ tissues, and reduce the production of reactive oxygen species and accumulation of lipid peroxide malondialdehyde. LF-CQPC08 can also activate the Keap1/Nrf2/ARE signaling pathway to promote high-level expression of the downstream antioxidants heme oxygenase 1 (HO-1), NAD(P)H : quinone oxidoreductase 1 (NQO1), and γ-glutamylcysteine synthetase (γ-GCS). As food-grade lactic acid bacteria, LF-CQPC08 has great potential and research value in removing heavy metals from food and alleviating the toxicity of heavy metals in the future.

Modelling the kinetics of biomass and lactic acid production during Rohu fish pickle fermentation

Fish pickle was prepared from Rohu (Labeo rohita) by fermentation for 15 days and the changes in biomass growth, lactic acid production, and pH were evaluated. The data obtained were fitted in two most widely accepted microbial growth models: Modified Gompertz, and Logistic model and three well known lactic acid production models: Luedeking-Piret, Monteagudo et al., and Balannec et al. model for lactic acid fermentation. Model constants and coefficients were determined by a nonlinear regression method. All the models were validated using statistical parameters namely, coefficient of determination (R2), root mean square error (RMSE), reduced chi-square (χ2) and the reduced sum of squares (RSS). The results revealed that the viable cell counts increased from 0.91×107 cfu/ml to 9×109 cfu/ml after nine days of fermentation. The lactic acid increased by about 11.6 times in 12 days and remained constant for the rest of the fermentation period. The pH decreased from 6.5 to 4.2 on the 15th day of fermentation and then increased slightly till the final day of fermentation. The Logistic model and Luedeking-Piret model were best fitted to describe the biomass growth and lactic acid production by LAB during the fermentation period of pickle. The growth-associated and non-growth associated coefficients were determined to be 0.813 and 0.005, respectively. Based on these estimated parameters, it is concluded that lactic acid production in the fish pickle was a mixed type.

Probiotic characteristics of Lactobacillus plantarum E680 and its effect on Hypercholesterolemic mice

BackgroundProbiotics have been reported to reduce total cholesterol levels in vitro, but more evidence is needed to determine the clinical relevance of this activity. Chinese traditional fermented pickles are a good source of lactic acid bacteria. Therefore, pickle samples were collected for screening lactic acid bacteria based on their ability to survive stresses encountered during gastrointestinal passage and cholesterol reducing potency.ResultsSeventy five lactic acid bacteria strains were isolated from 22 fermented pickles. From these bacteria, Lactobacillus plantarum E680, showed the highest acid (85.25%) and bile tolerance (80.79%). It was sensitive to five of the eight antibiotics tested, inhibited the growth of four pathogenic bacteria, and reduced the total cholesterol level by 66.84% in broth culture. In vivo testing using hypercholesterolemic mice fed high-fat emulsion, independent of food intake, found that L. plantarum E680 suppressed body weight gain and reduced total cholesterol and low-density lipoprotein cholesterol levels, with no effect on high-density lipoprotein cholesterol.ConclusionsChinese traditional fermented pickles are a good source for probiotics. L. plantarum E680, isolated from pickles, was acid and bile tolerant, sensitive to antibiotics, and reduced cholesterol levels both in vitro and in vivo. Based on these results, L. plantarum E680 may have potential as a novel probiotic for the development of cholesterol-lowering functional food.

Traditionally fermented pickles: How the microbial diversity associated with their nutritional and health benefits?

Abstract Historically, pickling is one of the oldest preservation methods of several foodstuffs such as vegetables, fruits, fish, and meat. Pickling imparts unique and desirable changes in flavor, texture and color that take place over time in fermented pickles. Microorganisms (mainly lactic acid bacteria, Micrococcaceae, Bacilli, yeasts, and filamentous fungi) play a pivotal role in the pickling of foodstuffs while affecting the quality and safety of the final product. This review focuses on the common traditional fermented pickles and their nutritional, therapeutic, and economic potentials. Furthermore, the technological progress in screening microbial communities associated with the traditional pickles is summarized. Finally, this paper will tackle with the role of pickles in filing the gap in food security, the safety aspect of traditional pickles and biofortication as an interesting technique to improve the quality of traditional pickles.

Microbiota Succession and Chemical Composition Involved in the Radish Fermentation Process in Different Containers.

Traditional Chinese fermented vegetables are a type of brine-salted fermented vegetable product. During the spontaneous fermentation, various compounds are produced, degraded, and converted, influencing the quality of the fermented pickle. To ascertain the effect of different containers on the fermentation process of the pickles, this study investigated the bacterial diversity and the chemical composition characteristics of the pickle (radish) fermented in commonly used containers including glass jars (GL), porcelain jars (PO), and plastic jars (PL). The correlation between chemical compounds and microbial community was further analyzed. The changes in pH values suggested that PL may facilitate the quickest fermentation of the pickles, while the process in PO progressed at the lowest rate. The PL brine samples contained higher levels of lactic acid and threonine, while more abundant volatile chemical compounds were evident in PO. The container materials had no significant influence on the microbial structure, wherein Lactobacillus was the absolute dominant genus in all containers. But container material did have an effect on the abundance of specific genus, such as Lactococcus and Pediococcus. The correlation between these major genera was also analyzed and gene function prediction indicated that the top three pathways were: carbohydrate metabolism, amino acid metabolism, and energy metabolism. Lactobacillus negatively correlated with methionine, tyrosine, lysine, and arginine, but positively correlated with ammonia, and lactic acid and acetic acid both just correlated with Pediococcus. This study provides new insights into the microbiota succession and chemical compounds involved in the vegetable fermentation.

Effects of garlic addition on bacterial communities and the conversions of nitrate and nitrite in a simulated pickle fermentation system

Garlic is a spice widely used in traditional pickle making. In this study, effects of garlic addition on bacterial communities and dynamic changes of nitrate and nitrite levels in a simulated pickle fermentation system were investigated under different conditions (with/without the inoculation of Lactobacillus plantarum or Escherichia coli). The result showed that garlic addition efficiently enhanced the growth of Lactobacillus and Weissella while inhibited a lot of undesirable microorganisms during the fermentation. Kinetic analysis revealed that garlic addition and L. plantarum inoculation both significantly decreased the conversion of nitrate and eliminated nitrite peak, but led to much higher level of remaining nitrate (above 1000 mg/kg). Correlation analysis suggested that nitrite conversion was mainly related with the growth of lactic acid bacteria, while nitrate conversion depended more on other microorganisms (like E. coli). Based on these results, introducing safe microorganisms with relatively high nitrate reductase activities and balancing the conversions of nitrate and nitrite were suggested for safer pickle production.

Exploration and Characterization of Novel Glycoside Hydrolases from the Whole Genome of Lactobacillus ginsenosidimutans and Enriched Production of Minor Ginsenoside Rg3(S) by a Recombinant Enzymatic Process.

Background: Several studies have reported that ginsenoside Rg3(S) is effective in treating metastatic diseases, obesity, and various cancers, however, its presence in white ginseng cannot be estimated, and only a limited amount is present in red ginseng. Therefore, the use of recombinant glycosidases from a Generally Recognized As Safe (GRAS) host strain is a promising approach to enhance production of Rg3(S), which may improve nutritional activity, human health, and quality of life. Method: Lactobacillus ginsenosidimutans EMML 3041T, which was isolated from Korean fermented pickle (kimchi), presents ginsenoside-converting abilities. The strain was used to enrich the production of Rg3(S) by fermenting protopanaxadiol (PPD)-mix-type major ginsenosides (Rb1, Rb2, Rc, and Rd) in four different types of food-grade media (1, MRS; 2, Basel Food-Grade medium; 3, Basel Food-Grade medium-I, and 4, Basel Food-Grade medium-II). Due to its tendency to produce Rg3(S), the presence of glycoside hydrolase in Lactobacillus ginsenosidimutans was proposed, the whole genome was sequenced, and the probable glycoside hydrolase gene for ginsenoside conversion was cloned. Results: The L. ginsenosidimutans EMML 3041T strain was whole genome sequenced to identify the target genes. After genome sequencing, 12 sets of glycoside hydrolases were identified, of which seven sets (α,β-glucosidase and α,β-galactosidase) were cloned in Escherichia coli BL21 (DE3) using the pGEX4T-1 vector system. Among the sets of clones, only one clone (BglL.gin-952) showed ginsenoside-transforming abilities. The recombinant BglL.gin-952 comprised 952 amino acid residues and belonged to glycoside hydrolase family 3. The enzyme exhibited optimal activity at 55 °C and a pH of 7.5 and showed a promising conversion ability of major ginsenoside Rb1→Rd→Rg3(S). The recombinant enzyme (GST-BglL.gin-952) was used to mass produce Rg3(S) from major ginsenoside Rb1. Scale-up of production using 50 g of Rb1 resulted in 30 g of Rg3(S) with 74.3% chromatography purity. Conclusion: Our preliminary data demonstrated that this enzyme would be beneficial in the preparation of pharmacologically active minor ginsenoside Rg3(S) in the functional food and pharmaceutical industries.

Lactobacillus fermentum CQPC06 in naturally fermented pickles prevents non-alcoholic fatty liver disease by stabilizing the gut-liver axis in mice.

Herein, we used a HFD/F to induce NAFLD in mice and intervened with CQPC06 to determine the preventive effect of CQPC06 on NAFLD and its potential regulatory mechanism. C57BL/6J mice were fed with LFD, HFD/F, HFD/F supplemented with CQPC06, and HFD/F supplemented with LDBS for 8 weeks to test the properties of the probiotic. Biochemical and molecular biology methods were used to determine the levels of related indexes in mouse serum, liver tissue, epididymal fat, small intestine tissue, and feces. The results showed that CQPC06 exhibited satisfactory probiotic properties, significantly inhibited mouse weight gain, and decreased the liver index and serum lipid levels, including ALT, AKP, AST, TC, TG, LDL-C, LPS, and HDL-C levels. The HOMA-IR index calculated based on the blood glucose levels and serum insulin levels showed that the HOMA-IR index of NAFLD mice treated with CQPC06 significantly decreased. From the molecular biology level, CQPC06 significantly increased the mRNA and protein expression of PPAR-α, CYP7A1, CPT1, and LPL in NAFLD mouse livers, and decreased the expression of PPAR-γ and C/EBP-α. Furthermore, CQPC06 enhanced the expression of ZO-1, occludin, and claudin-1 in the small intestine of NAFLD mice, and decreased the expression of CD36. CQPC06 decreased the level of Firmicutes and increased the levels of Bacteroides and Akkermansia in the feces of NAFLD mice, and the ratio of Firmicutes/Bacteroides was significantly decreased. CQPC06 is highly resistant in vitro and survived in the gastrointestinal tract and exerted its probiotic effect, altered the intestinal microecology of NAFLD mice, and played an important role in NAFLD prevention through the unique anatomical advantages of the gut-liver axis. There was a clear preventive effect with high concentrations of CQPC06 and it was stronger than that of l-carnitine.

Influence of different culture conditions on exopolysaccharide production by indigenous lactic acid bacteria isolated from pickles.

The objective of this study was to assess the effects of some culture conditions [temperature (20, 30, 37°C), incubation time (48, 72, 120h), pH (5.0, 6.0, 7.0), NaCl concentration (0, 3, 6%), carbon (glucose, fructose, lactose), nitrogen (sodium nitrate, ammonium sulfate, bacto-peptone), and mineral sources (calcium carbonate, ferric chloride)] on the exopolysaccharide (EPS) production by lactic acid bacteria (LAB) strains (belonging to Lactobacillus (L.) plantarum, L. namurensis, and Pediococcus (P.) ethanolidurans species) isolated from naturally fermented pickles. The maximum EPS production was determined at 30°C and pH 6.0. The highest amount of EPS was obtained after 120h of incubation, with glucose as carbon source, bacto-peptone as nitrogen source and calcium carbonate as mineral source for most of the tested strains. The EPS formation was not stimulated by NaCl, indicating that EPS formation of the tested strains was not a stress response. L. plantarum MF460 produced the highest amount of EPS at 30°C after 48h of incubation, which was 515.48mg/L. One of the most pronounced results of this study was that the EPS production of L. plantarum MF556 strain was increased up to 512.81mg/L with the addition of calcium carbonate to MRS medium. The effect of different culture conditions, particularly of incubation time, carbon, nitrogen, and mineral sources, on the EPS production often vary depending on the strain. Therefore, these apparent strain specific results demonstrated that the optimum culture conditions for the enhanced EPS production should be specifically determined for each LAB strain.

The characteristics and correlation of the microbial communities and flavors in traditionally pickled radishes

Pickled radish produced using the traditional fermentation method that radishes being fermented with the aged brine in the pottery altar is exceptionally popular and widely consumed around China. Although this traditional technique is usually associated with the production of high-quality fermented radish, the main features of radish prepared using this method remain unclear. This study revealed the characteristics of microbial diversity and flavors in radish fermented with aged brine in traditional pottery containers. At the phylum level, Firmicutes was the highest during the fermentation process. At the genus level, the abundance of Lactobacillus dominated. As for fungal composition, Pichia and Candida were the main genera, and the abundance of Pichia was significantly higher than Candida. This study also identified the volatile flavor compounds, some of them for the first time, and PCA revealed the separation between samples was dominated by dimethyl trisulfide and piperidine-2-thione. The correlation analysis suggested that Lactobacillus was negatively associated with 13 flavors, of which ten flavors were free amino acids (FAA). Enterobacteriaceae unclassified was correlated positively with 18 flavors, of which 14 were FAA. This study provided insight into the characteristics of fermented pickles produced using traditional fermentation techniques, and the relationship between microbiota and flavors.

Isolation of virulent phages infecting dominant mesophilic aerobic bacteria in cucumber pickle fermentation

Pickle is a type of mildly lactic acid fermented vegetable and is a traditional dish favored in China, Japan, and Korea. Corruption of spoilage bacteria and accumulation of nitrite during vegetable fermentation are common problems that affect the pickle industry and consumer health. In this work, cucumber juice was used as a vegetable model to study the dominant mesophilic aerobic bacteria (MAB) producing nitrite during pickle fermentation. Virulent phages infecting the dominant MABs combined with Lactobacillus plantarum M6 were used to control these bacteria. Enterobacter cloacae and Pseudomonas fluorescens are the dominant MABs in the fermentation of cucumber juice containing 4% or 8% NaCl, with isolation percentages reaching 30.6% and 23.1%, respectively. Virulent phages PspYZU5415 and EcpYZU01 were isolated using P. fluorescens J5415 and E. cloacae J01 as the host bacteria, respectively. These two phages show a broad host range and strong lytic activity, and their genomes contain no toxins and antibiotic resistance genes. PspYZU5415 and EcpYZU01 were combined into a cocktail (designated as Phage MIX) that effectively inhibits the growth of E. cloacae and P. fluorescens in cucumber juice with different salt concentrations. PhageMIX combined with L. plantarum M6 decreased the counts of P. mendocina and E. cloacae to undetectable levels at 48 h during the fermentation of cucumber juice artificially contaminated with P. mendocina and E. cloacae. In addition, nitrite content increased to 11.3 mg/L at 20 h and then degraded completely at 36 h. By contrast, P. mendocina and E. cloacae remained in the groups without PhageMIX during fermentation (0–48 h). Nitrite content rapidly increased to 65.7 mg/L at 12 h and then decreased to 21.6 mg/L at 48 h in the control group. This study suggests that PhageMIX combined with lactic acid bacterial strains can be used as an ecological starter for controlling the dominant MABs P. mendocina and E. cloacae and for reducing nitrate production during the early stage of pickle fermentation.

Effect of different fermenting containers on the deterioration of Sichuan pickle

Sichuan pickles, the traditional Chinese fermented vegetables, are produced in a variety of containers during both the homemade and industrial processes. To ascertain the effect of the different containers on deterioration of the pickle, this study investigated the physicochemical properties, flavor characteristics and fungi diversity of pickles fermented in glass jars (GL), porcelain jars (PO) and plastic jars (PL) at the stage of deterioration. The results revealed that the contents of lactic acid and butyric acid in the pickles were higher in the PL than in the other jars on the 31st day of fermentation. Fermented radish presented the lowest hardness in the PL, while flavor compound identification suggested differences in the flavor profiles amongst the containers. At genus level, the abundance of Pichia and Candida, the top two predominating genera, were also higher in the PL than in the GL or PO. Meanwhile, pellicles formed mostly in the surface of brine in the PL. Correlation analysis uncovered the relevance between flavor compounds and fungi communities. These results suggested that pickle deteriorates to greatest extent in PL. This study provides new insights to the effect of containers on the deterioration of fermented pickle.

Characterization of a probiotic starter culture with anti-Candida activity for Chinese pickle fermentation.

Probiotic starters for Chinese pickle fermentation were screened from three anti-Candida lactic acid bacteria (LAB). Similar to commercial starters, the candidates Lactobacillus plantarum AT4 and L. plantarum AT28 could acidize the pickle within 10 days. The isolates AT4 and AT28 maintained 6.0-7.0 log cfu ml-1 in the pickle products and their inhibition rates against Candida increased to 83.7% and 92.9% after fermentation, respectively. Only L. plantarum AT4 satisfied the essential probiotic requirements such as tolerance to the gastrointestinal environment (pH 2.0, 0.5% bile salts and 0.5% phenol) and adhesion to Caco-2 cells. The pickle product fermented with L. plantarum AT4 presented comparable levels of lactic and acetic acids, volatile profile and sensory value to the commercial one. The results suggested that L. plantarum AT4 can be used as a probiotic starter for industrial fermentation of Chinese pickle, and the pickled product may be utilized as a promising anti-Candida probiotic.

Plackett-Burman Screening Design for the Production of Fermented Fiddlehead Fern (Diplazium esculentum Retz.)

This study was performed to screen the variables that influence the quality of pickled fiddlehead fern. The fiddlehead fern pickles were subjected to Plackett-Burman Design (PBD) wherein the variables; nature of fiddlehead fern, levels of salt, fermentation time, fermentation temperature, levels of sugar, and levels of alum were screened. The eight-run screening designs performed in triplicates were subjected to physico-chemical and sensory analysis. Statistical analysis revealed that the pre-processing treatments of the fiddlehead fern, levels of sugar and fermentation time are the factors that significantly affect the fermented fiddlehead fern. Results showed that the blanching of fiddlehead fern before brining, high sugar concentration and longer fermentation significantly favor the sensory and physico-chemical properties of the fermented pickles. To optimize the exact levels of the significant variables, it is therefore recommended that these will be further subjected to optimization studies such as Response Surface Methodology.

Biogenic amine and fermentation metabolite production assessments of Lactobacillus plantarum isolates for naturally fermented pickles

This research aimed to assess the production of biogenic amines and fermentation metabolites by Lactobacillus plantarum isolates from randomly collected, naturally fermented pickles. Isolates were identified as L. plantarum strains based on the identification of the recA gene by colony PCR and 16S rRNA PCR amplification followed by sequencing. The production of three biogenic amines, cadaverine, putrescine and histamine, was measured in the identified strains with HPLC analysis. The fermentation metabolites formate, pyruvate, lactate, ethanol, and 2,3-butanediol were measured in the isolates with HPLC analysis. Forty-seven of the 78 isolates were identified as L. plantarum strains. Putrescine, cadaverine, and histamine were produced by almost all isolates. 9% of L. plantarum isolates produced total biogenic amines over 1000 mg/L. The biogenic amine concentration (mg/L) ranges for cadaverine, putrescine, and histamine were 13–298, non-detected–994, and non-detected–668, respectively. The total biogenic amine production was between 94 and 1332 mg/L. Five fermentation metabolites were detected with various concentration ranges (mg/mL): formate, 4.01–64.90; pyruvate, 0.10–0.98; lactate, 7.11–45.99; ethanol, 549.42–937.63; and 2,3-butanediol, 0.11–13.15. L. plantarum strains in naturally fermented pickles may produce biogenic amines, but most probably not at toxic limits.

Investigation of Functional and Structural Properties of Insoluble Dietary Fiber From Sichuan Natural Fermented Pickles With Different Salting Treatments

In this study, the functional and structural properties of insoluble dietary fibers (IDFs) from Sichuan natural fermented pickle vegetables, subjected to different saline treatments are investigated. The IDF is extracted using an ultrasonic‐assisted enzyme method. The primary measurable indicators that are determined, include the water‐ and oil‐holding capacity, swelling capacity, heavy metal adsorption capacity, bile acid salts adsorption capacity, antioxidant activity, and polyphenol content. Additionally, a structural analysis is also performed using infrared spectroscopy, thermogravimetry (TG), and scanning electron microscopy. Experimental results demonstrate that both high and low salt saline fermentations have no significant effect on the techno‐functional properties of IDF in vegetables (p > 0.05); however, the physio‐functional properties, including bile acid salts adsorption capacity, heavy metal adsorption capacity (Pb, As), and the antioxidant capacity are shown to be significantly enhanced (p < 0.05). The low salt saline fermentation is shown to have an improvement effect as compared to the high salt fermentation, which is further supported by the structural characterizations including the structure and chemical groups differences, morphological changes of particles, and thermal stability differences. The findings from this work reveal the effects of saline treatments on the functional properties of IDFs, which are extracted from Sichuan pickle vegetables. In addition, they provide a potential manufacturing technique to improve the quality of the DF in Sichuan pickle vegetables.

Optimization of lactic acid bacteria viability using fuzzy soft set modelling

Lactic acid fermented vegetables are important sources of vitamins and minerals. In recent years consumers demand for non-dairy based functional products has increased. Cabbage pickle has high enough concentrations of fiber and also it may show health effect with the containing high numbers of lactic acid bacteria. The aim of this study is to optimize mathematically cabbage-carrot pickle fermentation for the viability of Lactobacillus acidophilus, Lactobacillus casei cultures and the sensory scores in brine with 5% and 7% (w/v) salt concentrations. Viability optimization of lactic acid bacteria is done via the notion of “fuzzy soft set” method. Lb. casei, Lb. acidophilus, total lactic acid bacteria, Enterobacteriaceae sp., yeast-mould counts and pH values have been reported during the 30 days of storage. The results are compared with the control traditional fermented cabbage-carrot pickle. Organoleptic properties are evaluated. We conclude that the fermented pickle samples contain a significant number of beneficial lactic acid bacteria and high sensory marks at the end of the storage.