Production of high γ-aminobutyric acid (GABA) sour kimchi using lactic acid bacteria isolated from <Emphasis Type="Italic">mukeunjee</Emphasis> kimchi

A sour kimchi product with an elevated amount of γ-aminobutyric acid (GABA) was produced using starter lactic acid bacteria (LAB) for mukeunjee kimchi fermentation. The starter LAB were screened and isolated from the commercial mukeunjee kimchi product that showed the highest GABA content and was identified as Lactobacillus buchneri. The maximum GABA production of L. buchneri in MRS media was 5.83 mg/mL at pH 4.2 and the addition of 3% NaCl did not significantly (p>0.05) changed GABA production of L. buchneri. The amount of GABA in L. buchneri-inoculated sour kimchi was 61.65 mg/100 g, which represented about 8 times higher than the L. buchneri uninoculated kimchi (control kimchi). A sensory evaluation test of L. buchneri-inoculated sour kimchi and control kimchi showed that the L. buchneri inoculation may produce more sour kimchi than control kimchi, but there was no difference in the general acceptance between the 2 kimchi products (p>0.05).     

Effects of Different Salt Treatments on the Fermentation Metabolites and Bacterial Profiles of Kimchi

The effects of purified salt (PS) and mineral‐rich sea salt (MRS), both with different mineral profiles, on kimchi fermentation were studied using a culture‐dependent 16S rRNA sequencing technique and mass‐based metabolomic analysis. The different mineral profiles in the fermentation medium caused changes in the bacterial profiles of the 2 kimchi products. An increase of Leuconostoc species in MRS‐kimchi decreased the Lactobacillus/Leuconostoc ratio, which led to changes in metabolites (including sugars, amino acids, organic acids, lipids, sulfur compounds, and terpenoids) associated with kimchi quality. Although further studies on the relationship between these salt types and kimchi fermentation are needed, these results suggested that the MRS treatment had positively affected the changes of the kimchi mineral contents, bacterial growth, and metabolite profiles, which are linked to kimchi quality.     

Improvements in the Quality and Shelf Life of Kimchi by Fermentation with the Induced Bacteriocin-Producing Strain,Leuconostoc citreum GJ7 as a Starter

ABSTRACT: To improve the quality and self-life of kimchi, the induced bacteriocin-producing lactic acid bacteria (LAB), Leuconostoc citreum GJ7, was introduced into kimchi fermentation as a starter. The kimchi preparations were incubated at 7 °C for 12 to 15 d, and then stored at −1 °C. Thereafter, changes in their characteristics were monitored for 125 d. When a kimchi starter was introduced into a nonsterile and open kimchi fermentation system, over-ripening of kimchi was prevented during 125 d of storage. In the starter kimchi, Leuc. citreum GJ7 was the dominant organism, comprising 70% to 90% of the total flora, and no yeasts were detected during the entire storage period. However, in the nonstarter kimchi, the predominant LAB could not be determined and yeasts were detected after 50 d of storage. The viable cell number of the starter kimchi was 2 log CFU/mL higher than in the nonstarter kimchi at 125 d of storage. The texture (firmness) of the starter kimchi at 95 to 125 d of storage was similar to that of the nonstarter kimchi at 20 d of storage. Sensory evaluations of texture, off-flavor, and carbonated mouthfeel were significantly improved by the starter-fermentation. The results indicate that the application of the bacteriocin-enhanced Leuc. citreum GJ7 as a starter culture exerts microbial control, prevents over-ripening, and extends the shelf life of kimchi. Practical Application: Presently, we have shown that under the optimum fermentation condition the induced bacteriocin-producing LAB, Leuc. citreum GJ7, can regulate natural kimchi fermentation and has extended dominance within the microbial ecology of kimchi. The result is improved quality and shelf life of kimchi. Moreover, to control the growth of other microorganisms in open-fermentation and nonsterile conditions, this system may be usefully adapted for other food or environmental control systems.     

Selection of LAB strains for fermented red beet juice production

Authentic LAB strains were investigated for their lactic acid, H₂O₂, and biogenic amine production, and their effect on red beet betalains. There was no significant difference between the strains in respect of cell propagation in beet juice. Lb. curvatus 2770 provided the best pH drop. None of the investigated LAB excreted either histamine or tyramine, but in the spontaneously fermented juice both amines were present and the total amine level was high. H₂O₂ synthesis was similar and not higher than 1 mg l^–1. The betalain content showed greatest reduction in the case of spontaneous fermentation and similar values for the LAB strains.     

Microbial Succession and Metabolite Changes during Long‐Term Storage of Kimchi

Kimchi is often stored for a long period of time for a diet during the winter season because it is an essential side dish for Korean meals. In this study pH, abundance of bacteria and yeasts, bacterial communities, and metabolites were monitored periodically to investigate the fermentation process of kimchi for 120 d. Bacterial abundance increased quickly with a pH decrease after an initial pH increase during the early fermentation period. After 20 d, pH values became relatively stable and free sugars were maintained at relatively constant levels, indicating that kimchi fermentation by lactic acid bacteria (LAB) was almost completed. After that time, a decrease in bacterial abundance and a growth in Saccharomyces occurred concurrently with increased free sugar consumption and production of glycerol and ethanol. Finally, after 100 d, the growth of Candida was observed. Community analysis using pyrosequencing revealed that diverse LAB including Leuconostoc citreum, Leuconostoc holzapfelii, Lactococcus lactis, and Weissella soli were present during the early fermentation period, but the LAB community was quickly replaced with Lactobacillus sakei, Leuconostoc gasicomitatum, and Weissella koreensis as the fermentation progressed. Metabolite analysis using ¹H‐NMR showed that organic acids (lactate, acetate, and succinate) as well as bioactive substances (mannitol and gamma‐aminobutyric acid (GABA)) were produced during the kimchi fermentation, and Leuconostoc strains and Lactobacillus sakei were identified as the producers of mannitol and GABA, respectively. Practical Application In this study, we have shown that the growth inhibition of yeasts including Saccharomyces and Candida is necessary to extend the shelf life of kimchi in long‐term storage. Additionally, we have shown that a mixed culture of Leuconostoc strains and Lactobacillus sakei is necessary to produce kimchi that contains both mannitol and gamma‐aminobutyric acid.     

Radical scavenging capacities of saba-narezushi,Japanese fermented chub mackerel,and its lactic acid bacteria

Narezushi (salted and fermented fish with rice) is a traditional Japanese food prepared using lactic acid-fermentation. In the current study, the antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH^?)) and superoxide anion radical (O₂^?) scavenging capacities of four saba-narezushi (fermented chub mackerel with rice) products were determined. Lactose utilizing, bile resistant, acidophilic and antioxidative lactic acid bacteria (LAB) were also screened from 182 isolates derived from narezushi samples for use as starters of fermented foods as well probiotics. Radical scavenging capacities varied by product, with viable cell counts ranging from 7.9 to 9.4 log CFU/g and lactic acid content ranging from 0.27 to 1.2 mmol/g. Of the LAB isolates examined, five (four Lactobacillus plantarum and one Leuconostoc mesenteroides) were identified that were able to ferment lactose, grow in MRS containing 3 g/L bile, grow in broth adjusted to pH 3.6, and scavenge DPPH^? and/or O₂^? radicals. Two strains, Lb. plantarum 7FM10 and Ln. mesenteroides 1RM3, were able to grow and ferment in soybean milk and vegetable juice. These LAB also exhibited synergistic effects in milk fermentation, where samples containing both LAB showed a significant increase in O₂^? radical scavenging capacity.     

Source Tracking and Succession of Kimchi Lactic Acid Bacteria during Fermentation

This study aimed at evaluating raw materials as potential lactic acid bacteria (LAB) sources for kimchi fermentation and investigating LAB successions during fermentation. The bacterial abundances and communities of five different sets of raw materials were investigated using plate‐counting and pyrosequencing. LAB were found to be highly abundant in all garlic samples, suggesting that garlic may be a major LAB source for kimchi fermentation. LAB were observed in three and two out of five ginger and leek samples, respectively, indicating that they can also be potential important LAB sources. LAB were identified in only one cabbage sample with low abundance, suggesting that cabbage may not be an important LAB source. Bacterial successions during fermentation in the five kimchi samples were investigated by community analysis using pyrosequencing. LAB communities in initial kimchi were similar to the combined LAB communities of individual raw materials, suggesting that kimchi LAB were derived from their raw materials. LAB community analyses showed that species in the genera Leuconostoc, Lactobacillus, and Weissella were key players in kimchi fermentation, but their successions during fermentation varied with the species, indicating that members of the key genera may have different acid tolerance or growth competitiveness depending on their respective species.     

Spray drying conditions for orange juice incorporated with lactic acid bacteria

This work aimed to develop an orange juice powder by spray drying with lactic acid bacteria (Lactobacillus plantarum 299v and Pediococcus acidilactici HA‐6111‐2), testing their survival both during drying and storage (room temperature and 4 °C). Initially, the best conditions for spray drying were chosen to allow the best survival of each LAB: (i) inlet air temperature of 120 °C and (ii) 0.5:2 ratio of the orange juice soluble solids and drying agent added (prebiotics: 10 DE maltodextrin or gum Arabic). Survival of LAB was not affected by drying process, and it was higher when cultures were stored at 4 °C. A slightly higher protection was conferred by 10 DE maltodextrin, in the case of L. plantarum and at 4 °C. Pediococcus acidilactici was more resistant during storage at 4 °C, with logarithmic reductions lower than 1 log‐unit. It was demonstrated that it is possible to produce a functional nondairy product, orange juice powder supplemented with prebiotic compounds, containing viable LAB for at least 7 months, when stored at 4 °C.     

Development of fermented Hericium erinaceus juice with high content of L‐glutamine and L‐glutamic acid

Fermented plant beverages (FPB) with a high content of desirable principle components are served as functional foods from several years. Hericium erinaceus is famous for its antimicrobial, antioxidant, antihypertensive and antidiabetic nature. Accordingly, the current study was aimed to produce fermented H. erinaceus juice with a high content of L‐glutamine (Gln) and L‐glutamic acid (GA) through lactic acid bacteria (LAB) isolated from fermented Thai foods. LAB isolates were screened and identified the potent protease‐producing bacteria Enterococcus faecalis (G414/1) that facilitate the production of Gln and GA through protein hydrolysis. Box–Behnken design (BBD) and response surface methodology (RSM) were adapted for the optimisation of conditions for the increased production of Gln and GA during fermentation of H. erinaceus. We succeeded with an optimum concentration of cofactor (CaCl₂), pH and temperature for improved protease activity and subsequent Gln and GA production. The ability of isolated E. faecalis strain to produce Gln and GA was demonstrated in this study. Further, upstream processes like strain improvement and media optimisation will direct the way to produce enriched H. erinaceus based FPB.     

Selectivity and antimicrobial action of bovine lactoferrin derived peptides against wine lactic acid bacteria

In this study, the antibacterial activities of a bovine Lactoferrin pepsin hydrolysate (LFH) and a synthetic peptide derived from bovine lactoferricin (LfcinB_17–31) have been evaluated against Oenococcus oeni and three additional lactic acid bacteria (LAB) known to cause spoilage during winemaking processes. Inhibition of bacterial growth was demonstrated in vitro in synthetic broth media (MRS) for both LFH and LfcinB_17–31. The bactericidal activity of the synthetic peptide was also assayed and found to vary depending on the bacterial species and the matrix in which exposure to peptide occurred (either MRS broth or white must). Specificity of LfcinB_17–31 for Lactobacillus brevis, Pediococcus damnosus, and O. oeni was demonstrated in must fermentation experiments in which these three LAB co-existed with the winemaking Saccharomyces cerevisiae T73 in the presence of the peptide. Finally, fermentation experiments also showed that LfcinB_17–31 at inhibitory concentrations did not alter either fermentation kinetics or specific enological parameters.     

Characterization of High-Hydrostatic-Pressure Effects on Fresh Produce Using Chlorophyll Fluorescence Image Analysis

High hydrostatic pressure has the potential to affect food-related enzymes and microorganisms while retaining the produce’s characteristic properties. Although many studies on effects of high pressure on quality attributes of fruit and vegetables have been published, experimental results on the impact of high-pressure treatment on the physiological activity of products are rare. To characterize changes of the samples fast and noninvasive methods as well as a sensitive biological model system are required for this purpose. In this study, fresh lamb’s lettuce (Valerianella olitoria Poll.) was used as a model produce. For each treatment, two leaves were carefully inserted to small plastic pouches, sealed and then subjected to pressure (up to 7.5 min at 200 MPa) or thermal treatment (up to 1 min at 50°C). Chlorophyll fluorescence imaging was applied to measure the local and temporal dynamics of the physiological postprocessing effects. Measurements of the maximum photochemical efficiency F _v/F _m allows the immediate evaluation of photosynthetic activity as an indicator for cell and tissue vitality. Thermal treatment at pressure below 125 MPa and temperatures lower than 45°C showed minor fully reversible effects but a pronounced decline in the maximum photochemical efficiency was obtained after pressure treatment of 150 MPa and temperatures of 45°C or higher values. These changes were irreversible within 24 h of recovery time. Above these thresholds, high pressure and heat treatment may not be applicable for mild processing of highly perishable fresh produce. Chlorophyll fluorescence analysis has been proven to be a valuable tool for the rapid and comprehensive evaluation of postharvest processing of green perishables.     

Effects of Leuconostoc mesenteroides starter cultures on microbial communities and metabolites during kimchi fermentation

Kimchi fermentation usually relies upon the growth of naturally-occurring various heterofermentative lactic acid bacteria (LAB). This sometimes makes it difficult to produce kimchi with uniform quality. The use of Leuconostoc mesenteroides as a starter has been considered to produce commercial fermented kimchi with uniform and good quality in Korea. In this study, a combination of a barcoded pyrosequencing strategy and a ¹H NMR technique was used to investigate the effects of Leu. mesenteroides strain B1 as a starter culture for kimchi fermentation. Baechu (Chinese cabbage) and Chonggak (radish) kimchi with and without Leu. mesenteroides inoculation were prepared, respectively and their characteristics that included pH, cell number, bacterial community, and metabolites were monitored periodically for 40 days. Barcoded pyrosequencing analysis showed that the numbers of bacterial operational taxonomic units (OTU) in starter kimchi decreased more quickly than that in non-starter kimchi. Members of the genera Leuconostoc, Lactobacillus, and Weissella were dominant LAB regardless of the kimchi type or starter inoculation. Among the three genera, Leuconostoc was the most abundant, followed by Lactobacillus and Weissella. The use of Leu. mesenteroides as a starter increased the Leuconostoc proportions and decreased the Lactobacillus proportions in both type of kimchi during kimchi fermentation. However, interestingly, the use of the kimchi starter more highly maintained the Weissella proportions of starter kimchi compared to that in the non-starter kimchi until fermentation was complete. Metabolite analysis using the ¹H NMR technique showed that both Baechu and Chonggak kimchi with the starter culture began to consume free sugars earlier and produced a little greater amounts of lactic and acetic acids and mannitol. Metabolite analysis demonstrated that kimchi fermentation using Leu. mesenteroides as a starter was completed earlier with more production of kimchi metabolites compared to that not using a starter, which coincided with the decreases in pH and the increases in bacterial cell number. The PCA strategy using all kimchi components including carbohydrates, amino acids, organic acids, and others also showed that starter kimchi fermented faster with more organic acid and mannitol production. In conclusion, the combination of the barcoded pyrosequencing strategy and the ¹H NMR technique was used to effectively monitor microbial succession and metabolite production and allowed for a greater understanding of the relationships between the microbial community and metabolite production in kimchi fermentation.     

辣白菜中分离含内源性质粒的魏斯氏菌及其鉴定

为了探讨魏斯氏菌在辣白菜中起的作用和获得与明串珠菌相关乳酸细菌的质粒,从辣白菜中分离了魏斯氏菌。辣白菜是朝鲜民族的传统食品,在低温条件下大白菜经过乳酸细菌发酵而成的。将辣白菜汁液均匀涂布在含2%(m/v)CaCO3的MRS平板上,30℃恒温培养箱中培养24h～36h,在中国内地首次分离获得了魏斯氏菌。通过对该菌进行镜检、生理生化特性检测以及16S rDNA序列的系统发育树分析确定其分类地位。结果表明其属于Weissella cibaria,命名为kimshi006,在NCBI上的登录号为HM369807。这一魏斯氏菌菌株含有2条内源性质粒,其大小分别为大约3000bp和8000bp。     

Effect of Lactobacillus plantarum as a starter on the food quality and microbiota of kimchi

Lactobacillus plantarum has been reported to be responsible for acid increase at the later stage of kimchi fermentation and considered not inappropriate as a starter of kimchi. If functional L. plantarum strain can survive in large quantity in kimchi during fermentation, it may endow new functionality to kimchi. After 12 day fermentation at 4°C, L. plantarum, Leuconostoc mesenteroides, Weissella cibaria, Weissella confusa, and Lactobacillus sakei were the most prevalent ones in kimchi without a starter. In kimchi with a starter, L. plantarum was detected from the 1 day fermentation and throughout 25 day fermentation. There was no difference in pH between 2 kinds of kimchi. The acid content after the 21 day increased more in kimchi with starter when most kimchi is consumed before this time. Survival of a starter strain throughout the whole fermentation suggested the possible use of various functional lactic acid-producing bacterias (LABs) to kimchi endowing a new beneficial function to kimchi.     

Microbiological and physicochemical properties of dry‐cured neck inoculated with probiotic of Bifidobacterium animalis ssp. lactis BB‐12

The effect of inoculum level of Bifidobacterium animalis ssp. lactis BB‐12 probiotic strain and ripening period on the quality of dry‐cured neck was studied. The microbiological parameters (Enterobacteriaceae, LAB and TVC) and physicochemical attributes (pH value, a_w, TBARS index, colour) were determined directly after fermentation at 15 °C for 3 weeks, after 6 and 12 months of ripening at 4 °C. The highest LAB count and a lower pH value were found in the meat inoculated with probiotic strain at 6.6 log cfu g^?1 (B2) followed by inoculation with probiotic strain at 6.3 log cfu g^?1 (B1). Level of inoculation had not had an influence on water activity, TBARS index and total colour parameters. Changes of fat oxidation during half‐year of ripening were limited in probiotic meat samples compared to naturally fermented control meat (C). Based on the results, it can be concluded that the most favourable physicochemical and microbiological parameters of the dry‐cured neck were obtained after 6 months of ripening. At that time, the Bifidobacterium BB‐12 at both levels is a good potential starter for meat fermentation.     

Analysis of volatile compounds produced by different species of lactobacilli in rye sourdough using multiple headspace extraction

Profiles of volatile organic compound (VOC) produced by nine individual lactic acid bacteria (LAB) during rye sourdough fermentation were compared by automated SPME and GC/MS‐Tof. The dough samples were inoculated with individual strains, placed inside the headspace vials and incubated during next 24 h. The production or loss of VOC‐s was followed by adsorbing volatiles onto 85‐m Car/PDMS fibre in every 4 h. Volatile profiles differed among LAB species and divided LAB into two main groups – hetero‐ and homofermentative. Hetrofermentative LAB (Lactobacillus brevis; Leuconostoc citreum; Lactobacillus vaginalis, Lactobacillus panis) showed high production of acetic acid, CO₂, ethanol, ethylacetate, producing also hexyl acetate, ethyl hexanoate and isopentyl acetate. Whereas homofermentative LAB species (Lactobacillus helveticus; Lactobacillus casei; Lactobacillus sakei; Lactobacillus curvatus) produced a considerable amount of 2,3‐butanedione. Production of l ‐leucine methyl ester was unique for Lb. sakei, Lb. casei and Lb. curvatus strains. Lb. helveticus was the only LAB that produced benzaldehyde.     

Distribution of lactic acid bacteria in garlic (Allium sativum) and green onion (Allium fistulosum) using SDS-PAGE whole cell protein pattern comparison and 16S rRNA gene sequence analysis

Distributions of lactic acid bacteria (LAB) in garlic and green onion samples as kimchi sub-ingredients were analyzed by comparing the SDS-PAGE whole cell protein patterns and 16S rRNA gene sequence analysis. In total, 245 LAB were isolated from 10 garlic samples and differentiated into 7 groups by comparing SDS-PAGE whole cell protein patterns. The groups were identified as Leuconostoc, Weissella, and Lactobacillus through the 16S rRNA gene sequence analysis. A total of 115 LAB were isolated from 7 green onion samples, differentiated into 6 groups, and identified as Weissella, Leuconostoc, and Lactococcus. Leuconostoc was the most dominated LAB in garlic and Weissella was the most dominated LAB in green onion. The LAB identified in this study was found as dominant microorganisms in kimchi. This result suggests the possible contribution of LAB in garlic and green onion to the bacterial microflora of kimchi, especially during early stage of fermentation.     

Effects of electron beam irradiation on microbial inactivation and quality of kimchi paste during storage

The effects of electron beam irradiation on microbial inactivation and quality of noninoculated and inoculated (Listeria monocytogenes) kimchi pastes were examined. Kimchi paste samples were irradiated at doses of 2, 4, 6, 8 and 10 kGy and stored for 21 days at 4 °C. Irradiation (10 kGy) reduced the populations of total aerobic bacteria, lactic acid bacteria, and yeast and moulds in the samples by 1.72, 2.24 and 0.86 log CFU g^?1, respectively, compared to the control. In particular, coliforms were not detected at 8 and 10 kGy, and the population of L. monocytogenes in inoculated samples was significantly decreased by 2.67 log CFU g^?1. Electron beam irradiation delayed the changes in O₂ and CO₂ concentrations, pH, acidity and reducing sugar content observed in kimchi paste during storage. These results suggest that electron beam irradiation can be used to improve the microbiological safety and shelf life of kimchi paste.     

Microbiological and physicochemical characterisation of green table olives of Halkidiki and Conservolea varieties processed by the Spanish method on industrial scale

The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties.     

Diversity of bacteria and yeast in the naturally fermented cotton seed and rice beverage produced by Brazilian Amerindians

Microorganisms associated with the fermentation of cotton seed and rice were studied using a combination of culture-dependent and -independent methods. Samples of the cotton seed and rice beverage were collected every 8 h during the fermentation process for analysis of the microbiota present over 48 h. The lactic acid bacteria (LAB) population reached values of approximately 8.0 log cfu/mL. A total of 162 bacteria and 81 yeast isolates were identified using polyphasic methods. LAB (Lactobacillus plantarum, Lactobacillus vermiforme, Lactobacillus paracasei) were the most frequently isolated bacteria. Bacillus subtilis was present from 16 h until the end of the fermentation process. A decrease in pH value from 6.92 (0 h) to 4.76 (48 h) was observed, and the concentration of lactic acid reached 24 g/L at the end of the fermentation process. DGGE (denaturing gradient gel electrophoresis) was performed to determine the dynamics of the communities of bacteria and yeast, and the analysis revealed a predominance of LAB throughout the fermentation process. No changes were observed in the yeast community. The yeast species detected were Candida parapsilosis, Candida orthopsilosis, Clavispora lusitaniae and Rhodotorula mucilaginosa. Our studies indicate that the DGGE technique combined with a culture-dependent method is required to discern the dynamics in the fermentation of cotton seed and rice.