Exploring the anti-obesity effects of kimchi through enhanced thermogenesis in differentiated T37i brown adipocytes.

Background: Previous research has demonstrated the anti-obesity effects of kimchi in 3T3-L1 adipocytes and mice with diet-induced obesity by assessing the expression of obesity-associated genes. Additionally, recent studies have identified mechanisms involving thermogenesis that support these effects. Objective: This study aims to further investigate the anti-obesity properties of kimchi, focusing on its impact on thermogenic activity in differentiated T37i brown adipocytes. Design: The study first evaluated the antioxidant potential of kimchi using total antioxidant capacity (TAC) and ferric reducing antioxidant power (FRAP) assays. Optimal differentiation conditions for T37i adipocytes were established before proceeding with evaluations of cell viability, intracellular triglyceride (TG) content, lipid accumulation, and the expression of genes and proteins related to obesity and thermogenesis. Results: Kimchi maintained over 90% cell viability in T37i adipocytes at concentrations up to 1,000 µg/mL. Efficient differentiation of T37i preadipocytes was achieved using a medium containing 10% calf serum, 2 nM 3,3',5-triiodo-L-thyronin (T3), and 100 nM insulin. Kimchi significantly reduced intracellular TG levels and lipid accumulation, compared to the control group, and enhanced the expression of genes and proteins related to thermogenesis while reducing the expression of obesity-related genes. Discussion: The findings suggest that kimchi exerts its anti-obesity effects by modulating thermogenic and obesity-related pathways in brown adipocytes, which may be partially attributed to its antioxidant properties. Conclusions: Kimchi shows promise as a preventive measure against obesity by influencing metabolic pathways associated with both obesity and thermogenesis in T37i brown adipocytes.

Quantification of Pectobacterium carotovorum subsp. carotovorum in kimchi cabbage using a surface-enhanced Raman scattering platform with silver nanostructures.

Pectobacterium carotovorum subsp. carotovorum (PCC) is a notorious plant pathogen responsible for severe soft rot in kimchi cabbage, which results in significant economic losses. To detect PCC rapidly and accurately in kimchi cabbage, we developed a surface-enhanced Raman scattering (SERS) substrate on which silver nanospheres (AgNSs), nanowires (AgNWs), and nanoseeds are combined on a polydimethylsiloxane (PDMS) platform. The incorporation of Ag nanoseeds creates a higher density of hotspots, which ensures a low detection limit of 1.001 CFU/mL. Electron microscopy and spectroscopic analyses confirmed the successful fabrication of the substrate and its enhanced sensitivity. The SERS substrate exhibits excellent selectivity by effectively distinguishing PCC from other bacteria commonly found in kimchi cabbage. The substrate gives rise to strong Raman signals across PCC concentrations ranging from 101 to 106 CFU/mL. Additionally, a predictive model was developed for accurately detecting PCC in real kimchi cabbage samples, and the results were validated by polymerase chain reaction measurements. A sensitive, selective, and rapid approach for PCC detection in kimchi cabbage that offers a promising improvement over existing methodologies is presented.

Effects of gnotobiotic fermentation on global gene expression of germ-free vegetables.

Existing research has underscored the vital interplay between host organisms and their associated microbiomes, which affects health and function. In both plants and animals, host factors critically shape microbial communities and influence growth, health, and immunity. Post-harvest plants, such as those used in kimchi, a traditional Korean dish, offer a unique avenue for exploring host-microbe dynamics during fermentation. Despite the emphasis on lactic acid bacteria (LAB) in fermentation studies, the roles of host factors remain unclear. This study aimed to investigate the influence of these factors on plant transcriptomes during kimchi fermentation. We individually inoculated nine LAB strains into germ-free kimchi to generate LAB-mono-associated gnotobiotic kimchi and performed RNA-sequencing analysis for the host vegetables during fermentation. The transcriptomes of post-harvest vegetables in kimchi change over time, and microbes affect the transcriptome profiles of vegetables. Differentially expressed gene analyses revealed that microbes affected the temporal expression profiles of several genes in the plant transcriptomes in unique directions depending on the introduced LAB strains. Cluster analysis with other publicly available transcriptomes of post-harvest vegetables and fruits further revealed that the plant transcriptome is more profoundly influenced by the environment harboring the host than by host phylogeny. Our results bridge the gap in understanding the bidirectional relationship between host vegetables and microbes during food fermentation, illuminating the complex interplay between vegetable transcriptomes, fermentative microbes, and the fermentation process in food production. The different transcriptomic responses elicited by specific LAB strains suggest the possibility of microbial manipulation to achieve the desired fermentation outcomes.

Effects of Kimchi Intake on the Gut Microbiota and Metabolite Profiles of High-Fat-Induced Obese Rats.

With rising global obesity rates, the demand for effective dietary strategies for obesity management has intensified. This study evaluated the potential of kimchi with various probiotics and bioactive compounds as a dietary intervention for high-fat diet (HFD)-induced obesity in rats. Through a comprehensive analysis incorporating global and targeted metabolomics, gut microbiota profiling, and biochemical markers, we investigated the effects of the 12-week kimchi intake on HFD-induced obesity. Kimchi intake modestly mitigated HFD-induced weight gain and remarkably altered gut microbiota composition, steroid hormones, bile acids, and metabolic profiles, but did not reduce adipose tissue accumulation. It also caused significant shifts in metabolomic pathways, including steroid hormone metabolism, and we found substantial interactions between dietary interventions and gut microbiota composition. Although more research is required to fully understand the anti-obesity effects of kimchi, our findings support the beneficial role of kimchi in managing obesity and related metabolic disorders.

Investigating the Effects of Pink-Generating Ligands on Enhancing Color Stability and Pigment Properties in Pork Sausage Model Systems Cured with Sodium Nitrite or White Kimchi Powder.

In this study, we investigated the effects of different nitrite sources (sodium nitrite or white kimchi powder) and pink-generating ligands (cysteine, histidine, or nicotinamide) on the development and stability of cured meat color in pork sausage model systems over 30 d of refrigerated storage. The samples were prepared in a 2 × 3 factorial design with two nitrite sources and three ligands, and their physicochemical properties were evaluated on days 0, 15, and 30. Although white kimchi powder induced cured color development similar to that of synthetic sodium nitrite, it resulted in higher cooking loss and lower residual nitrite content in cured pork sausages (p < 0.05). The addition of cysteine resulted in significantly higher CIE a* values, cured meat pigment, and curing efficiency than histidine and nicotinamide (p < 0.05), while yielding lower pH values, residual nitrite content, and total pigment content (p < 0.05). The storage duration significantly reduced the residual nitrite and total pigment contents of the products. These findings suggest that white kimchi powder can serve as a natural alternative to sodium nitrite in pork sausage models and that the incorporation of cysteine has a favorable impact on the development and enhancement of cured meat color.

Intracellular pyruvate as one of the major bioactive substances of lactic acid bacteria isolated from kimchi.

The present study aimed to identify the metabolites associated with the physiological activity of kimchi-derived lactic acid bacteria (LAB). A clear difference was observed between the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging rates when the pyruvate content was high (273.5 ng/µL; radical removal speed 6.50% per min) and the rates when the pyruvate content had decreased (131.9 ng/µL; radical removal speed 3.63% per min). Additionally, the characteristics of LAB antioxidant activity (increase in ABTS radical scavenging activity with reaction time, low level of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity) were similar to those of pyruvate-derived activity. Hydrogen peroxide content (WiKim0124, 2.08 → 0.26; WiKim0121, 0.99 → 0.47; WiKim39, 1.93 → 0.24) and lactate dehydrogenase activity (WiKim0124, 1.53 → 0.00; WiKim0121, 0.73 → 0.01; WiKim39, 1.72 → 0.02) decreased more in heat-killed LAB than in non-heat-killed LAB. Accordingly, this resulted in increased pyruvate content and the inhibitory activity of lipid peroxide production increased by 2-3 times. Our findings indicate that pyruvate is one of the major metabolites regulating LAB physiological activity. PRACTICAL APPLICATION: The safety of utilizing live probiotics remains a topic of debate. To mitigate associated risks, there is a growing interest in non-viable microorganisms or microbial cell extracts for use as probiotics. Various methods can be employed for probiotic inactivation. Heat treatment typically emerges as the preferred choice for inactivating probiotic strains in many instances. The present study shows the distinctions between inactivating lactic acid bacteria (LAB) through heat treatment and non-heat treatment. It may serve as a valuable reference for selecting an appropriate inactivation method for LAB in industrial processes.

Determination of biogenic amine-producing lactic acid bacteria in kimchi varieties through in vitro analysis and low temperature fermentation.

This study analyzed biogenic amine (BA) content in three varieties (types) of kimchi (Baechu kimchi, Baek kimchi, and Yeolmu kimchi), identified the causative bacteria, and evaluated the gene expression associated with the BA formation during kimchi fermentation at 4 °C. Histamine content exceeding the toxicity limit was detected in a single Baechu kimchi product. Tyramine content in most Baechu kimchi products was approximately half of the toxicity limit. Other varieties had relatively lower BA content. Most BA producers isolated from all kimchi varieties were identified as Levilactobacillus brevis, which prominently produced tyramine. To clarify the role of L. brevis in tyramine formation in Baechu kimchi, fermentation experiments were performed using L. brevis BC1M20. The results showed that tyramine content and tyrosine decarboxylase gene (tdc) expression were higher in the inoculated kimchi than in the control. In addition, in the inoculated kimchi, the content decreased while the expression level was almost constant. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01627-8.

Kimchi Lactic Acid Bacteria Starter Culture: Impact on Fermented Malt Beverage Volatile Profile, Sensory Analysis, and Physicochemical Traits.

Starter cultures used during the fermentation of malt wort can increase the sensory characteristics of the resulting beverages. This study aimed to explore the aroma composition and flavor recognition of malt wort beverages fermented with lactic acid bacteria (Levilactobacillus brevis WiKim0194) isolated from kimchi, using metabolomic profiling and electronic tongue and nose technologies. Four sugars and five organic acids were detected using high-performance liquid chromatography, with maltose and lactic acid present in the highest amounts. Additionally, e-tongue measurements showed a significant increase in the sourness (AHS), sweetness (ANS), and umami (NMS) sensors, whereas bitterness (SCS) significantly decreased. Furthermore, 20 key aroma compounds were identified using gas chromatography-mass spectrometry and 15 key aroma flavors were detected using an electronic nose. Vanillin, citronellol, and ß-damascenone exhibited significant differences in the flavor profile of the beverage fermented by WiKim0194, which correlated with floral, fruity, and sweet notes. Therefore, we suggest that an appropriate starter culture can improve sensory characteristics and predict flavor development in malt wort beverages.

High Prevalence of Antibiotic Resistance in Traditionally Fermented Foods as a Critical Risk Factor for Host Gut Antibiotic Resistome.

This study aimed to assess the suitability of fermented food interventions to replenish damaged gut microbiota. Metagenomic assessment of published sequencing data found that fermented food interventions led to a significant increase in the gut antibiotic resistome in healthy human subjects. Antibiotic resistome and viable antibiotic-resistant (AR) bacteria were further highly prevalent in retail kimchi and artisan cheeses by metagenomic and culture analyses. Representative AR pathogens of importance in nosocomial infections, such as Klebsiella pneumoniae, Serratia marcescens, and vancomycin-resistant Enterococcus (VRE), as well as commensals and lactic acid bacteria, were characterized; some exhibited an extremely high minimum inhibitory concentration (MIC) against antibiotics of clinical significance. Exposing fermented food microbiota to representative antibiotics further led to a boost of the corresponding antibiotic and multidrug-resistance gene pools, as well as disturbed microbiota, including the rise of previously undetectable pathogens. These results revealed an underestimated public health risk associated with fermented food intervention at the current stage, particularly for susceptible populations with compromised gut integrity and immune functions seeking gut microbiota rescue. The findings call for productive intervention of foodborne AR via technology innovation and strategic movements to mitigate unnecessary, massive damages to the host gut microbiota due to orally administered or biliary excreted antibiotics.

Bacterial community of kimchi added with seafood based on culture-dependent investigations.

Previously, microbial communities of five commercial kimchi added with seafood and one kimchi without seafood were analyzed using a culture-independent (CI) method. In the current study, microbial communities of the same samples were analyzed using a culture-dependent (CD) method with two media: tryptic soy agar (TSA) and Lactobacilli de Man, Rogosa and Sharpe (MRS) agar. MRS agar showed a higher proportion of lactic acid bacteria, while TSA showed a higher proportion of Bacillus species. Leuconostoc mesenteroides became dominant over time except in kimchi added with hongeu (HBK, okamejei kenojei). In the case of HBK, Bacillus was dominant. The low pH of HBK was confirmed by cell size and heat treatment under pH 4-7 conditions that Bacillus could be present in the form of spores. With the CD method, only Lactococcus lactis, Leu. citreum, and Weissella cibaria were detected. With the CI method, only Pediococcus inopinatus was detected. A notable finding was that Leu. mesenteroides was more abundant than Latilactobacillus sakei with the CD method, whereas it was similar or lower with the CI method. This discrepancy was confirmed to be due to different rates of DNA recovered from the two strains. This shows that the assay method may influence the detection of these two strains.

Protective Effects of the Postbiotic Levilactobacillus brevis BK3 against H2O2-Induced Oxidative Damage in Skin Cells.

Postbiotics have various functional effects, such as antioxidant, anti-inflammatory, and anti-obesity. Levilactobacillus brevis BK3, the subject of this study, was derived from lactic acid bacteria isolated from Kimchi, a traditional Korean fermented food. The antioxidant activity of BK3 was confirmed through the measurements of 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and total antioxidant capacity (TAC). The wrinkle improvement effect was validated by assessing elastase inhibitory activity and collagenase inhibitory activity. The intracellular activity was confirmed using human keratinocytes (HaCaT) and human fibroblasts (HFF-1). BK3 protects skin cells from oxidative stress induced by H2O2 and reduces intracellular reactive oxygen species (ROS) production. In addition, the expressions of the antioxidant genes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were upregulated. Meanwhile, matrix metalloproteinase-1 (MMP-1) and collagen type I alpha 1 (COL1A1), involved in collagen degradation and synthesis, were significantly regulated. These results suggest the possibility of utilizing BK3 as a functional ingredient with antioxidant and wrinkle-improving effects.

Complete genome sequence of strain Lactiplantibacillus plantarum beLP1 a potential probiotic strain with antimicrobial properties isolated from kimchi.

The complete genome of the potential probiotic Lactiplantibacillus plantarum strain beLP1, isolated from kimchi in South Korea, was sequenced using Illumina and PacBio technologies. The genome comprises one circular chromosome and one plasmid without antimicrobial resistance genes.

Effects of seasonal harvest of kimchi cabbage on microbial and metabolic profiles of kimchi.

Kimchi cabbage, the key ingredient in kimchi, is cultivated year-round to meet high production demands. This study aimed to examine the effects of seasonal harvesting (spring, summer, fall, and winter) on the microbial and metabolic profiles of kimchi during 30 days of fermentation. Lactic acid bacteria distribution is notably influenced by seasonal variations, with Latilactobacillus dominant in fall-harvested kimchi group and Weissella prevailing in spring, summer, and winter. The microbial communities of spring and fall group exhibited similar profiles before fermentation, whereas the microbial communities and metabolic profiles of spring and summer group were similar after 30 days of fermentation. Seasonal disparities in metabolite concentrations, including glutamic acid, serine, and cytosine, persist throughout fermentation. This study provides a comprehensive understanding of the substantial impact of seasonal harvesting of kimchi cabbage on the microbial and metabolic characteristics of kimchi, providing valuable insights into producing kimchi with diverse qualities.

Development of smart colorimetric indicators for tracking kimchi freshness by loading aronia extract in agar, κ-carrageenan, and cellulose nanofiber films.

Color indicator films incorporating aronia extract powder (AEP) and biopolymers like agar, carrageenan, and cellulose nanofiber (CNF) were developed to monitor kimchi freshness. AEP-containing films showed strong UV-barrier properties, and reduced light transmittance by 99.12 % for agar, 98.86 % for carrageenan, and 98.67 % for CNF-based films. All AEP-films exhibited high sensitivity to pH changes and vapor exposure to ammonia and acetic acid. Color change notably influenced by the polymer type, particularly evident with ammonia vapor exposure, especially in the AEP/carrageenan film. The chemical structure and thermal stability of the biopolymers remained unchanged after AEP-addition. Tensile strength increased by 24.2 % for AEP/CNF but decreased by 19.4 % for AEP/agar and 24.3 % for AEP/carrageenan films. AEP-containing films displayed strong antioxidant activity, with 99 % free radical scavenging in ABTS and ~ 80 % in DPPH assays. Alkalized AEP-indicator films were more effective in detecting color changes during kimchi packaging tests. Among the labels, alkalized AEP/agar film showed the most obvious color change from green-gray (fresh kimchi, pH 5.5, acidity 0.48 %) to pale brown (optimal fermentation, pH 4.6, acidity 0.70 %), and pale violet-brown (over-fermented, pH 3.80, acidity 1.35 %). Alkalized AEP-indicator films offer promising real-time detection of packed fermented foods like kimchi.

Efficacy and Safety of WCFA19 (Weissella confusa WIKIM51) in Reducing Body Fat in Overweight and Obese Adults.

Background: WCFA19 (Weissella confusa WIKIM51), found during the fermentation of kimchi, is known for its inhibitory effects on body weight and body fat. This study looked at the impact of WCFA19 isolated from dandelion kimchi on weight loss in overweight and obese adults that are otherwise healthy. Methods: This study was conducted as a multicenter, double-blind, randomized, placebo-controlled study with 104 overweight and obese subjects. Subjects were randomized evenly into the test group (WCFA19, 500 mg, n = 40) or control group (n = 34) for 12 weeks from 14 June 2021 to 24 December 2021. Effects were based on DEXA to measure changes in body fat mass and percentage. Results: Among the 74 subjects analyzed, WCFA19 oral supplementation for 12 weeks resulted in a significant decrease in body fat mass of 633.38 ± 1396.17 g (p = 0.0066) in overweight and obese individuals in the experimental group. The control group showed an increase of 59.10 ± 1120.57 g (p = 0.7604), indicating a statistically significant difference between the two groups. There was also a statistically significant difference (p = 0.0448) in the change in body fat percentage, with a decrease of 0.41 ± 1.22% (p = 0.0424) in the experimental group and an increase of 0.17 ± 1.21% (p = 0.4078) in the control group. No significant adverse events were reported. Conclusions: Oral supplementation of 500 mg of WCFA19 for 12 weeks is associated with a decrease in body weight, particularly in body fat mass and percentage.

Bacterial diversity of baechu-kimchi with seafood based on culture-independent investigations.

Baechu-kimchi is a traditional Korean dish of fermented vegetables, in which kimchi cabbage is the major ingredient. Seafood is added to baechu-kimchi in coastal areas, giving this dish regional diversity. However, little is known about how the addition of seafood affects the bacterial diversity of kimchi. Therefore, in this study, the bacterial diversity of five varieties of baechu-kimchi with seafood and one variety of baechu-kimchi without seafood was analyzed using culture-independent techniques. In 81.7% of all kimchi analyzed, the predominant species were members of the phylum Firmicutes and the lactic acid bacteria, Latilactobacillus sakei, Leuconostoc mesenteroides, Pediococcus inopinatus, and Weissella koreensis. These organisms were similar to those identified in baechu-kimchi without the addition of seafood, which was used as a control group, and bacterial community of previously reported kimchi. Therefore, the results of this study confirmed that the addition of seafood did not significantly affect the bacterial community in baechu-kimchi.

Innovative food-upcycling solutions: Comparative analysis of edible films from kimchi-extracted cellulose, sorbitol, and citric acid for food packaging applications.

In this study, kimchi-extracted cellulose was utilized to fabricate edible films using a hot synthetic approach, followed by solvent casting, and employing sorbitol and citric acid as the plasticizer and crosslinker, respectively. The chemical, optical, physical, and thermal properties of these films were explored to provide a comparative assessment of their suitability for various packaging applications. Chemical analyses confirmed that the kimchi-extracted cellulose comprised cellulose Iß and amorphous cellulose and did not contain any impurities. Optical analyses revealed that kimchi-extracted cellulose-containing films exhibited better-dispersed surfaces than films fabricated from commercial cellulose. Physical property analyses indicated their hydrophilic characteristics with contact angles <20°. In the thermal analysis, similar Tg results confirmed the comparable thermal stability between films containing commercial microcrystalline cellulose-containing films and kimchi-extracted cellulose-containing films. Edible films produced from kimchi-extracted cellulose through food-upcycling approaches are therefore promising for applications as packaging materials.

Changes in volatile flavor compounds of Kimchi cabbage (Brassica rapa subsp. pekinensis) during salting and fermentation.

A main ingredient of Kimchi is Kimchi cabbage, which is soaked in brine to reduce its crispness. Volatile profile of raw Kimchi cabbage (RC) is changed during salting; however, characteristic aroma-active compounds of salted Kimchi cabbage (SC) have not been investigated. The objective of this study was to evaluate changes in aroma characteristics of Kimchi cabbage during salting and fermentation. Sulfur-containing compounds, such as sulfides and isothiocyanates, increased markedly by salting. (Z)-3-Hexen-1-ol, (Z)-3-hexenal, and hexanal decreased by salting. Hexanal was the most intense in RC, followed by 3-(methylthio)butanal, (Z)-3-hexen-1-ol, and benzenepropanenitrile. Dimethyl trisulfide had the highest log3FD in SC. Methyl (methylthio)methyl disulfide, allyl methyl trisulfide, and dimethyl tetrasulfide were detected only in SC. Dimethyl trisulfide, dimethyl tetrasulfide, methyl (methylthio) methyl disulfide, and allyl methyl trisulfide, decreased greatly in SC during fermentation. Our results demonstrated that characteristic odor of Kimchi cabbage could be significantly changed by salting and fermentation.

Impact of essential and optional ingredients on microbial and metabolic profiles of kimchi.

This study aimed to examine the impacts of essential and optional ingredients on the microbial and metabolic profiles of kimchi during 100 days of fermentation, using a mix-omics approach. Kimchi manufactured without essential ingredients (e.g., red pepper, garlic, ginger, green onion, and radish) had lower lactic acid content. The absence of garlic was associated with a higher proportion of Latilactobacillus and Lactococcus, while the absence of red pepper was associated with a greater proportion of Leuconostoc than the control group. In addition, red pepper and garlic served as primary determinants of the levels of organic acids and biogenic amines. Sugar was positively correlated with the levels of melibiose, and anchovy sauce was positively correlated with the levels of amino acids such as methionine, leucine, and glycine. These findings contribute to a fundamental understanding of how ingredients influence kimchi fermentation, offering valuable insights for optimizing kimchi production to meet various preferences.

Survival of O157 and non-O157 shiga toxin-producing Escherichia coli in Korean style kimchi.

Korean style kimchi contaminated with Shiga toxin-producing Escherichia coli (STEC) O157:H7 was the cause of an outbreak in Canada from December 2021 to January 2022. To determine if this STEC O157:H7 has greater potential for survival in kimchi than other STEC, the outbreak strain and six other STEC strains (O26:H11, O91:H21, O103:H2, O121:H19, and two O157:H7) were inoculated individually at 6 to 6.5 log CFU/g into commercially sourced kimchi and incubation at 4 °C. At intervals of seven days inoculated and control kimchi was plated onto MacConkey agar to enumerate lactose utilising bacteria. The colony counts were interpreted as enumerating the inoculated STEC, since no colonies were observed on MacConkey agar plated with uninoculated kimchi. Over eight weeks of incubation the pH was stable at 4.10 to 4.05 and the STEC strains declined by 0.7-1.0 log, with a median reduction of 0.9 log. The linear rate of reduction of kimchi outbreak STEC O157:H7 was -0.4 log per 30 days (Slope Uncertainty 0.05), which was not significantly different from the other O157 and nonO157 STEC strains (P = 0.091). These results indicate that the outbreak was not due to the presence of strain better adapted to survival in kimchi than other STEC, and that STEC can persist in refrigerated Korean style kimchi with a minimal decline over the shelf-life of the product.