Effect of Mollusca shell extracts on inhibition of kimchi over-acidification.

Mollusca species shell such as oyster shell (OS) and snail shell (SS), are discarded after taking the meat, and the discarded shell causes the environmental problems. Therefore, recycling shell waste could potentially eliminate the environmental problems. This study aimed to evaluate the potential of OS and SS as natural calcium resources. The minerals, calcium, magnesium, potassium, phosphorus and sodium were analyzed in OS and SS extracts. Among them, the calcium content was the highest: 36.87 (%) and 33.42 (%) in the OS and SS extracts, respectively. Further, the content of ionized bioavailable form of calcium in OS and SS was higher than that of CaCO3 under simulated gastrointestinal digestion conditions. Additionally, OS and SS were added to kimchi, and their inhibitory effect on kimchi acidification was evaluated by assessing pH, titratable acidity and microbial analysis. As the results indicated that the addition of OS and SS had little effect on inhibiting the growth of lactic acid bacteria. However, it was confirmed that calcium neutralizes the organic acids produced during fermentation. Overall, the results of this study provide preliminary information on the re-use of OS and SS extracts as ionized natural calcium supplements and fermentation retardants.

Metabolic shift during fermentation in kimchi according to capsaicinoid concentration.

The cultivar of red pepper used in kimchi contributes to spiciness, red color, and fermentation characteristics. Capsaicinoids are the main components of red pepper. Therefore, understanding changes in metabolites during kimchi fermentation according to capsaicinoid concentration is necessary to control the quality of kimchi. The purpose of this study was to investigate the effect of capsaicinoids on metabolites during kimchi fermentation. To profile the effect of capsaicinoid concentrations on kimchi fermentation, five kimchi samples were prepared using different concentrations of capsaicinoids (4, 12, 30.7, 40.9, and 50.3 mg/kg) and stored at 4 °C for 28 days. During kimchi fermentation, pH, titratable acidity, capsaicinoid concentration, total viable and lactic acid bacteria, free sugars, amino acids, and microbial community were evaluated. Each result was statistically analyzed for changes in capsaicin concentration and fermentation time. The capsaicinoid concentration did not change during kimchi fermentation but the growth of lactic acid bacteria changed. According to the growth of lactic acid bacteria, free sugar, amino acids, and microbial community changed with the capsaicinoid concentration. Overall, the results of this study provide preliminary information on the use of red pepper and capsaicinoids in the kimchi industry.

Changes in bacterial composition and metabolite profiles during kimchi fermentation with different garlic varieties.

Garlic, a key ingredient in kimchi, is an indispensable source of lactic acid bacteria, which are essential for fermentation. This study explored the effects of various garlic varieties on kimchi fermentation, focusing on changes in microbial communities and metabolite profiles. We observed that the type of garlic used did not significantly alter the microbial community. However, the presence of garlic itself made a significant difference. Specifically, kimchi with garlic showed higher abundance of Leuconostoc and Weissella, which are bacteria primarily responsible for kimchi fermentation. Additionally, kimchi containing garlic had increased levels of mannitol and fructose, which significantly influence taste; however, lactic acid and putrescine levels were decreased. Therefore, the addition of garlic directly contributes to the flavor profile of kimchi. Sixty-two metabolites were identified using gas chromatography and mass spectrometry. The variety of garlic added influenced the metabolite profiles of kimchi, particularly in the later stages of fermentation. These profiles were categorized based on the garlic's origin, whether from southern or northern ecotypes (R2X = 0.933, R2Y = 0.986, Q2 = 0.878). These findings confirm that both the presence and the variety of garlic significantly impact the microbial ecology and metabolites during kimchi fermentation, underscoring its essential role in the process.

Hepatoprotective efficacy and interventional mechanism of the panaxadiol saponin component in high-fat diet-induced NAFLD mice.

Dietary administration is a promising strategy for intervention in non-alcoholic fatty liver disease (NAFLD). Our research team has identified a biologically active component, the panaxadiol saponin component (PDS-C) isolated from total saponins of panax ginseng, which has various pharmacological and therapeutic functions. However, the efficacy and mechanism of PDS-C in NAFLD were unclear. This study aimed to elucidate the hepatoprotective effects and underlying action mechanism of PDS-C in NAFLD. Mice were fed a high-fat diet (HFD) for 8 weeks to induce NAFLD and treated with PDS-C and metformin as the positive control for 12 weeks. PDS-C significantly alleviated liver function, hepatic steatosis and blood lipid levels, reduced oxidative stress and inflammation in NAFLD mice. In vitro, PDS-C has been shown to reduce lipotoxicity and ROS levels while enhancing the antioxidant and anti-inflammatory capabilities in HepG2 cells induced by palmitic acid. PDS-C induced AMPK phosphorylation, leading to upregulation of the Nrf2/HO1 pathway expression and downregulation of the NFκB protein level. Furthermore, our observations indicate that PDS-C supplementation improves insulin resistance and glucose homeostasis in NAFLD mice, although its efficacy is not as pronounced as metformin. In conclusion, these results demonstrate the hepatoprotective efficacy of PDS-C in NAFLD and provide potential opportunities for developing functional products containing PDS-C.

Investigation of Metabolite Differences in Salted Shrimp Varieties during Fermentation.

Fermentation of salted shrimp involves the interaction of multiple factors. However, studies of the effects of shrimp variety and fermentation temperature on metabolites generated during fermentation are limited. Therefore, we investigated the effects of the shrimp variety, fermentation temperature, and fermentation period on the composition of fermented salted shrimp. Four different varieties of salted shrimp, namely, Detteugijeot (SSA), Red shrimp jeot (SSB), Chujeot (SSC), and Yukjeot (SSD), were prepared and stored at 5 and 10 °C for 5 months. The pH values ranged from 6.71 to 6.99, with SSD showing the lowest pH at both temperatures. Although total nitrogen content remained relatively constant, amino nitrogen exhibited an upward trend after 2 months and was particularly increased at 10 °C. This increase was attributed to variations in microorganisms and enzymes in the salted shrimp. Except for proline, citrulline, and ornithine, amino acid levels increased during fermentation with the highest amounts detected in SSA. Additionally, the levels of glutamic acid and branched-chain amino acids were found to be sensitive to fermentation temperature. Amino acid levels were apparently affected by species-specific metabolic pathways of the microorganisms present in each salted shrimp. Compared to the other varieties, SSB had significantly higher contents of adenosine triphosphate and hypoxanthine. A high hypoxanthine content could contribute to increased bitterness and an umami taste profile. Furthermore, the correlation between salted shrimp and metabolites was unique in SSB, whereas partial clustering was observed between the SSA and SSC.

Optimization of extraction and nanoencapsulation of kimchi cabbage by-products to enhance the simulated in vitro digestion of glucosinolates.

Kimchi cabbage is a well-known glucosinolate (GLS)-containing vegetable, but its by-products are discarded despite the presence of GLS. The aim of this study was the optimization of the extraction and nanoencapsulation of GLS from kimchi cabbage by-products to enhance the intestinal absorption of GLS. The optimal GLS extraction conditions included steaming thrice as pretreatment, utilizing 70% methanol, and ultrasonication at 20% amplitude for 15 min. Under these conditions, 80.11 ± 4.40 mg/100 g of GLS extraction was obtained and the extraction yield was 81.70 ± 4.73%. The optimized kimchi cabbage by-product extract (KCE) was coated with chitosan-lipid nanoparticles (KCE-NPs) and their stability and release under simulated in vitro gastrointestinal conditions were evaluated. KCE-NPs protected the encapsulated GLS under acidic gastric conditions and released 91.63 ± 0.76% of GLS in the simulated intestinal medium. Therefore, the proposed KCE-NPs are a promising delivery system for increasing GLS absorption.

Deletion of hepatic growth hormone receptor (GHR) alters the mouse gut microbiota by affecting bile acid metabolism.

Both growth hormone (GH) and gut microbiota play significant roles in diverse physiological processes, but the crosstalk between them is poorly understood. Despite the regulation of GH by gut microbiota, study on GH's influence on gut microbiota is limited, especially on the impacts of tissue specific GH signaling and their feedback effects on the host. In this study, we profiled gut microbiota and metabolome in tissue-specific GHR knockout mice in the liver (LKO) and adipose tissue (AKO). We found that GHR disruption in the liver rather than adipose tissue affected gut microbiota. It changed the abundance of Bacteroidota and Firmicutes at phylum level as well as abundance of several genera, such as Lactobacillus, Muribaculaceae, and Parasutterella, without affecting α-diversity. Moreover, the impaired liver bile acid (BA) profile in LKO mice was strongly associated with the change of gut microbiota. The BA pools and 12-OH BAs/non-12-OH BAs ratio were increased in the LKO mice, which was due to the induction of CYP8B1 by hepatic Ghr knockout. Consequently, the impaired BA pool in cecal content interacted with gut bacteria, which in turn increased the production of bacteria derived acetic acid, propionic acid, and phenylacetic acid that were possible to participate in the impaired metabolic phenotype of the LKO mice. Collectively, our findings suggested that the liver GH signaling regulates BA metabolism by its direct regulation on CYP8B1, which is an important factor influencing gut microbiota. Our study is significant in exploring gut microbiota modification effects of tissue-specific GH signaling as well as its involvement in gut microbiota-host interaction.

Effect of the addition of maltodextrin on metabolites and microbial population during kimchi fermentation.

Gelatinized starch sauce, one of the sub-ingredients have been widely used in kimchi for their roles in increasing viscosity of kimchi seasoning, and fermentation. Gelatinized glutinous rice (GGR), which is one of the most used starch sources in kimchi preparation. However, GGR is accelerated to the fermentation process but lead to a reduction in the shelf life of the kimchi. Therefore, in this study, we demonstrate the effectiveness of using maltodextrin (MD) as a novel starch source instead of GGR to slow down the rate of kimchi fermentation. The properties of the kimchi with MD and GGR fermentation (free sugar content, organic acid content, pH, and acidity) as well as their microbial growth rates after 12 days of fermentation were compared. After fermentation of 12 days, the free sugar of GGR-kimchi (GGRK) increased more rapidly than those of MD-kimchi (MDK), while higher sugar alcohol (mannitol) and organic acid contents were observed for GGRK than for MDK. Furthermore, initial aerobic and lactic acid bacteria counts were higher for GGRK than for MDK. These results indicate that fermentation proceeds at a slower rate in MDK than in GGRK, and they will provide a basis for further research into storage of kimchi. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05742-y.

Antioxidant and anti-inflammatory effects of solar salt brined kimchi.

Salt is an essential ingredient in the kimchi fermentation process. Solar salt has antioxidant, anti-cancer, and anti-obesity properties. The aim of this study was to determine the antioxidant and anti-inflammatory effects of solar salt brined kimchi. Purified salt (PS), dehydrated solar salt (DSS), 1-year aged solar salt (SS1), and 3-years aged solar salt (SS3) were investigated. Anti-inflammatory effects were determined by analyzing cytotoxicity, nitric oxide (NO) production, and inflammation-related gene expression in lipopolysaccharide-treated RAW264.7 cells. Antioxidant activities of DSS, SS1, and SS3 were higher than that of PS. Solar salt significantly inhibited NO production with low cytotoxicity and decreased inflammation-related gene expression. Kimchi containing solar salt (DSSK, SS1K, and SS3K) showed higher antioxidant activity than PSK. Additionally, DSSK, SS1K, and SS3K significantly inhibited NO production and decreased the expression of inflammation-related genes. Owing to the antioxidant and anti-inflammatory effects, using solar salt in kimchi preparation could have potential health benefits.

Panaxadiol saponin ameliorates ferroptosis in iron-overload aplastic anemia mice and Meg-01 cells by activating Nrf2/HO-1 and PI3K/AKT/mTOR signaling pathway.

Panaxadiol saponin (PND) is a latent targeted drug for the treatment of aplastic anemia (AA). In this study, we examined the effects of PND on ferroptosis in iron-overload AA and Meg-01 cells. We utilized RNA-seq to analyze differentially expressed genes in iron-induced Meg-01 cells treated with PND. The effects of PND or combined with deferasirox (DFS) on iron deposition, labile iron pool (LIP), several ferroptosis events, apoptosis, mitochondrial structure, as well as ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR pathway-related markers in iron-induced Meg-01 cells were examined by Prussian-blue staining, flow cytometer, ELISA, Hoechst 33342 staining, transmission electron microscope, and Western blot assays, respectively. Additionally, an AA mice model with iron overload was established. Then, the blood routine was assessed, and the number of bone marrow-derived mononuclear cells (BMMNCs) in mice was counted. Also, serum iron, ferroptosis events, apoptosis, histology, T lymphocyte percentage, ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR signaling-related targets in primary megakaryocytes of AA mice with iron overload were assessed by commercial kits, TUNEL staining, hematoxylin and eosin (H&E) staining, Prussian blue staining, flow cytometer, and qRT-PCR analysis, respectively. PND suppressed iron-triggered iron overload, and apoptosis, and ameliorated mitochondrial morphology in Meg-01 cells. Importantly, PND ameliorated ferroptosis-, Nrf2/HO-1-, and PI3K/AKT/mTOR signaling-related marker expressions in iron-induced Meg-01 cells or primary megakaryocytes of AA mice with iron overload. Moreover, PND ameliorated body weight, peripheral blood cell counts, the number of BMMNCs, and histological injury in the iron-overload AA mice. Also, PND improved the percentage of T lymphocytes in the iron-overload AA mice. PND attenuates ferroptosis against iron-overload AA mice and Meg-01 cells via activating Nrf2/HO-1 and PI3K/AKT/mTOR pathway and is a promising novel therapeutic candidate for AA.

Fabrication of Gold Nanoparticles and Cinnamaldehyde-Functionalized Paper-Based Films and Their Antimicrobial Activities against White Film-Forming Yeasts.

During storage and fermentation of kimchi, white film-forming yeasts (WFY) are generated on the surface of kimchi under various conditions. These yeasts include Candida sake, Pichia kudriavzevii, Kazachstania servazzii, Debaryomyces hansenii, and Hanseniaspora uvarum. Because of the off-odor and texture-softening properties of WFY that degrade the quality of kimchi, a method to prevent WFY is required. In this study, cinnamaldehyde (CIN) and gold nanoparticles (AuNPs) with a large surface area were grafted on a paper surface, which was termed the "Paper_AuNPs_CIN" film. CIN is an antimicrobial agent that is approved for use in food applications. In the as-fabricated Paper_AuNPs_CIN film, antimicrobial CIN molecules were physically adsorbed to the surface of AuNPs and simultaneously chemically synthesized on the paper surface via the imine reaction. The Paper_AuNPs_CIN film exhibited greater antimicrobial activity against the three WFY strains than a Paper_CIN film (which contains only CIN molecules). Since more CIN molecules were adsorbed to the large surface area of the paper-reduced AuNPs, the Paper_AuNPs_CIN film exhibited a higher antimicrobial activity. Using AuNPs and CIN simultaneously to inhibit the growth of WFY is a novel approach that has not yet been reported. The morphology and elemental mapping of the functionalized films were examined via scanning electron microscopy and energy-dispersive spectroscopy, elemental composition was analyzed via inductively coupled plasma optical emission spectroscopy, and chemical bonding and optical properties were investigated via Fourier transform infrared spectroscopy and diffuse reflectance spectroscopy. Additionally, agar-well diffusion assays were used to determine the antimicrobial activity against three representative WFY strains: C. sake, P. kudriavzevii, and K. servazzii.

Influence of salt concentration on Kimchi cabbage (Brassica rapa L. ssp. pekinensis) mass transfer kinetics and textural and microstructural properties during osmotic dehydration.

The effect of salt concentration (3%, 6%, and 9%) on the mass transfer kinetics of Kimchi cabbage during osmotic dehydration was investigated, including its influence on textural and microstructural properties and salt distribution. First, kinetics was analyzed using diffusion theory to determine the impact of the factors on moisture and salt transfer. Subsequently, using the Peleg, Azuara, Henderson-Pabis, and Page models, mathematical modeling of mass transfer (water loss and salt gain) was investigated. According to the statistical analysis, the Peleg model provided the best fit for the experimental results under the operating conditions. In addition, a novel viewpoint was proposed in which the salt content of Kimchi cabbage may be indirectly forecasted by monitoring solution salinity during osmotic dehydration. Higher salt concentration resulted in decreased hardness, gumminess, and chewiness in Kimchi cabbage. Scanning electron microscopy and energy-dispersive X-ray mapping images showed an intensification of moisture and salt transport with increasing salt content, which were confirmed using modeling studies. The results could be applied in the prediction of the target salinity of Kimchi cabbage during the salting process and could facilitate the improvement of final Kimchi product quality by producing salted Kimchi cabbage with uniform salinity.

Bactericidal Effect of Underwater Plasma Treatment on Waste Brine from Kimchi Production Process and the Evaluation of Reusability of Plasma-Treated Waste Brine in Salting Kimchi Cabbage.

Recycling waste brine from the Kimchi production process is an important environmental and industry issue. We applied an underwater plasma to reduce food-borne pathogens in the waste brine. The capillary electrodes supplied by alternating current (AC) bi-polar pulsed power were applied to treat 100 L of waste brine. The inactivation efficacy was analyzed using four different agars (Tryptic Soy Agar (TSA), Marine agar (MA), de Man Rogosa Sharpe Agar (MRS), and Yeast Extract-Peptone-Dextrose (YPD), respectively. The microbial population was reduced linearly with treatment time, irrespective of culturing medium. The inactivation followed the log-linear model (R2: 0.96-0.99). The reusability of plasma-treated waste brine (PTWB) was determined by five parameters (salinity, pH, acidity, reducing sugar, and the population of microorganisms) of salted Kimchi cabbage, and they were compared with newly made brine (NMB) and waste brine (WB), respectively. The results showed that the quality of salted Kimchi cabbage prepared by PTWB was not significantly different from that of NMB, indicating that the underwater plasma treatment is feasible to reuse waste brine in the salting process of Kimchi production.

Ginsenoside Rk3 Inhibits the Extramedullary Infiltration of Acute Monocytic Leukemia Cell via miR-3677-5p/CXCL12 Axis.

Background: Acute monocytic leukemia belongs to type M5 of acute myeloid leukemia (AML) classified by FAB, which appears a high incidence of extramedullary infiltration (EMI) and poor prognosis. In this study, we observed the inhibitory effect of ginsenoside Rk3 on the EMI of monocytic leukemia cells and initially explored its related mechanism of targeting the miR-3677-5p/CXCL12 axis. Methods: The MTT assay and colony formation assay were used to detect the inhibitory effect of Rk3 on proliferation. Both cellular migration and invasion were observed by the Transwell assay. The expression levels of miR-3677-5p, CXCL12, and CXCR4 were detected by RT-qPCR and Western blot, as well as overexpression of miR-3677-5p by transfected with lentivirus and detection of a dual luciferase reporter gene. The expression of MMP2 and TIMP2 was detected by immunofluorescence. Results: Rk3 effectively inhibits the proliferation, migration, and invasion associated with EMI of leukemia. The leukemia cells of M5 patients with EMI showed low expression of miR-3677-5p but high expression of the mRNA of CXCL12 and CXCR4. Overexpression of miR-3677-5p or intervention of CXCL12 effectively inhibited the proliferation, migration, and invasion of SHI-1 cells. The luciferase assay showed that CXCL12 was the downstream target gene of miR-3677-5p. After overexpression of miR-3677-5p or intervention of CXCL12 in combination with Rk3, the inhibitory effect on the proliferation, migration, and invasion of SHI-1 cells was more obvious. Importantly, Rk3 significantly regulated the expression levels of miR-3677-5p, CXCL12, CXCR4, and EMI-related functional proteins including MMP2 and TIMP2. Overexpression of miR-3677-5p or intervention of CXCL12 also regulated the expression of MMP2 and TIMP2. Conclusions: The leukemia cells of M5 patients with EMI appeared to have low expression of miR-3677-5p and high expression of the mRNA of CXCL12 and CXCR4, which may be used as indicators of EMI and poor prognosis. Rk3 is effective in inhibiting the EMI of SHI-1 cells by targeting the miR-3677-5p/CXCL12 axis.

Effects of salt type on the metabolites and microbial community in kimchi fermentation.

The taste of kimchi is greatly affected by the salt type used during fermentation. Here, we investigated the effects of salts with different mineral contents on the microbial community and metabolite profiles of fermented kimchi using multivariate statistical analysis. We evaluated different types of salt used to prepare kimchi, namely, solar salt aged for 1 year, solar salt aged for 3 years, dehydrated solar salt, and purified salt. The main microorganisms detected in kimchi were Weissella koreensis, Leuconostoc mesenteroides, and Latilactobacillus sakei. Leuconostoc and Weissella were mainly present in kimchi supplemented with solar salt. However, a high proportion of L. sakei was present in kimchi supplemented with purified salt and dehydrated salt. Additionally, using GC-MS-based metabolite analysis, we revealed that the content of free sugars, organic acids, and amino acids differed in kimchi fermented with different salt types. Therefore, we demonstrated that salt type had a pronounced effect on the resultant microbial community and the type and concentration of metabolites present in fermented kimchi.

A clinical study of peripherally inserted central catheter-related venous thromboembolism in patients with hematological malignancies.

This study aimed to explore the risk factors of peripherally inserted central catheter (PICC)-related venous thromboembolism (CRT) in patients with hematological malignancies and the predictive ability of the thrombotic risk assessment models (RAMs). The clinical data of the 117 eligible patients with hematological neoplasms at Mianyang Central Hospital with PICC from May 2018 to May 2020 were analyzed in this retrospective study. Thrombosis risk scores were calculated in patients with image-confirmed PICC-related thromboembolism. CRT occurred in 19 cases. Compared to the CRT-free group, the CRT group was older and showed higher body mass index (BMI), leukocyte count level, and the prevalence of diabetes mellitus. Multivariable logistic regression analysis showed that BMI (P = 0.03) was a significant risk factor for CRT. The area under the receiver operating characteristic curve for the Caprini scale (P = 0.01) was higher than that of the modified Wells scale (P = 0.94), the revised Geneva scale (P = 0.83), Padua scale (P = 0.59), and Michigan scale (P = 0.80). The sensitivity and specificity for the Caprini scale, Padua scale, modified Wells scale, the revised Geneva scale, and Michigan risk score were 63.3%/73.7%, 100%/0.00%, 95.9%/5.3%, 31.6%/73.7%, and 1.0%/99.0%, respectively. Caprini RAM had a better predictive ability for CRT in patients with hematological malignancies. Michigan risk score may not be better than Caprini RAM in this population.

Free Amino Acid and Volatile Compound Profiles of Jeotgal Alternatives and Its Application to Kimchi.

Jeotgal containing abundant free amino acids plays an important role in the unique savory taste (umami) and flavor in kimchi. However, it is also responsible for the unpleasant fishy smell and high salt content of kimchi. Therefore, the present study aimed to identify alternative jeotgal sources and investigate the fermentation properties of jeotgal alternatives added to kimchi. The tomato hot-water extract (TH2) and dry-aged beef hot-water extract (DBH) were selected as jeotgal alternatives for kimchi preparation based on their glutamic acid contents. Characteristics of kimchi with TH2 alone (JA1) and TH2 and DBH in combination (1:1, JA2) were compared with kimchi prepared using commercially available anchovy fish sauce (CON). The pH of JA1 and JA2 was slightly decreased during fermentation, whereas the salinity was significantly lower than CON (p < 0.05). Notably, the most effective factor of the savory taste of kimchi, glutamic acid contents of JA1 and JA2 were significantly higher than that of CON (p < 0.05). In conclusion, JA1 showed slower fermentation with lower salinity and higher glutamic acid content than CON. Overall, this study showed that JA1 derived from TH2 could improve the taste and quality of kimchi by increasing glutamic acid content and decreasing the unpleasant flavor.

Evaluation of onion juices quality following heat-treatment and their application as a sugar substitute in Kimchi.

This study was conducted to evaluate the quality of onion juices that had been heat-treated for different times as well as their use as a table sugar substitute in Kimchi. The onions were steamed at 100 ∘C for 30 min and boiled at 90 ∘C for 30, 60, and 120 min. The highest cycloalliin (0.76 mM), free-sugar (sucrose 1.66 g/L, glucose 8.62 g/L, and fructose 7.64 g/L), and malic acid (0.82 g/L) contents were observed in onion boiled at 90 ∘C for 120 min. The possibility of using heat-treated onion juices as an alternative to table sugar in Kimchi was evaluated by comparing the lactic acid bacteria count, pH, acidity, organic acid, and free-sugar in these juices with those in Kimchi prepared using table sugar (control). The total viable bacteria and lactic acid bacteria showed similar growth patterns as in the control. The average pH reduction and increase in titratable acidity (%) in all treated Kimchi samples during fermentation for 4 weeks were 1.18 ± 0.05 and 0.81 ± 0.06, respectively. Kimchi with onion juice heat-treated for 120 min (K120) had the most similar lactic acid and acetic acid contents to that in the control after fermentation for 4 weeks. The highest mannitol level after fermentation for 4 weeks was detected in K120, which showed better sensory qualities compared to the control.

Antioxidant activity and calcium bioaccessibility of Moringa oleifera leaf hydrolysate, as a potential calcium supplement in food.

Moringa oleifera leaf (ML) is rich in vitamins and minerals, specially abundant calcium, therefore it is widely used as a calcium supplement for food. This study aimed to investigate the antioxidant activity and calcium bioaccessibility of M. oleifera leaf hydrolysate (MLH) as a calcium supplement for kimchi. MLH was prepared under three different proteases, two different protease contents, and three different incubation times. Total phenol content (TPC), total flavonoid content (TFC), and antioxidant activities were investigated. Cellular activity and calcium bioaccessibility were also investigated. The highest calcium level of MLH was observed in 3% Protamex treatment for 4 h. TPC, TFC, and antioxidant activities of MLH in Protamex and Alcalase treatments were higher than those in Flavourzyme treatment (p < 0.05). Moreover, high cell viability and alkaline phosphatase activity were also observed in C2C12 cells. Kimchi containing MLH showed high calcium accessibility compared to kimchi alone. Taken together, the application of MLH could have potential as a calcium supplement for kimchi production.

Effects of combining two lactic acid bacteria as a starter culture on model kimchi fermentation.

This study aimed to establish a mixed starter culture to standardize the flavor of kimchi, a traditional Korean food. Leuconostoc mesenteroides and Lactobacillus sakei were selected for the culture based on their key roles in kimchi fermentation. The effects of various starter culture mixing ratios on the overall fermentation process were investigated. Fermentation was carried out at 15 °C for 72 h. In the microbial community analysis, a similar ratio to the initial mixed inoculated ratio was observed in the microbial environments. Treatment with high-rate L. mesenteroides inoculation, exhibiting hetero-fermentative characteristics, led to the production of mannitol (1393.11 mg/100 g), acetic acid (57.70 mg/kg), and lactic acid (1141.90 mg/kg), in addition to the induction of a rapid increase in the number of viable cells, thereby reducing the pH (pH 3.9). Conversely, treatment with high-rate L. sakei inoculation, exhibiting homo-fermentative characteristics, led to the production of less mannitol and acetic acid, with more lactic acid. Principal component analysis score plots showed a distinct difference in kimchi metabolites depending on the lactic acid bacteria (LAB) starter culture. Therefore, by using mixed LAB starter strains, this study demonstrated the value of various characteristics and standardized manufacturing of kimchi. LAB types and inoculation ratios greatly affected the types and concentration of metabolites in kimchi fermentation.