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.

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.

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.

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.

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.

Factors Influencing the Size of a Non-Traumatic Full-Thickness Rotator Cuff Tear: Focusing on Socioeconomic Factors.

This study aimed to identify the risk factors for non-traumatic rotator cuff tears in Korean adult patients who underwent surgical treatment, focusing on socioeconomic factors. A retrospective study was conducted with 659 patients who were diagnosed with a full rotator cuff tear and underwent surgical treatment. The outcome variable was the rotator cuff tear size (mm), as indicated by preoperative magnetic resonance imaging. Socioeconomic variables included occupation, education level, insurance type, and residential area. Univariate analyses were used to evaluate the relation between tear size and independent variables, and multivariate regression was used to estimate the effects of socioeconomic factors on tear size after adjusting for other variables. Significant differences were found in mean tear size according to age, occupation, residence area, and symptom duration (p < 0.05) in multivariate regression analysis. Rural residents had a 2.12 mm larger tear size than urban residents. Compared to National Health Insurance patients, the tear size of Medicaid beneficiaries was significantly larger (6.79 mm) in urban areas. The larger the rotator cuff tear, the greater the risk of retear and poor shoulder function. Therefore, policy efforts are required to expand access to medical care for the vulnerable.

Influence of Residence Area and Basic Livelihood Conditions on the Prevalence and Diagnosis Experience of Osteoporosis in Postmenopausal Women Aged over 50 Years: Evaluation Using Korea National Health and Nutrition Examination Survey Data.

Patients with osteoporosis are asymptomatic and are at risk for fractures. Therefore, early detection and interventions are important. We found that a population with a low socioeconomic status living in rural areas was reported to have a high osteoporosis prevalence but a relatively low diagnosis rate. Research on the disparity of osteoporosis prevalence and treatment from the socioeconomic perspective was conducted. This study aimed to investigate the influence of residence area and basic livelihood conditions on osteoporosis prevalence and diagnosis in postmenopausal women aged over 50 years. The cross-sectional data of 1477 postmenopausal women aged over 50 years obtained from the Korea National Health and Nutrition Examination Survey V-2 were analyzed. Univariate analyses were performed to calculate the prevalence and diagnosis rate according to risk factor categories. A multivariate logistic regression analysis was performed to identify the influence of residence area and basic livelihood conditions after controlling for other factors. The osteoporosis prevalence in basic livelihood beneficiaries (53.7%) and rural area residents (41.9%) was higher than that in non-beneficiaries (33.1%) and urban area residents (31.8%). There was no significant difference in the diagnosis rates in relation to the basic livelihood conditions or residence areas. The adjusted odds ratio for the prevalence among the beneficiaries living in rural areas was 2.08 (95% confidence interval: 1.06-4.10). However, the odds ratio for diagnosis was not significantly different. Earlier screening examination policies for osteoporosis in postmenopausal women with a low socioeconomic status living in rural areas are needed.

Prevalence and diagnosis experience of osteoporosis in postmenopausal women over 50: Focusing on socioeconomic factors.

Osteoporosis is the most common disease of the musculoskeletal system in old age. Therefore, research on osteoporosis risk factors is actively being conducted. However, whether socioeconomic inequality is associated with the prevalence and diagnosis experience of osteoporosis remains largely unexplored. This study aims to investigate whether socioeconomic inequality can be a risk factor for osteoporosis in postmenopausal women. Cross-sectional data of 1,477 postmenopausal women aged over 50 obtained from the Korea National Health and Nutrition Examination Survey V-2 were analyzed. Univariate analyses were performed to calculate the prevalence of osteoporosis and the rate of osteoporosis diagnosis experience according to the risk factor categories. Multivariate logistic regression analysis was performed to identify the independent variables' associations with osteoporosis prevalence and diagnosis experience. The prevalence of osteoporosis was 34.8%, while the diagnosis experience rate was 22.1%. The higher the age, the higher the probability of osteoporosis presence and diagnosis experience. The lowest household income level was associated with a 1.63 times higher risk of osteoporosis. On the contrary, this factor was not significant for diagnosis experience. These results were similar for the 50-59 and 60-69 age groups. Among postmenopausal women, those who are older and have low socioeconomic levels are at a high risk of developing osteoporosis. Moreover, the lower the socioeconomic level, the lower the awareness of osteoporosis. Therefore, there is a need to develop more proactive preventive measures in postmenopausal women with low socioeconomic levels.

Effects of different drying methods on physicochemical properties, volatile profile, and sensory characteristics of kimchi powder.

The effects of five different drying conditions on kimchi powder quality were determined by comparatively analyzing their physicochemical characteristics, volatile profile, and sensory evaluations. The moisture content of the kimchi powder obtained by each method was < 10%, and the yield after drying differed among methods ranging from 9.50 to 10.38% (p < 0.05). Electronic nose and tongue analyses demonstrated significant differences (p < 0.05) between samples based on the drying temperature. The particle size distribution did not differ considerably between drying methods, except for the ground kimchi (p < 0.05). The sensory evaluation test revealed that the flavor and taste were rated the highest for the kimchi powder prepared using HADHT. Therefore, hot-air drying at a high temperature was the most effective method for kimchi powder production owing to have a good flavor and taste and the shorter drying time.

Changes in quality properties of kimchi based on the nitrogen content of fermented anchovy sauce, Myeolchi Aekjeot, during fermentation.

This study was conducted to examine the effects of the total nitrogen (TN) concentration in anchovy sauce added to kimchi on chemical properties during kimchi fermentation for 56 days. Kimchi was assigned to one of the following five treatments: CTL (No anchovy sauce addition), T-1 (TN 1.16% anchovy sauce), T-2 (TN 1.41% anchovy sauce), T-3 (TN 1.59% anchovy sauce), T-4 (TN 1.79% anchovy sauce). The quality characteristics of kimchi were determined by measuring the pH, acidity, reducing sugar, volatile basic nitrogen (VBN), amino nitrogen (AN), and microbial composition. During fermentation, the acidity of all treatment groups increased, whereas the reducing sugar content decreased gradually during fermentation. There were no significant differences in pH and acidity or reducing sugar content. The VBN and AN contents increased during fermentation from 15.65 to 31.21%. Overall, these results demonstrate that the TN concentration of anchovy mainly affects the VBN and AN levels in kimchi.

Microbial Community Structure of Korean Cabbage Kimchi and Ingredients with Denaturing Gradient Gel Electrophoresis.

Kimchi is a traditional Korean fermented vegetable food, the production of which involves brining of Korean cabbage, blending with various other ingredients (red pepper powder, garlic, ginger, salt-pickled seafood, etc.), and fermentation. Recently, kimchi has also become popular in the Western world because of its unique taste and beneficial properties such as antioxidant and antimutagenic activities, which are derived from the various raw materials and secondary metabolites of the fermentative microorganisms used during production. Despite these useful activities, analysis of the microbial community present in kimchi has received relatively little attention. The objective of this study was to evaluate the bacterial community structure from the raw materials, additives, and final kimchi product using the culture-independent method. Specifically, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the 16S rRNA partial sequences of the microflora. One primer set for bacteria, 341F(GC)-518R, reliably produced amplicons from kimchi and its raw materials, and these bands were clearly separated on a 35-65% denaturing gradient gel. Overall, 117 16S rRNA fragments were identified by PCR-DGGE analysis. Pediococcus pentosaceus, Leuconostoc citreum, Leuconostoc gelidum, and Leuconostoc mesenteroides were the dominant bacteria in kimchi. The other strains identified were Tetragenococcus, Pseudomonas, Weissella, and uncultured bacterium. Comprehensive analysis of these microorganisms could provide a more detailed understanding of the biologically active components of kimchi and help improve its quality. PCR-DGGE analysis can be successfully applied to a fermented food to detect unculturable or other species.

Cytogenetic investigation of chromosomal aberrations in cells treated with plantamajoside from Plantago asiatica.

Plantago asiatica is a member of the Plantaginaceae family, and is widely distributed in East Asia. In our previous work, a single active compound, plantamajoside was isolated and confirmed to have glycation inhibitory activity, and did not possess toxicity during a 90 day repeated oral toxicity test in rats. In the present study, a chromosomal aberration test was performed to investigate the genotoxicity of plantamajoside. From the results of the cytotoxicity test, plantamajoside proved to be less toxic when it was treated combined with S9 cell fractions. However, there was a significant increase in structural aberrations during the short-term treatment of plantamajoside at its highest dose (5000 microg/mL) even when combined with S9. This seems to have been a natural phenomenon due to the very high dose of plantamajoside that was used. However, to confirm the safety of plantamajoside for its potential use as a phytochemical agent in health products, additional mutagenicity tests are necessary.