Commercial Kimchi Research Articles

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.

Lactococcus kimchii extends lifespan and alleviates motility decline in Caenorhabditis elegans through ins-20, an insulin-like peptide gene.

Lactococcus kimchii is isolated from commercial kimchi, which is a traditional Korean fermented food. This study was conducted to evaluate the probiotic effects of L. kimchii. Caenorhabditis elegans was fed L. kimchii, and its longevity, motility, and gene expression were examined. When fed a 1:1 mixture of Escherichia coli OP50 and L. kimchii (OP+LK), C. elegans had a significantly longer lifespan and increased locomotion than when it was fed OP alone. There was no significant difference in brood size between the OP+LK and OP groups, suggesting that these effects occurred in a dietary restriction-independent manner. RNA sequencing and Gene Ontology analysis showed that the expression of ins-20, an insulin-like peptide and agonist of the insulin receptor, was significantly upregulated in the OP+LK group. The ins-20 mutation annulled the effects of OP+LK on lifespan extension and motility. In addition, OP+LK failed to extend the lifespan of C. elegans deficient in daf-2, a receptor for the insulin-like signaling pathway. These results suggest that L. kimchii extends the lifespan and alleviates motility decline in C. elegans through the insulin signaling pathway, highlighting the potential of using L. kimchii as a beneficial bacterium for probiotics and postbiotics.

Preparation of food active packaging materials based on calcium hydroxide and modified porous medium for reducing carbon dioxide and kimchi odor.

Carbon dioxide and kimchi odor compounds, formed during fermentation, negatively affect the long-distance distribution of commercial kimchi. To address these issues, in this study, we modified different porous media (activated carbon, bleaching earth, diatomite, and zeolite) using sodium bicarbonate and silver (Ag) ions. Functional sheets were prepared using linear low-density polyethylene, calcium hydroxide, a porous medium, and a blowing agent. Various prepared porous media and sheets were effective in removing acetic acid, sulfur compounds (allyl methyl sulfide, dimethyl disulfide, allyl methyl disulfide, and diallyl disulfide), and carbon dioxide. Porous media with micropores exhibited a sulfur compound removal efficiency of 43.5%-99.4%, while no effect was observed on acetic acid removal. However, porous media with mesopores showed an acetic acid removal efficiency of 42.3%-90.7%, with no reduction in sulfur compounds removal. The impregnation of porous materials with sodium bicarbonate significantly (p < 0.05) enhanced the acetic acid removal activity. Ag modification improved the sulfur compound removal of the mesoporous bleaching earth and diatomite statistically (p < 0.05). Additionally, the incorporation of sodium bicarbonate-impregnated mesoporous media significantly improved carbon dioxide removal, reducing concentrations from 25.97% to 14.27% with respect to the control group. Our functional food packaging materials can solve the current issues in kimchi distribution by removing carbon dioxide and kimchi odor without affecting its quality. PRACTICAL APPLICATION: Food active packaging materials containing calcium hydroxide and modified porous medium are effective in removing carbon dioxide and kimchi odor (acetic acid and sulfur compounds). The removal of carbon dioxide and kimchi odor, which adversely affect the distribution and sale of commercial kimchi, can help solve the current issues with kimchi distribution without affecting its quality.

Catechin with Lactic Acid Bacteria Starters Enhances the Antiobesity Effect of Kimchi.

The antiobesity effects of kimchi with catechin and lactic acid bacteria as starters were studied in C57BL/6 mice with high-fat diet (HFD)-induced obesity. We prepared four types of kimchi: commercial kimchi, standard kimchi, green tea functional kimchi, and catechin functional kimchi (CFK). Body weight and weight of adipose tissue were significantly lower in the kimchi-treated groups than in the HFD and Salt (HFD +1.5% NaCl) groups. In addition, in the CFK group, the serum levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol were significantly lower and those of high-density lipoprotein cholesterol were markedly higher than the corresponding levels in the HFD and Salt groups. Moreover, CFK reduced fat cells and crown-like structures in the liver and epididymal fat tissues. The protein expression of adipo/lipogenesis-related genes in the liver and epididymal fat tissues was significantly lower (1.90-7.48-fold) in the CFK group than in the HFD and Salt groups, concurrent with upregulation of lipolysis-related genes (1.71-3.38-fold) and downregulation of inflammation-related genes (3.17-5.06-fold) in epididymal fat tissues. In addition, CFK modulated the gut microbiomes of obese mice by increasing the abundance of Bacteroidetes (7.61%), while in contrast, Firmicutes (82.21%) decreased. In addition, the presence of the Erysipelotrichaceae (8.37%) family in the CFK group decreased, while the number of beneficial bacteria of the families, Akkermansiaceae (6.74%), Lachnospiraceae (14.95%), and Lactobacillaceae (38.41%), increased. Thus, CFK exhibited an antiobesity effect through its modulation of lipid metabolism and the microbiome.

Increased Anticancer Activity of Organic Kimchi with Starters Demonstrated in HT-29 Cancer Cells

This study aims to investigate the effects of kimchi made with organic ingredients and lactic acid bacteria (LAB) as starters (Leuconostoc mesenteroides + Lactiplantibacillus plantarum) on HT-29 human colon carcinoma cells. Four types of kimchi (standard kimchi (SK), commercial kimchi (CK), anticancer kimchi (AK), and organic anticancer kimchi (OAK)) were evaluated. The results show that, among the different types of kimchi studied, OAK presents high DPPH free-radical scavenging activity and total phenol and flavonoid contents, and the MTT assay shows that the growth inhibition rate against HT-29 cancer cells is the highest. In addition, the quantitative reverse transcription polymerase chain reaction (RT-qPCR) results show that, compared to SK and CK, AK and OAK can effectively down-regulate the mRNA expression of anti-apoptotic gene Bcl-2 and up-regulate the mRNA expression of the cell cycle arrest genes p21 and p53; pro-apoptotic genes Bim, Bak, and Bad; and genes for caspases 3 9. Subsequently, a Western blot test confirmed that the expression of Bcl-2 decreased and the expressions of p53, Bax, and caspases 3 and 9 increased in OAK. The abovementioned results indicate that the anticancer kimchi prepared with organic ingredients and starters of lactic acid bacteria effectively present the best antioxidant activity and inhibit the proliferation of HT-29 cancer cells by promoting apoptosis and cell cycle arrest.

Strain-specific barcode PCR and quantitative PCR assay for identification and enumeration of kimchi starter, Leuconostoc mesenteroides DRC1506

Leuconostoc mesenteroides DRC1506 has been used as a starter to ferment commercial kimchi products for good organoleptic quality in Korea. Monitoring the starter during kimchi fermentation is essential for maintaining its quality. In this study, L. mesenteroides DRC1506 strain-specific barcodes PCR method was developed by comparative pan-genome analysis, and it was applied to the rapid and accurate detection and quantification of starter during kimchi fermentation. As a result, four nucleotide sequences, 788 bp, 585 bp, 319 bp, and 161 bp, were chosen as unique sequences for specific primers to detect DRC1506. Of these, the three primer sets, for 788 bp, 585 bp, and 319 bp, showed specific binding and barcode pattern bands with the genomic DNA of DRC1506 when tested against the genomic DNA of various lactic acid bacteria. In addition, a standard curve for quantitative PCR analysis of DRC1506 was established using the 161bp primer set, and it was accurately used to quantify the L. mesenteroides DRC1506 during kimchi fermentation. In conclusion, newly developed PCR method can be applied to rapidly and accurately monitor the population changes of L. mesenteroides DRC1506 during the kimchi fermentation process.

Changes and machine learning-based prediction in quality characteristics of sliced Korean cabbage (Brassica rapa L. pekinensis) kimchi: Combined effect of nano-foamed structure film packaging and subcooled storage

The prevention of over-ripening during storage and distribution is crucial for commercial kimchi products with a short shelf life. This study evaluated the effects of nano-foamed structure (NFS) film packaging and subcooled storage on the characteristics and stability of sliced Korean cabbage (Brassica rapa L. pekinensis) kimchi (KCK). The experiments were performed as factorial tests based on completely randomized designs. Subcooled storage (−3 °C) delayed total lactic acid bacteria (TLAB) growth and suppressed the changes in pH, titratable acidity (TA), and reducing sugar content (RSC) of KCK compared to refrigerated storage (4 and 10 °C). The headspace CO2 concentrations in NFS-1 and NFS-2 film packaging were maintained at < 6.1% throughout the storage (36 d), irrespective of the storage conditions. These results indicate that NFS film suppresses CO2 accumulation wherein subcooled storage prevents the over-ripening of KCK. Furthermore, we combined machine learning (ML) algorithms with experimental results to predict the quality of KCK. The ML-based algorithms, random forest and extreme gradient boosting trees were more accurate in predicting TA, RSC, and TLAB counts than multivariable linear regression. The study demonstrates an improved packaging system and optimal storage conditions for KCK, which can be extended to other kimchi and fermented products.

시판 김치 양념 제품의 품질 특성 평가

This study aimed to evaluate the physicochemical and microbiological quality of kimchi seasoning products purchased from an online shopping mall, using cluster analysis to inform consumers about the quality of commercial kimchi seasoning and enable them to make informed purchasing decisions. The clusters were classified into four groups: CKS02 to 03 (group I), CKS04 to 05 (group II), CKS07 to 09 (group III), and others (CKS01, CKS06, and CKS10) (group IV). Principal component analysis (PCA) validated the cluster characteristics and a strong correlation between the moisture content in group I, salinity in group II, capsaicinoids content in group III, and pH in group IV. Highly significant correlations were observed between the L (lightness) and b (yellowness) values, solid and moisture content, and viscosity and solid content of kimchi seasoning. The findings of this study provide information on the baseline quality of commercially available seasoning products, and it is expected that items with a high correlation among the seasoning qualities can be used as management indicators to ensure consistency.

Metagenomic comparison of homemade and commercial kimchi prepared in Korea and the United States

It is well known that there is a myriad of factors that determine the kimchi microbial composition during fermentation, including but not limited to, salt concentrations, temperature, raw ingredients, and even manufacturing processes. Because different environments breed different species of microorganisms, the location of where raw ingredients were cultivated can also affect the kimchi microbiota. Previous studies have shown that there is a significant difference in microbial composition between kimchi from different countries, but none has been made between homemade kimchi. Seven samples of homemade kimchi from the US and South Korea (equally made under the same fermentation conditions) and commercial kimchi were used in the study. High differences in genera relative abundances between Korean and the US homemade kimchi could be concluded. The results also exhibited differences in microbial composition and diversity levels between Korean and the US commercial kimchi. This study provides further insight into understanding the complexity of how kimchi microbiome is developed by having the results support the idea that the environment where raw ingredients originate from affect the kimchi quality and taste.

Development of Anti-inflammatory Probiotic Limosilactobacillus reuteri EFEL6901 as Kimchi Starter: in vitro and In vivo Evidence.

The use of probiotic starters can improve the sensory and health-promoting properties of fermented foods. In this study, we developed an anti-inflammatory probiotic starter, Limosilactobacillus reuteri EFEL6901, for use in kimchi fermentation. The EFEL6901 strain was safe for use in foods and was stable under human gastrointestinal conditions. In in vitro experiments, EFEL6901 cells adhered well to colonic epithelial cells and decreased nitric oxide production in lipopolysaccharide-induced macrophages. In in vivo experiments, oral administration of EFEL6901 to DSS-induced colitis mice models significantly alleviated the observed colitis symptoms, prevented body weight loss, lowered the disease activity index score, and prevented colon length shortening. Analysis of these results indicated that EFEL6901 played a probiotic role by preventing the overproduction of pro-inflammatory cytokines, improving gut barrier function, and up-regulating the concentrations of short-chain fatty acids. In addition, EFEL6901 made a fast growth in a simulated kimchi juice and it synthesized similar amounts of metabolites in nabak-kimchi comparable to a commercial kimchi. This study demonstrates that EFEL6901 can be used as a suitable kimchi starter to promote gut health and product quality.

Variations in nutritional and microbial composition of napa cabbage kimchi during refrigerated storage

The health benefits of kimchi are proven to be effective against many diseases. We studied the effects of prolonged refrigerated storage on health beneficial qualities of napa cabbage kimchi by assessing variations in nutritional composition, microbial diversity, total antioxidant capacity (TAC), and total polyphenol content (TPC). The carbohydrate content of kimchi drastically reduced during the first month of storage (from 58.7 to 41.6 g/100 g), while fat and ash contents increased. Total bacterial count declined (>80 folds) during 17 months of storage with no development of pathogenic microbes. Microbial diversity did not significantly alter during kimchi storage. Relative abundances of Lactobacillales and Firmicutes increased up to 3 months and Actinobacteria increased after 3 months of storage. TAC and TPC of kimchi increased up to 3 months of storage and declined after. The findings suggest consuming kimchi during the first 3 months of refrigerated storage to optimize beneficial microbes and health benefits. Novelty impact statement Evaluation of variations in health beneficial qualities of napa cabbage kimchi under prolonged refrigerated storage is important to determine the optimum time for consumption. The abundance of beneficial Lactobacillales bacteria increases together with total antioxidant capacity and total polyphenol content in tested kimchi up to 3 months of storage before declining. Tested commercial kimchi can be consumed within 3 months of refrigerated storage for optimum health benefits.

Comparison of Quality Characteristics of Commercial Kimchi Manufactured in Korea, China, and the United States.

Recently, kimchi has been recognized as a healthy food worldwide, prompting increased interest in its health benefits and quality characteristics. Although commercial kimchi is manufactured in various countries, little is known about quality differences between the kimchi from different countries. To clarify differences in quality characteristics, minerals, free sugars, organic acids, free amino acids, and volatile compounds, commercial kimchi manufactured in Korea, China, and the United States were investigated. The composition of the microbial community and antioxidant activity were compared. Mineral and free sugar contents were high in Korean commercial kimchi, while the organic acid content was relatively low. The free amino acid content was markedly higher in Korean kimchi than that in kimchi manufactured in China and the United States. In addition, the volatile compound content differed between the kimchi produced in different countries. Considering the microbial communities, Leuconostoc and Weissella were more abundant in commercial kimchi from Korea than that from China or the United States. Commercial kimchi in Korea showed the highest antioxidant activity. These results support the high quality and antioxidant activity of commercial kimchi manufactured in Korea, emphasizing its importance in the global kimchi industry.

Quantitative microbial risk assessment of pathogenic Escherichia coli in commercial kimchi in South Korea.

Owing to convenience, ease of preparation, and price, the consumption of commercial kimchi is gradually rising in South Korea. Here, we estimated the risk level posed by pathogenic Escherichia coli in commercial kimchi products using the quantitative microbial risk assessment (QMRA) approach to develop measures for preventing potential foodborne outbreaks from kimchi consumption. We collected 610 samples of commercial kimchi products produced in Korea, 267 kimchi samples from foreign countries imported to Korea, and 187 raw materials used in kimchi preparation, and analyzed them for contamination with pathogenic E. coli. A Predictive model was developed to observe the survival characteristics of pathogenic E. coli. A dose-response model was selected, and the risk level was estimated using @RISK software. Although a prior epidemiological study indicated the frequent occurrence of foodborne outbreaks arising from contaminated kimchi products consumed in food service facilities, we found a low probability of foodborne illness caused by pathogenic E. coli in commercial kimchi products.

Suitability Analysis of 17 Probiotic Type Strains of Lactic Acid Bacteria as Starter for Kimchi Fermentation.

The use of probiotic starters can improve the sensory and health-promoting properties of fermented foods. This study aimed to evaluate the suitability of probiotic lactic acid bacteria (LAB) as a starter for kimchi fermentation. Seventeen probiotic type strains were tested for their growth rates, volatile aroma compounds, metabolites, and sensory characteristics of kimchi, and their characteristics were compared to those of Leuconostoc (Le.) mesenteroides DRC 1506, a commercial kimchi starter. Among the tested strains, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Lacticaseibacillus rhamnosus, Lacticaseibacillus paracasei, and Ligilactobacillus salivarius exhibited high or moderate growth rates in simulated kimchi juice (SKJ) at 37 °C and 15 °C. When these five strains were inoculated in kimchi and metabolite profiles were analyzed during fermentation using GC/MS and 1H-NMR, data from the principal component analysis (PCA) showed that L. fermentum and L. reuteri were highly correlated with Le. mesenteroides in concentrations of sugar, mannitol, lactate, acetate, and total volatile compounds. Sensory test results also indicated that these three strains showed similar sensory preferences. In conclusion, L. fermentum and L. reuteri can be considered potential candidates as probiotic starters or cocultures to develop health-promoting kimchi products.

Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov., two novel species of the family Bacillaceae isolated from kimchi.

To date, all species in the genus Salicibibacter have been isolated in Korean commercial kimchi. We aimed to describe the taxonomic characteristics of two strains, NKC5-3T and NKC21-4T, isolated from commercial kimchi collected from various regions in the Republic of Korea. Cells of these strains were rod-shaped, Gram-positive, aerobic, oxidase- and catalase-positive, non-motile, halophilic, and alkalitolerant. Both strains, unlike other species of the genus Salicibibacter, could not grow without NaCl. Strains NKC5-3T and NKC21-4T could tolerate up to 25.0% (w/v) NaCl (optimum 10%) and grow at pH 7.0-10.0 (optimum 8.5) and 8.0-9.0 (optimum 8.5), respectively; they showed 97.1% 16S rRNA gene sequence similarity to each other and were most closely related to S. kimchii NKC1-1T (97.0% and 96.8% similarity, respectively). The genome of strain NKC5-3T was nearly 4.6 Mb in size, with 4,456 protein-coding sequences (CDSs), whereas NKC21-4T genome was nearly 3.9 Mb in size, with 3,717 CDSs. OrthoANI values between the novel strains and S. kimchii NKC1-1T were far lower than the species demarcation threshold. NKC5-3T and NKC21-4T clustered together to form branches that were distinct from the other Salicibibacter species. The major fatty acids in these strains were anteiso-C15:0 and anteiso-C17:0, and the predominant menaquinone was menaquinone-7. The polar lipids of NKC5-3T included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), and five unidentified phospholipids (PL), and those of NKC21-4T included DPG, PG, seven unidentified PLs, and an unidentified lipid. Both isolates had DPG, which is the first case in the genus Salicibibacter. The genomic G + C content of strains NKC5-3T and NKC21-4T was 44.7 and 44.9 mol%, respectively. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic analyses, strains NKC5-3T (= KACC 22040T = DSM 111417T) and NKC21-4T (= KACC 22041T = DSM 111418T) represent two novel species of the genus Salicibibacter, for which the names Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov. are proposed.

Supercooling as a potentially improved storage option for commercial kimchi

The supercooling degree (SD), which refers to the difference between the ice nucleation temperature and freezing point of kimchi, varies depending on the type of kimchi, manufacturer, recipe, and manufacturing season. The aim of this study is to investigate the major influencing factors for the supercooled storage of kimchi and to analyze the possibility of supercooled storage for commercial kimchi. Pearson correlation analysis determined that, in commercial kimchi manufactured between March and July 2018, the SD of kimchi correlated to the number of aerobic bacteria (P <0.01), however, was not associated with lactic acid bacteria. Moreover, the ice nucleation temperature of saline solution inoculated with aerobic bacteria was reduced from -3.03± 0.04 to -6.18± 0.11°C by 10 kGy gamma ray sterilization. Meanwhile, the ice nucleation temperatures of 1.8kg of commercial red cabbage kimchi and 500g of white cabbage kimchi manufactured in February 2020 were -3.93± 0.06°C and -3.57± 0.06°C, respectively, and they could be stored at -2.5°C for 12 weeks without freezing. Additionally, supercooled storage of kimchi at -2.5°C caused a fermentation delay effect compared to control storage at 1°C, considering the acidity and amount of lactic acid bacteria. Therefore, if the number of aerobic bacteria is controlled during the manufacturing process of kimchi, supercooled storage at temperatures below -2.5°C may extend the shelf life of kimchi. PRACTICAL APPLICATION: We have shown that aerobic bacteria are the key influencing factor for ice nucleation of kimchi during supercooled storage. Aside from the initial sterilization process, fermentation of kimchi can also be delayed by lowering the storage temperature below -2.5°C. Moreover, the method of direct cool refrigeration may have an industrial-level application.

Correlating Capsaicinoid Levels and Physicochemical Proper-ties of Kimchi and Its Perceived Spiciness.

Capsaicinoid content, among other factors, affects the perception of spiciness of commercial kimchi. Here, we investigated whether the physicochemical properties of kimchi affect the spicy taste of capsaicinoids perceived by the tasting. High-performance liquid chromatography (HPLC) was used to evaluate the capsaicinoid content (mg/kg) of thirteen types of commercial kimchi. The physicochemical properties such as pH, titratable acidity, salinity, free sugar content, and free amino acid content were evaluated, and the spicy strength grade was determined by selected panel to analyze the correlation between these properties. Panels were trained for 48 h prior to actual evaluation by panel leaders trained for over 1000 h according to the SpectrumTM method. Partial correlation analysis was performed to examine other candidate parameters that interfere with the sensory evaluation of spiciness and capsaicinoid content. To express the specific variance after eliminating the effects of other variables, partial correlations were used to estimate the relationships between two variables. We observed a strong correlation between spiciness intensity ratings and capsaicinoid content, with a Pearson’s correlation coefficient of 0.78 at p ≤ 0.001. However, other specific variables may have influenced the relationship between spiciness intensity and total capsaicinoid content. Partial correlation analysis indicated that the free sugar content most strongly affected the relationship between spiciness intensity and capsaicinoid content, showing the largest first-order partial correlation coefficient (rxy/z: 0.091, p ≤ 0.01).

Industrial applications of selected JFS articles

Industrial applications of selected <i>JFS</i> articles

Application of colorimetric indicators to predict the fermentation stage of kimchi.

Cabbage kimchi, a popular side dish in Korean cuisine, produces several fermentation by-products (FBPs). Kimchi is praised for its flavor, taste, and texture when suitably fermented at 0.7% to 0.9% total acidity, or a pH of approximately 4.1. Beyond this acidity level, the quality of the product decreases, negatively impacting consumers' purchase preferences. Therefore, the current study seeks to develop an optimally fermented (OptF) kimchi indicator that can be inserted into product packaging to evaluate its utility at 4 and 10 °C. A gradual change in the total color difference (ΔE) was observed during the kimchi fermentation stage, and the highest ΔE values were observed at 4 (34.87) and 10 °C (37.99), after 9 weeks. Moreover, the color-change response function value F(Xc) was more linear at 4 and 10 °C (0.981 and 0.984, respectively) compared to the ΔE over time, during kimchi fermentation. Coefficients of determination for F(Xc)-carbon dioxide (0.983), F(Xc)-pH (0.979), and F(Xc)-titratable acidity (0.974) were sufficient to meet the optimal polynomial regression model, while that for F(Xc)-lactic acid bacteria (0.881) was not. Standardized residuals of predicted data indicated that 95% of the residuals were in the range of -2.0 to 2.0. The regression analysis further suggested that the OptF kimchi indicator could be used as a kimchi fermentation indicator. PRACTICAL APPLICATION: Cabbage kimchi, a traditional Korean fermented food, produces several fermentation by-products. After the optimal fermenting stage, the sensory evaluation of cabbage kimchi and consumers' purchase preference decreases. This study describes an optimally fermented kimchi indicator and its utility at 4 and 10 °C. Our results demonstrate the ability of this indicator to predict the freshness and fermentation stage of kimchi without the need for sensory evaluation. This method could help increase the purchase preference for commercial kimchi.

Taste Characteristics of Commercial Low-Salinity Kimchi

The preparation of commercial, low-salinity kimchi needs to be carefully monitored to maintain the taste of kimchi. To address this, the taste profiles of three brands of commercial kimchi were examined using a taste sensing system, as well as a sensory evaluation. The average sensory score (4.3/9.0) in the overall taste of low-salinity kimchi (A', B', and C') was significantly lower than that (5.1/9.0) of conventional kimchi (A, B, and C). The explanation for the result of A' seemed to be its decrease in saltiness (3.51) and increase in bitterness (8.55) compared to those (6.55 and 7.65, respectively) of A. In B', the saltiness (4.25) and the overall taste (3.7) were significantly decreased compared to B (6.23 and 4.8, respectively). Interestingly, no significant difference was observed in the overall taste (5.1) and saltiness (6.70) of C' when compared to C (5.3 and 6.46, respectively), confirming that salinity is a crucial factor in determining overall taste. Consistent with this finding, the overall taste of low-salinity kimchi correlated positively with its saltiness (>0.98) and umami (>0.82). These results advocate the careful determination of salinity required to maintain the taste of conventional kimchi in preparing low-salinity kimchi, while also pointing towards the need to develop effective taste enhancers for supplementing overall taste.