Antioxidant effect of Kimchi supplemented with Jeju citrus concentrate and its antiobesity effect on 3T3‐L1 adipocytes

Citrus is cultivated throughout Jeju Island and is thought to possess some medicinal properties. Citrus concentrate is the most extensively utilized form of citrus in the food industry. In this study, antioxidant and antiobesity effects of Kimchi supplemented with citrus concentrate were investigated. Prepared Kimchi was infused with 7% citrus concentrate (CK) and freeze‐dried for analysis. Normal Kimchi (NK) without citrus concentrate was utilized as a control. Total phenol content (TPC), total flavonoid content (TFC), and antioxidant activities were examined. Cytotoxicity, intracellular triglycerides (TG), and total cholesterol (TC) levels in 3T3‐L1 adipocytes were also measured. Additionally, the inhibitory effects on lipid accumulation were trialed by measuring the oil‐red O (ORO)‐stained cells. TPC, TFC, and antioxidant activities of CK were significantly higher than those of NK (p < .05). CK showed less cytotoxicity and attenuated the lipid accumulation at all concentrations by reducing TG and TC levels compared to NK. The inhibitory effect of CK on lipid accumulation was observed via reducing ORO‐stained lipid droplets. Consequently, the antioxidant and antiobesity effects of CK were revealed in vitro. Furthermore, the addition of citrus may provide competitive price due to low production costs as well as health functionality

Antioxidant, Anti-Obesity, and Anti-Aging Activities of Jeju Citrus Blended Vinegar

Various types of vinegars have been developed as interest in their health benefits has increased. In this study, we prepared Jeju citrus blended vinegars (CBVs) by mixing premature mandarin vinegar and mandarin vinegar, with mandarin vinegar used as a control. The physicochemical properties of the vinegars, including pH, total acidity, and sugar content was determined. Moreover, antioxidant, anti-obesity, and anti-aging activities of the vinegars were investigated. Physicochemical analysis revealed that the CBVs had a pH similar to that of mandarin vinegar, whereas CBVs with relatively high premature mandarin vinegar content showed higher acidity and lower sugar content (p < 0.05). Moreover, the antioxidant activities and phenol contents of CBVs were significantly higher than those of mandarin vinegar (p < 0.05). Meanwhile, CBVs showed significantly decreased intracellular triglyceride, lipid accumulation, and anti-obesity related gene levels (p < 0.05), thereby highlighting their anti-obesity activity. In addition, CBVs showed anti-aging activity by increasing cell viability and cell lifespan, while decreasing the expression of senescence-related genes under H2O2-induced oxidative stress. Therefore, CBVs may be useful as a functional food with antioxidant, anti-obesity, and anti-aging effects in various food fields

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

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

Genome divergence in Brassica rapa subspecies revealed by whole genome analysis on a doubled-haploid line of turnip

Subspecies of Brassica rapa are morphologically and genetically diverse, and include a variety of fresh vegetables grown worldwide. Among them, turnip (B. rapa subsp. rapa) produces a large bulbous taproot, and thus is primarily consumed as a root vegetable in Europe and Asia. In comparison to Chinese cabbage (B. rapa subsp. pekinensis), however, genetic analysis and breeding of turnip is hampered in practice due in part to scarcity of useful genetic resources. In this study, we produced a doubled haploid (DH) line of Ganghwa turnip, an heirloom specialty crop in Korea that is usually propagated by open pollination. Microspores were isolated from young flower buds of Ganghwa turnip, and shoots and roots were sequentially regenerated in vitro. Chromosome doubling was induced with the colchicine treatment, and verified by flow cytometry analysis. The G14 DH line displayed uniformity in overall morphology compared to heterogeneous commercial Ganghwa turnips. The whole genome of G14 was sequenced on an Illumina HiSeq 4000 platform, and the reads mapped onto the B. rapa reference genome identified 1,163,399 SNPs and 779,700 indels. Despite high similarity in overall genome sequence, turnips and Chinese cabbage have different compositions of transposable elements (TEs). In particular, long terminal repeat (LTR) retrotransposons are more enriched in turnips than in Chinese cabbage genomes, in which the gypsy elements are classified as major LTR sequences in the turnip genome. These findings suggest that subspecies-specific TE divergence is in part responsible for huge phenotypic variations observed within the same species.N

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

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

Influence of Salinity on the Microbial Community Composition and Metabolite Profile in Kimchi

Kimchi, a popular traditional Korean fermented food, is produced by fermenting vegetables with various spices and salt. Salt plays an important role in the preparation of kimchi and affects its taste and flavor. This study aimed to investigate the effects of salinity on kimchi fermentation. The salinities of five sets of kimchi samples were adjusted to 1.4%, 1.7%, 2.0%, 2.2%, and 2.5%. The characteristics of each kimchi sample, including its pH, acidity, free sugar content, free amino acid content, organic acid content, and microbial community composition, were evaluated during kimchi fermentation. The low-salinity kimchi sample showed a rapid decline in the pH at the beginning of the fermentation process, a relatively high abundance of Leuconostoc mesenteroides, and high mannitol production. In the late fermentation period, Latilactobacillus sakei had a higher abundance in the kimchi sample with high salinity than in other samples. In the initial stage of fermentation, the metabolite composition did not differ based on salinity, whereas the composition was considerably altered from the third week of fermentation. The findings showed variations in the characteristics and standardized manufacturing processes of kimchi at various salt concentrations. Therefore, salinity significantly affected the types and concentrations of fermentation metabolites in kimchi