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

Effects of jogi, Micropogonias undulatus, addition on the production of volatile compounds in baechu-kimchi

Baechu-kimchi is a traditional vegetable fermented food using kimchi cabbage (Brassica rapa) as the main ingredient. A wide variety of ingredients can be used in kimchi depending on the specific region and even household. Although there have been a lot of studies examining various aspects of kimchi, there has been limited research on kimchi with added fish as a minor ingredient. Therefore, in the present work we aimed to assess changes in the volatile compounds of baechu-kimchi with the addition of seafood used as minor ingredients of kimchi. Sulfur compounds were the most commonly detected volatile compounds; 9 categories of volatile components were detected in total. Altogether, 30 sulfur compounds were detected, and among them, five sulfur compounds: (E)-1-(methyltrisulfanyl)prop-1-ene, 1-(methyldisulfanyl)-1-methylsulfanylpropane, (methyltetrasulfanyl)methane, 1-(methyldisulfanyl)-1-[(E)-prop-1-enyl]sulfanylpropane, and 1,1-bis(methyldisulfanyl)propane, were found only in jogi-added kimchi, thus confirming the influence of jogi addition. Principal component analysis revealed clear distinctions in the volatile compounds as a result of jogi addition as fermentation progressed. Moreover, when confirming the correlation with microbial populations, it was evident that the differentiation in volatile compounds was more attributable to jogi addition than microbial impact. In conclusion, the addition of jogi to baechu-kimchi led to an abundance of volatile compounds by the 20th day of fermentation.

Effects of umami substances as taste enhancers on salt reduction in meat products: A review

Sodium is one of the essential additives in meat processing, but excessive sodium intake may increase risk of hypertension and cardiovascular disease. However, reducing salt content while preserving its preservative effect, organoleptic properties, and technological characteristics poses challenges. In this review, the mechanism of salt reduction of umami substances was introduced from the perspective of gustation-taste interaction, and the effects of the addition of traditional umami substances (amino acids, nucleotides, organic acids(OAs)) and natural umami ingredients (mushrooms, seaweeds, tomatoes, soybeans, tea, grains) on the sensory properties of the meat with reduced-salt contents were summarized. In addition, the impacts of taste enhancers on eating quality (color, sensory, textural characteristics, and water-holding capacity (WHC)), and processing quality (lipid oxidation, pH) of meat products (MP) and their related mechanisms were also discussed. Among them, natural umami ingredients exhibit distinct advantages over traditional umami substances in terms of enhancing quality and nutritional value. On the basis of salt reduction, natural umami ingredients improve the flavor, texture, WHC and antioxidant capacity. This comprehensive review may provide the food industry with a theoretical foundation for mitigating salt consumption through the utilization of umami substances and natural ingredients.

Effect of headspace gas composition in kimchi packaging on the quality characteristics of kimchi

This study evaluated the effects of gas composition in kimchi packaging on kimchi quality. Completely sealed packaging without gas inflow/outflow during fermentation (S1), packaging allowing gas outflow (S2), and packaging allowing gas inflow and outflow (S3) were used. Microbial composition analysis, volatile compound content analysis, and sensory evaluation were performed to determine the differences in kimchi quality among samples. Metabolites were examined using principal component analysis. Gas composition analysis showed that the ratio of CO2 increased during the storage period in S1, the ratio of nitrogen and CO2 contents was constant in S2, and the ratio of oxygen was significantly higher in S3. No significant differences in the lactic acid bacteria number were observed. However, coliforms were only detected in S3, and yeast and mold proliferated faster in S3 than in S2 or S1. The main compounds detected in S1 and S2 were alcohols, whereas those in S3 were esters such as β-phenethyl acetate produced by yeast. Sensory evaluation showed that S3 had the lowest odor, taste, and overall scores, whereas S2 had the highest. In conclusion, the gas composition inside the kimchi package greatly affects the quality of kimchi. Our findings provide important data that can be useful in the manufacture of commercial kimchi.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05795-z.

Rapid Quantitative Analysis of Metabolites in Kimchi Using LC-Q-Orbitrap MS

Kimchi is a traditional Korean salted spontaneous lactic acid bacteria (LAB)-fermented food made using various vegetables. Organic acids, free sugars, and amino acids are key metabolites produced during LAB fermentation that determine the taste and quality of kimchi. However, each metabolite is typically analyzed using an independent analytical method, which is time-consuming and expensive. Therefore, in this study, we developed a method based on LC-Q-Orbitrap MS using which 20 types of representative fermented kimchi metabolites were selected and simultaneously analyzed within 10 min. The established method was validated, and its detection and quantification limits, linearity, precision, and accuracy were found to satisfy the Association of Official Agricultural Chemists (AOAC) validation guidelines. The 20 metabolites were simultaneously extracted from kimchi with different degrees of fermentation and quantitatively analyzed using LC-Q-Orbitrap MS. These results were analyzed using linear discriminant analysis and heat mapping, and the metabolites were grouped into early, middle, and late stages of fermentation. Malic acid (6.518-7.701 mMol) was only present in the initial stage of fermentation, and l-phenylalanine rapidly increased from the middle stage (2.180 mMol) to late stage (4.770 mMol). Lactic acid, which is representative of the sour taste of kimchi, was detected in the middle stage and increased rapidly up to 74.452 mMol in the late stage. In summary, in this study, 20 major kimchi metabolites were accurately analyzed within 10 min and grouped based on the degree of fermentation. Therefore, the method established in this study accurately and rapidly provides information on kimchi consumption and fermentation that could be highly valuable to the kimchi industry and kimchi consumers.

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.