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In this study, the changes in pH, organic acid content, acidity, and salinity of kimchi prepared at 0 days, stored 1-8 weeks at 4 and 10 ∘ C, and stored at room temperature for two days were analyzed. Organic acids content was analyzed by using analytical technique of high-performance liquid chromatography (HPLC). This method was also validated using quality assurance parameters of linearity, limits of detection and quantification (LOD and LOQ), precision, and spike recovery experiments. In the analysis of organic acids content (mg/kg), it was found that the kimchi stored for 1-8 weeks at 4 and 10 ∘ C showed gradual increase in the organic acids content during storage period. The order of organic acids was lactic acid > acetic acid > citric acid > malic acid > succinic acid > oxalic acid > fumaric acid. The pH values of kimchi stored at 4 ∘ C, 10 ∘ C, and 25 ∘ C were 4.1, 3.6-3.7, and 4.1, respectively.

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).

This study aimed to evaluate the safety (hemolysis and enzyme activity), probiotic properties (gastrointestinal tract tolerance, adhesion, hydrophobicity, and auto‐aggregation), and functional characteristics (antimicrobial, antioxidant, and β ‐galactosidase activities) of lactic acid bacteria (LAB), isolated from kimchi, in order to select a multifunctional LAB strain for starter culture in fermented food. The five isolated strains included Lactobacillus plantarum WiKim83, L . plantarum WiKim84, Pediococcus pentosaceus WiKim85, P . pentosaceus WiKim86, and L . plantarum WiKim87, as identified by 16S rRNA gene sequence analysis; they were confirmed to be nonhemolytic and not able to produce β ‐glucuronidase, a carcinogenic enzyme. Probiotic properties of the five LAB strains were evaluated relative to those of commercial Lactobacillus rhamnosus GG, and results revealed probiotic potential of three strains ( L . plantarum WiKim83, L . plantarum WiKim84, and L . plantarum WiKim87) to be superior. L . plantarum WiKim84 showed high antimicrobial activity against pathogens, and L . plantarum WiKim83 exhibited the highest antioxidant and β ‐galactosidase activities. Based on the probiotic and functional properties, the main characteristics of each strain were highlighted and two of them, L . plantarum WiKim83 and L . plantarum WiKim87, were selected as the most potent by principal component analysis. These strains showed antimicrobial, β ‐galactosidase, and antioxidant activities, which recommend their suitability as starter culture in various fermented foods.