Bioactive compounds and antioxidant activity in three types of Korean watery kimchi

Watery kimchi is a traditional fermented food served with its soup. In this study, we collected 21 samples of yeolmu mul kimchi (YMK), dongchimi (DC), and nabak kimchi (NK), respectively, which are the most popular watery kimchi in Korea. A composite sample of each watery kimchi was prepared for estimation of their bioactive compounds and antioxidant activities. Of the three kimchi types, YMK had the highest total carotenoid content (63.78 ± 4.88 mg/100 g, of which lutein, capsanthin, and β-carotene were the main carotenoids), and DC had the lowest (3.50 ± 0.12 mg/100 g). YMK also had the highest contents of chlorophyll (250.1 ± 3.91 mg/100 g), ascorbic acid (447.16 ± 8.95 mg/100 g), and capsaicinoids (2.51 ± 0.09 mg/100 g) compared to DC and NK. The lactic acid content was highest in NK (582.72 ± 29.10 mg/100 g). Moreover, YMK showed significantly higher antioxidant activity (ABTS and DPPH) than DC and NK (p < 0.05). Chlorophyll and antioxidant activity showed a strong positive correlation (p < 0.01). The results of this study highlighted watery kimchi as a potentially valuable source of bioactive compounds, and the carotenoids and capsaicinoids were affected by the supporting ingredients used in watery kimchi. Furthermore, watery kimchi provides 4.11% of the recommended daily intake of vitamin A according to the 2020 Korean dietary reference intakes.