Vitamin K variations in conger eel (Conger myriaster) influenced by harvest time and size

Abstract

This study analyzed the variation in vitamin K content in conger eel (Conger myriaster) caught off Tongyeong, Gyeongsangnam-do, Korea, focusing on the influence of size (large and small) and harvest period (monthly throughout 2021). We applied enzymatic extraction and HPLC-fluorescence methods for the analysis of vitamin K1 (phylloquinone) and K2 (menaquinone). The vitamin K content in conger eel varied significantly with size and harvest season (p<0.05). In large-sized samples, the phylloquinone content peaked in July (0.80±0.09 μg/100 g), while the highest menaquinone content was in May (0.79±0.11 μg/100 g). Conversely, in small-sized conger eels, the highest phylloquinone was found in December (1.94±0.15 μg/100 g), and the peak menaquinone level was in January (0.66±0.02 μg/100 g). The fat content was highest in July for large samples and in January for smaller ones. There was a positive correlation between fat and total vitamin K contents in conger eel (r=0.631, 0.667). Method validation and quality control measures ensured data reliability for vitamin K1 and K2 analyses. This study provides reliable information on the size and seasonal variations of vitamin K in conger eels, a staple in the Korean diet. This information is valuable for inclusion in Korea’s national food nutrition database and for formulating future national health and nutrition policies.