Determination of Phenolic Compounds in Adzuki bean (Vigna angularis) Germplasm

The aim of this study was to evaluate 30 phenolic compounds in adzuki bean germplasm. Adzuki 21653 had the highest content of total phenolics compounds ($6597\;{\mu}g\;g^{-1}$) while 104372 had the lowest concentration. The average total phenolic content of Japanese ($2432\;{\mu}g\;g^{-1}$) adzuki beans was higher than that of Korean ($2256\;{\mu}g\;g^{-1}$) adzuki beans. The average total phenolic contents were $2507\;{\mu}g\;g^{-1}$ in small sized adzuki beans from Japan and $2459\;{\mu}g\;g^{-1}$ in those from Korea. In large sized adzuki beans, the average total phenolic contents were $1315\;{\mu}g\;g^{-1}$ in Japanese seeds and $1232\;{\mu}g\;g^{-1}$ in Korean seeds. The average total phenolic contents in medium seeds were $2369\;{\mu}g\;g^{-1}$ in Japanese adzuki beans and $1397\;{\mu}g\;g^{-1}$ in Korean ones. In small seeds, the total phenolic contents of adzuki beans varied from $524\;{\mu}g\;g^{-1}$ to $6597\;{\mu}g\;g^{-1}$ in Japanese ones and from $375\;{\mu}g\;g^{-1}$ to $6569\;{\mu}g\;g^{-1}$ in Korean ones. Japanese and Korean adzuki beans were divided into landraces and wild adzuki beans. In this study, the wild adzuki beans showed higher contents of total phenolics than the native varieties. Specifically, the wild adzuki beans from Korea had the highest concentration of phenolics ($3403\;{\mu}g\;g^{-1}$). All adzuki bean germplasms were measured for their color and were classified into four groups accordingly: A; L < 30, +a, +b; B; L < 30, +a, -b, C; L > 50, +a, +b, D; L > 50, +a, -b. Especially, group B had the highest concentration of total phenolic compounds ($2827\;{\mu}g\;g^{-1}$), whereas group C had the lowest concentration ($1882\;{\mu}g\;g^{-1}$).