There are only a few reports on the antioxidative activity of bonito bouillon (Katsuo-Dashi soup stock)，a traditional Japanese seasoning, and their raw materials. The Dashi packs (powder-type soup stock) and evaporated Dashi (liquid type soup stock) are popular and are often used in Japanese meals, in which raw materials comprising dried bonito (Katsuo-bushi)，dried kelp (Kombu)，and dried shiitake mushroom (Lentinula edodes) are mixed. However, how much each raw material contributes to the antioxidative activity of the final products is unknown. So, we evaluated the antioxidative activity by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. In addition, dried bonito (Katsuo-bushi) are classified into the sub-groups of sun-dried bonito (Tempi-bushi)，smoke-dried bonito (Arabushi) and smoke- and mold-dried bonito (Kare-bushi). There have been several reports of antioxidative effects of phenolic compounds absorbed by Katsuo-bushi during the smoking processes of fresh bonito (making Katsuo-bushi). Several phenolic compounds with methoxy or acetyl groups have been identified as aromatic components that increase during the production of Ara-bushi and Kare-bushi. Here, we also report the relationship between the chemical structure of hydroxy methoxy acetophenone and the expression of its antioxidative activity by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) method. These results indicate that Dashi Packs and evaporated Dashi including a lot of Katsuobushi have a high antioxidative activity, which may originate from phenolic compounds that increased in volume during the smoking process.
