title: Simultaneous enhancement of free isoflavone content and antioxidant potential of soybean by fermentation with Aspergillus oryzae.
abstract: In order to determine the fungal strain and fermentation period which produce the highest antioxidant activity of fermented soy product, soybean was fermented with Aspergillus oryzae NL 5 isolated from Korean traditional meju produced in Sunchang Yeastopia Land in Korea, and was subjected to analyzing isoflavone profiles and assaying antioxidant activity. Antioxidant potential of the samples was evaluated by ferric reducing antioxidant power assay, 2,2'-azinobis (2-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity and total phenolic contents. In addition, antioxidant assay using fluorescent probes, 2',7'-dichlorofluorescin diacetate and dihydroethidium, in HepG2 cells was conducted for the samples. The results showed that both high isoflavone variety Aga 3 and medium isoflavone variety Daewon of soybean fermented with Asp oryzae NL5 for 4 to 5 d showed the highest increase in free isoflavone contents, together with the highest antioxidant activity. In conclusion, the antioxidant activity of fermented soy was proportional to the concentration of free isoflavones, and was significantly influenced by total isoflavone content of soybean variety and fermentation period. Practical Application:  Isoflavone profile and antioxidant capacity of soybean were widely variable during fermentation with Asp oryzae, and thereby it is recommended that meju (or koji) preparation condition, in particular, fermentation time is carefully optimized to maximize the antioxidant capacity of soy products fermented by Asp oryzae.
authors.affiliation: School of Applied Biosciences (BK21 program) and Food Science and Biotechnology, Kyungpook National Univ., Daegu 702-701, Korea. vision@knu.ac.kr
authors.forename: Dae
authors.initials: D
authors.lastname: Hwan Nam
authors.forename: Hyo
authors.initials: H
authors.lastname: Jung Kim
authors.forename: Ji
authors.initials: J
authors.lastname: Sun Lim
authors.forename: Kyoung
authors.initials: K
authors.lastname: Heon Kim
authors.forename: Cheon-Seok
authors.initials: CS
authors.lastname: Park
authors.forename: Jeong
authors.initials: J
authors.lastname: Hwan Kim
authors.forename: Jinkyu
authors.initials: J
authors.lastname: Lim
authors.forename: Dae
authors.initials: D
authors.lastname: Young Kwon
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Kim
authors.forename: Jong-Sang
authors.initials: JS
authors.lastname: Kim
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000032:analysis; D001236:Aspergillus oryzae / Q000378:metabolism*; D002460:Cell Line; D005285:Fermentation; D007529:Isoflavones / Q000032:analysis*; D051379:Mice; D010084:Oxidation-Reduction; D056910:Republic of Korea; D013025:Glycine max / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D007529:Isoflavones