Doenjang(Korean fermented soypaste) was suspected to be contaminated by aflatoxins from
Aspergillus flavus due to the traditional natural fermentation. However, the aflatoxins could be
destroyed even though A. parasiticus was contiminated on purpose during the manufacture of
the doenjang. Ammonia and browning products from the fermentation, increase of pH, sunlight,
especially the addition of charcoal degraded the formed aflatoxins during the process. On the
contrary, doenjang exhibited the strong antimutagenic and anticancer activities. The methanol
extract of doenjang showed antimutagenic activities against various carcinogens. The
antimutagenic activity still remained even in the boiling products of doenjang soup and doenjang
stew. The major active compounds found in doenjang were linoleic acid and genistein. Linoleic
acid showed antimutagenic and anticancer effect in vitro and in vivo. The hexane extracts of
doenjang inhibited the cyclin B1 formation and synthesis of mRNA of the cyclin B1, indicating the
extract arrested the cell cycle progression at G2-M. The doenjang extracts inhibited tumor growth
of sarcoma-180 in Balb/c mice, and prolonged the life span of the mice. The extracts increased
the glutathione S-transferase activity in the mice liver. Thus doenjang is safe from the aflatoxin
contamination if we prepare it by the traditional method, and also it can be a good cancer
preventive food.

Keywords: Doenjang, Aflatoxins, Antimutagenic, Anticancer