February 4, 2020 at 7:49 am

Lee Authors Article on Mold Used to Brew Sake, and its Carcinogenic Relative

Dr. Victoria Lee, portrait outdoors

Dr. Victoria Lee

Dr. Victoria Lee authored an article on the history of kōji, the mold used in brewing sake and soy sauce, and its close relation Aspergillus flavus. The latter can produce “aflatoxin,” a powerful carcinogen.

Wild Toxicity, Cultivated Safety: Aflatoxin and Kōji Classification as Knowledge Infrastructure” was published in the journal History and Technology.

Lee is Assistant Professor of History at Ohio University.

“Kōji, Aspergillus oryzae, enzyme maker extraordinaire, and gastronomic mold responsible for the brewing of sake, soy sauce, and miso, is today the ‘national fungus’ (kokkin) of Japan. Its identity, however, was not always so stable,” writes Lee in her introduction.

“This essay focuses on a moment of crisis beginning in 1960 that redefined kōji identity, a moment when the perception of this mold as a helpful, edible, living worker changed. In 1960, over 100,000 poultry in England died from an unknown disease named Turkey X. Investigators linked the disease to the peanut meal in the turkeys’ industrial feed, and identified the cause as a mycotoxin produced by the fungus Aspergillus flavus, secreted while the mold grew on nuts and grains during storage.

“Named ‘aflatoxin’, the toxin soon emerged as one of the most powerful carcinogens known in food, which caused proliferation of bile duct epithelial cells in the liver when consumed by rodents, fish, birds, or primates. Kōji – which was closely related to A. flavus and taxonomically part of the Aspergillus flavus-oryzae group at the time – came to be viewed in a new light, as a hazard and potential source of environmental contamination in the body.

“…The discovery of aflatoxin in 1960 and its association with the brewing mold, kōji, should have been well poised to threaten Japanese consumers’ turn to natural, nostalgic, traditional food. Such a reversal in consumer culture would have paralleled the shift that was taking place in biomedical research, from a focus solely on synthetic carcinogens to natural carcinogens as well,” Lee writes.

“Instead, sake, soy sauce, miso, and other brewed products that relied on kōji became valued culturally as culinary symbols of ‘native-place’ traditions that spanned millennia, at the same time as they continued to yield massive economic returns in the food industry. According to leading Japanese fermentation scientist Sakaguchi Kin’ichirō, around 1972, fermented goods accounted for close to 2% of Japan’s gross national product. In the wake of the aflatoxin crisis, the fact that kōji identity folded easily into the national celebration of domestically produced foods, which were lauded for their ‘high quality, safety and perfection of form’ in contrast to imported foods, cannot be taken for granted. Rather, it was a result of Japanese microbiologists’ efforts over the period of about a decade to reclassify the yellow-green kōji microbe as something quite different than its wild, commonly found in nature, and sometimes potently toxigenic yellow-green relative, Aspergillus flavus.”

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