The occurrence of aflatoxin M1 (AFM1) in pasteurized milk and dairy products was investigated by using direct competitive enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The recoveries of AFM1 from the samples spiked at levels between 5 and 500 pg/ml were 88.0-106.5% for pasteurized milk and 84.0-94.0% for yoghurt by ELISA. By HPLC, the recoveries were 103-120% for pasteurized milk and 87.0-93.0% for yoghurt. The limits of detection were found to be 2 pg/ml by ELISA and 10 pg/ml by HPLC. Among a total of 180 samples collected in Seoul, Korea, the incidence of AFM1 in pasteurized milk, infant formula, powdered milk and yoghurt was 76, 85, 75, and 83%, respectively, with a mean concentration of 18, 46, 200, and 29 pg/g, respectively, when determined by ELISA. These results obtained by ELISA were closely related to those by HPLC for AFM1 (r2 = 0.9783).

A survey for aflatoxin B1 (AFB1), fumonisin B1 and ochratoxin A (OTA) was conducted on 127 samples that included 30 food-grade barley, 32 barley foods, 18 food-grade corn and 47 corn foods, randomly collected during 1998-99 in Seoul, Korea. The presence of mycotoxins was analysed by direct competitive enzyme-linked immunosorbent assay (ELISA), and most of the positive samples from ELISA were confirmed using high-performance liquid chromatography (HPLC). Recoveries of AFB1 and OTA spiked at 10 ng g(-1) and FB1 spiked at 50 ng g(-1) were 106, 87 and 105% by ELISA, whereas those by HPLC were 80, 79 and 84%, respectively. Detection limits by ELISA for AFB1, FB1 and OTA were 1, 5 and 5 ng g(-1), and those by HPLC were 0.6, 35 and 1 ng g(-1). Naturally occurring AFB1, FB1 and OTA were found in 4/32 (12%), 2/32(6%) and 4/32 (12%) samples of barley foods with an average of 26, 16 and 9 ng g(-1), respectively. AFB1 and FB1 in corn foods were detected in 4/47 (8%) and 9/47 (19%) samples with the average being 20 and 74 ng g(-1), while no OTA was found in any corn foods samples. No AFB1, FB1 or OTA was detected in any of food-grade barley and corn samples. This is the first report on the natural co-occurrence of AFB1 and FB1 in barley and corn foods as well as on surveillance of OTA in Korea.

The incidence of food allergy, which is triggered by allergen permeation of the gastrointestinal tract followed by a T-helper (Th) 2-mediated immune response, has been increasing annually worldwide. We examined the effects of baicalein (5,6,7-trihydroxyflavone), a flavonoid from Scutellaria baicalensis used in oriental herbal medicine, on regulatory T (Treg) cell induction and intestinal barrier function through the regulation of tight junctions in a mouse model of food allergy. An allergic response was induced by oral challenge with ovalbumin, and the incidence of allergic symptoms and T cell-related activity in the mesenteric lymph nodes were analyzed with and without the presence of baicalein. Our results demonstrated that the administration of baicalein ameliorated the symptoms of food allergy and attenuated serum IgE and effector T cells. However, Treg-related factors were up-regulated by baicalein. Furthermore, baicalein was shown to enhance intestinal barrier function through the regulation of tight junctions. We also found that baicalein treatment induced the differentiation of Treg cells via aryl hydrocarbon receptors (AhRs). Thus, the action of baicalein as an agonist of AhR can induce Treg differentiation and enhance barrier function, suggesting that baicalein might serve as an effective immune regulator derived from foods for the treatment of food allergy.

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