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BACKGROUND Aflatoxin B1 (AFB1) is the most commonly occurring and the most toxic of all aflatoxins (AFs). It is responsible for liver cancer in animals and it is listed as a Group I carcinogen by the International Agency for Research on Cancer. Thus, it is necessary to find decontamination methods that show efficiency, specificity, low cost, and that allow the disposal of contaminated raw materials into the environment. This study evaluated the effects of enzyme concentration, pH, temperature and reaction time on AFB1 biotransformation by commercial peroxidase (POD) in a model solution (100 mmol L−1 phosphate buffer). RESULTS When 0.015 U mL−1 was used to treat 0.5 µg L−1 of AFB1, at pH 7.0–8.0 and 30–40 °C, for 8.0 h, the AFB1 biotransformation reached its maximum (97%). KM value of POD for the biotransformation of AFB1 was 0.0160 µmol L−1 (5 µg L−1) with a VMAX of 6.4 µmol L−1 min−1, which were determined based on Lineweaver‐Burk's plot. POD (0.015 U mL−1) effectively reduces AFB1 (97%) and M1 (65%) in UHT milk and AFB1 (24%) in lager beer samples acquired in markets of Rio Grande‐RS (Brazil). CONCLUSION The use of POD may be a strategy to mitigate the impact of AFs found in food to reduce the risk of consumer exposure. © 2018 Society of Chemical Industry

An investigation was conducted to standardize conditions for laccase and lipase activity required to maximize trichothecene degradation. The analytical methods were suitable and validated in model solutions for detection of five analytes (T-2 toxin, deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol and 15-acetyldeoxynivalenol), the methods were then applied in the degradation tests of these trichothecenes. The method of salting-out assisted liquid-liquid extraction (SALLE), using three different NaCl concentration levels, obtained recoveries in the range of 47.4-103.4% at pH 5.0 and 36.6-106.8% at pH 7.0, with an intra-day relative standard deviation under 15% for the majority of the compounds. Quantification limits remained in the region of 0.07 μg mL -1 for 15-acetyldeoxynivalenol and 0.3 μg mL -1 for nivalenol. Finally, the suitable analytical methods were applied in a study of trichothecene degradation by enzymatic action, resulting in a reduction of 12.3% for T-2 toxin, 68.4% for deoxynivalenol, 50.2% for 3-acetyldeoxynivalenol and 45.4% for 15-acetyldeoxynivalenol.

This study aimed at evaluating the potential of the peroxidase (PO) enzyme to reduce ochratoxin A (OTA) levels and its application to grape juice. Both commercial PO and PO extracted from rice bran were evaluated, respectively, regarding their activity towards OTA in a model system. The affinity between PO and OTA was verified by the Michaelis-Menton constant and the maximum velocity parameters, resulting in 0.27 μM and 0.015 μM min −1 for the commercial enzyme, and 6.5 μM and 0.031 μM min −1 for PO extracted from rice bran, respectively. The lowest residual OTA levels occurred when 0.063 U mL −1 of the enzyme was applied. Under these conditions, the OTA reduction was 41% in 5 h for the commercial enzyme, and 59% in 24 h, for PO extracted from rice bran. When the extracted PO, with the activity of 0.063 U mL −1 , was applied to whole grape juice, the OTA levels decreased to 17%, at 24 h. The capacity shown by PO for reducing OTA levels was confirmed in whole white grape juice, as a model system. This study may assist the wine industry to offer healthier products and add value to rice bran.

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