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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