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A.Soldado, V. Fernández-Ibáñez, A. Martínez-Fernández, S. Modroño-Lozano, F. Vicente
& B. de la Roza-Delgado.
Department of Animal Nutrition, Grasslands and Forages. Regional Institute for Research and Agro-Food Development (SERIDA). Villaviciosa (Asturias). Spain.

The establishment of fast and non-destructive methods for quality and safety of raw total mixed rations and ingredients evaluation is being demanded nowadays to avoid toxic substance presence. Animal feeds can be contaminated pre or after harvest, because mycotoxin formation is dependent on temperature, moisture content or insect activity as major factors.

In this work we have studied the presence or absence of aflatoxin B1 (AFB1), zearalenone (ZEN) and ochratoxin A (OTA) in total mixed rations and their ingredients. Near-infrared spectroscopy (NIRS) meets all the criteria of speed, response, reliability, cost-effectiveness and fitness for radically new approach to detect toxic metabolic by-products of fungi in animal feeds.

The reference values were carried out by HPLC mass spectrometry and the spectral data were recorded as log 1/R using two different NIRS equipments: A Foss NIRSystem 6500 spectrophotometer in a range of 400-2500 nm, and a Fourier transform near infrared (FT-NIR) spectrophotometer Spectrum One NTS (Near Infrared Testing System) by Perkin Elmer in a range between 10000-4000 cm-1 (1112-2500 nm).

The purpose of this study have been described the most suitable near-infrared wavelengths that could be used in high-speed sorting for presence or absence of AFB1, ZEN and OTA in animal feeds. The search of the most wavelength revealed that spectral differences for AFB1 are associated with bands between 480-600 nm attributed to colour changes in ingredient fungal infected; 870-1200 nm related with the NH in most amino acids; 1750-1800 nm to CH stretching mode corresponding at CH2 group and 2020-2190 nm could be attributed to NH and OH stretching modes. Bands located at 1820, 2140 and 2180 nm were related with fungal infection and assigned to the first overtone of the OH stretching modes of glucose, NH in amino acids and CH combination bands in cis isomers.

Our preliminary results show that NIR spectroscopy, as reputable and rapid laboratory methodology, has the best potential as a tool on inspection and control operations to detect the most toxic aflatoxins: Aflatoxine B1, minimizing risks in food and feed safety. Spectral information shows differences between non contaminated and contaminated samples. However, these preliminary results have established that spectral differences associated with critical bands between AFB1, ZEN and OTA is not a simple task.

Keywords:
Aflatoxin B1, zearalenone,  ochratoxin A, NIR spectroscopy, animal feeds, mycotoxins.