Browsing by Author "Zribi, Sirine"
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- Optimization and internal validation of a method for extraction and detection of ochratoxin A in cheesePublication . Zribi, Sirine; Rodrigues, Paula; Peres, António M.; Oueslati, SouheibMycotoxins are toxic secondary metabolites produced by fungi when they grow in food and feedstuff. Milk and dairy products especially cheese continue to raise concerns with regard to contamination with mycotoxins. However, for some items, such as cheese, there is a lack of precise information available about mycotoxin contents. The objective of this study was to develop an extraction, cleanup and detection method for the determination of ochratoxin A (OTA) occurrence in “Serra da Estrela” cheese. To achieve this goal, extraction conditions were selected by testing different OTA extraction methods. The influence of two variables on OTA recovery was evaluated: extraction efficiency of digestive enzymes (lipase and protease) and type of purification (liquid-liquid and immunoaffinity columns purification). Under optimized conditions, recoveries of OTA from spiked samples ranged from 62.7 to 70.6%. The HPLC determination by fluorescence detection allowed limits of detection and quantification of 0.45 and 1.51 μg/kg, respectively. A survey was conducted on twenty five “Serra da Estrela” cheeses obtained from 6 different certified producers using the proposed method. None of the samples was found to be contaminated with detectable levels of OTA.