Detection Methods for Aflatoxin M1 in Dairy Products

Abstract

Mycotoxins are toxic compounds produced mainly by fungi of the genera Aspergillus, Fusarium and Penicillium. In the food chain, the original mycotoxin may be transformed in other toxic compounds, reaching the consumer. A good example is the occurrence of aflatoxin M1 (AFM1) in dairy products, which is due to the presence of aflatoxin B1 (AFB1) in the animal feed. Thus, milk-based foods, such as cheese and yogurts, may be contaminated with this toxin, which, although less toxic than AFB1, also exhibits hepatotoxic and carcinogenic effects and is relatively stable during pasteurization, storage and processing. For this reason, the establishment of allowed maximum limits in dairy products and the development of methodologies for its detection and quantification are of extreme importance. There are several methods for the detection of AFM1 in dairy products. Usually, the analytical procedures go through the following stages: sampling, extraction, clean-up, determination and quantification. For the extraction stage, the use of organic solvents (as acetonitrile and methanol) is still the most common, but recent advances include the use of the Quick, Easy, Cheap, Effective, Rugged, and Safe method (QuEChERS) and proteolytic enzymes, which have been demonstrated to be good alternatives. For the clean-up stage, the high selectivity of immunoaffinity columns is still a good option, but alternative and cheaper techniques are becoming more competitive. Regarding quantification of the toxin, screening strategies include the use of the enzyme-linked immunosorbent assay (ELISA) to select presumptive positive samples from a wider range of samples, and more reliable methods—high performance liquid chromatography with fluorescence detection or mass spectroscopy—for the separation, identification and quantification of the toxin.

Pre-Concentration and Analysis of Mycotoxins in Food Samples by Capillary Electrophoresis

“…Immunoaffinity capillary columns are filled with antibodies, and in contrast to SPE columns, the analyte is retained and the interferents are eluted [ 16 ]. Notwithstanding time and costs, in general, immunoaffinity extraction has a high binding affinity and selectivity for mycotoxins as OTA and AFs and therefore it represents one of the most used pre-concentration approaches [ 16 , 23 ]. Immunoaffinity capillary columns (IACs) represent a robust and sensitive (ng/kg) method to purify AFM1 from dairy products with high recovery and precision.…”

“…In fact, this aflatoxin is related to the presence of AFB1 in animal feed. AFM1 is hepatotoxic and carcinogenic and represents a high risk for human health as dairy products are highly consumed in the daily diet and also because of its stability in milk processing and storage [ 16 ].…”

“…This became mandatory as human health could be at risk when simultaneously introducing more than one potential source of mycotoxin in the diet. The immunoaffinity methods, which use very selective immobilized antibodies, do not allow the analysis of multi-mycotoxins, but they are a part of the clean-up procedure and are used in a multi-approach involving a careful setup of sample preparation (extraction/clean-up) prior to analysis [ 16 ].…”

Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds

“…The detection of AFs is performed by several conventional methods based on the emission and absorption characteristics, such as liquid chromatography mass spectroscopy (LC-MS) [126], thin layer chromatography (TLC) [127], gas chromatography (GC) [128], high-performance liquid chromatography (HPLC) [129], immunoaffinity column assay (ICA) [130], and enzyme-linked immunosorbent assay (ELISA) [131].…”

Critical Comparison of Analytical Performances of Two Immunoassay Methods for Rapid Detection of Aflatoxin M1 in Milk

“…A wide range of methods for the detection of AFM 1 in milk and dairy products is currently available, however, achieving key analytical performances, such as sensitivity, precision and reliability, suitable to enforce regulatory limits in the low ng/kg range, is still quite challenging [23]. Screening tests can play an important role within the safety monitoring, allowing rapid decision making and interventions, also affecting the final price of food products.…”