06 FOOD SAFETY SUPPLEMENT: RAPID METHODS


developed method were published. Most of these studies relied on the nor-1 gene as a PCR target and it was demonstrated that strains lacking this gene or bearing a mutated version are aflatoxin non-producers. A few years later a similar strategy was applied for the determination of trichothecene producing Fusarium strains24


. Although more than twenty


studies have been published, all of them used genes from the trichothecene gene cluster as diagnostic sequences and most studies focused on conserved regions of the tri5 gene. This gene encodes for the first step in toxin synthesis and recent gene knock-out studies demonstrated the absence of all trichothecenes in tri5 deficient mutant strains. Analogue analysis methods have been developed for the quantification of all fumonisin producers, patulin producers, and enniatin producers with the biosynthesis genes fum1, idh, and ennsyn, respectively as PCR targets21


. Numerous studies were performed


with these PCR test to evaluate their performance for the analysis of food and especially to evaluate the potential of PCR as a screening tool to assess the mycotoxin content of the analysed samples. The measured amount of fungal DNAs was frequently related to the mycotoxin concentration in the samples.


However, the results of these studies varied considerably. Whereas some authors demon - strated good correlations between certain toxins and the abundance of the DNA of its producer, other groups completely failed to observe any correlation between these two parameters. It has to be considered that a certain


amount of fungal mycelium is able to produce different amounts of mycotoxins depending on environmental factors such as temperature or substrate availability. This – often poor – correlation between fungal biomass and toxins limits the application of (q)PCR assays for applications in the field of mycotoxin related food analysis. Although PCR is an inexpensive high throughput method, it has to be evaluated carefully for each application to see whether PCR analysis provides an alternative to other rapid test methods. In response to the increasing need for faster


and more cost-efficient methods for the determination of a wide range of chemical contaminants in different food commodities, the European Commission has funded a couple of research projects including CONffIDENCE (ww.conffidence.eu) and BIOCOP (www.biocop.org). It is expected that


these initiatives will not only save precious time in ever faster production cycles, but will also permit more food / feed samples to be monitored due to the lower cost per test and hence contribute to improved food safety.


References


1. Ricci, F, Volpe, G, Micheli, L and Palleschi, G (2007). “A review on novel developments and applications of immunosensors in food analysis.” Analytica Chimica Acta 605(2): 111-129


2. Maragos, CM (2009). “Biosensors for mycotoxin analysis: Recent developments and future prospects.” World Mycotoxin Journal 2(2): 221-238


3. Zheng, MZ, Richard, JL and Binder, J (2006). “A review of rapid methods for the analysis of mycotoxins.” Mycopathologia 161(5): 261-273


4. Chu, FS, Hsu, KH, Huang, X, Barrett, R and Allison, C (1996). “Screening of Paralytic Shellfish Posioning Toxins in Naturally Occurring Samples with Three Different Direct Competitive Enzyme-Linked Immunosorbent Assays.” Journal of Agricultural and Food Chemistry 44(12): 4043-4047


5. Laycock, MV, Jellett, JF, Easy, DJ and Donovan, MA (2006). “First report of a new rapid assay for diarrhetic shellfish poisoning toxins.” Harmful Algae 5(1): 74-78


6. Schubert-Ullrich, P, Rudolf, J, Ansari, P, Galler, B, Führer, M, Molinelli, A and Baumgartner, S (2009). “Commercialized rapid immunoanalytical tests for determination of allergenic food proteins: An overview.” Analytical and Bioanalytical Chemistry 395(1): 69-81


7. Skerritt, JH and Hill, AS (1990). “Monoclonal antibody sandwich enzyme immunoassays for determination of gluten in foods.” Journal of Agricultural and Food Chemistry 38(8): 1771-1778


8. Kahlenberg, F, Sanchez, D, Lachmann, I, Tuckova, L, Tlaskalova, H, Mandez, E and Mothes, T (2006). “Monoclonal antibody R5 for detection of putatively coeliac-toxic gliadin peptides.” European Food Research


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