On the endogenous content of formaldehyde in typical Italian cheeses

Commission Regulations EU 05.06.2014 n. 605[1] and UE 23/3/2015 n. 491[2] recently updated the classification of formaldehyde (FA) as carcinogen 1B – H 350 and the International Agency for Research on Cancer (IARC) classified FA as “carcinogen”. FA is added into some food products as antibacterial agent and preservative in food processing, but occurs also naturally in free and bound forms with protein residues yielding methylol groups, Schiff bases, methylene bridges, and other adducts. According to various authors, free FA is of toxicological interest and is measured as a potential adulterant. [3, 4] On the other hand, the main difficulty in FA analysis is the release of FA from the sample matrix, and Rehbein[3] recommended different procedures for measuring free FA and bound FA separately. Threshold limits for free FA naturally occurring in milk and dairy products is not officially defined even if some Authorities estimated a tolerable daily exposure. The aim of this paper concerns the analytical evaluation by high performance liquid chromatography- diode array detector (HPLC-DAD) of free FA content in typical Italian cheeses distributed on the Italian market, adopting an extraction technique and analytical operative conditions that allow an accurate evaluation of content limits not influenced by free FA added as a preservative. Standard addition method is adopted to determine the free FA derivatized with 2,4 dinitrophenylhydrazine (DNPH), realizing several spiking to evaluate the linearity. In various typical cheeses purchased on the Italian market the free endogenous FA content reached values lower than 200 microg kg-1. [1] Commission Regulation (EU) No 605/2014 of 5 June 2014 [2] Commission Regulation (EU) No 491/2015 of 23 March 2015 [3] Rehbein, H. Z. Lebensm. Unters Forsch 1987, 185, 292-298. [4] Metz, B.; Kersten, G.F. A.; Baart, G.J.E, de Jong, A.; Meiring, H.; ten Hove, J.; van Steenbergen, M. J.; Hennink, W. E.; Crommelin, D. J. A.; Jiskoot, W. Bioconjug. Chem. 2006, 17, 815-822.