Furan formation in sugar solutions and apple cider upon ultraviolet treatment

Authors: Fan, Xuetong; Geveke, David

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2007
Publication Date: 8/21/2007
Citation: Fan, X., Geveke, D.J. 2007. Furan formation in sugar solutions and apple cider upon ultraviolet treatment. Journal of Agricultural and Food Chemistry. 55:7816-7821.

Interpretive Summary: Furan, a possible carcinogen, is found in some thermally processed foods. Ultraviolet (UV) light is used commercially by some cider processors to disinfect apple cider. However, it is unknown whether UV light induces furan in apple cider and its constituents. This study was conducted to investigate possible furan synthesis in apple cider and its components due to UV treatment, and to evaluate whether UV pasteurization would result in furan formation in apple cider. Our results showed, for the first time, that UV could induce furan formation in apple cider, and fructose solution. However little furan was formed from solutions of sucrose, glucose, ascorbic acid or malic acid, suggesting that fructose was the likely source of furan in apple cider. When fresh apple ciders were UV treated to achieve the 99.999% reduction of E. coli, as required by the U.S. FDA, and often used by apple cider processor, less than 1 part per billion of furan was found. Overall, our results suggest that little furan was induced in apple cider if UV treatment is used for the purpose of pasteurization. The information is useful for regulatory agencies to evaluate the importance of furan in our food system and for apple cider industry to implement UV technology.

Technical Abstract: Furan is a possible human carcinogen induced by thermal processing of food. While ultraviolet C (UVC) is used to denominate apple cider and to sterilize sugar solutions, it is unknown whether UVC induces furan in cider or its major components. This study was conducted to investigate the possible formation of furan by UVC in apple cider and in solutions of common constituents of apple cider. Our results showed that UVC treatment induced furan formation in apple cider, and the major source of furan was apparently fructose. UVC treatment of fructose solutions produced a higher amount of furan, while very low concentrations of furan were induced by UVC in glucose or sucrose solutions, and virtually no furan was induced by UVC from solutions of ascorbic acid or malic acid. When an isotope (d4-furan) of furan was treated with UVC, d4-furan was destroyed rapidly even at low doses in fructose solution, suggesting that the accumulation of furan is the balance between destruction and formation. The UV sensitivity of E. coli K12 (a surrogate of E. coli O157:H7) in two types of apple cider was also determined. At UVC doses that could inactivate 5-log of E. coli, very low concentrations (<1 ppb) of furan were induced. Our results suggest that UVC could induce furan formation, but when used for the purpose of juice pasteurization, little furan was induced in apple cider.