C. R. Warner1 , G. O. Noonan1 , N. Sugimoto2 , A. Beisaw3 , W. Hsu3 , G. A. Perfetti1 , T. H. Begley1 , G. W. Diachenko1 , 1FDA, College Park, MD, 2National Institutes of Health Sciences, Tokyo, 3JIFSAN, University of Maryland, College Park, MD
A number of episodes of rapid-onset gastrointestinal illnesses associated with school lunches have been reported and, in the cases under consideration in this report, tortillas supplied by a single manufacturer were implicated.Extensive studies were performed in search of the causative agent(s).Analytical studies were carried out in other laboratories for bacterial toxins, heavy metals, pesticides and mycotoxins.As yet, these studies have not identified the etiologic agent.
Investigations of outbreak associated tortillas in this laboratory revealed unusually high levels of two food additives: bromate and propionate.Bromate levels equivalent to 1 to 3 ppm as potassium bromate were found.The amount of propionate, introduced as an antimycotic in the form of sodium or calcium propionate, ranged from 2.0 to 2.5% as equivalents of calcium propionate.These levels are substantially greater than the 0.13% to 0.6% found in non-outbreak tortillas; and the 0.3%, relative to the weight of flour that is standard practice in the baking industry.Alternatives to the excessive use of the salts of propionate should be investigated.
As the etiologic agent, neither propionate nor bromate was entirely consistent with the epidemiology of the outbreaks; therefore, work was continued with the Bioluminex® screening of the TLC chromatograms of tortilla extracts.This technique is effective for identifying compounds that are toxic to the bacteria on silica gel TLC plates.The Rf values of some interesting substances have been identified, and the extracts of these spots subjected to MS analysis.