In the November Journal of Agricultural and Food Chemistry, they report that in general, the more well done the meat, the more HCAs it contains. In the samples that were the most well done, HCAs laced beef at 5 to 10 parts per billion. This was almost 10 times the concentrations seen in meats cooked to the same doneness in the researchers' lab, observes study leader Mark G. Knize, and more than 100 times those found 3 years ago in fast-food burgers. J. Scott Smith and Basira G. Abdulkarim of Kansas State University in Manhattan present related data in the same issue. They compared HCAs in processed meats, like bologna and smoked sausage, with those in fresh-cooked beef.
Fat content can also prove important.
When fried under the same conditions, hamburgers that started with 5 percent fat developed up to five times the concentrations of HCAs as burgers starting with 15 percent fat. The reason, Smith suspects, is that the fat has an insulating effect. While the new data offer health-conscious cooks some food for thought, they also are prompting a genetic probe. Not all people make equal amounts of the enzymes that activate HCAs. Zheng plans to study whether those who make the greatest amounts of enzymes face the highest cancer risks from well-done meats.