Raising the amount of reducing sugars such as glucose in hamburgers can halve the quantity of possible carcinogens generated during cooking, scientists have found.
Experts at the Tokyo University of Pharmacy and Life Science in Japan say that one way to do this is to follow a Japanese recipe that adds one part chopped onion to three parts ground beef before cooking.
However, they also found that adding smaller quantities of the sugars actually increases the level of the potentially harmful substances.
Scientists have previously established that cooking beef generates chemicals such as heterocyclic amine mutagens that can induce genetic mutations in living cells. These compounds are thought to be carcinogenic in humans.
Kiyomi Kikugawa and colleagues report in the latest issue of the journal Genetic Toxicology and Environmental Mutagenesis that the quantity of these mutagens is linked to the quantity of reducing sugars such as glucose, fructose and lactose in the meat. The quantity of sucrose, often used as a food additive, did not have any effect on mutagenicity.
The scientists noted that raw ground beef usually contained 0.07 per cent glucose. When this was doubled, for example by adding 10 per cent wine to the ground beef before cooking, the level of mutagens also doubled.
However, if the quantity of added sugar was in excess of 0.7 per cent, for example if the beef was mixed with onion, the level of mutagens was halved.
"It is important to reduce the mutagenicity/carcinogenicity of cooked hamburger for human health," Kikugawa said.