Can the Mutagens in Cooked Beef Be Reduced?
Since mutagens were first observed in cooked meats, researchers in several different laboratories have explored various ways to reduce the amounts produced during food preparation. They have found that mutagenic activity can be lowered by adding antioxidants, soy or cottonseed flour, tryptophan, and various other food additives or sugars either alone or with starch. However, none of these additives is widely used commercially or at home. Consumer acceptance and possible changes in the taste, texture, and nutritional content of the cooked food need to be explored further.
Surveys have shown that more than 90% of American homes have a microwave oven. As a practical way to reduce the mutagen and fat content of beef, we studied microwave pretreatment of hamburger for various times before conventional frying either at 200 or 250°C for 6 minutes per side. Our tests used a standard commercial microwave oven set at 80% power for 0 to 3 minutes. The results were dramatic.
We found that the mutagen precursors in hamburger (creatine, creatinine, amino acids, and glucose), water, and fat were reduced up to 30% in the microwaved patties. The graph shows the amount of creatine remaining in the meat as a function of microwave pretreatment times. The fairly rapid loss of water-soluble mutagen precursors and fat takes place in the clear liquid that is released after microwaving. When this liquid is discarded before frying, mutagens in the cooked meat are reduced up to approximately 90% following frying, as shown in the table.
How is it possible that 90% of the mutagens disappear when the precursors are reduced by only 30%? The difference can be explained by second-order reaction kinetics. For example, if two reactants are needed, and each is reduced by 30%, then the product would be reduced by about 50%. If three reactants are required and all are reduced by 30%, the product would be reduced by 70 to 80%. It is also possible that some threshold level of precursor is necessary to produce a mutagenic response or that some inhibitor is formed after microwave pretreatment. As with other techniques to reduce mutagen content, the palatability of food may ultimately govern consumer acceptance of microwave pretreatment.