Carcinogens in Cooked Meat


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Carcinogens in Cooked Meat

  1. 1. Carcinogens in Cooked Meat Chemistry of Cooking Spring 2011 Griffin Kennedy Daniel Cohen Ruoxi Wang Tomomi Okajima
  2. 2. Mutagens and Carcinogens <ul><li>Mutagens cause mutations in the genome </li></ul><ul><ul><li>Different than naturally occurring mutation </li></ul></ul><ul><li>Carcinogens are compounds that cause cancer in an organism </li></ul><ul><ul><li>Can be due to mutation or impact on cellular metabolic pathways </li></ul></ul>
  3. 3. Carcinogenesis <ul><li>Series of mutations are involved in inactivating the tumor suppressing and DNA repairing genes in cells in the body </li></ul>
  4. 4. Heterocyclic Aromatic Amines <ul><li>Compounds containing at least one heterocyclic ring and one amine group </li></ul><ul><li>Many of these compounds are beneficial, e.g. niacin </li></ul><ul><li>Some have been found to be some of the most highly mutagenic substances </li></ul><ul><li>Mutagenic varieties are created when cooking meats </li></ul>
  5. 5. Formation <ul><li>Form regardless of proportion of constituents </li></ul><ul><li>Precursors: </li></ul><ul><ul><li>Phenylalanine </li></ul></ul><ul><ul><li>Threonine </li></ul></ul><ul><ul><li>Alanine </li></ul></ul><ul><ul><li>Creatine </li></ul></ul><ul><ul><li>Sugars </li></ul></ul>
  6. 6. Structures of Precursors <ul><li>Phenylalanine </li></ul><ul><li>Alanine </li></ul><ul><li>Threonine </li></ul><ul><li>Creatine </li></ul>
  7. 7. Products <ul><li>Common features: Imidazole ring (from creatine?), fused rings (probably through radical chemistry) </li></ul><ul><li>Mechanisms: undergoes crazy, unpredictable chemistry at high temperatures—Maillard reaction </li></ul><ul><li>Products formed at high temperatures </li></ul>
  8. 8. Structure of Products
  9. 9. Formation at High Temperature <ul><li>Pyrolysis: heat-based decomposition </li></ul><ul><ul><li>High temperature, long cooking time  more HAA </li></ul></ul><ul><ul><li>High activation energy </li></ul></ul><ul><li>Radical reactions </li></ul><ul><ul><li>mostly for polycyclic hydrocarbons, but also for HA’s </li></ul></ul><ul><ul><li>takes place more at higher temperature </li></ul></ul>
  10. 10. Influencing Factors in Formation <ul><li>Degree of cooking, type of meat thought to have effect, but not so much </li></ul><ul><li>Key variables: </li></ul><ul><ul><li>Temperature </li></ul></ul><ul><ul><li>Exposure to direct flame </li></ul></ul><ul><ul><li>Cooking time </li></ul></ul><ul><li>Cooking method </li></ul><ul><ul><li>Frying, broiling, grilling creates most HAA </li></ul></ul>
  11. 11. Prevention of Carcinogenesis <ul><li>Antioxidants prevent radical reactions that form nitrogen heterocyclic compounds in the Maillard reaction </li></ul><ul><li>Mechanism: inactivate intermediate radicals like pyrazinium cation radicals and pyridinium cation radicals -> reduce HA formation </li></ul><ul><li>Common antioxidative constituents in spices: </li></ul><ul><ul><li>Rosmanol --Carnosic acid </li></ul></ul><ul><ul><li>Rosmadial --Epirosmanol </li></ul></ul><ul><ul><li>Carnosol --methyl camosate </li></ul></ul>
  12. 12. Spices as Antioxidants <ul><li>Experiment: add spice powder on surface of beef 24 hours prior to frying up to 180 degrees </li></ul><ul><li>Spices used: </li></ul><ul><ul><li>Rosemary </li></ul></ul><ul><ul><li>Sage </li></ul></ul><ul><ul><li>Thyme </li></ul></ul><ul><ul><li>Garlic </li></ul></ul><ul><ul><li>Brine (contains sodium nitrite) </li></ul></ul><ul><li>All spices show antioxidative properties and reduced HA formation </li></ul>
  13. 13. Sources <ul><li>Pariza, M.W., Ashoor, S.H., Chu, F.S., and Lund, D.B. (1979) Cancer Letters 7 , 63-69. </li></ul><ul><li>Dolara, P., Commoner, B., Vithayathil, A., Cuca, G., Tuley, E., Madyastha, P., Nair, S., and Kriebel, D. (1979) Mutation Research 60 , 231-237. </li></ul><ul><li>Murkovic, M., Steinberger, D., and Pfannhauser, W. (1998) Springer Verlag 207 , 477-480. </li></ul><ul><li>Jackson, L.S., Knize, M.G., and Morgan, J.N., 1999, Impact of Processing on Food Safety, Kluwer Academic/Plenum Publishers, Chapter 12. </li></ul>