whereRU: Aresty Poster 12 - Off-Flavors in Beer: A Literature Review by Aresty Posters 2009

Off-Flavors in Beer: A Literature Review of Melanoidins and Strecker Aldehydes
Nicholas Sawyer (nsawyer2@eden.rutgers.edu ) and Aaron Lulla (alulla@eden.rutgers.edu)
Advisor: Dr. Gavin Swiatek, Department of Biochemistry and Microbiology, Cook College, Rutgers University
Carbohydrate degradation in beer produces ?-dicarbonyl intermediates, which further degrade into Strecker aldehydes (Hofmann and Schieberle, 2000, ?Formation of Aroma-Active Strecker-Aldehydes by Degradation of Amadori Compounds,? J. Agric. Food Chem, 48: 4301-4305) and melanoidins (Kroh, L.W. et. al, 2008, ?-Dicarbonyl compounds ? Key Intermediates for the Formation of Carbohydrate-based Melanoidins. Ann. NY Acad. Sci, 1126: 210-215). The pathway for ?-dicarbonyl degradation is generally understood (Rowe, Chemistry and Technology of Flavors and Fragrances, 2005), but the factors favoring the formation of Strecker aldehydes versus melanoidins is not known. Previous studies have demonstrated that ?-dicarbonyls can be photolyzed to form reactive free radicals (Takagi, H. et. al, 1980, J. Phys. Chem, 84: 478-483). We hypothesized that ?-dicarbonyl photolysis would favor the formation of Strecker aldehydes. We stored several beer samples in different lighting environments: complete darkness, UV light, fluorescent light, and natural light. The samples were evaluated by high-performance liquid chromatography (HPLC) and size-exclusion chromatography (SEC) to determine the relative amounts of Strecker aldehydes and melanoidins produced from ?-dicarbonyl degradation.