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FOOD SCIENCEKevin AllenBoiled Salad Anyone?Consumers who like their veggies raw may find themselves in theposition of “making faith-based purchases when it comes to produce,”says Kevin Allen, a UBC food safety expert who studies E. coli andother pathogens.In May, several U.S. states issued massive recalls for romaine lettucecontaminated by E. coli. Days later, the Canadian Food InspectionAgency also issued a recall of romaine lettuce.Currently, government and beef and produce industries haveprocedures in place to monitor and test for E. coli O157:H7 bacterium.However, there are not yet any detection methods available to showa strain such as E. coli O145 which was associated with the romaineoutbreak in May.While it is important that consumers continue to include fresh fruitand vegetables in their diet, notes Allen, they also need to understandthat our produce is not risk free. “Certain commodities such as alfalfasprouts and certain leafy greens are frequently associated withfoodborne disease.”An important facet of Allen’s work is looking at how and why E. coli isso successful at finding its way into, and surviving in, our food chain.Prior to joining LFS in January as an assistant professor in theFood, Nutrition and Health program, Allen worked within industry,researching a vaccine to minimize E. coli O157 prevalence in cattle. Hecontinues this task at UBC.Allen is also comparing various strains of E. coli O157 to devise betterfood safety policies and intervention strategies. This fall, he will collectphysiological data on how different stressors such as heat or chemicalsaffect the bacteria.“What we’re going to do is look at stress response and virulence geneexpression and compare three lineages to see if there are differencesexplaining why these lineages are linked differentially tohuman disease.”Roasting Coffee Beans a Dark BrownProduces Valued AntioxidantsTwo LFS food scientists have pinpointed more of the complexchemistry behind coffee’s antioxidant benefits, tracing valuablecompounds to the roasting process.The study, led by MSc student Yazheng Liu and Prof. David Kitts, foundthat the prevailing antioxidants present in dark roasted coffee brewextracts result from the green beans being brownedunder high temperatures.Liu and Kitts analyzed the complex mixture of chemical compoundsproduced during the bean’s browning process, called the “Maillardreaction.” The term refers to the work by French chemist Louis-Camille Maillard who in the 1900s looked at how heat affects thecarbohydrates, sugars and proteins in food, such as when grillingsteaks or toasting bread.Antioxidants aid in removing free radicals, the end products ofmetabolism which have been linked to the aging process.“Previous studies suggested that antioxidants in coffee could betraced to caffeine or the chlorogenic acid found in green coffee beans,but our results clearly show that the Maillard reaction is the mainsource of antioxidants,” said Liu.“We found, for example, that coffee beans lose 90 per cent of theirchlorogenic acid during the roasting process,” said Kitts, LFS foodscience professor and director of the Food, Nutrition andHealth program.The study sheds light on an area of research that has yieldedlargely inconsistent findings. While some scientists report increasedantioxidant activity in coffee made from dark roasted beans, othersfound a decrease. Yet other theories insist that medium roast coffeesyield the highest level of antioxidant activity.“We have yet to fully decipher all the complex compounds in roastedcoffee beans. We only know the tip of the iceberg,” said Kitts, who hasbeen studying Maillard reaction chemicals over the past 25 years.The study received support from the Natural Science and EngineeringResearch Council (NSERC) of Canada.Faculty of Land and Food Systems Annual Report 2009 | 2010 25