Geochemistry Reveals the Geographic Origin of Food
Is that Serrano ham from Spain … Are those Tiger prawns from Australia … Is that Kona coffee from Hawaii? Thanks to the science of geochemistry and the use of trace elements and isotopic signatures, questions surrounding the authenticity and purity of products in a global marketplace can be answered with a fair degree of certainty, according to speakers at Session 050 “Food profiling for geographical origin: Chemists have solutions” on Sunday afternoon, July 18.
Antonietta Gledhill, Waters Corp., (Booth 6614, 6713) discussed food profiling for product authenticity and adulteration testing. The goal of food profiling is to take complex matrices and make them clear and simple—not an easy task—through the use of various analytical methods, said Gledhill. UPLC and MS provide good specificity, selectivity, and sensitivity, but the testing can be expensive. Experimental considerations include resolution, fragmentation & separation, and peaks of interest.
Robyn Hannigan, Univ. of Massachusetts, discussed sourcing food using trace elements and radiogenic isotopes. “Using trace element chemistry can distinguish geographic source,” said Hannigan. When trying to resolve geographic sources, it’s important to know all potential sources and how the samples were stored. Use the results to develop a reference library of known sources, she explained.
Hannigan described two case studies—tomatoes from Arkansas, Mexico, and Guatemala, and shrimp from the Gulf of Mexico and the Atlantic Ocean. Using ICP-MS analysis for trace elements yielded fair results for distinguishing tomatoes from Arkansas, Mexico, and Guatemala. After analyzing for the isotope strontium, the testing method classified the tomatoes by their geographic location with 100% accuracy. Following acid digestion of shrimp shells, ICP-MS analysis identified shrimp from the Louisiana coast with 80% accuracy and shrimp from the Georgia coast with 92% accuracy.
Russell Frew, Oritain Global Ltd. and Univ. of Otago Dunedin New Zealand, discussed case studies of beef, tea, honey, and coffee. The technology can distinguish tea from different plantations only a few miles from each other, said Frew. Geochemical provenance of foodstuffs is effective, he concluded.