title: Changing carbon isotope ratio of atmospheric carbon dioxide: implications for food authentication.
abstract: Carbon isotopes are often used to detect the addition of foreign sugars to foods. This technique takes advantage of the natural difference in carbon isotope ratio between C(3) and C(4) plants. Many foods are derived from C(3) plants, but the low-cost sweeteners corn and sugar cane are C(4) plants. Most adulteration studies do not take into account the secular shift of the carbon isotope ratio of atmospheric carbon dioxide caused by fossil fuel burning, a shift also seen in plant tissues. As a result statistical tests and threshold values that evaluate authenticity of foods based on carbon isotope ratios may need to be corrected for changing atmospheric isotope values. Literature and new data show that the atmospheric trend in carbon isotopes is seen in a 36-year data set of maple syrup analyses (n = 246), demonstrating that published thresholds for cane or corn sugar adulteration in maple syrup (and other foods) have become progressively more lenient over time.
authors.affiliation: Department of Geology, Colgate University, Hamilton, New York 13346, USA. wpeck@mail.colgate.edu
authors.forename: William H
authors.initials: WH
authors.lastname: Peck
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Tubman
mesh_terms: D031002:Acer / Q000737:chemistry; D000388:Air / Q000032:analysis*; D002119:Calcium Carbonate / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D002247:Carbon Isotopes / Q000032:analysis*; D005502:Food / Q000592:standards*; D005506:Food Contamination; D005579:Fossil Fuels; D010788:Photosynthesis; D010944:Plants / Q000737:chemistry; D013549:Sweetening Agents / Q000032:analysis
chemical_list: D002241:Carbohydrates; D002247:Carbon Isotopes; D005579:Fossil Fuels; D013549:Sweetening Agents; D002119:Calcium Carbonate