Food Authenticity Using Natural Carbon Isotopes (12C, 13C, 14C) in Grass-fed and Grain-fed Beef

Natural carbon isotopes, C-12, C-13, and C-14, help to authenticate/trace foods and beverages. Levels of total carbon (TC), C-13 (delta C-13), and C-14 in muscle and lipid tissues from grass-fed versus grain-fed steers are reported. The delta C-13 in muscle versus lipid of steaks were around 5 parts per thousand higher in grain over grass-fed (p<0.05). The delta C-13 and (14)(C) levels were higher in muscle over lipid tissues while the opposite was true for TC (p<0.05). TC content was around 20% higher in lipid over muscle due to different elemental compositions, lipid versus muscle, not carbon isotopes discrimination.