AN - 27 Measuring δ18O and δD of Commercial Apples to Verify Region of Origin

The agricultural, food and beverage industries can benefit from a technique to rapidly distinguish between the geographical provenance of similar raw and processed food products grown or produced in different regions. Stable isotopes can provide this fast screening capability. Every fruit, leaf or vegetable producthas 13C, D and 18O stable isotope ratios unique to the plant type and local growing conditions(groundwater, temperature and amount of sunshine). These unique isotope ratios effectively affix apersistent atomic level geographical “bar code” to all plant matter and to many related animal products(e.g. honey, carries the signature of the primary feedstock of the bees that make it). Stable isotope ratios can in some cases be used to determine whether premium products such as honey and olive oil are 100% genuine or have been adulterated with cheaper ingredients1. (See Picarro Application Notes 23 and 28)

Despite government regulations mandating the verification and certification of the origin and authentic content of foodstuffs in the European Union and the United States, stable isotope ratios are still rarely used for this purpose. The high cost, complexity and time required to make these measurements using traditional scientific instrumentation, as well as the level of special expertise required, are significant barriers to widespread usage outside of university or laboratory. A new generation of simple-to-use, turnkey instruments which can in seconds or minutes provide stable isotopes for a wide range of samples at a fraction of the cost per sample of traditional instrumentation. These instruments are based on a proven technology called CRDS (Cavity Ring-Down Spectroscopy). In this application we demonstrate the simplicity, precision and discriminatory power of using CRDS to measure δ18O and δD isotope values forapples grown in different U.S. states (California and Washington).