AN 13 - Measuring δ18O and δD for Commercial Foods

Many parties in the agricultural, food and beverage industries can benefit from a technique to rapidly distinguish between similar raw and processed food products with very different provenance. Stable isotopes can provide this fast screening because every fruit, leaf or vegetable product will have ¹³C, D and ¹⁸O isotope ratios unique to the plant type and local growing conditions (groundwater, temperature and amount of sunshine). Indeed, it has long been known for example, that these ratios can be used to determine whether premium products such as honey and olive oil were genuine or treated[1]. Yet in spite of growing public pressure to unequivocally verify and certify the origins and authenticity of foodstuffs, stable isotope ratios are still rarely used for this purpose. This is because of the high cost, complexity and time required to make these measurements using traditional instrumentation, as well as the level of special expertise required. Fortunately, this has now completely changed with the advent of simple-to-use, turnkey instruments which can quickly provide these ratios on a wide range of samples, often in seconds or minutes, and for a fraction the cost of traditional instrumentation. These instruments are based on a proven technology called WS-CRDS (wavelength scanned cavity ring down spectroscopy). In this application we demonstrate the simplicity and discriminatory power of measuring δ¹⁸O and δD for two different apple types and for oranges grown in two different regions.