Where does your juice come from? Food forensics uses the natural abundance of environmental isotopes to trace the geographic region-of-origin of foods
Stable isotope ratios are known to reflect geographical variation and have therefore been widely used to trace the provenance of various agricultural products. We have authenticated orange juice labelled as 100% pure, made in New Zealand, using stable isotope analysis.
The isotopic composition of hydrogen and oxygen of soil water is highly dependent on the isotopic composition of meteoric precipitation, which in turn is highly dependent on geographical location. Hydrogen and oxygen stable isotope analysis in plants reflect the isotopic composition of soil water and transpiration enrichment. For example, pure orange juices of Asia, Australia and New Zealand origin have distinctive oxygen isotope 18O values depending on geographical location, which give an indication of where the juice is from. These isotopes are also used to ensure the juice is fresh and not made from concentrate where water has been added to dilute the juice. Carbon isotopes 13C are also used to investigate if the label claims of “no sugar added” are true of false. When cane sugar is added to sweeten juice the carbon isotopes of the juice become more positive as cane sugar has different isotope values to the natural fruit sugars found in juice. By comparing the 13C values of the juice with washed pulp, we can estimate the amount of cane sugar added to a non-compliant product.
Preventing adulteration of cane sugar and corn syrup in honey is the key to providing a top grade product for market
Intentional adulteration of honey with cane sugar or corn syrup is a common occurrence in many overseas countries; therefore most importers require a sugar adulteration test of honey before purchase. This basic but crucial sugar test is based on the difference between the ratio of carbon isotopes (13C and 12C) of cane sugar or corn syrup and that of honey. When sugar is added to the honey, the carbon isotope value of honey will be changed, while the carbon isotope value of protein naturally found in honey is unchanged. By measuring the ratio of the isotopes 13C and 12C contained in a honey sample and its associated protein, we can detect the possible addition of cane sugar or corn syrups.
Stable carbon isotope analysis of honey adulteration is a well-developed method suitable for the detection of added cane sugar or corn syrup in honey. This method allows fast, inexpensive and reliable results, providing quality assurance for New Zealand honey importers and exporters.
For more information, please contact:
Mike Sim, Head of Department, Isotope Biogeoscience, GNS Science