The apple never falls far from the tree. … But where is the tree?
Tracing the origin of food is important for both producers and consumers.
No one wants to pay more than usual for an Italian Golden Delicious apple only to find out that it’s actually a crab apple from Scunthorpe, U.K.. Equally, growers want to be fairly compensated for maintaining traditional, sustainable farming practices. Food labeling provides a guarantee for both producers and consumers, ensuring quality for the consumer and protection for the regional producers from cheaper imitations.
Food labeling, however, can be manipulated and used fraudulently. Objective analytical methods are required for reliable food tracing. Isotopes provide a powerful means to trace the origin of food products. The basic idea is that crops inherit their isotopic fingerprints from the soil, water and air from which they are grown, and this isotopic signature passes into the products made from those raw ingredients.
There are many different isotope systems that we can choose to look at, but one of the most powerful for food origin is strontium isotopes. The strontium isotopic signature of rocks (and therefore soil) is highly variable and often can be different region to region, or even valley to valley. What’s more, it doesn’t change with the season, and is not altered when it is taken up by plants. As such, strontium isotopes provide a very useful tool for spatially pinpointing the origin of food.