Japan has some of the strictest food labelling guidelines in the world, with all processed foods made or handled there subject to mandatory country of origin labelling. However, as many products are made up of a wide variety of different ingredients, determining where everything comes from and making the corresponding disclosure on labels can be a major challenge. Japanese law states that the origin of the most predominant ingredient by weight must be on the label. Even though it’s not strictly necessary to list the origin of further ingredients, food manufacturers are strongly encouraged to disclose these as well. For specialists such as Dr. Suzuki, who analyze food products, finding out where certain ingredients come from is no easy task.
"To trace the geographical origin of wheat flour used in bread, we examined the stable carbon, nitrogen and oxygen isotope ratios of wheat flour proteins. The isotope ratios of the glutenin fractions correlated positively with those of wheat flour," she explains. "We then determined the carbon, nitrogen and oxygen isotope ratios of the wheat glutenin fractions from bread samples made of wheat flour from Canada, the USA and Japan and found that carbon and nitrogen ratios of the wheat glutenin fractions in bread made from Japanese wheat flour were lower than those of the other samples. Our results suggested that stable isotope analysis of wheat glutenin fractions is a potentially useful tool for tracing the geographical origin of wheat flour in bread."
The issue with processed foods is that in addition to the main ingredients, there are other elements that influence the mix, such as seasonings and cooking methods. Thankfully however, stable isotope ratios are not easily affected by processes and additives, but with heavily processed foods with multiple ingredients, isotopic ratios can reflect values for all constituent elements. That’s why specialists such as Dr. Suzuki and her team use pre-treatment methods to extract ingredients from raw materials to ensure more accurate results.