Products sold as fruit juice must not contain any added sugar—only the sugar that occurs naturally in the fruit. However, adulteration with foreign sugars is difficult to detect analytically because added syrups can mimic the natural sugar profile. An IGF project coordinated by FEI is therefore developing a new analytical method to detect foreign sugars in fruit juices and fruit juice concentrates. The goal is to reliably verify the authenticity of fruit juices. What is labeled as fruit juice must not contain any added sugar—only the sugar that naturally comes from the fruit.