The orange juice market is huge. Â Unfortunately some processors try to cut corners by extending the juice with sugar, pulpwash and water. Â But the ruse can be detected by some clever science. Â Oxygen in nature occurs as two possible isotopes, O-16 and O-18, which differ slightly in mass. Â The natural abundance of O-18 is only about 0.2%, but it is more abundant in water in growing plants because the heavier isotope is less likely to evaporate. Â So a juice diluted with water from non-biological sources will have a different isotope distribution and an instrument called a mass spectrometer can detect this. Â The authorities have already used this method to put the squeeze on some OJ fraud artists.
