Analysis of diacetyl in yogurt by two new spectrophotometric and fluorimetric methods

Two new methods (spectrophotometric and fluorimetric) are reported for the determination of diacetyl in yogurt. The diacetyl was isolated by distillation and condensed with isoniazide. This solution was then treated with Zr(IV) to form a complex, which was measured with these two methods. Average recovery of diacetyl was 96.8% for spectrophotometry and 99.1% for fluorimetry, while precision was RSD = 2.5 and 1.0%, respectively. The concentration of diacetyl in yogurt ranged from 0.79 to 2.77 μg/g. The two procedures gave statistically similar results. The fluorimetric method was compared with a traditional method (gas chromatography), for which acetaldehyde, acetone, methanol, and ethanol were also determined.