Flavor threshold for acetaldehyde in milk, chocolate milk, and spring water using solid phase microextraction gas chromatography for quantification

The detection threshold of acetaldehyde was determined on whole, lowfat, an d nonfat milks, chocolate-flavored milk, and spring water. Knowledge of the acetaldehyde threshold is important because acetaldehyde forms in milk dur ing storage as a result of light oxidation. It is also a degradation produc t of poly(ethylene terephthalate) during melt processing, a relatively new packaging choice for milk and water. There was no significant,difference in the acetaldehyde threshold in milk of various fat contents, with threshold s ranging from 3939 to 4040 ppb. Chocolate-flavored milk and spring water s howed thresholds of 10048 and 167 ppb, respectively, which compares favorab ly with previous studies. Solid phase microextraction (SPME) was verified a s an effective method for the recovery of acetaldehyde in all media with de tection levels as low as 200 and 20 ppb in milk and water, respectively, wh en using a polydimethyl siloxane/Carboxen SPME fiber in static headspace at 45 degreesC for 15 min.