The changes in the volatile components of three butter samples were st
udied during freeze storage for 7.5 months. The amount of carbonyl inc
reased and reached a maximum after 4.5 months of storage. Afterwards t
he carbonyl decreased. The lactons reached its maximum after storage o
f 3 month. The increase of the carbonyls caused by peroxidation of uns
aturated fatty acids was taken as indication for the deterioration of
the butter samples during storage.