Abstract: The changes in the volatile flavor composition of fresh milk fan during storage were analyzed by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), gas chromatography-olfactometry (GC-O) and descriptive sensory evaluation. A total of 70 volatile flavor compounds were detected, and 19 characteristic flavor compounds identified by GC-O were accurately quantified, and their odor activity values (OAV) were calculated. Sixteen of these compounds with OAV greater than 1 were identified as key aroma components. The sensory properties, key aroma components and storage time of milk fan were analyzed by partial least squares (PLS). The results showed that the storage period of milk fan could be divided into three stages. The first stage was the first day, and the sensory quality of milk fan was the highest at this stage, which may be related to the high content of ester components such as ethyl acetate and ethyl hexanoate. The second stage comprised the fourth and seventh days. At this stage, milk fan had mild sensory quality and the characteristics of wine aroma, which may be related to the content of ethyl butyrate. The third stage comprised the 11th and 15th days, where the sensory quality of milk fan was the worst, and the contents of all esters and lactones except for delta-decalactone decreased with storage time.

Key words: milk fan; key aroma components; gas chromatography-olfactometry; descriptive sensory evaluation