Abstract:

Head-space-solid phase micro-extraction coupled with gas chromatography-mass spectrometry (HS-SPME-GCMS)
and gas chromatography-olfactometry (GC-O) were used to analyze and identify variations in the volatile compounds
of fresh, boiled and pan-fried Sipunculus nudus. The results showed that there were a total of 34, 44 and 46 volatile
compounds detected in fresh, boiled and fried S. nudus, respectively. A further analysis showed that the most abundant
volatile components offresh S. nudus were aldehydes, alcohols and ketones. Boiling and frying processing reduced the
relative contents of aldehydes, alcohols and ketones but increased pyrazines. The relative contents of aldehydes, alcohols
and ketones, identified as the major flavor compounds in S. nudus, followed the descending order of fresh (60.48%) > boiled
(46.58%) > fried (28.09%) samples. However, the relative content of pyrazines was in the ascending order of fresh (0%) <
boiled (1.39%) < fried (10.70%) S. nudus. As detected by GC-O, fresh S. nudus had 9 key aroma compounds including
heptanal, octanal, (E)-2-nonenal, (E)-2-octene aldehyde, nonanal, 2-undecylene aldehyde, α-pinene, 3-octanone, and
2-propyl-1-heptanol, boiled S. nudus had 12 key aroma compounds including heptanal, octanal, nonanal, 2-undecenal, (E,E)-
2,4-dodecadienal, 2,3-octanedione, 2-methyl-2-undecanethiol, 2-butyl-3-methylpyrazine, α-pinene, longifolene, toluene, and
ethylbenzene, and fried S. nudus had 10 key aroma compounds including heptanal, octanal, (Z)-2-decene aldehyde, nonanal,
2-undecenal, 2,5-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, 2-ethyl-1-hexanol, and toluene. The
different processing methods influenced the formation of volatile flavor in S. nudus. This finding can provide a theoretical
basis for the development of technologies for further processing of S. nudus.

Key words: Sipunculus nudus, fresh, boiling treatment, frying treatment, volatile flavor compounds