Abstract:

The effect of different slaughter methods, i.e., knocking on head, gill removal, cryogenic temperature death and
asphyxial death, on the volatile components of grass carp meat was investigated by using electronic nose and solid phase
micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS), as well as the effect on its
lipoxygenase (LOX) activity. The maximal LOX activity of 4 500 U/mL was detected in crude enzyme solution from the
meat of grass carp killed by knocking on its head. The electronic nose could distinguish the red meat rather than belly and
back meat of grass carps killed by four different methods. SPME was able to effectively adsorb volatile components in
grass carp. A total of 31, 18 and 31 volatile components were detected in the red, back and belly meat of grass carp killed
by the first method, with carbonyl and alcohol compounds accounting for 65.31%, 76.22% and 65.21% of the total volatiles,
respectively. A total of 27, 27 and 32 volatile components were identified in the red, back and belly meat of grass carp killed
by the second method, with carbonyl and alcohol compounds representing 65.00%, 79.32% and 90.30% of the total volatiles.
A total of 34, 29 and 29 volatile components were found in the red, back and belly meat of grass carp killed by the third
method, with carbonyl and alcohol compounds comprising 70.09%, 70.53% and 69.24% of the total volatiles, respectively.
A total of 27, 20 and 20 volatile components were found in the red, back and belly meat of grass carp killed by the fourth method,
with carbonyl and alcohol compounds representing 78.04%, 75.99% and 71.27% of the total volatiles, respectively. To conclude,
the different slaughter methods have significant effects on the activity of LOX and the volatile components of grass carp meat.

Key words: grass carp, electronic nose, solid phase micro-extraction-gas chromatography-mass spectrometry (SPME-GCMS), lipoxygenase (LOX)