Abstract:

Objective: To investigate the effects of different rinsing treatments on the deodorization of minced catfish
meat. Methods: The nutritional composition of catfish meat was measured under three different rinsing treatments, i.e.,
unrinsed (M1, control), rinsed with an aqueous solution of 0.5% sodium bicarbonate and 0.25% sodium pyrophosphate
adjusted to pH 6.5 (M2) and with distilled water (M3). The changes in odor substances were measured by Flash E-Nose
at three time points for pH (i.e., starting, extreme and fish spoilage points) during cold storage. The obtained data
were subjected to principal components analysis (PCA), and changes in the main volatile compounds were examined
to judge the effectiveness of different rinsing treatments for deodorizing catfish meat. Results: Rinsing resulted in an
increase in both protein and moisture contents and a significant reduction in fat content compared with the control
group, and M2 was more effective than M3. The Flash E-Nose could detect and distinguish quite well the volatile
substances of samples from the three groups. 2-Methyl amyl aldehyde, aldehydes, 3-methyl-3-sulfonyl-1-butanol,
trimethylamine (TMA) and other compounds, which synergistically constituted to the fishy odor of catfish, were
detected in the control sample. Effective removal of trimethylamine was achieved by rinsing. Conclusions: The quality
of the fish can be improved by using the mixed rinsing solution. The major fishy substances existing in catfish flesh are
2-methyl aldehyde, 3-methyl-3-sulfonyl-1 hydroxy butylalcohol and TMA. After rinsing process, the relative contents
of 2-methyl aldehyde, 3-methyl-3-sulfonyl-1 hydroxy butylalcohol decrease significantly, and TMA can be removed
completely. Therefore rinsing could effectively deodorize catfish meat, especially by using the blended solution.

Key words: catfish, surimi, rinsing, electronic nose, volatile substances, deodorization