Abstract:

Four thawing methods including natural air thawing, thawing in still water, microwave thawing and air-blast
flowing water thawing were individually used to thaw on-board-frozen Scomber japonicus stored at −18 ℃, and the changes
in water-holding capacity, salt-soluble protein, total volatile basic nitrogen (TVB-N), histamine content and texture properties
were analyzed. Meanwhile, electronic nose analysis and microstructure observation were conducted. The results indicated
that highly significant correlations existed between thawing time and either TVB-N or histamine content, and between water
holding capacity and either thawing loss percentage or salt soluble protein content. Fisher discriminant analysis (FDA) of
the electric nose data could clearly distinguish among the various thawing methods, and the obtained results were consistent
with those of TVB-N and histamine measurement. Among these thawing methods, air-blast flowing water thawing was the
best, because it greatly maintained the water-holding capacity, salt-soluble protein, texture, and microstructure. It was also
advantageous in saving the thawing time and costs compared with other thawing methods. Overall, air-blast flowing water
thawing is an ideal thawing method for frozen Scomber japonicus.

Key words: on-board-frozen Scomber japonicus, thawing methods, freshness, quality