Abstract:Effects of still-air freezing, immersion freezing and liquid nitrogen freezing on the quality changes of Antarctic krill were researched by testing the indexes of salt-soluble protein, water-holding capacity (WHC), sensory evaluation, Ca2+-ATPase activity, and tissue section. The results indicated that the freezing rate of the krill by immersion freezing exhibited 1.39-fold higher than that of still-air freezing. And the freezing rate of the krill by liquid nitrogen freezing was 100 cm/h. By still-air freezing, the krill showed significant decrease in WHC, salt-soluble protein, Ca2+-ATPase activity and sensory quality, and a loose muscles structure. Antarctic krill by immersion freezing showed a little better quality than that by still-air freezing, without remarkable decrease in WHC, salt-soluble protein and sensory quality (P>0.05) by liquid nitrogen freezing. The reduction rate of Ca2+-ATPase activity of the krill by immersion freezing was 5.21% and muscles fibril was compact and netlike. This research demonstrated that different freezing methods significantly affected the freezing rate of the krill. There was a correlation between the quality change and the freezing rate. The quality of Antarctic krill could be maintained better by means of liquid nitrogen freezing.
