Abstract:

The effect of immersion chilling and freezing (ICF) in comparison with static air freezing (SAF) on the quality
of Pacific white shrimp, Litopenaeus vannamei was investigated by monitoring the changes in total volatile basic nitrogen
(TVB-N), thiobarbituric acid relative substances (TBARS), pH, salt soluble protein, Ca2+-ATPase activity, polyphenol
oxidase (PPO) activity and sensory evaluation during frozen storage. The results showed that TVB-N content, TBARS
value, and pH of shrimps frozen by ICF were higher than those of SAF the shrimp during frozen storage. These parameters
were significantly increased with extending frozen storage time (P ＜ 0.05). Salt soluble protein, Ca2+-ATPase activity and
PPO activity of shrimps were decreased with prolonged frozen storage time, indicating gradual denaturation of proteins
and quality deterioration of the shrimp. However, the quality deterioration of Pacific white shrimp was attenuated by using
ICF than SAF. Furthermore, sensory evaluation showed that although both methods caused the texture, odor, color and
appearance to deteriorate more or less, ICF provided higher sensory evaluation scores than SAF. Based on these results, ICF
appears to be more beneficial for maintaining the quality of Pacific white shrimp during frozen storage.

Key words: Litopenaeus vannamei, immersion chilling and freezing, static air freezing, quality changes