3.2. Water activity variation
Variations in the water activity values are presented in Fig. 1B.
The value of water activity was 0.991 at initial time. With the
storage time increasing, the water activity significantly decreased
in all tilapia samples. The data also showed that the samples
in 5 C had significant lower water activity values than the others.
During frozen storage, fluids migration and ice crystallization
would lead to the variations in the water activity as shown in our
study. Meanwhile, the changes resulted in the development of
honeycomb microstructure in muscle tissues (Tsironi & Taoukis,
2014). Thus, the water activity was also associated with the
microstructure of samples muscle tissue.