It can be seen that the shrimps with/without chemical treatment tended to indicate red
color after freezing and thawing. The effect was more pronounced
with the treatment of both lysine and arginine at higher concentration
which possibly increased the solubilization of protein in
muscle as well as pigments, predominantly carotenoids in the
shrimp muscle (Andres-Bello, Barreto-Palacios, García-Segovia,
Mir-Bel, & Martínez-Monzo, 2013). The result was in accordance
with the work reported by Chantarasuwan, Benjakul, and
Visessanguan (2011).
The appearance and color of uncooked and cooked samples over
all treatments are depicted in Fig. 1. It is obvious that all cooked
shrimps treated with amino acid at any concentration (except
lysine at 2.0 g/100 ml) resulted to products with similar appearance
to STPP-treated sample. Shrinkage of fresh and control as well as
NaCl-sample treated shrimp could be observed.