Comparison of freezing and thawing treatments on muscle properties of whiteleg shrimp (Litopenaeus vannamei)

Whiteleg shrimp (Litopenaeus vannamei) is traded as a frozen food. Changes in texture of thawed muscle are a negative economic factor. This study evaluated and compared two freezing methods, cryogenic and forced convection, and two thawing methods, at 4 and 25C by histological, textural and electrophoretical tests. Insignificant interaction was found between the two main effects for any of the evaluated texture parameters (shear force, fracturability, hardness and water-holding capacity). Significant differences (P < 0.05) were found in muscle protein sarcoplasmic fraction. Interaction of the main effects was only observed when analyzing microstructure. In all treatments, a significant increase in melanosis was detected when compared with unfrozen specimens. Because texture was not significantly affected by either freezing method, for commercial purposes, we suggest forced convection freezing because it is cheaper. For research concerning cell and tissue structure, cryogenic freezing is recommended. Thawing at 4C is recommended for marketing purposes.