Effects of Freezing and Thawing Methods and Storage Time on Physicochemical Properties of Freshwater Prawns(Macrobrachium rosenbergii)

Physicochemical changes in prawn muscle as related to freezing and thawing procedures were monitored during 6 months frozen (-29°C) storage. Lipid oxidation (formation of TBARS) in raw muscle tissue reached a maximum between 1 and 3 months and then decreased thereafter. The kinetics of TBARS formation depended on the presence or absence of shell and rate of thawing. Texture (shear force) of raw muscle decreased slightly (3.5–8.1%) but shear force of cooked prawns increased considerably (13–27.9%) during storage. Cooking loss was higher for shell-off (20.2%) prawns than for shell-on prawns (14.4%), and correlated with increased toughness of cooked muscle. Shells did not protect raw muscle against lipid oxidation but reduced its cooking loss. Electrophoretic analysis showed no protein changes except that the intensity of all protein bands decreased slightly after 6 months storage.