The loss in frozen shrimp weight after overnight thawing at 4 °C ranged from 1.94% to 2.38%, Table 1, according to product type. This loss was higher in IQF than in block frozen product. Also, peeling, removing of head and vein caused slight rise in thawing loss of frozen shrimp. The higher thawing loss was noticed in IQF peeled deveined, block headless whole, block headless raw, and IQF peeled headless frozen shrimps than other products. According to Dore and Frimodt (1987) block frozen shrimp products have long storage life than IQF ones.
The pH value of the different shrimp products was above 7.0, Table 1. The same observation was stated by Chen et al. (1990) for fresh shrimp stored in ice. Data of Jeyasekaran et al. (2006) indicated that the pH of white shrimp was lowered from 7.8 to 6.82 in the end of storage period in dry ice, 32 h. In this study, the range of pH of the different frozen shrimp products was varied from 7.48 to 7.92. It was higher in both block whole raw and block broken frozen shrimp products than other ones. This means that removal of peels, head and vein, as well as freezing method, block or IQF, may slightly affect the pH of shrimp. The muscle tissues of shrimp after applying such processes became soft and more exposed to break and loss of their water soluble contents during handling.