BULLARD and COLLINS: PHYSICAL AND CHEMICAL CHANGES OF PINK SHRIMP 



higher gain in weight was observed in the ice-held 

 shrimp. The ice-held whole shrimp gained 11% in 

 the first 1.5 days, maintained this weight for 8.5 

 days, and decreased thereafter. These gross 

 changes in weight were caused by changes in the 

 water, solids, and salt content of whole shrimp 

 with time of holding (Collins 1960, 1961). 



The pH of the brine was 3.92 at the beginning of 

 the experiment and rose to 6.85 during the first 12 

 h but varied between 6.1 and 6.9 during the re- 

 mainder of the experiment. The flow of carbon 

 dioxide was regulated at approximately 0.2 1/min 

 but was shut off occasionally to reduce excess loss 

 of carbon dioxode to the environment and buildup 

 of foam. 



Hand -Peeled, Raw, Pink Shrimp Meats 



Gross weights of hand-peeled, raw meats in- 

 creased rapidly in both holding systems (Table 2). 

 The salt and sodium content of the raw peeled 

 meats from the MRSW system increased rapidly 

 during the first 2 days to 2% and 0.85%, respec- 

 tively, and remained at this level over the remain- 

 der of the holding period. Potassium decreased 

 during the holding period (MacLeod et al. 1960). In 

 the ice system, however, the meats slowly lost salt, 

 presumably due to the leaching effect of the ice 

 melt. 



Based on chemical tests, the quality of shrimp 

 held in the MRSW system was considered accept- 

 able through 9.5 days. There was a slight increase 

 in the total volatile acid value at 9.5 days and in 

 the trimethylamine value at 10.5 days, suggesting 

 that quality deteriorated slightly after 8.5 days. In 

 the ice system, quality was acceptable up to 6.5 

 days, borderline at 7.5 days, and unacceptable 

 thereafter. 



Because of the large excess of ice used in this 

 holding experiment, the commercial limit for 

 holding shrimp on ice would probably be less than 

 6.5 days. In this study, it appears that pink shrimp 

 held in the MRSW system can be held for several 

 days longer than in ice. 



Hand-Peeled, Raw, Washed, 

 Pink Shrimp Meats 



The solids content (Table 3) for the hand-peeled, 

 raw, washed meats when expressed as percentage 

 composition, was nearly equal from the two hold- 

 ing systems after the effects of salt were removed 

 by subtraction. In both systems there was a rapid 

 decrease in percentage solids (increased moisture) 

 for the first 5 days, but the percentage solids re- 

 mained about equal thereafter. Salt, sodium, and 

 potassium followed the same trend as the raw, 

 peeled meats but at a lower level due to the wash- 

 ing. 



The data on gross weight and composition (Ta- 

 ble 3) are not useful for direct comparison of recov- 

 ery of meat between the two holding systems be- 

 cause of differences in moisture and salt content. 

 When recalculated on a constant basis (salt-free, 

 84% moisture), recoveries of raw, washed meats 

 were much higher for the ice system than for the 

 MRSW system (Figure 1). This observation was 

 confirmed when recoveries of protein were com- 

 pared for the two systems (Figure 1). The sharp 

 drop in recovery at 6.5 days for the ice system 

 suggested that soluble proteins were retained 

 through the mild washing technique used in this 

 experiment until spoilage became evident (the 6.5 

 day break point). In the MRSW system, however, 

 the soluble proteins were leached gradually into 

 the aqueous system. 



Table 2. — Change in weight and analytical values with time of holding 2,100 g of hand-peeled, raw, pink shrimp meats in modified 



refrigerated seawater (MRSW) and ice. 



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