BULLARD and COLLINS: PHYSICAL AND CHEMICAL CHANGES OF PINK SHRIMP 



Table 4. — Change in weight and analytical values with time of holding 2,100 g of hand-peeled, washed, cooked, pink 

 shrimp meats in modified refrigerated seawater (MRSW) and ice. 



ice caused by poor peeling characteristics. These 

 adjusted weights and the protein data (Figure 2) 

 showed a rapid decrease from both holding sys- 

 tems to 4.5 days, a leveling off to 10.5 days, and 

 another decrease at 11.5 days. 



Under commercial fishing and processing condi- 

 tions, payment for landed shrimp is based on 

 weight, and weight depends upon time of holding 

 and system used. In our equipment, ice-held 

 shrimp gained more weight and gave a greater 

 recovery of cooked meats than shrimp in the 

 MRSW system. Based on the weight of whole 

 shrimp (Table 1) and the weight of cooked meats 

 (Table 4), therefore, MRSW-held shrimp gave 

 much lower yields than ice-held shrimp, aver- 

 aging 13.9 and 16.4%, respectively. This differ- 

 ence in yield between systems would be reduced 

 when the processor adjusts the weight of infill for a 

 proper cut-out weight. Overall, the only difference 

 in yield between systems is that caused by changes 

 in water and salt content in the whole shrimp, i.e., 

 landed weight. Under production conditions, 

 MRSW has a slight advantage over ice because 

 whole shrimp gain less in MRSW than in ice. It is 

 believed that the laboratory data on the MRSW 

 system would be representative of an MRSW hold- 

 ing system on a boat, but icing techniques may 

 vary considerably from laboratory to boat, and the 

 results obtained in the laboratory may differ from 

 those in commercial practice. 



Sodium chloride, sodium, and potassium fol- 

 lowed the same general trends as the previous 

 subsamples. The lower levels ( 1.1% NaCI, MRSW; 

 0.3% NaCI, Ice) were caused by cooking. 



The carotenoid index, previously used to indi- 

 cate comparative quality between production var- 

 iables (Collins and Kelley 1969), showed an in- 

 crease with increase in time of holding shrimp in 



< 



UJ 



s 



:^ 



O 

 O 



z 



UJ 



t— 



o 



400 



350 



300 



250 



MRSW 



90 



80 



70 



60 



3456789 10 11 

 TIME OF HOLDING, days 



12 13 



Figure 2. — Recovery of hand-peeled, cooked pink shrimp meats 

 with time of holding 2,100 g of shrimp in modified refrigerated 

 seawater (MRSW) or ice, expressed on a salt-free, 75% moisture 

 basis and protein. 



both systems. The index, expressed on a dry basis, 

 unexpectedly increased rather than decreased 

 with holding time. We suggest that the peeling- 

 washing technique used in this experiment was 

 less severe than that used during commercial 

 machine peeling and that the 26% loss of protein 

 in cooked meats over the holding period caused a 

 pseudoincrease in the carotenoid content. In 



77 



