174 DESCRIPTION OF IMPORTANT FISHERIES AND THEIR PRODUCTS 



through various sized holes in five size categories. Visual inspection fol- 

 lows, to correct errors made by the grader and to remove broken shrimp 

 as well as extraneous matter. 



Shrimp are placed in the cans by hand and are carefully weighed. The 

 put-in weight varies with the size of the shrimp, the species, and the 

 manner of blanching. The cost of the raw material requires careful super- 

 vision of the quantity packed in each can. Satisfactory automatic filling 

 machines have not yet been developed in the shrimp canning industry. 

 In 1959 about two-thirds of the United States shrimp pack was put in 

 cans containing 43-^ ounces of shrimp, one-fourth in cans containing 5 

 ounces, and the remainder in cans containing 23-^, 3, and over 5 ounces. 



The filled cans are carried by conveyor belt to the closing machine. 

 En route, a hot solution (or less often hot water plus a salt tablet) is 

 added to the can of shrimp. This produces 'Svet-pack" shrimp, the nor- 

 mal product. The saline solution varies in strength, this also having a 

 marked effect on the quality of the finished product. Whether the solu- 

 tion is added as a concentrated brine which is then diluted with hot 

 water, directly as brine of the final concentration, or as water and salt 

 tablet, the final strength of the solution is approximately 25° salinometer. 



The vacuum in canned shrimp is not ordinarily produced by an 

 exhaust machine or in a steam box, but as a result of the heat of the 

 saline solution. The closing machine ejects enough saline solution to 

 produce the required head space and then seals the lids on the cans. 



The filled cans are removed to the retorts in metal baskets. The proc- 

 essing is done at a temperature of 250°F under pressure. Processing time 

 varies with the size of the can, being 12 minutes for the common sizes 

 of 211 X 300 and 307 X 113. At the end of the processing time the 

 steam valves are closed, the blow-out valves opened, and the retort is 

 flooded with water. This stops the cooking process quickly since shrimp 

 are easily ruined by overcooking which softens them and reduces the 

 shelf life. The cans are cooled to approximately 100°F. This provides 

 sufficient heat to dry the cans after draining and helps prevent rusting 

 of the containers. The cans are placed in cases after being thoroughly 

 drained and dried. In one plant on the Gulf, storage of the finished 

 product is at reduced temperatures, refrigerated rooms at about 65°F 

 being used. 



The above process describes the preparation of "wet-pack" shrimp. 

 "Dry-pack" shrimp, once an important item, are ordinarily no longer 

 prepared in the American industry except by special order. The process 

 differs from that described in that the shrimp are usually blanched for 

 8 to 10 minutes, the cans are lined with parchment paper, no liquid is 

 added, and the shrimp are processed for GO minutes at 250°1\ 



