570 MARINE PRODUCTS OF COMMERCE 



Gulf Coasts use wild-grown oysters harvested from public reefs. The stock deliv- 

 ered to canneries frequently contains a large proportion of undersized and young 

 oysters. Without washing the shells they are unloaded directly into the steaming 

 cars, which have a capacity of SM barrels (22 bushels) each. The loaded cars are 

 run into a steam box with doors at each end, and are steamed from 10 to 15 min- 

 utes at 245° F (118.30° C) (12-pounds pressure). The technique, however, varies 

 somewhat in difiFerent plants, and the steaming time may be only from 6 to 10 

 minutes at 250° F (121° C) (15-pounds pressure), not including the "come-up" 

 and "blow-down" times, which are usually from 6 to 8 minutes and 1 minute, re- 

 spectively. Under steaming the shells of the oysters open and lose a great portion 

 of their juice. The cars are then rolled into a shucking room and the meat is 

 removed while hot. After being dropped into a galvanized flume the meats are 

 forced by a stream of cold water to the washing tanks where a considerable 

 quantity of grit and shell particles is washed and trapped by baflEes. Washing 

 continues from 20 to 30 minutes; then the meats are transferred by dip nets to 

 screen-bottomed trays, in which they are left to drain for 20 minutes. After 

 inspecting and grading, the meats are packed in cans and weighed. The filled 

 cans are conveyed to the sealing machine where hot 1 per cent brine is added 

 and the cans are sealed. Time of processing depends on the size of the can. Five- 

 ounce cans are usually processed for 17 minutes at 240° F (115.6° C), others 

 for 19 minutes at 240.5° F (115.6° C), or for 10 minutes at 250° F (121° C). 



Pacific oysters used in canning are grown from imported Japanese seed planted 

 on privately owned bottoms. They are either picked at low tide or dredged and 

 loaded on scows which at high water are towed to the cannery. At the wharf the 

 oysters are shoveled into an elevator consisting of a watertight trough mounted 

 on an endless chain. A spray of water at a pressure of about 50 pounds psi 

 is used to wash the mud from the oysters as they go up. The oysters are then 

 placed on cars of about 8-bushels capacity each; these are pushed along the 

 slightly inclined track to a cylindrical steam chest of heavy construction with 

 doors at each end. Time and temperature of precooking vary from 3/2 to 6 min- 

 utes at 240.5° F (115.6° C) (10-pounds pressure) and from 10 to 15 minutes at 

 212° F (100° C) (atmospheric pressiu-e). 



The oysters are shucked into 3-gallon buckets containing 1 gallon of water 

 or 2 to 3 per cent brine. 



Some canneries prefer to use a continuous precooker which consists of a seat 

 conveyor enclosed by an insulated iron housing. The precooker may be 75 feet 

 long; the average time required for precooking is 7/2 minutes, but the speed of 

 the progress of oysters through the precooker may be regulated. Moist steam is 

 delivered from perforated pipes which extend the full length of the cooker both 

 above and below. The maximum temperature reached by this arrangement does 

 not exceed 210° F (98.9° C). It is claimed that the continuous process has cer- 

 tain advantages, for it requires less labor and less plant space. There is also less 

 shrinkage of oyster meat. 



Precooked oysters are removed with a knife and placed for washing in a metal 

 tank equipped with a perforated false bottom. After thorough washing, aided by 

 aeration or blowing, the shucked oysters are emptied on a conveyor and sorted 

 in four grade sizes: large, medium, small, and cuts, the last grade comprising 

 damaged oysters. 



