have maintained salmon roe processing operations 

 at canneries in the northwestern United States 

 and Alaska. The processing of salmon roe is an art 

 rather than a formulated production procedure, 

 and numerous minor differences are found in the 

 various recipes employed. The following is, of 

 necessity, a generalized description of the produc- 

 tion operation. 



Roe from the butchered salmon is received in the 

 egg house, cleaned of extraneous fish material, and 

 rinsed to remove blood. From 27 to 38 kg of roe are 

 placed in a vat containing 200 liters of saturated 

 brine into which has been added either 0.02-0.05% 

 nitrate or 0.05-0.07% nitrite (equivalent to 500-700 

 ppm.). 



The mix is agitated mechanically for approx- 

 imately 20 min. The actual length of time is 

 determined by technicians who consider a range of 

 variables, such as the size of roe, the freshness of 

 fish from which roe was obtained, and temperature 

 of brine solution. Larger roe, as from king or chum 

 salmon, are held in the brine longer. Brine batches 

 may be used for several changes of roe; normally, 

 they are changed four or five times in an 8-h day. 



After removal from the vat, the roe are drained 

 and graded by size and color. Nitrite level of the 

 roe at this time is about 50 ppm. The roe are then 

 packed in 10-kg wooden boxes which are lined with 

 sheets of plastic. After each layer is packed, it is 

 lightly salted with a fine grind sodium chloride. 

 The boxes are slightly overfilled, and the lids 

 placed on without nailing. They are then stacked 

 with weights on top to form a press. The boxes are 

 cured in this fashion for as long as 7 to 10 days, 

 depending on ambient temperature conditions. 

 During the curing period, the desirable red color of 

 sujiko develops, and nitrite residuals drop to less 

 than 5 ppm. It is possible that the color enhancing 

 action of the nitrite may be due to its inhibiting 

 effect on color destroying oxidative enzymes in the 

 roe. 



Following pressing and curing, the product is 

 inspected. If satisfactory, the lids are nailed down, 

 and the boxes are stored at -5°F (-20.6°C) at the 

 cannery and placed aboard transport vessels to 

 Japan. In Japan, the same storage conditions 

 apply until the product is sold to the retail 

 markets. 



Production Survey 



Duplicate 10-kg samples of commercially 

 produced red and pink salmon roe products were 



obtained from four of the five major sujiko 

 processors. The processing plants were located on 

 Kodiak Island in the Gulf of Alaska, southwest of 

 Anchorage; Hawk Inlet in the Admiralty Islands, 

 west of Juneau; Cook Inlet, large inlet which 

 Anchorage is at the head of; and Ketchikan, 

 southeast Alaska on the south side of Revil- 

 lagigedo Island. Duplicate 10-kg samples of roe 

 from three species of salmon— red, chum, and 

 king— were obtained from the fifth major producer 

 located at Puget Sound, Wash. All of these samples 

 were obtained after their delivery to Japan. It was 

 decided to sample the roe in Japan so that storage 

 conditions would be more nearly identical to those 

 received by the product going to consumers. Upon 

 return of the samples to this country, NCA 

 delivered them to NMFS. The samples were com- 

 posited in a Hobart silent cutter, packaged in 

 Mylar' bags, and sealed. A portion of the compos- 

 ite sample was returned to NCA for determina- 

 tions of residual nitrites and NaCl content. 



Experimental Pack 



Using roe from the same batch of fish, one test 

 pack and one control pack of salmon roe were 

 prepared by NCA. The test pack was prepared in a 

 saturated brine containing 700-ppm. nitrite, while 

 only a saturated brine was used to prepare the 

 control pack. The packs were cured at a tempera- 

 ture of 60°F (15.6°C) for 7 days and then stored for 

 6moat-5°F(-20.6°C). 



Materials 



The solvents-methylene chloride, pentane, and 

 ethyl ether-were purified by distillation. Sol- 

 vents, silica gel, and Celite 545 were tested prior to 

 use to assure the absence of interfering peaks. 



Analytical 



The multidetection method for the analysis of 

 volatile A^-nitrosamines in foods developed by 

 Fazio, Howard, and White (1971) was used in this 

 investigation. Because of the high phospholipid 

 content of the salmon egg samples, William T. 

 Roubal of the Northwest Fisheries Center, NMFS, 

 NOAA, found it necessary to make some 

 preliminary modifications in the procedure (Fazio, 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



684 



