Cooperative program for the certification of interstate shellfish shippers.

  • United States. Public Health Service. Division of Environmental Engineering and Food Protection.
Date:
1962
Catalogue details

Licence: Public Domain Mark

Credit: Cooperative program for the certification of interstate shellfish shippers. Source: Wellcome Collection.

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    tively warm water of Chesapeake Bay al- though the water quality is high and the areas are free of pollution (2). Ifa coliform MPN of 2,400/100 grams of soft-clam meats is ex- ceeded in two successive samples of clams as harvested from approved areas the State shellfish control agency should investigate to determine the probable cause. Studies on the bacteriological quality of mussels harvested from approved areas in the Canadian Maritime Provinces, New England, and the Middle Atlantic States indicate that the water to shellfish coliform relation- ships are similar to those described for soft shell clams. However, mussels may have somewhat higher MPN’s than other shellfish species harvested from like areas. It is emphasized that the foregoing bac- teriological relationships apply only to shell- fish at the time of removal from the growing areas and not to shell stock in storage for any appreciable period of time, or to shucked shellfish. The influence of shucking, packing, and storage on the bacteriological quality of the shucked product has been recognized for years. One investigator has reported a posi- tive correlation between plant sanitation or operating practices and the standard plate count of the product (63). The Canadian Department of National Health and Welfare in 1950 pointed out that most of the United States shucked Eastern oysters sold in Canada had high coliform MPN’s, high standard plate counts, or both. They reported that of 77 shipments of shucked Eastern oysters from the United States, 44.2 percent had a coliform MPN of less than 230 while 41.5 percent had coliform MPN’s in excess of 16,000 per 100 grams. These results, when interpreted in accord with the 1946 Manual of Recommended Prac- tice for Sanitary Control of the Shellfish In- dustry indicated the oysters were from a pol- luted source or had been grossly mishandled (64). The significance of these results was dis- cussed at the 1950 meeting of the Canadian Interdepartmental Shellfish Committee. On the basis of limited information on the sani- 28 Coliform M PN’s of Oysters Sampled at Time of Harvesting Percent of Samples ! in Stated Group Coliform MPN per 100 gms. meats De@ssi than 250) tec a eee eee 63 Iséssvthaned,, 200 os ee ee 90 Less*thtan’ 24/000. 4). Poe Bh ee 97 Less-than 160;0009n%.S'ei oat - 100 1 No. of Samples, 30. Source: Proceedings, 1956 Shellfish Sanitation Workshop; Bacterio- logical Examination as an Indicator of Sanitary Quality of Market Shellfish, Kelly, C. B. tary quality of similar shellfish sold on the American markets, it was decided to establish an interim bacteriological standard for shucked Eastern oysters sold in Canada. This standard was based on the premise that an increase in the bacteria content of market shellfish was unavoidable. Adoption of this interim standard by Canada resulted in a significant improvement in the sanitary qual- ity of shucked oysters imported from the United States (2). In 1950 the Public Health Service, in co- operation with the Government of Canada and several State health departments, investi- gated the bacteriological changes occurring during the processing and shipment of oys- ters from Chesapeake Bay to selected market areas. The study demonstrated a marked deterioration in bacteriological quality dur- ing shucking and shipment to market (65). In 1954 and 1955 the Virginia Department of Health also investigated the changes in bacteriological quality which took place in oysters during shucking and packing (2). It was found that in the winter months about two-third of the samples of shell oysters had coliform MPN’s of 230 or less per 100 grams. However, during the summer months few samples were under 230/100 grams and only 25 percent were below 2,400. On the “as packed” product during the winter months 10 percent of the samples had a coliform MPN of 230 or less, 50 percent were 2,400 or less, 75 percent were 9,000 or less, and 90 percent were below 24,000 (2). The bacterial changes taking place during the harvesting and processing of oysters in