(Sections and item numbers refer to PHS Publication 33, Part II, Sections C & E, Rev. 1964.)

APPENDIX B (in Shellfish Sanitation Manual)

Recommended Code-dating System for

Shucker-Packers and Repackers

The following code-dating system is recommended to the States in establishing their State-wide uniform code-dating system for shucker-packers and repackers as required by item 24:

A five-digit number and letter system should be established which will reflect the year, the month, the day of the month, and the morning or afternoon in which the shellfish were packed or repacked. Larger packers may wish to indicate morning or afternoon packing by using the letter "A" or "p" in their code system.

It is further recommended that repackers be required to precede their code-dating digits with the letter "R" to indicate the product is repacked.

Date of Purchase Not applicable since shucker-packer dredged these oysters from his own leased ground.

(EXAMPLE OF USE OF FORM BY SHELL STOCK SHIPPERS (INCLUDES "BUY" BOATS AND "BUY" TRUCKS)

* Date of purchase not applicable since oysters were tonged by shellstock dealer FLA.

APPENDIX Y

TIME-TEMPERATURE EFFECT ON BACTERIOLOGICAL QUALITY OF STORED OYSTERS

By

C. B. Kelly

Shellfish Sanitation Branch
Public Health Service

INTRODUCTION

One of the major problems in the sanitary control of shellfish is the frequency of exceedingly high coliform densities and plate counts in shucked oysters on arrival at marketing and distribution points. This matter has been of concern to shellfish control authorities for a great many years. Occasionally the plate count and coliform densities and often the fecal coliform densities are of such order of magnitude that the product is obviously unacceptable for consumption. In view of the confirmed observations that commercial shucking houses and repacking establishments generally show good sanitation practices and bacteriological examinations of the product demonstrate relatively low bacterial counts, the problem in maintaining bacteriological quality at the market level would seem to be involved in the time-temperature conditions of storage and transportation from processing area to point of distribution. Cooperative field studies between producing and receiving States have demonstrated these vast differences in bacterial densities, but because traced lot type studies of commercially handled products are difficult to conduct and even more difficult to control, firm knowledge has not been gathered on the actual increases in specific lots of shucked oysters.

The more fundamental approach therefore has been attempted. Commercial packs of shucked oysters processed by industry and stored under carefully controlled conditions of storage should reveal more definitive information concerning the time-temperature effect on the bacterial quality of shucked oysters. This approach has been followed by a number of workers, but in most instances the temperature of storage has not been adequately bracketed to show the relative effect of various temperature situations. In this report temperatures ranging from that produced by packing in ice to the Shellfish Sanitation Manual requirement of 50°F. has been encompassed. Further the studies have been conducted on the two most commonly used species in this country, the Eastern oyster, Crassostrea virginica and the Pacific oyster, Crassostrea gigas.

The studies on the Eastern oysters were conducted by the Gulf Coast Shellfish Sanitation Research Center, Dauphin Island, Alabama. The Pacific oyster studies were conducted by the Northwest Shellfish Sanitation Research Laboratory, Gig Harbor, Washington. Except for the difference in species procedures followed in the two studies were identical; thus a direct comparison can be made to reveal any species differences.

MATERIALS AND METHODS

Since the procedures followed were identical, description of materials and methods will apply to both studies. Shucked oysters were purchased from commercial shucking establishments and the test portions were prepared as follows:

A large lot of shucked oysters, sufficient for one experiment was taken directly from the regular production of the shucking plant. This lot was washed or blown in the normal fashion and transferred to a skimmer. The lot was again thoroughly mixed on the skimmer and packed by plant personnel in 12 ounce or 16 ounce containers. The cans were then packed in ice and transported to the laboratory where, after withdrawing two cans of oysters for the initial sample, the remaining were subdivided for storage at the three selected temperatures.