6 COMMERCIAL FISHERIES REVIEW Vol. 13, No. 7 



GROUPS B-l B-2 AND B-3: ASCORBIC ACID WAS ADDED DIRECTLY TO THE FRESH 

 SHUCKED OYSTER MEATS. THE MATERIAL WAS FIRST DISSOLVED IN A SMALL 

 QUANTITY OF WATER AND THEN THOROUGHLY MIXED WITH THE OYSTERS. THE 

 oysters' IN GROUP B-l CONTAINED 100 MILLIGRAMS OF ASCORBIC ACID PER 

 POUND OF OYSTER MEATS; THOSE IN GROUP B-2 CONTAINED 200 MILLIGRAMS 

 PER POUND; AND THOSE IN GROUP B-3 CONTAINED 300 MILLIGRAMS PER POUND. 



GROUP B-4: CITRIC ACID WAS ADDED DIRECTLY TO THE OYSTERS IN THE SAME 

 MANNER AS IN GROUPS B-l, B-2, AND B-3 IN A CONTENTRAT I ON OF 300 MIL- 

 LIGRAMS PER POUND OF OYSTER MEATS. 



GROUPS C-1 AND C-2: THE OYSTERS WERE FIRST FROZEN IN ONE POUND BLOCKS 

 IN A MOLD AND THEN GLAZED. THE BLOCKS OF OYSTERS IN GROUP C-1 WERE 

 GLAZED IN PLAIN WATER; THOSE IN C-2 WERE GLAZED IN TWO-PERCENT AS- 

 CORBIC ACID SOLUTION. 



GROUP D: THIS GROUP CONSISTED OF COMMERCIALLY SHUCKED FRESH OYSTERS 

 WITH NO FURTHER TREATMENT. 



The oysters in Groups A, B, and D were packaged in moisture-vaporproof cello- 

 phane bags, heat sealed, and then placed in waxed cartons. Ihose in Group C, after 

 freezing in blocks, were glazed, wrapped in sheets of moisture-vaporproof cellophane, 

 and packaged in waxed cartons. 



All samples were frozen at a temperature of approximately -20° F, and were stored 

 as 0°F. A sufficient number of san^les were prepared to permit examinations at 

 monthly intervals for a period of one year. 



Sample B-4 was included for comparative purposes. Samples C-1 and D were used 

 at the controls. 



EXAMINATION OF SAMPLES 



At intervals, the samples were removed from storage and were allowed to thaw at 

 room temperature. Ihe general appearance of the oysters was noted and palatability 

 tests with the raw oysters ware made by a panel of 3 or 4 members of the laboratory 

 staff. Scores were based on appeeirance , flavor, and texture of the product. A sam- 

 ple receiving a weighted score below 85 was considered unacceptable. It was not pos- 

 sible to have the same taste panel after the sixth month's test. To wrtiat extent this 

 affected the scores after this time is, of course, not known. 



Determinations of pH of the oyster liquor were made initially, and at intervals 

 of several months during frozen storage. A Beckman pH meter, Laboratory Model G, was 

 used for making these determinations. 



RESULTS 



Ihe average palatability scores for the oysters are given in table 1. Although 

 considerable variation in scores occuired from month to month, due possibly to dif- 

 ferences in individual oysters within the pack and to the change in the taste panel, 

 no one group receiving a particular treatment has consistently stood out as being 

 superior or inferior. The final scores, after the oysters had been held in storage 

 for nearly a year, were with one exception (B-4) indicative of an acceptable product. 

 However, this one exception was very close to attaining an acceptable score. No off- 

 flavors due to addition of ascorbic or citric acids were reported by the judges. 



The average scores for appearance of the oysters are given in table 2. Practi- 

 cally no differences in the appearance of the oysters were noticeable through the 

 sixth month of storage. After that time, slight changes in appearance occurred but 

 there was no definite indication that the ascorbic acid had an appreciable effect in 

 preventing discoloration of the oysters. Some darkening occurred in all groups. 



