NUTRITIVE VALUE AND QUALITY OF FISH 367 



pal regulations have become so extensive that consultation of both the 

 regulations and the standard references is advisable (see bibliography 

 Chapter 30). 



Specifications. A specification is an accurate description of the techni- 

 cal requirements for a material, product, or service and includes the pro- 

 cedure by which it will be determined that the requirements have been 

 met. Specifications are best known through their extensive use by the 

 federal supply agencies; the General Services Administration has issued 

 specifications for almost every commodity. Private buyers, institutions, 

 local governments, and state purchasing agencies make extensive use of 

 federal specifications in their purchasing, often with the addition of sup- 

 plementary requirements. The form of federal specifications and their 

 application in fisheries is most important for these reasons. 



Grade Standards. Inasmuch as a specification or a legal standard 

 describes a product on the basis of minimum acceptable characteristics, 

 grade standards are desirable for many products. The broad category of 

 products meeting the minimum standard is further segregated into two 

 or three grades on the basis of accepted quality factors. Factors impor- 

 tant to the desirability and market value of the product are used, e.g., 

 flavor, color, texture, uniformity of quality, and physical defects. Food 

 standards are developed primarily by the federal government, by the 

 U.S. Department of Agriculture for most foods, and by the Bureau of 

 Commercial Fisheries of the U.S. Department of the Interior for fishery 

 products. Such standards may be mandatory as is the case of meat stand- 

 ards or voluntary as is true of fishery standards. Since the inception of the 

 fishery standards program in 1954, twelve fishery product standards have 

 been developed and promulgated to meet marketing requirements. Dur- 

 ing 1961 such standards were used under a system of voluntary govern- 

 ment inspection on a continuous plant or lot basis to inspect and certify 

 185 million pounds of fishery products. 



Objective Quality Criteria. Application of present fishery specifications 

 and standards has demonstrated the need for objective criteria and 

 methods to measure varying degrees of freshness and keeping quality. 

 In the case of actual spoilage of fishery products, chemical determination 

 of one or more spoilage breakdown products, such as indole in shrimp, 

 trimethylamine in cod fillets, and total volatile acids in canned fish, pro- 

 duces useful results. The major problem still largely unsolved appears to 

 be the practical measurement of the rather subtle but nevertheless im- 

 portant factors that enhance the palatability and, therefore the value, 

 of really fresh fish and shellfish. Essential knowledge of the chemistry and 

 reactions of odors, flavors, and textures of fresh fish is needed. Modern 

 research tools such as gas chromatography, spectrophotometry, mass 



