THE DEPARTMENT of Agriculture is in the process of deciding whether or not Americans -- who eat an average of 15 quarts each of ice cream annually -- need the department's judgement on "the quality characteristics of ice cream." Although little doubt exsists that your 15-quarts-a-year ice cream eater wants to be spooning in nothing but a quality, the trickier question had to do with defining "quality." Federal standards have been set for ice cream. A gallon must weigh at least 4.5 pounds. It must contain at least 1.6 pounds of solids. Twenty percent must be milk solids. But these standards and others, deal with what ingredients the manufacturers can pump into the ice cream, not what pleasures the eater gets out of it. Some connoisseurs of ice cream will tell you that the thick, chewy and high-butterfat product offers the highest quality, while others insist that sweet creaminess and airliness are the real criteria for greatness. Joseph Heller argued in his novel "Something Happened" that "you can't get good ice cream aymore. It tastes like gum and chalk." Yet the crowds continue to line up at the gun and chalk shops asking for double scoops, with sprinkles. And they don't mind paying for it. According to the International Association of Ice Cream Manufacturers, the price of ica cream went up 9 percent from Swptember 1976 to september 1977, while dairy products in general rose only 4 percent.

USDA officials say they are not sure how they want to grade the ice cream; a "study draft" is in the works to be followed by a proposed rule. A shield on the carton saving Grade A, B or C may be oiffered, or perhaps a shield with "premium," "choice" or "good." The taste buds of Uncle Sam already grade such foods as meat, poultry, egg, butter, cheese and instant nonfat dry milk. But of all the foods on the table, ice cream, it seems to us, is among those calling for the most subjective judgment. It has already been a long struggle to get full ingredient labeling, a requirement that will take effect July 1, 1979. That, coupled with the already existing standards, is a generous double-dip of information for the ice cream eater.

If the department goes ahead with its plans - some 133 federal tasters are now on the payroll and presumably ready to take on ice cream - the consumer may find a bitter taste awaiting him. Manufacturers have the option of accepting or rejecting the USDA labels (only 75 percent of all broilers are graded, for example), but if they do want it, the cost is absorbed by the manufacturer. That means the consumer pays. In many cases, though, it is likely to be the consumer who has already made a judgment - or at least is entirely capable of doing so. If so, why should you have to pay extra for something you already know?