US chocolatemakers tune in to a more discerning US

American chocolate lovers are becoming a sophisticated breed. They're not only buying M&Ms, but are spending more of their money on so-called ''designer'' and imported chocolates. Recognizing this shift in taste, the big US chocolatemakers are broadening their lines with products for consumers of every age.

Chocolate manufacturers have at least three groups to target in the $5.5 billion market. The biggest is the ''gatekeeper'' group - parents buying for children between the ages of 5 and 12. Two-thirds of the money spent on chocolate is spent by those parents, observes William Deeter, a spokesman at M&M Mars, the biggest US chocolate company, with sales estimated at about $1.2 billion. The next largest group is older teen-agers and young adults, who buy for themselves.

But now that the biggest segment of the US population are people 20 to 30 years old, the chocolate industry is shifting to a more mature market - which means a shift in taste. ''The baby boom era is getting a more sophisticated palate,'' notes Timothy Rugh, spokesman for the Chocolate Manufacturers Association of USA.

European chocolatemakers have benefited from that maturing taste and US manufacturers are responding to the competition. They're devoting more attention - and marketing dollars - to those discerning palates.

The taste that appeals to that mature market is European-style chocolate, which is not made with milk and is not as sweet as milk chocolate. ''Adults have developed a taste for semisweet chocolate,'' explains Lenore Cooney, who represents the Chocolate Manufacturers Association. ''So more companies are coming out with dark chocolate.'' The three largest domestic producers, M&M Mars , Hershey, and Nestle, have all introduced semisweet bars, after concentrating on milk chocolate in the past.

And then there are the US manufacturers who specialize in products with more ''snob appeal,'' aimed at sophisticated palates. Godiva Chocolatier, a subsidiary of Campbell Soup, sells its straight-line chocolate for about $18 a pound. There is a market for luxury sweets, says Thomas Fey, president of Godiva. He cites the recession as one reason. ''As discretionary income has been squeezed, people entertain at home more and enjoy trying new kinds of food.'' Godiva has grown almost fivefold in the last five years.

Ronald Morrow, first vice-president of research at Shearson Loeb Rhoades Inc. , agrees: ''There is often in recessionary times a trading down in product, but up in quality.'' If a person cannot buy a car, he hypothesizes, he or she can at least buy a fine chocolate.

But unlike Godiva's Mr. Fey, analyst Morrow thinks the market for such pricey food is very narrow. ''You don't find a guy out of work in Detroit buying expensive chocolate.'' It has been selling best in wealthy areas of such cities as New York, Los Angeles, Boston, and Chicago, he says.

American manufacturers don't appear to be worried about consumers' ever-shifting taste. The whole market is growing as Hershey, M&M Mars, and Godiva, in particular, wage aggressive advertising campaigns. And there appears to be room for everyone - because chocolate is in, as the 10,000 people who spent an entire weekend in San Francisco last October tasting and learning about chocolate can attest. So can Sandra Boynton Workman, who wrote a fast-selling humor book, ''Chocolate, the Consuming Passion.'' And so can Milton Zellman, publisher of Chocolate News, a bimonthly newsletter that started in 1980 and now has a readership of 16,000.

In addition, domestic producers point out that imported chocolates have only about 5 percent of the US market. ''You have a rather competitive, healthy domestic market. . . , and it would be hard for importers to get a large share, '' notes James Eldris, manager of financial information at Hershey. Foreign manufacturers could not produce enough chocolate to take a large share of the US market, adds Mr. Eldris. ''In just our test market, we tax their production capacity.''

And domestic producers don't accept that American taste has made a permanent shift. The mainstay of the domestic market - some 75 percent - is low-end milk chocolate and bars, says Mr. Rugh of the Chocolate Manufacturers Association. And domestic manufacturers are coming out with higher quality, but still relatively inexpensive bars, which sell for about $1.25. These will provide imports with some healthy competition, domestic producers say.

Most important, in about five years the population will shift back to the gatekeeper group, as the children of the baby boom's 20- to 30-year-olds reach the chocolate-bar threshold of around 5 years of age.

There may be minor shifts in taste, but chocolate will never fall from favor, says Barbara Resnick, a Chocolate News writer. ''Chocolate isn't a fad. It's been in our hearts and souls forever. It always will be.''