THE ANNUAL 4th of July celebration this afternoon at the U.S. embassy in Paris will be slightly more "American" than in previous years.

On instructions from Ambasador Evan Galbraith and his wife, the wine will be a non-vintage brut produced by Paul Masson, to be served to 1,200 invited guests at today's garden party, accompanying such traditional Yankee fare as ham, turkey and potato salad.

The toasting beverage will, of course, be called sparkling wine, the French being to sensitive to the use of the term champagne on anything not produced in that region. But whatever it is called, it was selected only after Marie Helene "Bootsie" Galbraith herself tasted three alternatives. She is considered one of the most informed wine connoisseurs now in the U.S. diplomatic corps. Having lived abroad for most of the 17 years that she has been married, she, like her husband, has developed her palate on French wines. Their private collection reflects that bias.

Galbraith credits a new-retired Parisian wine merchant, Jean-Baptiste Chaudet, for advising her on several major purchases of Bordeaux and Burgundy wines in the late 1960s. Proudly displaying the original sales slip, she notes that their 1962 Chateau Canon cost only 20 francs a bottle. But with the many empty racks and barren shelves in the embassy's two concrete caves, and the franc at seven to the dollar, she considers this a good time to "stock up on some good French wine."

When the Galbraiths arrived in Paris last year, they inherited the contents of two cellars which -- while modest by collectors' standards -- contain 10 times the amount of premium wine as President Reagan's wine cellar at the White House. The Galbraith's predecessors, who dealt almost exclusively with the Groupe Rothschild organization, left a legacy of about five cases each of 1978 Chateau Lafite Rothschild, 1978 and 1979 Chateau Dunart Milon Rothschild; several cases of 1970 and 1971 Chateau Duhart Milon; and more than 20 cases of Chateau La Cardonnee, a cru bourgeois. The embassy's cellars also contain four bottles of 1961 Chateau Talbot, about four cases of 1978 and 1979 Chateau Beychevelle, a case of Dom Perignon champagne and several cases of 1976 and 1978 Chateau Pontet Canet, which Marie Helene Galbraith prefers to serve at "working lunch."

Embassy staff director Denise Cardenet, who has observed the ebb and flow from the embassy's cellars for the past 14 years, concedes that American ambassados "have favored the Bordeaux wines." Indeed, several cases of 1976 and 1979 Corton Charlemagne have to compete with nearly 1,000 bottles of claret in these American-owned wine vaults.

There are a few isolated bottles of California wine scattered about the two cavernous cellars. Two bottles of Heitz 1973 Cabernet lie above single fifths of Clos du Val's 1978 Cabernet, Rutherford Hill's 1975 Zinfandel and Burgess' 1976 Cabernet. In racks at the rear of one cellar are two cases of Phelps' 1980 Early Harvest Johannisberg Riesling, about a case of Domaine Chandon's Napa Valley Brut and four bottles of Trefethen 1976 and 1978 Chardonnay. "Giscard really liked the 1976 Trefethen Chardonnay," noted Cardenet in reference to the former French president, who sampled the Napa Valley wine following a concert at the residence two years ago.

During President Reagan's recent visit in Paris, the embassy served only California wines. A one lavish dinner, a Heitz 1974 Martha's Vineyard Cabernet Sauvignon followed a 1979 Grgich Hills Cardonnay. They were very well received, according to Marie Helene Galbraith. "But I don't remember any specific comments," she recalled. "We were too busy talking with Olivia de Havilland." Although the current strength of the U.S. dollar makes California wines relatively expensive now in France, she believes that American wines "will have their day in court."

She is aware of the current worldwide explosion in the consumption of white wines, yet strongly prefers les rouges. Recalling a visit to the Clos Vougeot vineyards in Burgundy where she observed grapes being crushed, she noted that red wines are more nutritious because, unlike white wines, they undergo initial fermentation with the skins and stem from the grapes. "Everyone knows that the highest concentration of minerals and othr nutrients in fruits or vegetables is in the skins," she said. "When a red wine is really good," she added, "ca glisse dans la gorge comme le bon dieu en culottes de velour (it slips down the throat like the god Lord in his velvet knickers)."

But for July 4 the wine will be white and imported from home, a wine most appropriate for celebrating the birthday of America.