What with radiation from Chernobyl depriving Italians of their traditional salads and contorni of green vegetables with their pasta, one would think they had enough preoccupations about food for the moment.

But few subjects have captured their imagination lately as has the cultural fallout from a clash between two of the world's preeminent tastemakers, Valentino of Rome, the elegant prince of Italian fashion, and McDonald's Corp. of Des Plaines, Ill.

In dispute in the courts here is the right of the American hamburger house, a new arrival here, to perfume the Roman air with the essence of Big Mac and fries within scenting distance of the patrician Valentino and his exalted staff and clients.

When McDonald's opened here in March, it was in an extravagantly remodeled sandwich shop on the famed Piazza di Spagna, backing on the elegant Via Gregoriana palazzo where Valentino maintains his main offices and haute couture salons.

To open what is billed as the world's largest MacDonald's on the first two floors of his 17th-century building, Jacques Bahbout, the Egyptian-born French owner, was forced to install a complex of outside ventilators to air the 450-seat restaurant. Those vents, unfortunately, give out onto Valentino's swank offices and, according to legal depositions filed last week, not only cause undue noise but also waft such a wind of grilled burger and fried potato that Valentino employes are forced to keep their office windows closed -- particularly offensive in Rome during the spring.

While Valentino refuses to air his grievances to the press in person, the seriousness with which he views the problem may be seen in his choice of Giuseppe Consolo as the lawyer hired to shut down McDonald's. Consolo is the high-powered attorney who three months ago won acquittal for Bulgarians accused of having orchestrated Mehmet Ali Agca's 1981 attempt on the life of Pope John Paul II.

Judge Domenico Bonaccorsi last week heard the initial motions against McDonald's from Consolo and appointed an engineer to make a technical inspection of McDonald's pending another hearing on the issue next month That decision was made after Valentino employes testified before the court about how the odors of Big Mac wafting through their windows made clothing the elite somewhat difficult.

Bahbout was traveling in the United States this week and unavailable for comment. Even if Bahbout wins the case, he is in for a rough time,for almost since the moment the Rome city council approved his license to vend Big Macs on the historic Piazza di Spagna, the council has had second thoughts. The novelty of Big Macs in Rome has flooded the square and its Bernini fountain with thousands of young people whose motorcycles and discarded McDonald's burger bags and milkshake cups have transformed one of the Eternal City's loveliest landmarks into just another crowded teen hangout. If Valentino does not force McDonald's to close, or modify its business habits, the council itself is threatening to do so. Somehow, it has been decided, McDonald's just doesn't fit the image Romans want for the Piazza di Spagna.