ALBA, Italy -- The truffle is not a trifling subject in this sophisticated provincial town of 32,000. Residents do talk of wine in the fall. After all, the vineyards of Barolo are only a few kilometers to the south of those of Baresco are just to the north. But the aura of the truffle -- like its aroma -- is powerful and haunting. Local Langhe truffles are said to be the best in all Italy, and when the harvest is large and of good quality, as it is this year, Alba puts on a happy face.

There is an annual "truffle festival" in October, which includes a number of cultural events. But the real celebration takes place in homes and restaurants with the ritual of "shaving" the new, fresh truffles over bowls of risotto or salad.

The spirit of gastronomic research led me, my wife and a friend to sample them in almost every combination available. The sensation that hits you first is the smell. White truffles, particularly the white truffles of this region, have an unforgettable aroma. Must, surely, and a hint of garlic. Someone once said that it is difficult to describe the flavor of a black truffle, but having tasted a truffled dish you will forever after immediately note its absence in a similar preparation.

White truffles are less subtle. They immediately transform a dish, particularly when added to somthing hot such as risotto. They have the texture of a firm mushroom. The garlic hint is there at the first bite, but it doesn't intensify. You are left with a sense of the crunchiness of even a thin slice and the earthy perfume, what one writer described as that "divine and slightly suspect odor, like everything that smells really good."

Eating truffles was such a challenge that I chose to save my energy and declined an invitation to participate in a truffle hunt. (The departure time, 3 a.m., may have been a factor.)

Truffle lore is served at a more reasonable hour, however. During dinner and a lunch the amiable proprietor of Da Beppe, Alba's leading restaurant, told us a great deal about these mysterious fungi. Almost everyone else we encountered managed to elaborate on his explanations.

To begin with basics, truffles -- like old movies -- come in black and white. The whites actually are shaded toward gray, but they could never be mistaken for blacks. They don't smell or taste the same and they are prepared in very different fashions.

The black truffle is the object that garnishes so many haute cuisine dishes and writings. It is French in spirit and needn't concern us for very long. Black truffles from Umbria do find their way into a few sauces (and into cans marked "Perigord, France" for that matter), but in the Langhe region they are virtually ignored. The white truffle reigns supreme.

Both types of truffle are found growing beneath the ground among the roots of oaks and a few other trees. To find these rugged little nuggets of gold, hunters employ dogs. In Perigord, pigs as well as dogs have been employed in this exotic pursuit. But not in Piedmont. Truffle hunting is a cottage industry if ever there was one. The hunter, equipped with a curved iron tool, a flashlight and his dog, sets out in the dark. Why at night? The official reason is that there is little to distract the animal in the quiet of the night. A more cynical explanation is that a hunter wants to keep secret the location of the truffles he finds as they tend to reappear in the same place during the season. When the dog catches the scent of a truffle, his master digs it out and pops it into a basket. Meanwhile, the dog is kept occupied with a scrap of bread.

The mud-encrusted truffles are vaguely round and range in size from acorns to pregnant golf balls with an occasional tennis ball thrown in. Most of them are sold at exchanges where prices are fixed and based on availability. The white truffle season begins earlier than the season for black truffles and goes on into the new year. Quality will vary sharply from one year to another, as will supply. But demand has grown and the crop in France and Italy has dwindled since World War II, so prices range only from high to higher.

Black truffles are always served cooked. Those that come to U.S. gourmet shops in cans have been cooked to the point of pasteurization and, most experts feel, have lost much of their pungent odor and nutty texture. Once prepared they may be chopped, sliced or carved. The peelings are used in sauces and pates.

The white truffle is almost never cooked. It is more tender than its black cousin and, on the slightest provocation, will crumble. This not only is an embarrassment to the novice gourmet, it angers him. He realizes just how much all those little bits are worth, but isn't sure what to do with them.

The first step, though, is to clean the truffle. This is best left to someone else. It is a tedious, painstaking task that calls for a knife and a brush to remove clods of dirt and the grains of sand that cling to the truffles' wrinkled surface. Fresh truffles sold in the U.S. have been cleaned, which almost makes the price seem fair.

Next the cook or host needs a sharp knife, a truffle-cutting blade on the food processor or, perhaps best of all, a hand-held truffle cutter. This is a smooth piece of metal or wood into which a blade, perhaps two inches wide, has been inserted. The gap between the blade's edge and the flat surface is altered by a screw or pressure from a finger, thus determining the thickness (or, for a restaurateur, the thinness) of each slice. The truffle is shuttled across the blade at the table and the slices drop onto the food below. Lots of slices, if you're lucky.

We tried them on rice and on pasta, over puff pastry filled with fontina cheese. They often are served, either cold or hot, with parmesan cheese, too. We weren't served that preparation, but they went very well with thinly pounded pieces of raw veal and in a salad with mushrooms and a superb olive oil. At Ristorante Belvedere at La Morra, a justly famous place with a sweeping view over the vineyards of Barolo, the white truffles were shaved over cardoons that had been covered with fonduta, a cheese sauce. Only when paired with cooked mushrooms in a risotto was the flavor lost. The dish already was woodsy enough.

They cost a lot. The supplement for a serving of them on a dish at Da Beppe was 6,000 lira, or roughly $7.50 in addition to the price of the dish. But the other great fungi of the fall in Italy, the giant wild mushrooms called porcini, cost just as much. And considering the price once they cross the Atlantic, it was a bargain. A survey of several specialty shops in New York City revealed prices of $30 to $35 an ounce for fresh, imported white truffles.

Those who want to pursue the subject may telephone Balducci (212-673-2600) or Manganero's (212-563-5331). There are no fresh white truffles on sale in Washington. Fresh black truffles, for those who can wait until next month, should cost only about $25 per ounce this year. Better yet, at those prices, plan a trip to Italy.