JAZZ PIZAZZ. At the New Orleans Jazz and Heritage Festival, the music is hot ...

Everything was hot about this year's New Orleans Jazz and Heritage Festival -- the temperature, the seasoning in the heaping helpings of local cuisine, and of course, the music. During two weekends in late April and early May, a total of about 220,000 music fans crowded onto the grassy infield of the Fair Grounds race track for the city's annual rite of spring -- a chance for adults and children to roam the infield with a plateful of jambalaya or an exotic ethnic dish, in search of good music.

There was no shortage of performers. About 3,000 musicians provided continual music from eight stages, including a tent for gospel performances, plus Economy Hall, a tent for traditional jazz that included two dance stages for people who didn't want to take their music sitting down.

The musical lineup was strong, not only at the fair but also at the 16 nighttime concerts. Trumpeters Wynton Marsalis and Miles Davis shared the billing (but not the stage) at two sellout performances, and Sarah Vaughan displayed her distinctive phrasing and scatting in a concert with Ellis Marsalis, the jazz pianist who is also Wynton Marsalis's father.

If the list was strong, it was also diverse, featuring such performers as Tania Maria, a new singing discovery from South America; blues and country singer Bonnie Raitt; Ry Cooder, the singer who also composed the music for the movie ``Paris, Texas''; a smattering of Cajun groups; and such distinctive groups as ``Kid'' Thomas and the Algiers Stompers, the Famous Zion Harmonizers, and the tuba ensemble from Tennessee Tech University.

In the festival's 16 years, the lineup has veered away from a pure-jazz format, and there are good reasons for it. Audiences for jazz concerts declined in the 1970s, and many of the original practitioners of this type of music are no longer around.

Cajun, country, and rhythm-and-blues groups were brought in to fill the gap, to give attention to other forms of regional music and draw customers who might not turn out for an all-jazz event. But as the festival grew from a tiny event to become one of the biggest festivals in the world, purists complained that it was growing away from its musical roots.

In an attempt to appease these patrons and to give traditional jazz the exposure it deserves in the city of its birth, Economy Hall was added two years ago. Audiences have packed it ever since, not only to hear veteran jazzmen like the Preservation Hall band but also to enjoy such groups as the New Leviathan Oriental Fox-Trot Orchestra, a New Orleans ensemble that specializes in turn-of-the-century tunes.

Meanwhile, in the Gospel Tent, where the banner of a sponsoring funeral home flapped above the crowd, the master of ceremonies hollered, ``Is everybody having a good time?''

The spectators, who were fanning themselves like worshipers in a country church, stopped eating long enough to holler back, ``Yeah!''

In 197O, jazz impresario George Wein came up with the idea for a festival that capitalized on the many forms of jazz found here while also celebrating Louisiana's heritage in food, folk art, and other forms of music -- Afro-Caribbean, Mardi Gras, gospel, cajun, zydeco, blues, soul, rockaboogie, and even opera. (The city had the first opera house in North America.) Despite the richness of music, however, ``this really isn't a music festival,'' emphasized Allan Jaffe on the day of my visit to the festival. Mr. Jaffe is one of the directors of the New Orleans Jazz and Heritage Foundation, the nonprofit vehicle through which profits from the festival are chaneled back into local cultural activities. Before the day was over, as if to underscore the diversity, he would be asking: ``Have you tried the Crawfish Monica?''

With more than 80 varieties of regional specialties available at booths and tents spread around the Fair Grounds, it's no wonder chefs from other parts of the country come expressly to sample the dishes.

The Crawfish Monica booth was staffed by a crew of students and teachers from the culinary apprentice program at Delgado College here.

At another tent, the fried chicken and potato salad were being served up by members of the Second Mount Triumph Missionary Baptist Church. ``This is music to my stomach,'' said a smiling patron at the barbecued-shrimp booth run by volunteers at Sheriff Charles C. Conti's victims assistance program.

If foods are one world into which festivalgoers can easily get sidetracked, then folk arts is another. Thanks to grants from the New Orleans Heritage and Jazz Foundation, there are many displays of unique regional arts and crafts.

Tents scattered around the Fair Grounds offer, for example, displays of the intricate beadwork of Mardi Gras Indian costumes, of the uniquely decorated ``second line'' umbrellas for jazz parades, of bread sculptures with religious themes and fig pastries in the shapes of fish, birds, and flowers from the heritage of the Sicilian-Americans now living in the area, and countless other fascinations.