Making Balsamic in Sonoma

Every fall, as the sugar content of the grapes at Rocky Hill Farm in Sonoma becomes ideal, a group of old friends gathers for the harvest -- not to make wine, but to make balsamic. Our leader, Paul Bertolli, assembles his equipment to crush the grapes. He sets up the stainless steel vat where the grape juice will simmer before it's held in the balsamic room and then is transferred into the barrels that he has imported from Modena. Formerly the chef at Chez Panisse and Oliveto in Oakland, Bertolli, is also the founder and curemaster of Fra'Mani Handcrafted Salumi in Berkeley.

Bertolli studied the traditional process of making balsamic in Modena, Italy, years ago. Upon his return, he got a small group of us to commit to the ritual every year, which is how I ended up on a hillside in Sonoma so early on a Saturday morning that the dew was still on the grapes. We harvest about a ton of black Syrah grapes, piling them high into huge, square plastic containers that get trucked over to a flat driveway. There, the grapes are crushed, and the stems are spewed out onto the ground. The juice is collected in plastic tubs and poured into the huge vat that's placed over a powerful outdoor burner.

The must, or musto, as it is called in Italy, gently bubbles away, giving off a foam that must be continuously scooped off so that cloudiness doesn't have a chance to set in. After 32 hours, the 75 gallons of juice has reduced to about 40 gallons of must. The lovely condensed juice is then cooled and poured into a holding container in the aging house, where it becomes a complex liquid layered with flavors of the earth and the grape.

After a few months or two the must is poured into barrels of varying sizes and types of wood -- chestnut, cherry, ash, oak, mulberry and acacia -- the traditional woods used in Modena to fashion barrels. In Modena, barrels sit in the hot attics of Italian houses for decades, the perfect atmosphere for the aging process to occur. Barrels are often retained by parents and given as dowry when a young daughter from Modena marries.

The true balsamics -- Aceto Balsamico Tradizionale di Modena or di Reggio Emila -- are aged for 12 years, bottled in traditional glass bottles, and finally approved by master tasters. These small imported treasures go for anywhere from $75 to $400 for an ounce or two.

Most of the balsamic sold in the U.S. is an approximation or cheap imitation -- usually nothing but a concoction of strong vinegar, concentrated grape juice, and caramel coloring. This type is not aged in the traditional barrels. But the version we're making is a good alternative for the thrifty-minded. It's labeled Condimento Balsimico, the name used to designate vinegars made by producers outside of the traditional regions of Modena or Reggio Emilia, or by those who have released their product without the approval of the consortium.

During the night after the harvest in Sonoma, participants take turns getting up to scoop off the foam under the bright light of a big orange harvest moon. It will only be a couple of months until our batches of California balsamic are ready.