Just when I'm purring along in no-place-could-be-better-than-Humboldt-mode, some other locale saunters by, its gaze smoldering over a frothy beer glass, and my heart wobbles.

This time it's Oregon. Sweet, seductive Oregon, which made Saccharomyces cerevisiae the official state microbe. To even have a state microbe is geekily wonderful. To choose yeast, the microbe that makes beer bubble and bread rise, well ... here's lookin' at you, Oregon.

Yeast rocks.

While hops and malt are out there taking applause for the wonderful beer you drink, yeast has been toiling backstage, moving scenery and adjusting lighting so that everything else seems flawlessly fantastic.

Unless you brew beer yourself, you may not know how much magic is stage managed by this little microbe. Yeast feasts on sugars in the watery grain soup that is ready to be turned into beer. It grows and flourishes, giving off alcohol and carbon dioxide as waste products. Depending on which yeast a brewer puts to work, the beer can be cloudier or clearer, more or less alcoholic, sweeter or tarter. The rich, almost bready flavor I once attributed only to malted barley? It's the yeast, too. Hint of cloves or bananas? Yeast.

"People don't realize how much it can affect a beer's flavor," says Drake Mollberg, co-owner of Redwood Curtain Brewing Co. in Arcata.

Redwood Curtain is great place to start paying attention to yeast. Mollberg brews with more varieties than any other local brewery, and he lists some basic yeast information along with other ingredients on Redwood Curtain's ever-changing beer menu.

"We play around yearly with 10 to 12 yeast strains," Mollberg says, a range that wasn't as easily available when older, more established Humboldt breweries were starting out. By comparison, Eel River and Mad River breweries routinely use one strain of yeast, Lost Coast and Six Rivers most commonly use two, and Humboldt Regeneration, three.

As yeast grows and multiplies, it can also strengthen ties between homebrewers and breweries, which sometimes give away their excess yeast, just as neighborhood bread makers pass along their sourdough starter.

Michael Kraft, president of the Humboldt Homebrewers, says if he's planning a beer that calls for an American ale yeast, he'll takes an empty Mason jar along when he stops in to drink at Mad River Brewing in Blue Lake.

"It's cool. It entices you to order a pint or two," Kraft says. Along with the sense of community promoted by this sharing, the yeast itself is great. "It's going to be fresh, probably from this past week's stuff. It's really vital. It gets going very fast." Six Rivers and Humboldt Regeneration also share their yeast if they have extra, and other local breweries have said they would if asked.

Kraft, too, enjoys exploring the ways and wiles of yeast. He recently brewed a single starting recipe then added different yeasts, in separate fermenting containers, to create a blonde ale and a crisper, slightly frutier Kolsch-style ale. You could try this at home — or you could head down to San Diego, where a large yeast producer named White Labs has established its own tasting room to help people drink in the effects of varying strains of yeast.

"It's definitely worth checking out," says Ari Friedman, a bartender at Dead Reckoning Tavern in Arcata who visited White Labs about a year ago. "It's an educational experience. It's really fun to see how just the change in yeast can change the nose, the body, the sweetness, everything."

Sabrina LoPiccolo, White Labs' marketing manager, says tasting flights that showcase the same beer made with four different yeast strains is especially illuminating.

I so want to try this.

Meanwhile, though, it's almost time for Hops in Humboldt, where there's something new to try for every beer fan. I'm especially curious about two Crescent City breweries, Port O'Pints and SeaQuake Brewing, which will be pouring at the festival for the first time. Neither distributes in Humboldt yet, although both hope to, so the Aug. 27 festival in Fortuna will be your first chance to give them a try here at home. Also intriguing and new this year is H2ops, a non-alcoholic, sparkling hop water. Really.

Hops in Humboldt is always too big fully appreciate in just a day; this year, beer wrangler John Taylor expects about 150 different beers and ciders supplied by around 40 commercial breweries and cideries, plus six to 10 homebrewers. (The homebrew often runs out in the first couple of hours, so plan accordingly.) All six Humboldt breweries plan to be there, but Ridge Rd. Brewing, a tiny Southern Humboldt operation that made its debut at last year's Hops in Humboldt, won't be back. It ceased operations earlier this year after running up against permitting and cost issues.

A Date with Beer

Thursday, Aug. 18 through Sunday, Aug. 21: It's community appreciation weekend at HumBrews in Arcata, featuring all-day happy hour discounts on pints and mixed drinks on Saturday and Sunday, plus music on Thursday and Friday.

Saturday, Aug. 27: Hops in Humboldt runs from 1 to 5 p.m. at Rohner Park in Fortuna, with VIP admissions beginning at noon. $35 in advance; $45 at the gate and $75 VIP. Do take transit or travel with a designated driver; you can find safe ways to get there and back on the festival website.

Thursday, Sept. 1: Bring your yeast questions and/or your own homebrew to the regular monthly meeting of Humboldt Homebrewers (now an Ink People project), starting at 7 p.m. in Humboldt Beer Works in Eureka.

Thursday, Sept. 1 through Sunday, Sept. 4: A four-day celebration to mark the fourth anniversary of Humboldt Regeneration Brewery and Farm in McKinleyville kicks off at 7 p.m. Thursday with a small, brewer-led tasting event ($30 tickets; limited to about 10 people). Friday brings the release of a new, aged sour red ale, Saturday a mystery flight night, and Sunday a community potluck, from noon to 7 p.m.

Sunday, Sept 4: Head out to the Mateel Community Center for the SoHum Beer Fest and Barbecue Smoke Off, from 4 to 9 p.m. with unlimited tasting from 10 breweries and a still-growing number homebrewers, plus live music and a barbecue tasters' choice competition. It's not too late to enter your beer or barbecue; phone 923-3368 for details. It's $15 for barbecue and music only; $30 for all that plus beer.

Saturday, Sept. 10; The beer bash vibe moves north to Lost Coast Brewery, with a lawn games, music, food trucks and plenty of beer from 2 to 7 p.m. Food and beer are sold separately at the main event. A $20 VIP ticket gets you a brewery tour, chicken wings and tastes of two specialty beers, including a grapefruit IPA, between 2:30 and 5 p.m.

Tuesday, Sept. 13: Music, comedy and other talents go on display during the employee talent show starting at 6 p.m. at Mad River Brewing.

Friday, Sept. 30: See what one of Berkeley's newest breweries is up to during the Fieldwork Brewing tap takeover at Dead Reckoning Tavern in Arcata. Six different Fieldwork beers will be on tap, and a representative will be on hand to answer questions.

Carrie Peyton Dahlberg is having a tough time deciding between Oregon and San Diego for her next beer field trip. Reach her with your brew news at [email protected].