Anchor Brewing Releases Their First Ever Sour Mash Beer, Zymaster No. 7: Potrero Hill Sour-Mash IPA®

November 12, 2014

San Francisco, CA (November 12, 2014) Today, Anchor Brewing Company announces the release of the seventh brew in their Zymaster Series, Potrero Hill Sour-Mash IPA® (ABV 7%).

Anchor, already a pioneer in craft brewing, moved to San Francisco’s Potrero Hill in the late 1970s. In 1993, Anchor repurposed a small corner of their brewery and began distilling whiskey from a mash of 100% rye malt, now known as Old Potrero®. Although they have experimented with beer and hops in the distillery, Anchor has never used rye or sour mash in the brewery—until now.

“I’ve always been intrigued by the rye whiskey we make and its unique rye flavors so I thought it would be fun to use rye in a beer; and why not the rye sour mash from our distillery?,” said Mark Carpenter, Brewmaster at Anchor Brewing Company. “Brewing with rye can be difficult—it often gums up brewing systems—but our unique blend of rye malt, barley malt, and rye sour mash avoided such problems. Don’t let the name mislead you—the mash in Potrero Hill Sour-Mash IPA is sour but the beer is not. Instead, the sour mash is blended with our regular mash, creating a unique piquancy.”

Zymaster No. 7: Potrero Hill Sour-Mash IPA’s journey begins in Anchor’s distillery, where they prepare a 100% rye malt mash just as they would for their rye whiskey. After transferring it to a small open fermenter, the distillers pitch the yeast and wait. Five days later, the brewers mash in the brewhouse, using a blend of pale barley malt and rye malt. Then they add the sour mash from the distillery, which lowers the pH of the brewery mash. By introducing sour mash before the boil instead of after it, Anchor is able to create a distinct tartness in the brew without sourness.

In the brewkettle, Anchor uses four additions of Nelson Sauvin, a dual-purpose hop from New Zealand. An English ale yeast contributes dry, clean flavors and Zymaster 7’s unique tropical aroma is a result of dry-hopping with Nelson, as well. All in all, a perfect blend of tartness, hoppy bitterness, and subtle spiciness creates a thirst quenching IPA with a clean, crisp finish and tropical complexity on the nose.

Anchor Zymaster No. 7: Potrero Hill Sour-Mash IPA will be available in limited release in 22 oz. bottles and on draught in select restaurants, bars, and at the Anchor Brewing Taproom in San Francisco.

Read more about our Zymaster Series of special brews at

About Anchor Brewing Company
Anchor Brewing Company’s roots date back to the California Gold Rush making it one of America’s oldest breweries. Its Anchor Steam® Beer is San Francisco’s original since 1896. In 1965, Fritz Maytag acquired and revived the struggling brewery at a time when mass production of beer dominated and seemed unstoppable. Maytag started a revolution in beer that originated today’s craft beer movement. An undisputed icon, Anchor is America’s first craft brewery where beers are handmade in our traditional copper brewhouse from an all-malt mash. At Anchor, we practice the time-honored art of classical brewing, employing state-of-the-art methods to ensure that our beers are always pure and fresh. We know of no brewery in the world that matches our efforts to combine traditional, natural brewing with such carefully applied, modern methods of sanitation, finishing, packaging and transporting. See what we are brewing today at

About Anchor Brewing Zymaster ® Series
Zymaster® is a new word coined by Anchor Brewing to describe a brewmaster with hands-on experience throughout the a-to-z process of creating a new beer, from the research and selection of the raw materials and development of a recipe to brewing, fermentation, cellaring, and finishing. Harvest One American Pale Ale is the fifth addition to the Zymaster® Series, a unique series of beers from Anchor Brewing, rooted in its exceptional respect for the ancient art and noble traditions of brewing, featuring extraordinary ingredients, innovative techniques, and unusual flavors.