Yesterday’s experiment told me that next time I’ll sour mash the brew. To do that, make your wort as usual but chill down to 120 degrees. Pitch lactobacillus in one of two ways, either as a culture you bought or through throwing a few grains of malt into the warm wort. Keep air away from the wort to avoid culturing acetobacter – you’ll get a vinegary taste if you do. To keep air away, either cover the wort with plastic wrap and by that, I mean floating the plastic on the wort, or use a blanket of carbon dioxide to keep oxygen away from the wort’s surface. In 12-24 hours, take a sample and if it’s tart enough, boil and add your hops. Caution: Don’t let anything you can’t sterilize fairly harshly come in contact with the soured wort. Lactobacillus can be hard to get rid of once you have it. I keep a separate setup of buckets, racking canes and so forth for anything soured. I sour the mash in my kettle since it will be boiled and everything else is very clearly marked. Duct tape is good for this.
Chances are the original beer was soured after the boil. Lactobacillus Delbruckii is sensitive to hop oils so it won’t work quickly as a culture once the beer is hopped. Lactobacillus Brevis is not but it will require very careful handling – it’s a very aggressive spoilage bacterium! To sour in storage, again, cool the wort to 120 degrees. Innoculate the wort and let it cool slowly for a few hours to let your lacto get going, then finish cooling and pitch brewer’s yeast. Let the beer ferment, then bottle or keg as usual. The beer will sour slowly, taking up to three months to develop tartness.
Hat tip to Ron Pattinson for tips on the recipe and techniques used to develop this recipe.