Kettle souring

Quirks of brewing: Kettle souring

• quick-acting bacteria that deliver a distinctive, citric sour to beers like Berliner weisse, gose
• Lactobacillus
• it can acidify a wort in the course of a weekend-no years of barrel-aging required
• it does not create layers of flavor, aroma the way wild yeast do 
• traditional methods: sour mashing, pitch pure cultures of lactobacillus, pitch lactic acid straight in beers
• today's method: kettle souring

1. conduct a lactic fermentation on a whole batch of wort
2. do this in brew kettles(Lactobacillus likes very warm, consistent temperatures)
3. lactic fermentation produces a very acidic wort, without funky flavors a sour mash might produce
4. then boil it right in the kettle to purify it
5. finally, the brewer has a wort of a stable, predictable pH 
6. it can use to acidify another beer to the level she desires
7. both acidified and fresh worts go through a standard alcohol fermentation

That sounds intriguing. I thought that acidity produced by Lactobacillus was merely a sign of a failure of controlling an optimal fermentation temperature. The author of the article also said that the kettle souring method is the key to brewing a tart IPA, which could be the next big trend of the US craft beer scene where people more and more want juicy and fruity IPA. And when a touch of acidity that even our palate doesn't notice meet fruity hop oils, it can bring a smart consequence without adding real fruits.