Lactobacillus plantarum is a popular choice for kettle souring, easily acidifying the wort to 3.3-3.6 pH in under 48 hours. Optimum temperature is 100°F-110°F. L. plantarum is hop sensitive, we advise not to use any hops until souring is satisfactory.
Lactobacillus brevis is another popular strain for kettle souring projects. This strain works well at 95°F-105°F. Expect pH of 3.3-3.6 pH in under 48 hours. L. brevis is known to be more hop tolerant than other lactobacillus strains.
Our most popular option, a blend of both Brevis and Plantarum, allowing the bacteria to effectively sour wort over a wider active temperature range.