German brewers have traditionally lowered their mash pH by using the Reinheitsgebot-friendly technique of souring a small portion of wort, called sauergut, and adding it to the mash. Sauergut can be made by adding a small amount of barley malt (already naturally crawling with Lactobacillus) to water. The wort will then acidify and sour, as quick as in just few hours when kept about 108–112 °F (42–44 °C). A common practice is making the sauergut 12–24 hours before brewing, letting the sauergut sour to around pH 3.5 or under, and then portioning it off into the main mash to adjust the pH as necessary. Many brewers find adding sauergut to their mash is an easy way to adjust the pH and put a unique flavor print on their beer. Learn more about this technique and how to use it in your own brewing with BYO’s Technical Editor Ashton Lewis.