Changes

A regular strength starter of a volume of 2-3 cups should be prepared for the bottle dregs. The starter is prepared as normal, and without hops. If the brewer has only one bottle or wants to keep multiple bottle dregs separate from each other, the starter wort can be poured directly into each bottle and covered with aluminum foil or plastic wrap. Alternatively, the dregs from multiple bottles can be combined into a single vessel (such as a glass jug) with the starter wort, and covered with aluminum foil, plastic wrap, or an airlock. The starter should be stored at room temperature, or can be stored at a higher temperature if bacteria is the main microbe that the brewer is after. The mouth of the bottle may be flamed with a lighter to kill any wild yeasts that might have landed on the area. Keep the starter for at least one week, and monitor for activity. Visual activity may not always be present, may be brief, or minimal. Monitoring the pH and the gravity can assist the brewer with deciding whether or not the commercial sour beer has any viable microorganisms still alive in it.