Fill 1.15 gallons of water in the brew kettle; heat to 158 °F. Shut of heat.
Add the malt extract and stir thoroughly to dissolve completely. You do not want to feel extract at the bottom of the kettle when stirring with your spoon. Turn the heat back on and bring to a boil.
Boil the wort for 10 minutes to sanitize without hops, then chill to 110 °F. Acidify with lactic acid to a pH of 4.5. Pitch the Lactobacillus directly into the boil kettle. Keep the temperature at 110 °F using an electric heater or other method for 36 hours or until the pH reaches 3.5.(Alt keep at room temp for 6 days). Perform a second boil for 45 minutes, adding the hops with 30 minutes remaining. Chill the wort to below 70 °F, pitch the yeast, and ferment until SG 1.014. Add the guava and allow fermentation to finish.
Rack the beer, prime and bottle condition, or keg and force carbonate.