These bladders/bags are ideally suited to brewers who want to do the “no chill” brewing method. Also called Hot Packing, the idea is fill these bags directly after boil and then let the wort cool down in the bag. This mehhod avoids the chilling stage, thus saving considerable time on brew day. After filling, screw on the cap and let the wort cool. Use immediately after it has cooled down or store refrigerated for short periods of time. Most brewers transfer from this bag into their preferred fermenter, but it is possible to directly ferment in these bags using a #7 stopper and airlock
Hot packing and the storage of wort at room temperature has been done in Australia as a common practice for decades. Because of the temperature of wort entering the bag, any bacteria are killed. However there does exist a small chance of Botulism contamination for wort that is hot packed and stored. Botulism spores can survive a boil and are only killed through high temperature pasteurization. We always recommend using the wort as quickly as possible once it has cooled.