For those breweries that package, an automated bottling (or canning) line is obviously a necessary piece of equipment. And it is actually mesmerizing to watch as bottles (or cans) are fed into the machine, lined up, rinsed, filled, topped, sprayed, and sent off to be packaged with others.
You’ve probably noticed when you’ve been on brewery tours that the employees manning the line wear gloves. This is in part for safety reasons, but it’s also because it’s cold. Standard filling lines run the beer right from the bright beer tanks and into the bottles or cans, and when the beer comes out of the bright tank, it’s anywhere from just above freezing to the 40s Fahrenheit.
That makes sense for the majority of beers—especially for lagers, which thrive under colder temperatures, and even for most ales when it comes to serving temperatures. But for the breweries that practice bottle- or can-conditioning, where yeast is added to a bottle or can to ferment the residual sugars in the beer and thus create a more layered and effervescent beer-drinking experience, cold filling has it disadvantages. Typically, the ale yeasts these brewers use need warmer temperatures to get down to doing their job. So if yeast is added to a package with cold beer, it needs to wait until the beer warms to begin the important fermentation work.