The things you find on your travels 🙂
Meuse Brewing makes bottle-conditioned beers.

Real beer primer: Beer is the result of yeast munching it’s way through the sugars released from a mash made of grains and hot-water. The yeast turns the sugar into alcohol and carbon dioxide. The carbon dioxide dissolves into the beer, giving it the fizz. The yeast will continue to generate alcohol and carbon dioxide until the alcohol level reaches a level to kill the yeast, or until all the sugar is used up. Usually all the sugar is used up after 10days (or so), and the beer is put into a barrel. The beer remains fizzy until the barrel is opened.
The fizz will last for two or three days after the barrel is opened. As will the yeast. So real beer needs to be drunk within three days of opening. A standard barrel holds 36 gallons(UK) or 234 pints, so you had better draft some friends. Or own a pub.
For those who cannot drink a barrel of beer, there are bottles. Half pint or full-pint bottles. When the beer is bottled, a little sugar is added. This encourages the yeast, still present in real beer, to get back to work, and produce more alcohol and more carbon dioxide. So when you pour the beer out of the bottle, it always has a fizz. The beer bottles are traditionally closed with a metal cap, and the bottles stored upright for a couple of weeks. The yeast will fall to the bottom of the bottle and creates a little sediment. You can pour the beer carefully so that the yeast stays in the bottle.
Meuse makes real beer. You will find the sediment at the bottom of the bottles.

Typical beer primer: Bar owners have a real problem with real beer. It needs careful handling. Real beer does not like travel. Nor does it respond well to changes in temperature. Quite a problem for breweries as well. In the past, each area had it’s own little brewery. If you tried to expand, your local buyers could only drink so much beer, so you had to ship your beer further out. Which means that the beer lost it’s fizz, and taste. The bar owners would not pay for it. Customers would not drink it. Enter the bright (brite) tank.
After the beer has fermented for 10 days or so, it will be filtered, to remove the yeast. Often the beer is also pasteurised to extend it’s shelf-life. Now the beer is flat. The bright tank puts that carbon dioxide back into the beer. Even if the beer is not pasteurised, the bright tank is used to add extra carbon dioxide. The beer is then placed into kegs, bottles and cans.
Variations include
(a) beer not being pasteurised. Still need to add carbon dioxide, to make the beer fizzier.
(b) carbon dioxide can be added at the serving station whilst the beer is being poured. There is a gas tank attached to the barrel, or serving line, to add fizz as the glass is being poured.
(c) bottles and cans may be pasteurised after being filled. I have seen UV-light used on bottles. Bottles and cans may be heated after filling.
(d) Guinness uses nitrogen. Back in my day as a bartender, there was a little nitrogen canister that would be cliped onto the barrel. Today’s cans use a little hollow plastic ball that holds liquid nitrogen, under pressure. When the can is opened, the pressure is released, nitrogen bubbles out of the plastic ball and into the Guinness.

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Germany, seen as the home of beer, typically will not pasteurise their keg beer, but will add carbon dioxide. This will ensure the beer is fizzy 3 days after opening. German bottles and cans are usually pasteurised, so that they can be stored on shelves for a long time.

Belgium is home to strong beer in bottles, brewed by monks. Belgium beers are usually bottle-conditioned. Some of these bottles are corked, so need to be stored lying down, the same as you would lay down a bottle of wine.