Co hovori wikipedia:

"How low-alcohol beer is made

Low-alcohol beer starts out as regular alcoholic beer, which is then cooked in order to evaporate the alcohol. This is possible because alcohol has a lower boiling point than water, making it easier to boil off. As opposed to water, which boils at 100 °C (212 °F), alcohol will boil at 78.6 °C (173.5 °F). Most modern breweries also utilize vacuum evaporation to preserve flavor and speed up the boiling process. In essence, the beer is placed under a light vacuum to facilitate the alcohol molecules going into gaseous phase. If a sufficient vacuum is applied, it may not even be necessary to cook the beer.

An alternative process called reverse osmosis does not require heating. The beer is passed through a filter with pores small enough that only alcohol and water (and a few volatile acids) can pass through. The alcohol is distilled out of the alcohol-water mix using conventional distillation methods. After adding the water and remaining acids back into the syrupy mixture of sugars and flavor compounds left on the other side of the filter, the process is then complete."

Cize alkohol sa odstrani fyzikalne - bud destilaciou alebo reverznou osmozou.

Povoleny obsah alkoholu sa lisi podla legislativy od 0.05% do 0.5%. Podla wiki existuje pivo, ktore neobsahuje ziaden alkohol:

"Kirin Free, produced by Kirin Brewery Company of Japan, contains 0.00% ABV. This beer is produced without fermentation."

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Kazdopadne sa nemusite bat, ze nealko pivo bude nejako chemicky kvalitativne odlisne od alko piva - skor to bude brecka, ktora sa neda pit. :D