How light beer is made

An added enzyme lets yeast eat starch fragments it normally leaves, cutting carbs from about 14 grams to under 3.

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The short version

Light beer is brewed like regular beer, but the brewer reduces the starch fragments called dextrins that give beer about a third of its calories. An enzyme, a longer mash or part-replacement of malt with corn syrup does it. Carbohydrates can fall from about 14 grams to under 3 per 12-ounce serving.

Mash the grain

Malted barley is soaked in hot water to turn its starch to sugar, making a sweet liquid called wort. Some light-beer makers use high-enzyme barley malt and a longer mash to convert more starch.

Goes in
Barley Water Malted barley
Boil with hops

The wort is boiled for roughly one to two hours with hops, which adds bitterness and aroma. Some brewers replace part of the malt with corn syrup, which leaves fewer dextrins behind.

Goes in
Hops Corn syrup
Break down the dextrins

The enzyme amyloglucosidase goes into the cooled wort. It turns dextrins, starch fragments yeast cannot normally eat, into fermentable sugar.
Ferment with yeast

Yeast eats the sugar for around ten days, turning it into alcohol and carbon dioxide. With more sugar available the beer comes out stronger than the finished product should be.

Goes in
Baker's yeast
Dilute and carbonate

Brewers add carbonated water to bring the alcohol back down. The beer is conditioned and filtered a last time before packaging.

Goes in
Water Carbon dioxide
Can or keg it

The finished beer is filled into cans, bottles or kegs.

Goes in
Aluminum can

End of the lineLight beer

Worth repeating

Dr. Hersch Gablinger applied for patents on his amyloglucosidase process in Switzerland in 1964, and the United States granted his in 1968.
Miller Lite was not marketed nationally in the United States until 1975.
In Australia, Canada and the United Kingdom, light beer means lower alcohol, not lower calories.