'Hoppy' beer without exploding bottles and too much alcohol

September 19, 2018, American Chemical Society
'Hoppy' beer without exploding bottles and too much alcohol
Credit: American Chemical Society

The forgotten art of "dry-hopping" beer to enhance flavor is back in vogue. But this practice sometimes has undesirable side effects, such as an unexpectedly high alcohol content and high pressures that could cause beer bottles to break. Now, research published in ACS' Journal of Agricultural and Food Chemistry explains the biochemical basis of these unintended consequences, which could help brewers create "hoppy" beverages without the quality-control and safety issues.

During production, grain is mashed and steeped in hot water to convert starch into sugars. The liquid extract is then boiled with hop flowers to impart bitter flavor and a pleasant aroma and to limit bacterial contamination. Yeast is then added to ferment the sugars into alcohol. In dry-hopping, hops are added during or after the fermentation stage, meaning the resulting beer is less bitter. Although hops were previously thought to be inert ingredients, recent evidence suggests they contain biologically active compounds that restart the fermentation process and alter the final composition of beer. Thomas Shellhammer and Kaylyn Kirkpatrick wanted to identify the source of these changes.

The researchers dry-hopped a commercial beer and showed this boosted its carbon dioxide (CO2) and , while lowering its carbohydrate content. They found that the activity of starch-degrading enzymes associated with hops—including amyloglucosidase, α-amylase, β-amylase and dextrinase—altered the composition of carbohydrates in the beer, shifting the balance to more fermentable sugars and thus increasing the . The scientists also found that the amount of hops used, the duration and temperature of the process, and whether yeast was present affected the results. They say that brewers could use their findings to better control beer quality and safety when producing this trendy beverage.

Explore further: A brewer's tale of proteins and beer

More information: Kaylyn R. Kirkpatrick et al. Evidence of Dextrin Hydrolyzing Enzymes in Cascade Hops (Humulus lupulus), Journal of Agricultural and Food Chemistry (2018). DOI: 10.1021/acs.jafc.8b03563

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4 comments

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Phyllis Harmonic
5 / 5 (1) Sep 19, 2018
Good beer is one of life's true pleasures!
machapungo
not rated yet Sep 19, 2018
Hops cannot start fermentation UNLESS they are contaminated with some kind of yeast.
First they said " In dry-hopping, hops are added during or after the fermentation stage, meaning the resulting beer is less bitter. "
We home crafted (NOT FROM A KIT) brewers know from experience that this is BULL- ONY !!!! Especially when the hops are added during fermentation.
We also know hops add bitterness when added after fermentation but not as much.

The ONLY reason I would add hops BEFORE fermentation , which is during a rolling brewing boil, would be to add bitterness and then I would use a buttering hop and not a flavoring hop because by the time the boil has finished there would not be enough flavor from a flavoring hop to put in your eye. But, I would not do that either because plenty of bitterness can be achieved by adding the hops during fermentation.
Makes me wonder if these authors have actually had much experience at producing a tasty bear of any IBU.
machapungo
not rated yet Sep 19, 2018
Hops cannot start fermentation UNLESS they are contaminated with some kind of yeast.
First they said " In dry-hopping, hops are added during or after the fermentation stage, meaning the resulting beer is less bitter. "
We home crafted (NOT FROM A KIT) brewers know from experience that this is BULL- ONY !!!! Especially when the hops are added during fermentation.
We also know hops add bitterness when added after fermentation but not as much.

The ONLY reason I would add hops BEFORE fermentation , which is during a rolling brewing boil, would be to add bitterness and then I would use a buttering hop and not a flavoring hop because by the time the boil has finished there would not be enough flavor from a flavoring hop to put in your eye. But, I would not do that either because plenty of bitterness can be achieved by adding the hops during fermentation.
Makes me wonder if these authors have actually had much experience at producing a tasty bear of any IBU.
AmeliaR
not rated yet Oct 10, 2018
I believe many people misconceive "hoppy beer" as the only beer that has hops in it. Hops are one of the four basic ingredients of beer. So even a beer that doesn't taste "hoppy" still has hops in it. I think that without hops, beer probably would be overly sweet. It is the balance between bitterness and sweetness that most seek. I am sure the chemical balance can be challenging for many people who are attempting to brew their first few tries by high CO2 pressures, resulting in bottles rupturing.

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