This is where I will try to post, as often as I can, on beer topics that are related to my beer, the beer I drink, and my beer education.

Wednesday, March 01, 2006

Day 23, Brewing Science: Hops

We spent the entire day and the very end of yesterday discussing hops. There is more to them than I thought. For instance, did you know that the tannin and protein content in hops add to foam retention and cling in finished beer? Another interesting thing, was to find that hops change over time but the perceived bittering value stays constant. This is because of the alpha (a) and beta (b) acids. The a-acids contain the bittering value, i.e. 6%. The kilning of the hops is where the some of the b-acids are converted to a-acids. The b-acids, though in their original form do not affect bitterness, will oxidize over time, and basically transform into an a-acid. Of course, when this happens the perceived bitterness is a little on the harsh side, the final perceived bittering value does remain constant. It should be noted that some brewers, i.e. AB Corporation, still insist on fresh hops because they think the fine bittering value, from pure a-acids, are more desirable on the palate. AB continues to surprise me with their integrity. Guiness on the other hand, recycles their spent hops into their weak wort (this is when you take your last runnings from mashing and use it as the mash water for your next mash), thereby maximizing the extraction of harsh bitterness.


Blogger Lost Cause said...

On that subject ... have you heard of the Hops Extract Corporation of America? Couple years ago in one of my classes we toured their facility in Yamima and they told us about a (at the time)new hops extraction process involving CO2 super critical fluid extraction.
I can't say as i understood the more technical aspects but what i found useful and "cool" was the fact that by comparison to 200 lbs of baled hops (20 cubic feet of space) ... the extract was 3.5% of that or less then 1 cubic foot. Basically more bang for the buck really.

*I still have the flier they gave us ... which is were i quoted space stats from ... *

9:34 PM

Blogger joemonkey said...

As cool as super critical CO2 extraction sounds, it is not used hardly at all because it extracts not just the alpha-acids but also the proteins and tannins, and it produces a green solution. Ethanol and Liquid CO2 are more the two most common solvents used for extraction, because they only extract the alpha-acids, and more importantly turns the fluid a brilliantly bright yellow.
I should note that there are actually some benefits to proteins and tannins, but if that is what you want, you might as well just use pellets because they are cheaper.

2:26 PM

Blogger Andy said...

Guinness continues to surprise me with their shenanigans. They've a history of being cheap, conniving bastards.

2:36 PM

Blogger joemonkey said...

Someone asked one of my Professors if Guiness actually marinates a dead cow in the fermenting tanks. My professor seriously seemed to consider it, but then informed us that everyone knows it is a sheep.

10:15 AM

Blogger Andy said...

God that's unsanitary. But damned if I don't want a lamb kebab that's been marinating in Guinness.

9:11 PM


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