Alpha acid and hop quantities

[agentgonzo]

Just to check, does a hop with a high alpha-acid content add more antiseptic qualities to the beer? Given most of the aroma and flavour is driven off in the boil, will 2oz of 5%AA hops have a similar effect on the beer as 1oz of 10%AA hops in terms of
A) Beer character and flavour
B) Antiseptic qualities leading to how quickly the beer will go off.

cheers

[BigEd]

I don't think the AA% has anything to do with the antiseptic qualities of hops. Those attributes come from another component of the plant. Some Belgian beers are made with aged hops containing almost no bittering alpha acids but the hops still contribute their preservative qualities.

[agentgonzo]

I don't think the AA% has anything to do with the antiseptic qualities of hops.

http://en.wikipedia.org/wiki/Hops#Brewing
Alpha acids have a mild antibiotic/bacteriostatic effect against Gram-positive bacteria, and favor the exclusive activity of brewing yeast in the fermentation of beer.

[steve_flack]

I'm not so sure the antiseptic properties of hops are that powerful in modern beers as the hop rates are often pretty low. In SteveD's beers however things may be different....

1 IBU is 1 ppm (1mg/L) of isomerised alpha acids in the beer - the amount of acidity they contribute to the beer is tiny.

I'm sure the low pH, lack of oxygen and presence of alcohol are more effective.

[oblivious]

I don't know what is supposed to make them antiseptic but I would have thought their acidic nature would have helped though ??

this lipids bind to the surface of micro flora interfering with there cell membrane and reproduction.

this is supposable one of the reasons what you should not re use yeast from very high IBU beers

This is a patented method to wash the yeast


The antibiotic penicillin works in a similar manner

not tet

[agentgonzo]

I'm sure the low pH, lack of oxygen and presence of alcohol are more effective.

From memory, beer before about the 1400s was brewed without the use of hops. In the 1400s, the dutch introduced hops to the brewing process and found that the beer kept a lot better as a result. The pH, lack of O2 and alcohol will probably help too. Don't know which does more, but they found that the hops really helped and that's why we have hops in the beer today (flavour too)

It's an interesting experiment to do as well - brew unhopped beer. I haven't done it myself, but did a very low hopped beer when I was very low on hops. Prob about 3/4oz of hops in total. A different taste, and it was noticeable that the beer only kept for a couple of days after exposing it to the air (normally can last at least a week)

[steve_flack]

On the other hand, practically anything will grow in unfermented hopped wort so maybe it's the lack of oxygen, lack of simple sugars.

[agentgonzo]

On the other hand, practically anything will grow in unfermented hopped wort so maybe it's the lack of oxygen, lack of simple sugars.

Very true. But hops definitely help with the longevity of fermented beer. Back to the original question, will beer hopped with twice the amount of 5%AA hops keep as well as one hopped with 10%AA hops?

[agentgonzo]

Searching google for some of oblivious' words, I came across this:
Fundamentals of beer and hop chemistry.
http://www.scielo.br/scielo.php?pid=S01 ... ci_arttext

It's quite heavy on the chemistry, but does seem to suggest that it's the alpha-acids that are the major antimicrobial component of hops. This leads me to think my original hypothesis was correct, but could use a second opinion!

[Graham]

From memory, beer before about the 1400s...

That's one hell of a memory you've got there.

[oblivious]

Now that's an impressive bit of knowledge although I may have to deduct points as I suspect it's your job to know stuff like that

Na, now it more protein discovery/technology's mainly fetal-uterine interactions


But i am very familiar with the methods/technology they use

[booldawg]

I will now always keep a bottle of beer in the first aid kit for all those cuts and grazes