We have IBU; we also need ISU

pH.

 

“I'm wondering if an International Sourness Unit can be determined.”

I am not a sour beer expert but I would expect that the sour beers that are very sour have a lower beer pH than a sour beer that is only moderately or mildly sour.

I suppose an ‘easy’ solution would be to simply just list the beer’s pH on the label?

Below is something that relates to this discussion:

“The pH of the eight sour beers I tested ranged a full point (as pH is a logarithmic scale the Berliner Lambic was 10 times more acidic than the Big Funky Ale).

4.1 - Big Funky Ale

3.7 - Cherry/Raspberry Lambic 2.0

3.7 - Irma

3.5 - Dark Saison III

3.4 - Buckwheat Amber

3.3 - Fruit Salad 3.2 - Apple Brandy Solera

3.1 - Berliner Lambic

At the high end of that range beers taste tart, while down at 3.1 they have a bracing acidity. For the most part the readings confirmed what we tasted, but it was surprising to see what the different levels of acidity translated to. The one surprise was that despite both testing 3.7, the Irma tasted much sourer than the Fruit Lambic, maybe the acidity was offset by the higher alcohol?”

http://www.themadfermentationist.com/2011/11/measuring-sour-beer-ph.html

@OldSock

Cheers!


Edit: Upon further reading it appears that just simply using pH to ‘measure’ sourness is not sufficient:

“The character of the acidity is not solely a matter of the pH however. Different acids contribute various characters to the beer. A beer that has a pH of 3.5 from the presence of lactic acid will have a much mellower character than a beer that has the same pH resulting from acetic acid. Other characters in the beer including residual sweetness can balance the acidity as well.”

 

pH is 1000x better at determining sourness than IBU is to determining bitterness.

 

This topic came up back in July with nearly the same topic title.

Perceived sourness is not as simple as measuring a solutions pH level because something as simple as residual sugar totally skews our perception.

For example: a pH of 3.5 with little to no residual sugar (very dry beer) will taste significantly more tart than a pH of 3.5 with some residual, unfermented sugars.

 

I like this

 

I was expecting the title to stand for 'International Smell Units', regarding the hop aroma of a beer. Although distinct from IBU, there would probably be way more variation between samples. Also tons of uncertainty would be associated with measuring a small quantity of volatile, aromatic vapor.

 

I'm not so certain that a scale can be developed because I think I've read that sourness is dynamic, and the beer keeps getting more sour over time. Whether it ever reaches a final level of sourness, I don't know, but it seems like it should.

 

I thought the topic was going to be International Sweetness Units, specifically for Bruery beers.

 

Good one!

But seriously sourness and pH are close but the component of tartness also plays a factor.

 

While true, pH is as good at measuring perceived sourness as IBU is at measuring perceived bitterness. So if the question is what measure for sourness is analogous to the way IBUs measure bitterness, then pH is the answer.

 

Sour beers use a variety of different critters to make the sourness and they mature at different rates so even if a brewer put an ISU on the bottle it could be very different by the time you poured it into a glass.

 

This is my take as well, but in fairness the IBU can change over time just the same. We would just be setting ourselves up for even more freshness debates.

 

That is correct; IBUs will fade with time.

Cheers!

 

International sweet units, for me.

 

You are absolutely right. I had a sage beer from Indeed on a Monday when it was tapped and you could smell the sage wafting from the glass from across the table. By Wednesday, with the same beer in the same keg, you could smell the beer about halfway up as you lifted your glass to drink. By Friday you had to stick your nose in the glass to detect any sage. I don't think hops go quite as fast as sage but the hops in same beer will smell and taste a little different fresh from the brewery and at one, two and three months. It will depend on the beer and how much hop aroma they feature but the hop aromas and flavors do change quite a lot for some beers. IBU itself is a little misleading because when the brewer added the hops, the hardness of the water, the richness of the malt and a number of other actors will impact our perception of the bitterness of the beer. I still like seeing the information listed on the bottle - along with the bottle date.

 

/thread

 

most soda (or pop for you weirdos) is 2.3-3.5 pH. while i get that pH would be a good indication for beers (as soda vs beer is apples and oranges)...i can see some beers where the sourness has been masked a bit to carry a lower pH. maybe like a Lindemann's lambic that's been sweetened.

 

I don't need a specific level of sour. I would, however, like an indicator of sourness. Even if it's anecdotal. Expectations play such a big part in my experience with a beer. And others too I'm sure. I remember when Brux came out, so many people were disappointed it wasn't a sour bomb. By the time I tried it, I kind of knew what to expect. And holy crap, that beer was delicious. It was wild, not sour. And I thought it was phenomenal. If I went in expecting Consecration or Oude Tart, I would have been very disappointed.