Bittering hops question

If all of the aroma and flavor are boiled out of the hops when boiled for 60 minutes, why have I found a couple of recipes that call for additions of separate hop types with the same (or similar) AA values at the same time.

All I have been able to ascertain is that bittering hops are used for the bittering only and no flavor or aroma components are left. With that train of thought, why not use a sum amount of a single type hop.

I have searched the net over and am wondering if the recipes in question were brewers just using leftover hops to reach an AA value and the brew turned out fine.

Thanks for the info,
Castaway

No, different bittering hops have different ratios of bittering compounds. We talk about alpha acids, but not much about betas. Also, some hops like Columbus have an astringent component.

Analysis of hop alpha- & beta-acids & beer iso-alpha-acids by micellar electrokinetic chromatography and diode-array detection during beer production
Presenter: Ekaterina Lebedeva, "Baltika" Brewery

Compounds derived from hops determine the bitter taste of beer. Hops and hop extracts used in the wort boiling process contain three main alpha-acids (humulone, cohumulone, adhumulone) and three beta-acids (lupulone, colupulone, adlupulone). During wort boil, six iso-alpha-acids are formed from the three hop alpha-acids. Control of the contents and ratio of alpha- and beta-acids in hops and the concentration of iso-alpha-acids in wort and beer is very important for the brewery, because bitterness is one of the main flavor and taste characteristics of beer.

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Thanks. Another mystery starting to unravel for me!!

Having talked to a brewmaster for Labbatt's, retired after 35 years and now the brewmaster at local brewpub. There is no aroma or flavor to imparted by any hops boiled vigorously for 60 or more minutes. It's all about the Alpha oils at that point.

I've used columbus many times as bittering hops (60+ min) in beers ranging from lighter lagers to dark beers and can notice no diff in astringency than any other hop.

Those Mega breweries may make crappy beer but they do know just about all there is to know on the technical side of things. Even the former Labbatt's brewmaster is jaded about there choice of ingredients. But as he said. People by it, then mega-breweries make it. And if the marketing dept manages to convince people to drink stuff made form 40% Glucose syrup, it ain't the brewer's fault.

Do you know that the megabrewers (at least in Canada) regularly hit 95% efficiency without astringency?? Of course they also do high gravity ferments then dilute so I wonder if that makes any diff?