Whats the reason for using lower AA% hops at boil?

[ChrisG]

I have just bought a 100g bag of Target hops for £5 and they have an Alpha Acid of 10%.

Whats the reason for using say Goldings or Fuggles with AA of 4% as first boil hops? Would it not be more cost efficient to use say 20 grams of Target instead of 50 grams of Goldings to bring it to the same IBU?

Just wondered if there was and advantage, as I would rather save my Goldings for aroma and use the Target for bittering as it would go further. Also with a 90min boil all flavour and aroma of the Goldings and Fuggles would be lost anyway.

Is it just a case of what people have to hand?

[agentgonzo]

You will get a different taste if you use different hops. You'll lose a lot of the flavour and aroma (hence addition of hops late in the boil) but some will remain. Other than that, I'm not sure. I asked a similar question a while ago

[Northern Brewer]

Whats the reason for using say Goldings or Fuggles with AA of 4% as first boil hops? Would it not be more cost efficient to use say 20 grams of Target instead of 50 grams of Goldings to bring it to the same IBU?

Yes, it would be cheaper and more efficient to proceed the way you suggest and this is how many big breweries brew their ales. However, it has long been said that the bitterness associated with high alpha hops can be somewhat harsh and on this basis the best ales utilise the best hops.

I suspect that much depends upon the type of beer you're aiming to produce. The likes of stouts probably don't really care!

I tend to use both Fuggles and Goldings in my darker bitters and have concluded that flavour aside, they do have different bitterness profiles, which enables me to tweak my brews. Goldings impact more upon the rear of the tongue and the bitterness is ever so slightly metalic, but mellows beautifully with conditioning. Fuggles meanwhile seem to impact more on the front of the tongue and the bitterness isn't so spikey. By blending the two I can create a real mouthful of flavour.

[Gurgeh]

agrreing with NB, there's no reason not to use high alpha hops for the boil - that is the reason they exist. I would suggest not using target with safale SO4 as many have noted (though not recently) that they aren't friends.

GW's london pride clone uses target for bittering and it's one of the best brews you could hope to make (IMHO)

[hoppingMad]

A good question. The main reason, IMO, is for brewing a beer within its "style" and specific example.

Some people can detect the hop used for bittering even after an hours' boiling and if Goldings are called for in the style, then it will produce a beer closer to that style than if say... Target had been used.
Personally for me, I tend to use the bittering hop I have on hand, and worry about the middle and late additions more carefully, as you say, these additions are what you're going to taste and smell much more easily. When dry hopping, I would be even more careful with hop choice, as this is going to mean a huge difference in flavour profile. Yes money can be saved by the use of higher AA bittering hops, but at the expense ( possibly) of style fidelity.

[ChrisG]

Thanks everyone, explained and understood

Cheers!