alpha acid in heather

Can anyone here tell me the alpha acid value of heather tips? I recently brewed a batch of scottish-ish beer using heather tips and would just like to know to compare to the alpha acids/ibu's in hops.
Thanks ahead of time if anyone can help!

Alpha acids are only found in hops. Hope your heather ale turns out!

False.

The hop constituents that are the major contributors to bittering are humulone, cohumulone, and adhumulone. They are all alpha acids by definition because of their structure. There are thousands of alpha acids. Also, hops are not the only plants that contain humulone, cohumulone, and adhumulone. Furthermore, humulone, cohumulone, and adhumulone are common names for these compounds, r-isovaleryl, r-isobutyryl, or r-methylbutyryl, and these names are used almost exclusively in conjunction with brewing.

Through experimentation, we know that if we measure the hop alpha acids we can use that to replicate the bitterness in beer to a known level.

The problem in estimating the bitterness contributed by something other than hops is that the chemistry of the ingredient being used has not been studied to the same extent. This is where "trial and error" comes in.

I know that heather and spruce have been used as a replacement for hops, but you'll need to research what the amounts used were.

Actually, it is true. These particular compounds are, unless there has been a recent discovery to the contrary, unique to hops. Perhaps other plants have similar compounds. I think theredben may be confusing alpha and beta as is alpha-acetolactate where those letters describe the stereochemistry with the designations for hops acids where alpha means that there are 2 isopentene groups (at 1 and 5) and where beta means there are 3 (2 at the 5 carbon). The " ", "co", "ad", "post", "pre" and "adpre" designations describe the the side chains at carbon 3 and apply equally to the alpha and beta acids i.e. cohumulone (alpha) and colupulone (beta) both contain a isobutyryl side chain. While I suppose any alipahtic chain could conceivably be attached at C3, only 7 seem to known.

Bitterness in hops is attributable (mostly) to the alpha acids because they isomerize in the boil more readily than the betas. The perceived bitterness of beer has been found to correlate well with absorption at 275 nm at acid pH where iso alpha acids absorb more than the betas though the betas absorb there as well. The 275 reading thus correlates well with ISO alpha acid concentration - 1 IBU is approxiamtely 1 mg/L. Knowing the acid contents of hops we can make some assumptions about utilization and estimate what the bitterness should be. We can check with the 275 nm measurement.

In a different, though bitter, plant the bittering principals are not humulones but other substances where the correlation between perceived bitterness and some simple laboratory measurement are not, AFAIK, known. Thus you will have to rely on the experience of others. Considering heather tips: there may be "cultivars" of heather that contain more or less of whatever their bittering principals are than others and growing conditions may have an effect as well. IOW, the general concepts are the same as with hops though the bittering compounds may be different. I think you will just have to experiment.

Thanks for the replies, I will just have to see how it turns out. Interesting discussion. Although I really like hops, big IPA's in particular, I'd really like to learn a little on how they did it with out hops. Does anyone know of any studies done on heather qualities? I've googled it a bit and none of it seems to really answer the questions.
Thanks again, everyone.

Just to clarify my position: I don't have nearly the scientific background you guys do on this subject, but I just knew that there was no conversion from a certain AAU amount to an equivalent amount of heather tips. Basically I was just using layman's terms for your fancy scientific info. Thanks for the details though.

moinkyschmoink - I think the issue with heather tips is that the varieties used nowadays in gardens are not going to be the same as used 200+ years ago. Ornamental plants(heathers) change so much quicker than agricultural crops (hops).