Pre-Harvest Hop Testing - 2020
The diversity of hop varieties is amazing. For traditional brewing purposes, different hops are used to create different styles of beer. For example, low alpha acid (low bitterness) varieties such as Hallertau or Saaz are used to create Pilsners, and high alpha acid varieties like Chinook are used in IPA's.
I have talked with many Brewers and their #1 requirement of purchasing hops is "Quality!", so.......what does quality really mean?
Hop Growers spend much of their efforts maintaining and protecting their crop throughout the growing season. Across the Northern half of the United States, near the end of July, the harvest season begins. Proper harvest timing could be the most important aspect of growing a "Quality" hop.
Why is timing important? If you pick too early, you will have low alpha acids and a grassy aroma. If you pick too late, they will have a garlic/onion aroma, or give an off-taste. If this happens, you may not be able to sell your hops.
So, when do I harvest? Well, many ways to determine "ripeness" of hop cones have been explored. But, the most accurate and dependable technique is having the cones tested. When analyzed, we determine the top 3 indicators of harvest timing: dry matter, alpha acids, & co-humulone, as well as HSI. For each of your varieties we will indicate if each of these are in range (time to pick!). Reviewing the AAR Pre-Harvest Hop Reports allows you to prioritize your harvest.
To test whether or not a hop crop is ready to harvest, you gather a good sampling of cones from each variety, filling up a sandwich size baggie (~1 oz), put them in a box, add some newspaper for insulation, then ship them to our lab.
For more info on sending samples, and our online lab, CLICK HERE or send me an email.... firstname.lastname@example.org
Happy 4th everyone!
There is a ton of information out there about alpha and beta acids with the current craft IPA boom. Plant suppliers, producers and brewers need to characterize their products to brew great beer and achieve effective marketing. I see many references to % cohumulone and % colupulone, and hope to clearly and concisely define what these numbers refer to, and where they come from.
The % cohumulone (an alpha acid) and % colupulone (a beta acid) numbers can only be obtained but analyzing hops by HPLC (High Performance Liquid Chromatography). The figure above is the output from the ASBC International Method, we see cohumulone (an alpha acid) and colupulone (a beta acid) identified. When someone indicates they have 4% Alpha Acids (with 25% cohumulone), they are referring to the numbers obtained from this method. Let's break it down.....
So on a weight basis, (% or g/100g(same thing)) the hops has a total of 4% or 4grams per 100g of hops. This value is all the alpha acids added together.
Cohumulone is analyzed and we find the hops contains 1% cohumulone. So, we describe the amount of cohumulone to be 25% relative to the total. 1/4=.25 x100 = 25%
These values should be more clearly defined as (cohumulone - 25% of the Total Alpha Acids)
Same exact process for the calculation of colupulone as it relates to the total amount of beta acids.
Who cares? and Why? Well, there are many advantages to characterizing your products or ingredients in this way. First, the realtive amounts of colupulone and cohumulone can be a strong indicator of what variety being analyzed, grown, or used in brew, just by simply comparing the results to variety catalogs. In addition, dry hopping and the aroma associated has put a keen focus on the role of beta acids in the brewing process (which until recently, has been diminished). So, more details here about the hops helps in fine tuning.
Also, this information can better define the total amounts to be added based on seasonal variability. Lastly, I have found this method procedure is more rugged and accurate than the more widely used spectrophotometric assay (we do this too).
So, get more bang for your buck, know your product, sell more of it, and brew a better beer. Thanks, ZL
Zach Lilla, Lead Chemist at AAR has over 17 years of analytical chemistry experiece focused in the areas of Food, Dietary Supplements, Beer, Wine, Hops, and Distillate Analysis.
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