Terpenez for Dayz
Back in January we brewed a brand new beer at Hops & Grain Brewing called Terpene Dream APA. We utilized a couple of our 7 bbl pilot fermenters to split a 15 bbl batch into two 7 bbl batches and test out a couple new yeast strains from Imperial Organic Yeast. We purchased four 7 bbl fermenters late last year for trials such as these and they've been loads of fun. Since we have a 15 bbl brewhouse they are a nice way to split batches to test out single variables such as dry-hopping or yeast strains while keeping everything else the same, literally coming from the same knockout.
Not only have they been quite educational for us as we explore new dry-hopping processes and ingredients but they've also allowed us to extend that educational experience to the folks who visit our tap room. Maybe it's just because I used to be an teacher but I've always enjoyed brewery visits where I felt like I learned something new. That could be just learning more about the brewery or it could be learning more about the processes that they use. That transparency, I believe, is what draws people to visiting breweries and we've worked hard to provide a level of transparency at Hops & Grain that is engaging and educational for our staff and for our customers.
With Terpene Dream we wanted to test out an interesting, albeit relatively dangerous, yeast strain. This yeast strain is a sub-species of Saccharomyces Cerevisiae and what makes it different, and dangerous, is its ability to utilize unfermentable dextrins and break them down into simple fermentable sugars. Most Saccharomyces strains lack the ability to process or break down dextrins. But this particular yeast strain that we were interested in, Saccharomyces diastaticus, does have the ability to break down dextrins as well as producing a very unique aroma and flavor profile that more resembles a fruity Brettanomyces strain than a Saccharomyces strain. It's also similar to Brettanomyces in that it can literally ferment a beer down to almost complete dryness and if packaged too soon or stored improperly, a secondary fermentation can occur when these dextrins are broken down into fermentable sugars. This can lead to all kinds of issues ranging from off-flavors to exploding cans and bottles. The folks at Good Beer Hunting published this great piece about Diastaticus and the real world issues that it has presented for brewers around the world. Definitely worth a read.
My interest in this strain was more in regards to the biotransformation potential and the flavors and aromas that could be derived when hops were introduced while active yeast was still in solution. Biotransformation has been a topic of discussion for some time amongst brewers large and small, some of my favorites can be found on Scott Janish's blog, scottjanish.com. There have been numerous studies conducted that essentially prove that monoterpene alcohols from hops can be metabolized and transformed in the presence of yeast. One in particular is Geranoil, which lends more on the floral side but can exhibit wonderful citrus characteristics when metabolized and transformed by yeast. Given that this peculiar new yeast strain has the ability to break down and metabolize dextrins I wondered what it could do in regards to metabolizing terpenes.
The grain bill for Terpene Dream was pretty simple and we focused on high oil content hops for both the whirlpool additions as well as dry-hopping. I chose Chinook, Nugget and Mosaic for their higher quantities of Linalool and Geraniol and also because I just really like the flavor profiles of each of those hops together. And the results were pretty tasty. Both 7 bbl batches maintained all the same variables with the exception of yeast strain used. One of the tanks utilized a yeast strain known for it's fruity ester profile, especially when fermented at the higher end of the temperature range. It was also a yeast that we were fairly familiar with. The other was a blend of an English Ale strain and Diastaticus. They both fermented fairly consistently and were both dry-hopped with the same amount of Chinook, Nugget and Mosaic. The Diastaticus batch was a bit slower to reach that gravity and went thought a bit of a stall around 5 Plato. After a few days it picked back up and moved along to terminal. They both finished with a very pleasant hop profile full of citrus and jammy notes but the Diastaticus batch exhibited a very unique ester profile that had notes of stone fruit and pear alongside some slightly phenolic characteristics. At first they were pretty exciting but after about a week in kegs it kicked off a secondary fermentation and proved to be quite the annoyance for our draft system. And the dryness felt out of place for the desired profile of the beer. Overall I preferred the batch fermented with non-diastaticus yeast.
All in all the results were great but I didn't find the diastaticus batch to be as interesting as I'd hoped. Additionally, the headache of trying to manage an aggressive yeast like that with beer headed out the door for distrubiton was more than I really cared to bother with. Our on-site quality control lab was crucial for this experiment in a number of ways but most importantly was the ability to run samples through PCR analysis. We knew that the yeast blend contained diastaticus but what became more important was ensuring that we effectively killed it off after emptying and cleaning the fermenter and brite tank the held that batch of beer. Diastaticus can spread rapidly and the peace of mind that DNA sequencing provided definitely helped me sleep at night.
This week we're releasing a new batch of Terpene Dream and for the first time we'll be packaging it in cans for sale in our tasting room as well as throughout our Austin distribution footprint. Not much has changed with the original recipe and we're still showcasing Chinook, Nugget and Mosaic in the dry-hopping. We're excited to welcome this beer to our lineup of other experimental hoppy offerings like Lupulin Rodeo, Pellets & Powder and our Dispensary Series.
If you get a chance to try Terpene Dream I'd love to know what you think! Hit me with a comment here or on the twitters @hopsandjosh