I apologize again for the inactivity on the blog. I haven’t been brewing much the last half a year. The wife and I bought a house in the end of last year and we’ve been renovating it since. We finally moved in a couple of weeks ago, and have started settling in. So soon I’ll be able to return to brewing again! Anyways, last week I attended the 5th International Young Scientists Symposium on Malting, Brewing and Distilling, which was arranged at Sierra Nevada’s brewery from April 21-23, 2016 in Chico, California, USA. First of all I want to thank Ken Grossman, Sierra Nevada, Charlie Bamforth and all the other organizers for a fantastic conference (especially Sierra Nevada for their generosity)! The conference featured great scientific and social program, awesome food, a relaxed atmosphere, amazing people and delicious beer! I myself presented some of the recent research we’ve been conducting on lager yeast hybrids at VTT the past year (I’ll post a link to the presentation slides soon!). To sum up, we’ve been looking at how the ploidy of new lager yeasts affect their phenotypical properties. I’ll be writing up a more detailed post on this particular research soon, as we just had a manuscript on this work accepted.

As I mentioned, there were a lot of interesting presentations during the conference! I thought I’d write some short notes / summaries of all the presentations in case you are interested. Since there were a lot of presentations, I’m splitting this post into three parts. Anyways, here is the first third of the summaries:

• Keynote: How Craft Brewing is Transforming the Way We Think About Hops and Hop Flavor by Tom Shellhammer

Tom opened the conference with an interesting talk on the current situation of hop use in the craft industry and hop research at OSU. Craft brewers are using more and more of the global hop production, which also has shifted from being ‘bitter hop’-dominated to being ‘aroma hop’-dominated. Tom also reminded the audience that 1 IBU is not the same as 1 ppm iso-alpha acid. This is particularly relevant with heavily dry hopped beers, where oxidized alpha acids (which are bitter, but not as bitter as iso-alpha acids) can influence the IBU value. In some commercial (dry hopped) beers that had been analysed at OSU, they had observed very high levels of oxidized alpha acids. Another point that was brought up, was that the perceived bitterness gets saturated at high IBU levels (i.e. very little sensorial difference between a 80 IBU beer and a 100 IBU beer). Tom also showed a very interesting figure (which Daniel Vollmer showed again later in his presentation), showing the relationship between hop oil content in Cascade hops sourced from different farms and the hop aroma intensity in beers brewed with these hops (determined by a sensory panel). What was extremely interesting was that there seemed to be no correlation what so ever. The beer brewed with the Cascade hops with lowest oil content actually seemed to have one of the highest aroma intensities. Furthermore, many of the Cascade hops that had the highest oil contents produced beers with the lowest aroma intensities. This just shows that blindly looking at hop oil contents in hops doesn’t actually tell very much about what kind of hop aroma it will give to the beer. If I remember correctly, Tom also suggested that there was no correlation between linalool or myrcene concentrations and the hop aroma intensity either, meaning that there are other key aroma compounds responsible for hop aroma out there that still need to be identified.

• Towards the release of a 2-row barley variety for California craft malting and brewing by Joshua Hegarty

Joshua talked about how they have attempted to breed a 2-row barley variety that would be suitable for the ‘harsh’ growing conditions in California. These include an abundance of plant pathogens and dry conditions. They had crossed different parent strains, and selected superior varieties which they had then tested in the field. The new breeding lines had shown good yields and malting quality in the field trials. Using gene mapping they had also found several regions associated with disease tolerance in barley.

• Impact of barley varieties on malt and beer flavor by Lindsay Barr

Lindsay presented some research on the influence of barley varieties on malt and beer flavour that had been carried out at the New Belgium Brewing. Barley variety seems to have quite a big influence on both wort and beer flavour (at least according to their sensory panel). However, there didn’t seem to be any correlation between the flavours that were observed in the wort and the beer. Beer age seemed to have had a bigger impact on the beer flavour than the barley variety.

• Selective pressurized liquid extraction of hop oil from hop cones by Katy Orr

Katy talked about some of the hop-related research that had been done at Sierra Nevada Brewing. Her background was in environmental chemistry, where she had used different extraction methods to quantify hydrocarbons from environmental samples. Here, she talked about how they had tested two different extraction methods, selective pressurized liquid extraction and Likens Nickerson distillation, to test the efficiency of their hop torpedo. Both methods seemed to have yielded quite similar results for some of the compounds that were analysed. However, the main points that were brought up were that the extracted amount does not equal the actual contents and subsequently the importance of good internal standards (that behave chemically and physically as similarly as the compound of interest as possible).

• Pro-oxidative effects on the storage stability of German Perle and Czech Saaz pellet hops by Mark Zunkel

Mark had compared the stability of Perle and Saaz hops exposed to oxygen at room temperature during a 9 month period. The hop storage index (HSI; which measures the loss of alpha and beta acids spectrophotometrically) of Perle remained quite stable for around 4 months, after which there was a more rapid loss of the hop acids. Saaz seemed to have remained slightly more stable than Perle, but also experienced a more rapid loss in the latter half of the experiment. Unsurprisingly, both hop varieties suffered a rapid loss of hop oil in the pro-oxidative environment (50% loss of hop oil in a week). This just shows that aroma hops should be stored cold and without the presence of oxygen!

• The effect of hopping regime, cultivar and yeast ß-glucosidase activity on terpene alcohol levels in beer by Daniel Sharp

Daniel talked about the research he had been doing on the release of hop terpenes into beer from hop glycosides. This is an interesting topic for brewers interested in hop aroma, as aroma-active compounds can potentially be released during fermentation through the hydrolysis of hop-derived glycosides in the beer. He had tested the beta-glucosidase activity of a wide range of brewing yeast strains, and then selected strains with high and low activity. Surprisingly, beta-glucosidase activity didn’t seemed to affect the maximum hydrolysis level that was achieved during fermentation (and this level was much lower than the positive control where purified enzyme was added to wort). It just took a slightly longer time to reach this level with the low activity strain. Daniel didn’t seem to see any correlation between beta-glucosidase activity and the amount of aglycones in the beer. Higher glycoside extraction was achieved with whirlpool and dry hopping compared to kettle hopping. Some varieties that seemed to be high in glycosides were Columbus, Centennial, Simcoe and Summit.

• Creating a gin utilizing novel Scottish Botanicals: A University-Industry collaboration by Margaux Huismann

Margaux talked about her MSc project, which was carried out as a collaboration between Edinburgh Gin and ICBD. During the project, she and 3 other students had developed a gin featuring Scottish (coastal) botanicals. They went to the Scottish coast to forage for interesting botanicals, and then distilled them in lab scale to develop a recipe. The recipe was then used at larger scale at the distillery to produce a commercial product. One botanical in particular, Bladderwrack, seemed to have given off a strong ‘fishy’ aroma during distillation, and its volatile aroma compounds were analysed in more detail. We later got to try the actual gin, and it was really nice (not at all as salty or ‘fishy’ as I first was expecting). Thanks Margaux!

• Keynote: Impact of brewing practice on yeast performance by Katherine Smart

Katherine talked about some of the research she has been doing the last 15 years. This research has been focused mainly on repitching, yeast viability, stress tolerance and petite mutants. Most interesting to me was the work on why ‘1st Generation’ yeast (i.e. yeast that have already undergone one fermentation) seem to start fermentation faster than ‘0 Generation’ yeast (i.e. yeast that come straight out of the propagator). One cause, is that G1 yeast bud faster than G0 yeast (i.e. enter the replication cycle faster) and (if I remember correctly) are able to use glucose faster from the wort. G1 yeast also seem to use less FAN from the wort, which I found interesting (less nitrogen demand or more biosynthesis?). They had also used high-throughput screening systems to isolate osmo- and ethanol tolerant strains. A quite interesting remark was that strains are seldom good at both, i.e. an osmotolerant strain is rarely ethanol tolerant as well. One good point that was made regarding these high-throughput systems is that you find what you are looking for. These isolates may have high tolerance, but may otherwise perform badly in wort or produce off-flavours.

• Cambridge Prize Lecture: The Influence of Yeast Handling on Petite Mutant Formation by Stephen Lawrence

Congratulations to Stephen for winning the Cambridge Prize! Stephen talked about the research he had carried out, which won him the Cambridge Prize. His research was focused on petite (or respiratory-deficient) mutants in brewing, and during his presentation he also talked about various stresses the yeast are subjected to during fermentation. Petite mutants (i.e. cells with damaged mitochondrial DNA) form during fermentation as a result of fermentation stresses, and these can accumulate when yeast is repitched for several generations. These petites perform worse in several regards compared to wild type cells, so their accumulation is not desirable from a brewer’s point of view. Some interesting points that were brought up, were that older cells (i.e. cells with more budding scars) were more susceptible to petite formation and that lower mtDNA copy numbers actually didn’t increase the likelihood of petite formation (e.g. older cells tend to have more mtDNA copy numbers). This seems to suggest that the accumulation of mtDNA damage has a higher impact on petite formation than the copy numbers of mtDNA. This was a very interesting talk, and the topic still seems to be quite poorly understood. It will be interesting to follow the topic in the future.

Parts two and three will be posted during next week!