Predicting the effects of hop blending

Chris Smart, Head of Brewing Services

Beer brands utilise a blend of specific hop varieties in their recipes to give it a distinct aroma and flavour. But if any of these hop varieties are in short supply, which is becoming more common with the arrival of novel hop varieties, this creates a problem for the brewer. Ongoing research is investigating techniques for predicting the sensory attributes of blending hops in beer. The aim of this work is to help the brewer accurately match the sensory profile of any aroma hop which may be in short supply, with a blend of alternative hops. Listen to Chris Smart explain the issues involved and techniques employed in this fascinating talking head.

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This project was initiated mostly by the brewers and also by some of our member companies, particularly hop merchants, because there's a renewed interest in using hops to produce beers with different flavours, different aroma characteristics at the moment.

With more than 200 hop varieties to choose from, there's a lot of possibilities obviously out there. not only in terms of single hops but also in terms of blending hops to get to some sort of interesting beer at the end of. That's particularly true in the craft sector in lots different countries around the world, but also the bigger breweries for a number of years have been looking at some these new hop varieties in terms of new products and developing new products. So, there's a lot of interest across the whole of the industry in hops at the moment. There's also an interest from the marketing perspective too, so you can now buy products and beers that are made with named hops, either individual hops or a range of different hops in those beers. So, it's being used very much as a marketing tool as well to bring people and educate people into beer which has been really successful in lots of different countries. But, of course, blending hops and finding the interesting characteristics and how they might play through to the final beer is very difficult to do.

The supply of hops in recent years has been very challenging, certainly in the last year, in 2015, in some parts of the world hop yield and hop growth was significant lower then it was expected to be partly because of weather conditions. Certainly, in Europe the amount of rainfall over the summer months just before cropping was very low so that really influenced the crop yield of some of the aroma hops, at least, in that part of the world, so it's been very difficult. Supply of proprietary hops has been difficult for a very long time because they're produced at low levels but also, particularly in the craft sector, there's a huge demand so there's a poor supply and there's a high demand for some of these varieties and finding alternatives and ways in which you can compensate for those missing aromas they're missing flavours is extremely difficult.

Predicting the final characteristics, in terms of aroma and also flavour, of hops in a final beer is extremely difficult. I would say and, I hope most people would agree in the industry, it's more art than science. So, finding some way in which you can actually predict what different hops will produce in the final beer, is of a huge amount of interest. What we've done is we've taken some sensory approaches but also analytical approaches to understand what happens to those hop compounds throughout the process and to see if you can predict using that scientific approach what a final beer will look like. Approaches so far been really interesting, one of the things we've done is looked at hop teas, which is very common way of trying to understand the characteristics, particularly the aroma characteristics of hop varieties. What we have found is that you take those hop teas and those hops and you brew them through to the final product, the hop teas are a very poor predictor of the hop characteristics in the final beer product, so hop teas are not a great way of doing blending work. What we have discovered is that you need to brew individual hops through to the final beer and then take that data in terms of sensory, also analytical, take it as a whole, analyse it and that way you should be able, we think to be able to understand how to blend different hops get to the final beer.

What we have done is, we've done that with a particular hop variety called Amarillo. Amarillo is a proprietary hop, it's in huge demand, it's probably the most expensive hop variety in the world but it's provided at very low levels by comparison to most, so in huge demand. In order to be able to match that we’ve taken a hop that we found was very similar to Amarillo but was missing certain characteristics. We found another hop variety which compensated those characteristics, we blended them expecting to have to do several different brews to get it close to Amarillo. We did the first blend, gave it to our expert train panel they assessed it and, in a difference test, they could not tell the difference between the two. Obviously, we were delighted.

The next steps to this project are in two parts: firstly, we're going to start to look at timing of addition - when is the best part of the process to add hops to make sure you maximise the flavour and the aroma that comes through to the final beer? There's a lot of interest in the moment in using the pilot pressure, called the whirlpool to add the hops to develop those aroma characteristics, but we're going to look at the whole process from kettle from boiling, all the way through whirlpool, fermentation and also in conditioning as well. So, we'll look at the whole of the process and we'll see what kind of information we get in terms of sensory but also analytically, in terms of those compounds and where they go to throughout that part of the process, so that's the first part timing of addition.

The second part is looking at dry hopping a hugely important area, particularly the craft sector, but also something that's becoming more important for the large companies as well. So, what we're going to do is we're going to look at equipment and methodologies, and approaches around dry hopping to try to understand what happens and all these different methodologies, all those different equipment to those hop characteristics through that process. But also, very importantly, we want to look at efficiencies, and extraction efficiency in particular, of some of these hop compounds - what's the best way to maximise it? We're pretty sure that some companies are using way more hops than they actually need to deliver those characteristics, but nobody's really done a scientific analysis of this so that's what we're going to do.

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