By Mathis Geserer, Hopsteiner
There are many factors that might have an influence on the hop derived aroma and bitter impression of a beer. This article shares some general thoughts on how to take most of these factors into account when working on new recipes or refining existing ones.
Based on these considerations, I will share my approach on hopping two variations of an IPA, based on the same wort.
Beer style
The first step when working on a new recipe is to define all properties of a beer that might affect the hopping. Starting with basic key data such as original gravity and level of attenuation, alcohol content and the yeast-induced aroma profile all need to be considered.
The malt bill is also essential in this process, especially if it contains raw grain, sugar, caramelized or roasted, even smoked malts. Beers that carry lots of adjuncts such as sugar, tend to be less robust, therefore cannot cope with as much bitterness as an all malt beer.
Large proportions of roasted malt in the grist also need to be considered, as these may contribute bitterness in the finished beer. After the foundation recipe is decided, it is the brewer´s decision to either keep his hopping true to the style or work out his own variations.
Hop products
The main limiting factor for aroma hop dosages in the brewhouse is the whirlpool capacity. We would like to avoid too much hot trub entering the wort cooler or transferred to fermentation.
To reduce the whirlpool load, we can either use a product such as Hopflow (CO2- or total resin extract) at the beginning of the boil or partially substitute aroma dosages with Aroma Extract or Lupulin Pellets in the late kettle and whirlpool dosages, with the addition of hop oils in the cold part of the brewery.
Dry hopping-induced beer losses in the cold part may also be reduced by using Lupulin Pellets.
Hop oils that reflect the natural oil composition in hops can mimic the same or a similar dry hopping aroma (1). They should be applied during active fermentation to avoid an artificial aroma caused by the more volatile compounds, such as myrcene and beta-caryophyllene.
Linalool-based hop products on the other hand may be used inline pre-filtration or directly in the bright beer tank to replace or support whirlpool or dry hopping dosages.
Hop varieties
Usage of varieties with a high alpha content, such as Herkules, Polaris, Eureka or Apollo is another effective way to help to reduce kettle hop load beer losses.
By providing most of the necessary alpha acids from early to mid-boil additions, we have capacity left to work on the aroma profile with low or mid-alpha varieties, such as Tettnanger, Hallertau Tradition or Akoya in late or whirlpool additions.
Dosage ratio and technique
The dosage ratio in the brewhouse has significant influence on the bitterness, as well as the aroma profile of the finished beer.
When aiming for a rather clean up-front bitterness, without the need for significant hop aroma, we utilise a single dosage at the
beginning of boil or introduce a split dosage, in a ratio of 80:20 to 50:50 for early and mid-boil additions.
If we aim for a more versatile bitter profile and if more hop aroma is desired, we can apply two or three dosages throughout the boil supported by a whirlpool dosage in a ratio of 50 (beginning of boil): 30 (mid-boil): 20 (end of boil/Whirlpool).
In any scenario, more than one hop dosage results in a positive contribution of flavour stability of the finished beer (2).
When it comes to whirlpool additions, we also have some flexibility.
Using varieties with higher oil content, containing a large share of terpene-alcohols, help in reducing the total amount of hops. A high alpha content limits the dosage rates due to increased isomerization. This must be considered when using hops with a high alpha and high oil content for the late hop dosage, where varietal aroma characteristics are required, such as Lotus.
In general, cooling the whirlpool to ~85 °C reduces isomerization significantly, allowing us to increase the hop dosage. If we are aiming to create a beer that is fruity and citrusy, varieties high in geraniol, such as Bravo, Cascade or Motueka, will help facilitate biotransformation during main fermentation (3, 4).
To help calculate the bitter dosages, we have created an overview of isomerization rates, depending on the contact time from our pilot brewery (table 1). These values will differ depending on the used brewhouse set-up, wort composition and need to be analytically validated, but may be used as a guide.
Table 1. Isomerisation rate of Pellets vs. Extract over time
In the cold part of the brewery we can perform dry hopping at numerous points throughout active fermentation and into the final attenuated beer.
The earliest point of addition is when the yeast has switched from aerobic to anaerobic metabolism and pH value drops down first tenths. That way, we avoid microbiological issues in the fermentation.
An early dose of geraniol rich hops during active main fermentation, combined with a yeast with high biotransormation potential, results in a more fruity and citrusy product than it would by using the same hop dosage rate in the final attenuated beer (4).
Always keep in mind that high rates of dry hopping during active main fermentation will cause an increase of fermentable extract and therefore attenuation, resulting in an increased alcohol level in the finished beer. This refermentation can cause overcarbonation and gushing in the packaged beer.
To achieve a more variety specific charateristic in beer, it helps to add the dry hops in the maturation tank.
Dosing rates for dry hopping range from a total of 0.3 kg/hl up to 3.0 kg/hl when using Pellets type 90. This mainly depends on the oil content of the pellets and the aroma intensity one aims for.
Additional bittering by alpha acids and unspecific bitter compounds of the hops needs to be considered in the overall bitter balance.
IPA variants from base beer
Our base recipe is a 16 °P wort, with a malt bill consisting of 65-70% base malt such as Pilsener or Vienna or a combination of both, 10-15% caramelized malt, 10% wheat malt and 10% oat flakes.
We aim for an apparent final attenuation of 75-80%, resulting in 6.5-7% abv. by fermenting with an ale yeast.
West Coast IPA
With a robust malt body, with a higher proportion of caramelized malt and in combination with the moderate final attenuation, it comfortably allows us to aim for 60-70 analytical IBUs in the brewhouse. This creates a strong bitter profile without being
unbalanced.
The sensory perceived bitterness will be lower than the analytical and allows us to add dry hopping dosages without exceeding the overall sensory IBUs. We achieved target bitterness with three dosages throughout the boil.
To reduce beer losses in the whirlpool we start with a high alpha pellet, Hopflow or a hop-extract dose at the beginning of the boil, that covers ~30 IBU (50% of total IBUs). The first dose is supported by a mid-boil dose covering ~18 IBUs provided by high-alpha pellets. For
these two applications any bittering variety will do, ranging from classics such as Herkules or Magnum to more recent varieties such as Polaris, Eureka! or Bravo.
However, the perceived bitterness will differ with the variety used, it is up to the brewer to decide the characteristics they require.
Generally speaking, lower alpha aroma varieties are also suitable for bittering if less intensity or smoother bitterness are desired. This makes sense for low IBU beers with a small overall kettle hop dosage that can cope with the increased hop load.
These bittering dosages are complemented by a whirlpool addition, covering the ~12 IBUs left (20% of total IBUs).
Since we are dealing with a West Coast IPA, we are aiming for a more variety specific hop characteristic in the beer. We have already created some fruitiness with our whirlpool dosage and utilise a single dry hopping dosage into the final attenuated beer.
Again, the higher the oil content, a lower dosage can be used and subsequently lower beer losses.
Variety specific characteristics can be enhanced by using the same hop in the whirlpool as for dry hopping. The aroma profile can be anything from resinous and spicy, to citrusy and fruity, depending on the varieties used.
New England IPA
To meet the requirements of this beer style, we need to create a hopping regime with a low bitter intensity and a strong juicy aroma profile. That said, we aim for 35-40 IBUs in the brewhouse that are balanced by the malty body of our 16 °P wort and includes a proportion of
caramelized malt.
The foundation of the hop profile, is a small dosage of bitter hops in the begin of the boil of ~10 IBUs. This dosage helps with forming the hot trub as well as inhibiting the formation of foam during the boil. High alpha pellets of any variety will do this job.
The rest of the IBUs are dosed in the whirlpool at a reduced temperature of ~85°C, to create an intense aroma characteristic, without over-emphasizing bitterness.
The introduction of geraniol rich hops into the whirlpool, as well as the first dry hop, supports biotransformation during fermentation (4).
The first dry hopping dose is added at 20 % of final attenuation. This is our main dry hopping dosage, as vigorous yeast activity causes CO2-purging of mono- and sesquiterpenes.
Due to the low alcohol content at this stage, the solubility of certain hop oil compounds in the beer is reduced. That way we can push the hop aroma to the fruity and citrusy side while purging some of the spicy and greenish aroma.
To add a more variety specific characteristic to the hop aroma or simply increase the overall aromatic impression, a smaller second dry hop addition at the end of main fermentation or into the final attenuated beer, can be added.
All above considerations are transferrable to other beer styles and can help with your hopping regime. A low IBU lager with an intense hop aroma for example, might be hopped using the brewhouse hopping regime of the New England IPA.
A 35-40 IBU Pilsener can work with the hot part additions of the West Coast IPA as long as the ratio between bitterness and sweetness is balanced to fit the style, by adjusting the total IBUs to a level the original gravity can cope with.
This article spotlights the usage of mainly pellets, extracts and hop oils. There are various special hop products, technologies and procedures that can help with reducing beer losses, increasing iso-alpha- and aroma yield, enhance foam stability or provide light stability.
Closer examination of all these subjects would go beyond the scope of this article, but at Hopsteiner we would be happy to support you creating new or revising existing beer recipes.
Please find further information on hops and hop products at www.hopsteiner.com or contact [email protected].
References:
1. Feiner, A., Mitter, W., A tasting of specially hopped beers, Brauwelt International no.
4, 2014.
2. Kunz, T., Frenzel, J., Wietstock, P.C., Methner, F.-J., Possibilities to improve the
antioxidative capacity of beer by optimized hopping regimes, Institute of Brewing &
Distilling, Research article 2014, wileyonlinelibrary.com, DOI 10.1002/jib.162.
3. Takoi, K., New classification of geraniol-rich hops, Brauwelt International no. 2,
2014.
4. Takoi, K., Itoga, Y., Takayanagi, J., Kosugi, T., Shioi, T., Nakamura, T., Watari, J.,
Screening of geraniol-rich flavor hop and interesting behavior of β-citronellol during
fermentation under various hop-addition timings, January 2014, Journal of the
american society of brewing chemists 71(1), DOI: 10.1094/ASBCJ-2014-0116-01.
