A Guide to Dry Hopping

Hops have been used in brewing for 800 years, helping to balance flavours, and stop spoilage bacteria ruining the beer. The concept of a “hop heavy” beer started in the 18th Century when beers which were sent to India were highly hopped to survive the long journey from the UK. Whilst that started the style of India pale ales, or IPAs, today the style is abundant in pubs, bars and homes as the taste for hops continues to grow.

Hops are a magical ingredient and can impart different flavours and aromas depending on how they are used. During the boil, hops will add bitterness (expressed as IBUs) if added early on, and towards the end of the boil will add a range of flavours and aromas.

What Is Dry Hopping?

Dry Hopping is adding hops to the beer post-boil. The high temperatures of the boil can evaporate essential oils meaning the beer won’t necessarily get all those delicate hop flavours and aromas. Because the hops are added well below the evaporation temperature of certain essential oils, all the aroma and flavour compounds stay in the beer without adding bitterness.

When’s a Good Time to Dry Hop?

There are pros and cons to dry hopping at different times. Some brewers will add hops three days into fermentation. This is because the yeast will be at its peak activity, and if you’ve looked at a fermentation through a glass carboy, you’ll see there’s a lot of activity going on in there. The benefit of adding a hop charge now would be that activity helps to “stir” the hops in increasing hop utilisation.

The drawback to this is the aromas can be “pushed out” of the fermenter along with all the CO2 created from fermentation. For a long time brewers would wait until fermentation had finished before adding hops for this reason. But with the growth of hazy and NEIPA styles, more brewers are adding a charge at this time as this also creates a hop haze.

The other time is about five days into fermentation, or when fermentation has almost died down. This will contribute less haze whilst imparting those essential oils, and is more suitable for classic West Coast or English IPAs. The hops may not get “stirred up” from the yeast activity, but less aroma will be driven off by the lack of CO2.

It’s also increasingly common for beers to have hop charges at both times. Known as double dry hopping (DDH), this is when a beer is given more than one hop charge. This way you can reap the benefits of both. This is also recommended for NEIPAs and beers with big hop character.

How do I Dry Hop?

There are a few methods to this. It’s possible to throw the hops in as they are. The benefit is this has the lowest risk of infection as nothing else is being added to the brew which could spoil it. The downside to this is loose hop leafs and/or pellets can clog taps and syphons, get into bottles and generally make the rest of the brew process difficult. Cold crashing can mitigate a lot of this.

Placing the hops in a muslin cloth, a large stainless steel tea strainer or nylon bag will keep the hops nice and tidy and prevent them jamming up bits of equipment. The downsides to this are it’s another “thing” which comes into contact with the beer and therefore poses an infection risk; and the hops are much more bunched together meaning they get utilised less. 

This can be mitigated by paying attention to sanitisation. Muslin, nylon and stainless steel can be boiled before use, or soaked well in Chemsan. Ensuring the bags aren’t too packed with hops will also allow better extraction, and for those huge hop charges more bags can be added.

Adding marbles or stainless steel ball bearings (both of which can be easily sanitised) to the sack will weigh it down. This will prevent the bag causing infections (floating bags can cause pellicles), and all hops will be in the beer and utilised to their fullest extent.

What Temperature is Best for Dry Hopping?

If you can control temperature, 21°C is recommended for dry hopping. The warmer it is the more hop oils will be extracted, however going any warmer might start to stress any yeast still at work, resulting in off flavours. 

Whilst 21°C is the ideal temperature, it’s not detrimental if you can’t get the beer to this temperature. If you’re using a lager yeast which can’t be held warm for example, add the hops at whatever temperature you can!

How Long Should the Hops be in the Fermenter?

Three to five days is a good amount of time. If you can draw off samples in a sanitary way, then it’s recommended to do this until you get the hop character you’re after. If hops are in too long they can impart a grassy flavour on the beer. This is dependent on a range of factors though, just keep an eye on the brew and remove the hops when the flavour suits you!

Is There Any Risk of Infection?

Hops are naturally anti-microbial and were originally used to keep beer drinkable for longer. As mentioned above, throwing hops in by themselves presents very little risk to introducing spoilage bacteria, and a good sanitisation regime will help prevent ruined batches if using something to contain the hops.

What is Wet Hopping?

Wet hopping is something else altogether. These days, it’s referred to using freshly picked hop cones in the beer. Most hops are picked, processed, dried and frozen. Using them straight off the bine will add a different character than using dried. 

If you have any other great tips on dry hopping we’d love to hear them in the comments.