First wort hopping, or FWH is an old process where a brewer adds a large amount of his finishing hops to the kettle during the transfer from the mash tun. As the kettle fills with hot wort, the hops steep and release all the important oils and resins.
Generally, aromatic oils are insoluble and evaporate during boiling. But by steeping the hops before the boil, the oils have more time to oxidize to soluble compounds, which means there’s a greater chance that the oils are retained in the beer during the boil.
First wort hopping used to be a common procedure but was discontinued at some point in the last century. In 1995, a research was carried out on Pilsner style beers using the first wort hopping method which found that the resulting beers had a finer hop profile.
The research was carried out in two German breweries. Both made two versions of a Pilsner following the similar ingredients and recipes. In both cases the first wort hopped beer had higher IBUs than the non first wort hopped beer. Despite the higher IBU, the beers tasted better, with a uniform bitterness when compared to the traditional hop addition beers.
The researchers of this study recommend that first wort hopping should consist of at least 30% of the total hop addition. This should be the later aroma hops and not the bittering hops.
How is First Wort Hopping done
First wort hopping is best suited for beers that require noble hops, and is not suited for beers that want a strong hop oil presence or fruity hop aroma.
All you need to do is add a huge portion of the hop bill (30-50%) to the kettle as the wort is being transferred. The hops will steep in the wort and remain for the duration of the boil.
Be sure to use low alpha acid hops that are usually used as aroma additions. Isomerization occurs at temperatures below boiling, so more hops in the wort for a longer period during the boil will increase the total bitterness of the beer. Since the pH levels are higher for pre-boiled wort, this allows for better isomerisation.
The reason for using first wort hopping is due to the fact that it changes the beer’s hop profile, which will be easily noticeable in moderately hopped brews. Many brewers claim that these pre-boil additions result in subtle notes that can be noticed even in hop-intensive beers. The new hop flavors aren’t easily definable, and the chemistry behind first wort hopping isn’t totally understood, but usually an adjustment of 10% is added to the calculated bitterness in IBUs.
Do you FWH? Please comment below and share your experiences.
Sources: How to brew by John Palmer