Bitterness in beer

The distinctive bitterness in beer is achieved from the hops added to boiling wort during the brewing process, where compounds in the hop leaf called alpha-acids (primarily humulone) undergo isomerisation to produce iso-α-acids (isohumulone) adding bitterness and producing a balance to the naturally sweet flavour of wort.


Modern styles of beer have seen an increase in hops added at different stages of the brewing process, including at the end of the wort boil (late-hopping) and near the end of fermentation (dry-hopping).

It has been thought that late-hopping and dry-hopping do not contribute to IBUs in beer, however, in Hackney Brewery, an english brewery, brewers have been able to conduct an investigation into this with a very fast and easy in-house quality control without the need for a chemical laboratory: CDR BeerLab®.

The case study: the Effect of Late and Dry-Hopping on IBU Value


The aim of this project was to measure the IBU value of two Hackney beers during late-hop additions (hops added right at the end of the wort boil) and during dry-hopping (hops added during fermentation) with a final IBU measurement taken on the finished product.

All IBU determinations performed during the study were done with CDR BeerLab®, which allowed waiting times to be reduced and analyzes to be performed easily on the production line.

For the study, a wort sample was taken before any late-hop additions and cooled to room temperature before the bitterness was analysed.

At the end of boil, the wort was chilled to 80°C before being transferred to the fermentation vessel (FV). During this time a sample was taken from the copper every 5 minutes and bitterness analysed.

During transfer to the FV, a sample was taken from it every 15 minutes and bitterness analysed. After transfer to the FV, yeast was added and a sample was analysed for bitterness before and after each dry-hopping, with a final sample taken for analysis from the finished packaged product.

Bitterness variation in the beers analyzed: Hackney Kapow! and Hackney APA



Using CDR BeerLab®, in Hackney Brewery, contrary to popular belief they have demonstrated a considerable increase in IBU value from both late and dry-hopping suggesting that alternative compounds present in hops (such as humulinone) do in fact contribute to the IBU value during the brewing process.

The traditional methods for measuring bitterness often requires a laboratory with a laboratory technician, UV/Vis spectrophotometer, water bath, glassware, solvents etc. and can take anywhere from 15 – 30 minutes. Using the CDR BeerLab®, the IBU of a beer sample can be recorded in approximately 6 or 7 minutes and can be performed by anyone.

CDR BeerLab® uses the optimized EBC reference method, the analysis can be performed directly at every step of the beer production process and so you have the possibility to study your recipe optimizing the additions of the hops and monitoring the actual extraction of the bitter.


  • It is well demonstrated the contribution of the late and dry hoping to IBU
  • You are able to check your hops, as a raw material, monitoring the IBU yeld during the beer making process
  • With CDR BeerLab® YOU have the IBU reference method in your brewery!