Testing the bitterness of Beers and Ales

Bitterness in beer is measured on the International Bitterness Units (IBU) scale. This measures the amount of primarily iso-α-acids in a beer which is the acid found in hops that gives beer it’s bitter taste.

Hops growing

The most widely used method to measure IBU is through spectrophotometry. Whilst some procedures require many steps, the method of using Hach LCK 241 vials to measure bitterness makes this job relatively simple.

This technique extracts the primarily iso-α-acids from the acidified sample with iso-octant, and the concentration contained in the iso-octane extract is determined by means of spectrophotometry giving a measurement in Bitter units (BU) ≥ 2 and at an accuracy of BU ± 0.5.

To outline how simple the steps to this method are: 1) In a quartx-glass cuvette add iso-octane to a 1mL sample 2) Shake vigorously 3) Leave the cuvette to stand to separate the phases 4) Remove the organic phase using a pasteur pipette 5) Dispense into the a clean quatz-glass cuvette 5) Wipe clean your cuvette and place in spectrophotometer to evaluate.

The LCK 241 vials are designed to be used in conjunction with the Hach DR6000 UV VIS Spectrophotometer, this will have pre-set methods installed that allow you to measure bitterness at a set UV wavelength.


If you are looking to measure other aspects of your beer such as colour, this spectrophotometer can also be used for this test too, you can find out more about that in our previous blog here.

If you would like more information about this method or want to find out more about beer testing please get in contact one of our technical support team on 01954 233 120, support@camlab.co.uk or fill in the contact form below.