Lesson 8 - Brewing with Hops

Although it is due to hops being used in beer. We can’t measure the IBU of hops. So, what does an IBU really mean anyway? How bitter is an IBU in taste?

As we have just seen, IBUs are a value calculated from the results of spectrophotometry of bitter substances extracted from beer into iso-octane. It is usually assumed to be around 1 mg of iso-α-acids in 1 L of beer but IBU is not the same as mg/L iso-α-acids as measured by HPLC.

That still doesn’t really answer the question of ‘How bitter is an IBU in taste?’ How many IBUs should you add to make a beer of low, medium or high bitterness?

This is difficult to answer, as the perceived bitterness can be affected by so many factors besides the IBU value. These include the amount of residual extract in the beer, the carbonation, the alcohol level, the polyphenol level and types, and even the person tasting the beer!

As a starting point in selecting a target IBU, we can refer to beer style guidelines. These guidelines give a bitterness range that the organisations who publish them feel some consumers might expect for a particular beer style. These guidelines might be useful; if you brewed an American light lager with an IBU of 60, you would have some angry and confused consumers! That said, the vast majority of beer consumers worldwide have no idea of who the Brewers Association or BJCP are, let alone how many IBU they feel are appropriate for the beer they are drinking. It is better to brew a beer that you and your consumers enjoy than to worry about sticking to a style. The right level of bitterness is the level at which the beer tastes great!

You can search online for the beer style guidelines published by the Brewers Association or BJCP.

Let’s move on to find out how hops are added.