The International Bitterness Unit (IBU) was introduced in the 1950s and 1960s to quantify the perceived bitterness of a beer. Over the years, IBU calculations have evolved to provide more accurate measurements.
In this article, we will explore Maximum International Bitterness Units (MIBU), a new and more precise method for calculating IBU contributions in modern beer brewing. It is an essential aspect of brewery equipment.
Today, brewers utilize the IBU range to guide recipe development and maintain consistent bitterness levels in their beers. Most beers fall within the IBU range of 5 (very low) to 120 (very high). However, it is important to note that the IBU range does not solely reflect the quality or overall perception of bitterness.
The most commonly used formula for calculating IBUs is the Tinseth formula, developed by Glen Tinseth in 1997. This formula takes into account the wort volume, hop quantity, hop alpha acid percentage, and boiling time to determine the total IBUs in the finished beer.
Tinseth, Rager, Garetz, Mosher, Noonan, and Daniels have each created their own formulas for calculating IBUs, with variations in how they approach hop utilization.
In modern beers, the IBU range no longer accurately represents the bitterness. This is due to the fact that hops used in the 20th century often had oxidized flavors caused by inferior packaging, handling, and storage methods.
Our recommended method for calculating IBUs is using the mIBU calculation developed by Paul-John Hosom in 2015. Maximum IBU (or MIBU) is an adaptation of the Tinseth IBU formula, incorporating optimizations that are more suitable for today’s beers. MIBU accounts for post-boil bitterness contributions by considering additional equipment and process parameters such as kettle size, cooling method, hop stand procedure, and hop temperature. This results in a more accurate prediction of IBU contribution over time.
How is MIBU Calculated?
MIBU takes into account the wort temperature and volume during various stages of the brewing process, including boil, hop stand, and cooling. The formula calculates the instantaneous IBU contribution for each time interval based on the wort temperature and volume, and then accumulates all the results to find the total IBU contribution for each hop addition.
What makes MIBU more accurate?
- Carry-over bitterness from hops added during the hop stand;
- Bitterness contributions from both boil and hop stand hops during the cooling phase;
- Changes in volume due to evaporation during the boil.
MIBU also provides the option to apply an alpha-acid solubility limit, which restricts the total IBUs when a large amount of hops is added. Furthermore, it offers the option to use advanced pellet processing methods, an improvement over the traditional practice of using an expansion factor. Additionally, MIBU provides a chart to visualize bitterness contributions over time for all hop additions.