Digging into the Hazy IPA

It is easy for us “old-school brewers” to joke about the cloudy-IPA style, and dismissively suggest to just do the opposite of what is required to make clear beer. Although there is truth in this suggestion, it requires an in-depth understanding of physical stability that is not exactly common knowledge. In brewing jargon, the term “physical stability” is used to describe how well the appearance of beer holds up to aging. Beers with excellent physical stability do not change in appearance over time. Unstable beers, however, may begin life as crystal clear, straw-colored Pilsners, and morph into an entirely different liquid, that oftentimes include unusual and visually unappealing flakes in the beer and on the bottom of the bottle. Cloudy beers also change over time as cloud particles succumb to gravity and slowly settle to the bottom of the bottle, or react with other compounds in beer to form large, funky looking flocs.

So let’s walk down this path and talk about brewing hazy beers. The primary sources of haze precursors in most filtered beers are the brewing grains and hops. Some beers are hazy because of microbiological problems, but the majority of non-biological hazes arise from reactions between proteins and polyphenols, aka tannins. Less common hazes include starch hazes, beta-glucan hazes and gels, and hazes associated with metal ions from water and/or equipment. And then, of course, there are those hazy, unfiltered beers that are cloudy because of yeast in suspension.

Proteins from grains react with polyphenols from grain and hops, and when this happens the protein-polyphenol complex causes light to scatter and the beer to appear hazy. Barley, wheat, oats, and rye are all rich in protein and typically contain between 8-15% protein. Malted grains lose some protein in the malting process to rootlets (removed after kilning), but the composition by weight is not dramatically affected by the malting process. The nature of these proteins, however, is significantly changed during malting by proteolytic enzymes. The totality of changes to the grain kernel that occur during malting are simply referred to as “modification”, and it is generally true that well-modified grains improve the physical stability of beers.

When German brewers first began brewing lagers in North America, they quickly learned that North American barley had more protein than the barleys they were accustomed to using back in Germany. Malt extract yield, color, flavor, and enzymatic power are all influenced by barley protein. And the physical stability of beer is directly affected by malt protein. For these reasons, German brewers began diluting malt protein with maize and rice.

You want to brew hazy beer, and it really helps to begin with grains that are more likely to contribute haze-active proteins. Think undermodified or unmalted cereals. Flaked oats, wheat, and rye are some of the go-to grains for these beers. And you may want to pick up some rice hulls with these grains because these grains do tend to gum things up!

But proteins alone do not make for hazy beer; polyphenols are also needed to form haze particles. Malted barley and hops are the two main sources of polyphenols in beer, and if you want hazy beer these ingredients are the obvious source of polyphenol. There is a practical limit to the amount of polyphenol contributed by malt because adding more malt increases wort OG. This leaves hops, and hazy IPAs typically have bunches of these green goodies added at various points in the brewing process. More about this later in the column.

Aside from raw material type and quantity, what other things are done to improve beer stability? Intensive mashing schedules, long kettle boils, the use of kettle finings, and whirlpools are brewhouse processes that improve beer stability. Cold conditioning, the use of beer finings, flocculent yeast strains, prolonged storage, filtration, and centrifugation (commercial practice only) are cellar practices to improve stability and promote clarification. And controlling storage time and temperature are both critical to physical stability once beer is packaged. Consider omitting finings, choosing non-flocculent yeast strains, skipping the cold crash, limiting time in the secondary and consuming your cloudy concoction quickly after packaging. A trick is to store bottles cool, but not cold, and to chill the bottles shortly before serving so that the chill haze formation is delayed until it is time to consume.

Science takes time, and there are many unanswered questions about what is really happening with these beers. But the anecdotal evidence points to hops as a key part of this equation, and it seems that large doses of hops, especially when added in the fermenter as dry hops, are very haze-positive. This makes sense because hops contain polyphenols. This is certainly not news, and brewers producing clear IPAs have struggled with hop hazes. What is different is the intensity of the haze.

Some brewers have suggested that adding hops during fermentation interferes with yeast flocculation because of hop oils depositing on the yeast cell wall. Others point to the large addition of polyphenols late in the process. Whatever the explanation, high dry hopping rates (2+ pounds per barrel/1+ ounce per gallon/7.5+ grams per liter) seems to coincide with some of the hazier brews out there. The interesting thing about this explanation is that removing yeast with a centrifuge does not seem to remove the haze, so the yeast flocculation explanation may not be correct.

Hopefully this helps to clarify some of the big points about haze. Your question opens the door to opinions about the astringency found in some of these beers. I’ll just say I am not a big fan of that character, and I am not a fan of beers that have vegetal and grassy notes from the extreme use of hops. This is where hop selection becomes important. Not only hop variety, but specifics about the variety and different preparations made from given varieties.

Selecting hops after harvest is not an option for homebrewers and most smaller craft breweries, but this does not mean that you cannot select hops. Hops that don’t smell great are not magically transformed when added to beer, so if you open a bag that smells strong of onion or garlic and you do not want that aroma in your beer, don’t add the hops. This sounds simple, yet can be frustrating and expensive when contemplating not using something you purchased. Choosing hop products is another option. If you want lots of hop aroma, but not so much hop matter, consider using lupulin powders, hop extracts, or Type 45 pellets. And it is up to the brewer, not the recipe written by someone else, to decide how much hops to add.

Several years ago, some were seemingly obsessed with IBUs and beers became more and more bitter, to the point where many of these brews were unpleasant and unbalanced. There is a similar thing happening today where brewers and beer lovers are talking about hopping rates in pounds per barrel as if super high hopping rates are a badge of honor. I suggest focusing on aroma and flavor quality and not trying to figure out how to top the hopping rate charts. But if you are after the extreme in hop flavor and aroma, the sky is the limit. Just remember that wort and beer losses increase with hopping rate, and brewing these beers can be very expensive if concerns about efficiency are thrown out with the bath water!

In summary, consider the following brewing tips:

• Derive about 20-25% of total wort extract from unmalted cereals
• Omit the Irish moss
• Select yeast strains with low flocculation properties
• Do not cold crash after fermentation
• Add hops late in the boil, in the whirlpool, and late in fermentation
• Consider chilling beer to drinking temps immediately before consumption
• Leave the bread flour in the cupboard

Response by Ashton Lewis.