Troubleshooting Hard Seltzer

Seltzers finishing with a yellowish tint is a common problem for many seltzer makers. If you’re using a yeast nutrient (and you should), one source of that color is the organic nitrogen in the nutrient, which is a necessary component for a healthy fermentation. Yeast nutrients with high levels of organic nitrogen will contribute even more color to your seltzer. Once boiled with sugar or held for a long time at a high temperature, yellowing can occur as a result of Maillard reactions. 

Haze is not a typically desirable trait in seltzer, but it can happen when yeast is stressed and doesn’t flocculate efficiently. Save the haze for your NEIPAs.

Recommendations

First, keep in mind that this yellowish color may appear more intense in bulk (e.g., in a carboy) than in a pint glass. Once conditioned and poured into a regular serving size, the color may be less apparent — try pulling a small sample to see how it looks before making any major changes to your processes.

To help reduce the extent of Maillard reaction-induced yellowing, we’d recommend adding the nutrient at flameout. This timing will not only sanitize the solution, but also make sure the nutrient spends as little time as possible exposed to high heat alongside the sugar, reducing the chances for color pickup.

One common method for removing color pickup from seltzer is to do as the large-scale producers do, and run your seltzer base through a carbon filter before carbonating. Some seltzer makers also like to add flavorings that also add color for added visual interest, though this will of course prevent your seltzer from being completely clear.

Another trick is to ferment to a higher gravity and dilute your base down to your desired target. Even when yeast ferments to a higher ABV, it doesn’t necessarily increase the esters and higher alcohols that it puts out. Consequently, when you dilute the base, you’re also diluting any other flavors present in the base, further aiding in reduction of unwanted color and flavor — more on that next.

When fermenting, wait to crash until your yeast has settled to ensure a clearer finished product. Finings can also help create a clear seltzer. Any typical beer finings should work for seltzer, as well as employing traditional filtration processes to clear up the seltzer.

Many strains of wine and distillers’ yeast tend to have poor flocculation because they haven’t been selected through re-pitching. Lutra is a great strain for seltzers because it is highly flocculant and helps to produce clear seltzers without providing many issues with filtration or fining.

Sulfur aromas can often be an indication of a non-ideal fermentation when it comes to seltzer making. This typically is a consequence of too little of a particular nutrient, or even too much. Maillard reactions on the hot side can affect nitrogen sources in nutrients, which can reduce their efficiency and stress the yeast, leading to more sulfur off flavors.

One variable that crops up more frequently than others is the amount of time the nutrient spends at high temperatures, whether in the boil or whirlpool, however this is still mostly anecdotal — we are hoping to have some further research about this soon.

Another common concern with seltzer making is a wine-like aroma remaining after fermentation has concluded. This aroma tends to pop up when simple sugars are fermented out.

Recommendations

First of all, temperature control can help immensely. Following your boil, chill as quickly as possible to minimize the time your nutrient is spending at high temperatures. Not only will this help with reducing color pickup, it also helps keep those nitrogen sources intact, which will make your yeast happy.

Our recommendations for avoiding unwanted flavors are similar to what we suggest for reducing color pickup in seltzers: fermenting to a higher gravity and diluting down to your desired serving strength can also help reduce unwanted aromas and flavors. Carbon filtration is the best way to reduce the perception of those compounds — large-scale seltzer producers use expensive filtration systems to strip all color and flavor out of their seltzer base, which unfortunately isn’t very feasible on a smaller scale.

Additionally, any flavors you’d like to add to the seltzer will generally help to mask unwanted flavors. Seltzer fermentation can be a bit confounding, and some amount of fermentation-derived flavor is unavoidable, but there are ways to subdue those flavors and embrace the ones you want to be there.