Ask Mr. Wizard

Wort Aeration Temperature For Kveik Yeast


Dirk Kissing — Almelo, Netherlands asks,

John Palmer states in his book How to Brew “You should not aerate when the wort is hot, or even warm. Aeration of hot wort will cause the oxygen to chemically bind to various wort compounds. Over time, these compounds will break down, freeing atomic oxygen back into the beer where it can oxidize the alcohols and hop compounds producing off-flavors and aromas like wet cardboard or sherry-like flavors. The generally accepted temperature cutoff for preventing hot wort oxidation is 80 °F (27 °F).”

Since I’m using kveik yeast (Voss) that has an optimum pitch temperature of 102 °F/39 °C I’m a bit worried. Am I risking hot wort oxidation at that temperature?


Several years ago, I was on a panel discussion at an annual MBAA (Master Brewers Association of the Americas) meeting held in Chicago. A question related to general suggestions about “stuff” was lobbed to the panel. Thanks moderator! Luckily, I waited to comment after the other panelists offered their sage advice about stuff. This gave me a little prep time to offer that brewers should avoid making absolute statements, especially when it comes to using process declarations as part of marketing. Seems like too many brewers make statements that are later backed away from as things change. This question kind of falls into that camp.

Many statements about process are often taken out of context. John Palmer’s point about not aerating hot wort falls under the “best practices” umbrella. No argument with that general rule. But general rules are just that; they are general and not intended to be absolutes. A great example of aerating hot wort is when traditional brewers use coolships and/or Baudelot coolers . . . those cool looking copper washboard things that sort of resemble an art deco urinal that could be found at a fancy beer hall. Coolships and Baudelot coolers (falling film chillers) expose hot wort to air, allowing the wort to pick-up oxygen from the environment upon cooling. That’s just part of the process with these devices, and commercial brewers who use them today for certain specialty beers do not have special rooms that are devoid of oxygen to prevent hot wort from being exposed to oxygen . . . although some brewer has probably done this or will be doing it after reading this jab!

Lines in the sand aside, you may want to consider if wort aeration is even required for what you are doing. There is a Voss Kveik dried yeast produced by Lallemand. Not sure of Lallemand’s general suggestions about wort aeration and dried yeast these days, but Lesaffre Yeast (producers of the Fermentis line of dried yeast) has been educating brewers about when aeration is needed. As it turns out, many, if not most, dried yeasts are propagated under conditions resulting in lots of glycogen. This is different from how yeast grow in a typical brewery fermentation, making the oxygen requirements of these yeasts different from yeast that have been harvested from a previous fermentation or grown under conditions that push yeast into anaerobic metabolism even when there is ample oxygen added to the propagator; the latter happens when the Crabtree Effect is in full-effect.

You could try aerating 79 °F/26 °C wort, pitching, and allowing the fermentation to warm up as action kicks in.

Let’s assume that you want to harvest and re-use your kveik yeast. Maybe you decide to use a traditional yeast stick or yeast ring, or maybe you use a glass flask equipped with a lid. Whatever the method, you plan to collect and re-use your yeast. Do you aerate your wort for subsequent worts? Brewing is all about pragmatism. Let’s assume you don’t aerate your wort and the yeast performs poorly. Your next move may be to aerate to see if aeration, or the lack thereof, affects fermentation. The way I see it, you don’t have to worry so much about beer oxidation if your yeast are not happy and healthy.

Now let’s go one step further. Assume that aeration does improve fermentation and beer flavor when re-using your yeast, but you discover that your beer is not so stable when stored. Now is the time to consider how aerating warm wort may be affecting stability. You could try aerating 79 °F/26 °C wort, pitching, and allowing the fermentation to warm up as action kicks in. The takeaway message is that general rules are never cast in stone and are intended as guidelines to help folks find success. Here’s to great beer and never saying never!

Response by Ashton Lewis.