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Ask the Experts: John Palmer

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John Palmer is the author of How to Brew and the co-author of Brewing Classic Styles with his good friend Jamil Zainasheff. Together they co-host the popular brewing podcast, Brewstrong. John is a regular on the international homebrewing competition circuit, having been invited to speak and judge at conferences and competitions in such diverse locations as Australia, Argentina, North Dakota, and Kansas, and Orlando. John has been brewing for nearly 20 years, and has frequently underwhelmed his compadres in the Crown of the Valley Brewing Society with his brewing frequency and colorful witticisms to “brew as I say, not as I do.”

John is a metallurgical engineer by trade and has particularly applied himself to understanding the processes of brewing from an engineering point of view, including malting, mashing, water chemistry, lautering, clarity, color, and foam retention. In 2007, John was deeply honored with an AHA Governing Committee Recognition Award for Outstanding Service.

Read more about John Palmer in Featured Brewer of the Week.

Bill from Ontario asks:
John, in How to Brew you seem to recommend a somewhat thinner mash (1.5 – 2.0 quarts of water per pound of grain) than has been used traditionally by most homebrewers (typically 1.2 – 1.4 quarts per pound). Are there benefits of a thinner mash that cause you to recommend this? And when designing a new mash tun, do you recommend a larger size to allow room for the greater volume of water a thinner mash requires?

Palmer answers:
This turned out to be a difficult question to answer in terms of hard facts. The recommendation flows from two sources. First, a review of professional brewing journals shows that grist ratios of 1.5-2.5 quarts per pound (3-5 liters/kg) are common, and are even cited as being standard by brewing textbooks like the Technology of Malting and Brewing by Wolfgang Kunze, and Briggs et al., in Malting and Brewing Science. Why do they commonly use these higher ratios? Probably initially because it made pumping the mash easier, but the fringe benefits have been substantiated. Kunze states that higher ratios are used to preserve the color and fermentability of pale beers while lower ratios are used for darker beers to gain more aroma and complexity of flavor. Malting and Brewing Science cites Harris (1962) stating that ratios of 1.5-3 quarts per lb (3-6 L/kg) generally favor maximum fermentability, while maximum yield is obtained at 1.25 quarts per lb (2.5 L/kg). However, these effects are a distant second to the effect of mash temperature.

My second reason is that I had noted from my own experimentation that multiple infusion mashes (or step mashing with multiple infusions if you prefer) often resulted in grist ratios of near 3 quarts per lb, and that I had no problems with the conversion of the mash. After discovering that the professionals accepted higher ratios as well, I promoted them for being useful to homebrewing techniques like multiple infusion mashing. The only downside is the total volume of the mash as you noted. So, yes, I recommend planning for a larger mashing vessel. I often use a 15 gallon pot for mashing a five gallon batch.

Dylan from Pennsylvania asks:
Your book, How to Brew, is one of the most widely used resources for introductory brewing knowledge and troubleshooting brewing/fermation/finished beer issues.

What issues have you struggled with in your own brewing and where do you turn for more info or assistance?

Palmer answers:
What issues have I struggled with? Primarily indecision and lack of credible references! Whenever I have a question about brewing, I try to drill down to the most basic reason Why?, and build the answer from there. I routinely turn to the other homebrewing texts to look for answers (Papazian, Daniels, Mosher, Miller, etc). If the question is more technical, I look it up in Kunze’s Technology of Brewing and Malting, or Malting and Brewing Science by Briggs et al., or Brewing by Lewis and Young. If the question is really cutting edge, then I will turn to the professional brewing journals of the American Society of Brewing Chemists and the Master Brewers Association of the Americas. I am a member of both and being able to search the abstracts is a goldmine. If I can’t find the answer anywhere, I turn to friends who have focused on that subject. I remember trying to find the gelatinization temperature range of wheat and rye when I was writing the book and contacted a friend in Australia, who put me in touch with a friend of his in Finland, whom was able to find the answer in a book on Cereal Science and Technology. Brewers are very helpful people worldwide.

Jeff from Tennesse asks:
John, thanks for the great info over the years. This is Jeff. I have been an ale brewer for the past few years but now have a spare fridge to lager in. My first attempt followed the guidelines in Brewing Classic Styles to the tee. The pilsner I brewed came out undrinkably rotten egg like and butter popcorny. I lagered for 4 weeks then carbed in kegerator hoping conditioning would help. Still undrinkable. I now have it out in the basement which is 67 degrees and I shook up the corny hoping to get whatever yeast that are left into solution to consume the diacetyl. Saflager dry yeast was used, s-23. Thanks in advance for any recommendations.

Palmer answers:
Those two symptoms indicate that the fermentation was not complete. The rotten egg sulfur smell means that the fermentation was not vigorous enough for the CO2 to scrub the sulfur compounds out of the beer, and the buttery popcorn is a sure sign of diacetyl, which means that the yeast pooped out or were chilled into hibernation before conditioning was complete.

Some lager yeasts throw more sulfur than others, but the sulfur compounds originate in the malt. A longer boil will help reduce the sulfur in the wort, and a larger pitching rate or a warmer fermentation generally will produce a more vigorous fermentation to scrub those compounds out. The high diacetyl can be controlled by pitching fresher yeast, and ensuring that the yeast are not stressed when they hit the wort. The use of liquid versus dry yeast does not guarantee better beer, but if a liquid yeast is used, and was pitched to a starter before pitching to the wort, then that yeast will be healthier and have better vitality than dry yeast that was simply re-hydrated. Your message doesn’t say, but I suspect that a combination of yeast packet age, lack of a starter, and cooler than optimum fermentation temperatures contributed to your problem. To clean up the diacetyl, you should pitch a starter at high krausen for best results.

Sal from California asks:
Well, I guess all questions are allowed and I beg your pardon if this one is too basic. It is, however, a nagging problem for which I have long searched for an answer. I have multiple times attempted to add fruit juice, purée or paste to my brews, but the result is always disappointing - and often absolutely undrinkable. Last weekend I dumped a whole batch of dry stout - to which I had added homemade peach purée - down the drain. It was terrible.

My "beers with fruit-derivate addition" acquire a bitter, "woody" taste that only gets worse with time. The phenomenon seems to be more pronounced with the increase of solid content - i.e., it worse with fruit purée than fruit paste, and worse with fruit paste than fruit juice.

I thought the problem was due to contamination with bacteria or wild yeast - even though there was no evidence of it whatsoever - but that does not seem to be the case, as I've attempted several pasteurization techniques (and temperature ranges/patterns) but can't notice any improvement at all... Changing the "moment" of addition of fruit product from one brewing step to another (say, primary fermentation, early secondary fermentation, late secondary fermentation) does not impact the (poor) results significantly either.

Curiously, I have no problem adding "non-fruit vegetable products" to beers. I've added carrot purée to an experimental batch and the result was not bad at all - but if I add banana paste or something alike, well, it's a whole different - and much less pleasant - story.

Final words: the problem seems to be worse with less acidic fruits. Maybe these issues have indeed biologic origin and the citric acid in these fruits is dampening the problem??? Oh well...

Thanks a lot for sharing you expertise, John. And congrats to the AHA for this initiative - pretty cool indeed.

Palmer answers:
This is an interesting question that could have several possible causes. The key clue though is that it gets worse with time. It could be contamination by Brettanomyces or Pediococcus, although those are not typically described as bitter and woody. Those flavors can be an aspect, but I wouldn’t expect them to be the dominant description, and I suspect you would be describing phenolic aromas and flavors as well if infection were the case.

I have a feeling your problem is oxidation and staling of the lipids and fatty acids from the fruit. It makes sense that the less acidic fruits would tend to have more alkaline oxidation compounds and therefore taste more bitter. Mold may also be a factor, and again, a less acidic wort would be more likely to develop mold. I recommend that you talk to someone that makes wine at your local brewshop; they will probably be much more familiar with this type of off-flavor since it seems to be fruit-related. I have never studied wine myself, but I bet it would be helpful in this case.


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