General Category > Ask the Experts

Ask the Experts: John Palmer

<< < (2/3) > >>

Tom from Michigan asks:
I have a few questions about secondary fermentations. I've read both pros and cons for 2nd fermentations and it is driving me crazy what to do. One, are they necessary for lower Gravity beers?

Two, what is the dividing line between low gravity and high gravity beers? Is it 1.060 and higher?

Three, I have an American Brown Ale in the primary right now, a SG of 1.058, Should I secondary ferment this or not?

Your advice is appreciated, thanks for all you do!

Allen from New York asks:
John, please talk about why or why not you would NOT use a secondary fermenter (bright tank?) and why or why not a primary only fermentation is a good idea. In other words, give some clarification or reason why primary only is fine, versus the old theory of primary then secondary normal gravity ale fermentations.

Palmer answers:
These are good questions – When and why would you need to use a secondary fermenter? First some background – I used to recommend racking a beer to a secondary fermenter. My recommendation was based on the premise that (20 years ago) larger (higher gravity) beers took longer to ferment completely, and that getting the beer off the yeast reduced the risk of yeast autolysis (ie., meaty or rubbery off-flavors) and it allowed more time for flocculation and clarification, reducing the amount of yeast and trub carryover to the bottle. Twenty years ago, a homebrewed beer typically had better flavor, or perhaps less risk of off-flavors, if it was racked off the trub and clarified before bottling. Today that is not the case.

The risk inherent to any beer transfer, whether it is fermenter-to-fermenter or fermenter-to-bottles, is oxidation and staling. Any oxygen exposure after fermentation will lead to staling, and the more exposure, and the warmer the storage temperature, the faster the beer will go stale.

Racking to a secondary fermenter used to be recommended because staling was simply a fact of life – like death and taxes. But the risk of autolysis was real and worth avoiding – like cholera. In other words, you know you are going to die eventually, but death by cholera is worth avoiding.

But then modern medicine appeared, or in our case, better yeast and better yeast-handling information. Suddenly, death by autolysis is rare for a beer because of two factors: the freshness and health of the yeast being pitched has drastically improved, and proper pitching rates are better understood. The yeast no longer drop dead and burst like Mr. Creosote from Monty Python’s The Meaning of Life when fermentation is complete – they are able to hibernate and wait for the next fermentation to come around. The beer has time to clarify in the primary fermenter without generating off-flavors. With autolysis no longer a concern, staling becomes the main problem. The shelf life of a beer can be greatly enhanced by avoiding oxygen exposure and storing the beer cold (after it has had time to carbonate).

Therefore I, and Jamil and White Labs and Wyeast Labs, do not recommend racking to a secondary fermenter for ANY ale, except when conducting an actual second fermentation, such as adding fruit or souring. Racking to prevent autolysis is not necessary, and therefore the risk of oxidation is completely avoidable. Even lagers do not require racking to a second fermenter before lagering. With the right pitching rate, using fresh healthy yeast, and proper aeration of the wort prior to pitching, the fermentation of the beer will be complete within 3-8 days (bigger = longer). This time period includes the secondary or conditioning phase of fermentation when the yeast clean up acetaldehyde and diacetyl. The real purpose of lagering a beer is to use the colder temperatures to encourage the yeast to flocculate and promote the precipitation and sedimentation of microparticles and haze.

So, the new rule of thumb: don’t rack a beer to a secondary, ever, unless you are going to conduct a secondary fermentation.

Liam from Ohio asks:
I seem to lose my hop flavor in the final product?? no matter how much I put it. gravities are in the 60's, fresh, med carbonation?  How much grain for a boil or where to find formula? They always write about O2 but never say how many liters for how long? Sorry for the three questions but these always come and thank you.

Palmer answers:
Hop flavor and bitterness will fade due to oxidation, so that may be your problem. The oxidation product of isomerized alpha acid is not bitter, and will fade with time, depending on the amount of oxygen present in the package and the temperature (warmer = faster). It could also be your hop source – if the hops are old or stored poorly before you buy them, then there will be a lot less bitterness going into your beer than you are calculating. It’s hard to say without knowing more about your ingredients and process.

How much grain for a boil? Do you mean how much grain or grist to boil for a decoction step? That information is in the current edition of How To Brew on pages 172-173. Basically, the decoction volume is equal to the desired change in temperature multiplied by the quantity of the total grain weight multiplied by its heat content (.4) plus twice the initial water volume, divided by the quantity of the difference in temperature between the decoction and the initial temperature of the mash multiplied by the quantity of the decoction grain weight multiplied by its heat content (.4) plus twice the decoction water volume. In other words, the decoction volume is equal to the ratio of the heat content of the two masses.

How many liters of oxygen for how long to achieve 10 ppm in the wort? That is a difficult question because there are so many factors. The only definitive answer is to measure it with a dissolved oxygen meter as you are adding it. The variables are: the oxygen flow rate (the quantity being presented to the wort), the wort temperature (controls the solubility of oxygen in the wort), the size of the bubbles from the diffusion stone (the contact area for diffusion/solubility), the depth of the stone in the wort (the contact time as the bubble rises to the surface) and the wort volume. The combination of all those factors against the amount of wort you are trying to fill with oxygen will determine how long it will take to achieve 10 ppm. There is a very good discussion of wort oxygenation in the new book Yeast, by Chris White and Jamil Zainasheff. To make a long story short, a 1-2 minute flow from one of those Bernz-0-matic oxygen cylinders thru a typical 0.5 micron airstone should achieve 10-14 ppm in 5 gallons of wort that is less than 75°F.

Bruce from Washington asks:
Question 1 - On your residual alkalinity spreadsheet, you designate water profiles as appropriate to malty, balanced, and bitter styles based on chloride to sulfate ratio. What is the background for that? Intuitively it seems reasonable, but I have not seen it mentioned in many other books I have read.
Question 2 - My system includes a stainless kettle that I use to boil and heat hot liquor, and a round beverage cooler mash / lauter tun with a false bottom. After mash conversion, and before I batch sparge, I need to get the sparge water out of my boil kettle. I transfer it to a second cooler. But I usually heat my sparge water to 180F or higher. On a Sunday Session from way back, Chris Graham mentioned that the coolers are only food grade to a temperature somewhere in the 150F range. Would you be concerned about holding 180F sparge water in a plastic cooler?

Palmer answers:
The chloride to sulfate ratio is mentioned in several brewing texts but it is not something that gets a lot of attention or description. Generally when it is mentioned, the author states that effect of the ratio is independent of the actual concentrations, and that the effect is limited to a 2:1 or 1:2 type balance. This should be taken with a grain of salt I think. Colin Kaminski of Downtown Joe’s and I are working on the water book for the Brewing Elements Series from Brewers Publications, and he has conducted lots of experiments on this effect. His data shows that Sulfate to Chloride ratios of up to 9:1 have positive effects on hoppy beers, but a Chloride to Sulfate ratio of 2:1 is about as high as you want to get before the beer flavor starts being adversely affected. We will work to define the effect better in the book.
The term “Food Grade” is commonly used but does not have a fixed definition – much like the term “edible” does not necessarily mean “non-toxic”. Being a metallurgist, I don’t have a strong grasp of organic chemistry and suggest we find an organic chemist on the forums and ask them this question. That being said, here is my advice for using plastics with hot water: If you can smell plastic, chances are that it is not good for the flavor of your beer, and two, hot plastic tends to behave plastically, and deforms. Depending on the plastics used in the cooler, the health risks may be minimal, but the physical risks from thermo-mechanical failure may be high.

Rick from California asks:
Can you give any advice on making a gluten free beer?
Here is a copy of the recipe that I am starting with:
6 lbs Sorghum (8.0 SRM) Extract 80.00 %
1 lbs Corn, Flaked (1.3 SRM) Grain 13.33 %
8.0 oz Rice, Flaked (1.0 SRM) Grain 6.67 %
1.00 oz Hallertauer Hersbrucker [4.00 %] (60 min) Hops 14.6 IBU
1.00 oz Cascade [5.50 %] (30 min) Hops 15.4 IBU
1.00 oz Cascade [5.50 %] (2 min) Hops 1.7 IBU
1 Pkgs Safale American (DCL Yeast #S-05) Yeast-Ale

Palmer answers:
Alas, I have not brewed with Sorghum malt extract. From what I understand it has an earthier, grainier flavor than barley, and has some tannic bitterness as well. It probably needs less IBUs per recipe than a barley malt extract recipe would for the same style. Looking at your recipe, I do notice two problems – the flaked corn and the flaked rice. These are starch adjuncts and need enzymes for conversion. They need to be mashed with barley malt or enzymes to convert the starches to fermentable sugars. You could use malted sorghum and its enzymes, but there is a catch – sorghum’s gelatinization temperature is above the denaturing temperature for the alpha and beta amylase, so a special cereal/decoction mash is called for if you are going to make an all-grain brew with sorghum. The sorghum malt extract does not require mashing of course, but you will not get any utilization from the rice or corn without it, and you will not get any utilization from the rice or corn without it, and you will not get much flavor from steeping them.

Paul from Texas asks:
Read your book (the actual paperback) and it is a fantastic reference now. My question is this: I am a big fan of bold Belgian beers and trying new techniques. I am considering trying an open fermentation for an up and coming brew and want to know about the so called CO2 covering the beer? I have read that it doesn't keep bugs out and others say it is a fantastic repellent since it is heavier than oxygen and bugs can't breath. I feel like the latter is more likely since this was the process before people started using closed vessels. Any help is much appreciated.

Palmer answers:
Do open fermentations naturally repel insects? Or do they die and fall in during their reconnaissance? I don’t know, but several of my friends that routinely practice open fermentations actually practice “covered” open fermentations, using a pot lid to keep out dust and other airborne debris during the ferment. I would recommend that you at least use aluminum foil to tent the top of the fermentor with the edges overhanging the sides to prevent critters from fowling the brew. If there is several inches of freeboard above the fermentation, the CO2 will form a blanket but it does not keep oxygen out of the krausen, in fact, that is why the yeast form a krausen on top - better access to the oxygen to catalyze regeneration. After the krausen falls, you will want to transfer the beer to a closed fermentor for conditioning and to prevent oxidation of the beer. Check out Wild Brews by Jeff Sparrow, Farmhouse Ales by Phil Markowski, and Brew Like a Monk by Stan Hieronymus for more insight into brewing Belgian styles.


[0] Message Index

[#] Next page

[*] Previous page

Go to full version