March 5, 2010

2 Things Literature Says You Should Do That You Shouldn't

1. Rehydrate dry yeast.

Some folks worry about osmotic shock and then make a practice of rehydrating dry yeast in warm water before pitching into wort. Please don't rehydrate in water. Rehydrating dry yeast in water can strip your yeast of essential free amino nitrogen (FAN) that is needed for growth and proliferation. Rehydrate in wort (just sprinkle over the top, don't stir, don't do anything but sprinkle).

2. Vorlauf or Wort Recycling in the mash

The collecting of wort as it runs out of the lauter tun and pouring it back over the grain bed is commonly practiced. Many brewers claim that recycling should be done to settle the grain bed. Please don't recycle. This practice can not only lead to hot side aeration, but will strip out fatty acids that are essential for proper yeast nutrition. In particular, North American grains tend to be low in fatty acids to begin with, so please don't Vorlauf domestic grains.


  1. This is the first time I've heard of the no Vorlauf. Can you go into more detail? Do you strain your wort to avoid the husk and other materials that you get before the bed is settled? In a RIMS system, isn't it continually recycling the wort?

  2. Brewpunk,

    Lipids are long-chain unsaturated fatty acids and are essential for proper yeast metabolism. Yeast use lipids during the growth phase, so a lack of fatty acids can lead to slow starts, stuck fermentations, and expedited autolysis. Fermentation flaws such as off flavors and head retention problems can also evolve from lipid-depleted worts. Ever pour a glass of foam or get a ridiculously huge amount of foam that takes 8 minutes to go away? Low levels of lipids are often responsible for gushing. Lipids affect acetate ester formation, too - the less lipid, the more acetate esters. Worts produced from domestic grains contain about 3.2-3.5 mg/l whereas European malts contain something like 18-26 mg/l, so this is of particular concern when using domestics.

    To argue with myself, first runnings contain not only lipids but husks and other stuff that are loaded with tannins, silicates, and unconverted starches. Silicates cause haze. Tannins impose an astringent graininess to beer. Unconverted starch into your kettle can also produce haze and off flavors in finished beer. Vorlaufing helps avoid these issues. But I don't have these issues, thanks to a good hot break, a good cold break, and careful yeast selection.

    To answer your question regarding straining: I don't. A few solids in the kettle provide nucleation sites to which kettle trub will adhere.

    [A quick side note to David: I never recommend filtering beer because lipids tend to stick to filter materials.]

    Take a moment to consider your fermentations. Are you experiencing long lag periods, sluggish fermentations, or unpleasant aromas? If not, then don't worry too much about supplying more lipids or any other nutrient. And if your fermentations are presenting any of these symptoms, first examine other potential causes like poor aeration of the cold wort or inappropriate pH levels.

    I've never used a RIMS or HERMS or direct fire (i.e. - Brutus 10, system, but they do recirculate wort continually. Perhaps your brewing buddies are willing to have a brew-off: I vote for making a light lager without making a starter nor adding nutrient. I may be wrong, but I would guess that a cooler tun and vourlauf-less lauter makes for a cleaner fermentation than any of these systems.

    I, personally, do not recirculate wort because that practice strips essential lipid components and, in my experience, leads to more problems than it corrects.

    [To Vaughn: We'll argue about whether Hot Side Aeration is as fairytale as a unicorn or as real as a Clydesdale in another post.]

  3. Sorry, I forgot to mention how the act of recirculating actually strips out fatty acids: they stick to your grain husks like gnats to a fly strip.

  4. I'm anything but timely. HSA is said to begin at 86 deg F. Sure I'll agree there is some merit if your an aggressive recirculator, but doesn't the boil remove the O2? Even if you use a counter flow chiller, there is no place to introduce O2 prior to it the cooling.

    Is there a cheap and easy way to measure lipids? Since they are present in the grain ahead of time, I don't see how recirculating the vorlauf will actually remove the fatty acids. Grain husks are saturated with water. Oil doesn't stick to water well. You would have to measure the final product before boil and after boil with both techniques.

    I'm not saying your wrong, but I have doubts.

  5. HSA is not a myth, but is way too complex to discuss in one blog. Listen to Dr. Charles Bamforth from UC DAVIS explains some of the myths and legends surrounding the controversial topic and instructs brewers on how to deal with HSA based on his own extensive research.

  6. If vorlaufing just a couple liters would create noticeable deficiencies in yeasts health, then is follows that a system that recirculate during the entire mash, (effectively vorluafing the entire mash volume many times over) would have those deficiencies increased many times over. That is clearly not the case as evidenced by the many many home and professional breweries that use continuous mash recirculation without issues with yeast health.

  7. How many fatty acids do you need for yeast nutrition? I normally use a RIMS, but I transfer the wort into a carboy with residual star san foam. It was my understanding that star san is composed of long chain fatty acids and thereby becomes food for the yeast. Is there enough to replace what's lost during RIMS? If one pitches a healthy starter and aerates, does it really matter how many fatty acids are available to the yeast?

  8. Never said HSA is a myth. I just think activity before the boil will have minimal to no impact. But, there is an easy solution. Don't have any splashing. Simply have an inch or so of liquid above the output of the recirculater.

    Lipids and fatty acid will flow more when heated. The husk is saturated with water. Again, you would have to measure the difference in technique. I have read that the impact of not enough lipid and fatty acid is the beer will develop an astringent flavor. I guess proof is in the product. If you have astringency issues, its someplace to look.

  9. I use a 10 Gal Brutus 10 Clone with constant Recirculation. But I also use yeast nutrient, healthy yeast rinsed pitches, 30 seconds of pure O2 through a stone, and very good temperature control in primary. most of my beer tends to be too dry. :)

    PDX Brewers Board

  10. Jeremy - On hydrating dry yeast: It is not just "literature" that suggests this, it is part of the explicit directions on every packet of Danstar.

    Methinks some evidence should be supplied when making claims that directly contradict manufacturer's instructions.

  11. As to rehydrating, people come down on both sides of the issue all the time. There are dry yeast manufacturers who say not to rehydrate and those who say you should. Since this is a blog, I'd say the author is entitled to claim whatever he wants without being required to supply supporting studies. I'd also say that the people who are careful enough to rehydrate dry yeast and pitch it properly are likely using liquid yeast and/or starters anyway. I doubt that anyone is going to be swayed from a tried-and-true method by a blog post, lest it come from Charlie P himself.

  12. I know this is an older post, but I just read it and I'm confused by your stance on vourlaufing. You say "a few solids" in the kettle provide nucleation sites and places for kettle trub to stick to - ok. What method of separating wort from grain are you using when you mash - false bottom? Stainless braid? Something altogether different and magical? If I didn't recirculate I'd definitely have more than a few solids in my kettle. I do want to be clear that I'm ok with trub and I even like it in my fermenter, because with good hot break and good cold break, it quickly drops to the bottom of my carboys and I've always been left with clear beer. I'm just thinking, if I didn't vourlauf at all, I'd have quite a bit more of that stuff in the kettle. I also don't get why you're saying that recirculation would be stripping anything from the grains. If I'm collecting that husky wort in a pitcher, and returning it back to the main volume of husky wort... how has the husky wort composition changed just by being in the measuring pitcher for that long? I don't follow you there.

  13. I'll jump in on this older post too, it is my first time coming across it. If lipids are going to get stuck to grain husks, I highly doubt a little vorlaufing is going to increase that much. In order for the delipidification (ok not a word, but it works) of wort to occur as you state through vorlaufing, the lipids would have to come out of the grain - avoiding the husk on the way out, settle at the bottom of the MLT - again without coming into contact with any grain husks on the way, and also resist detaching from the grain husks during sparging, which uses an even higher water temp that would potentially help break whatever loose bonds any errant lipids happen to form with the grain husks. My guess would be that the lipids stick to the husks through hydrogen bonds, as that is how lipids stick to each other, and hydrogen bonds are easily broken by heat.

  14. Why couldn't you just start the wort recirculation process before sparging to get your grain bed filter established and then rinse through with the hot sparge water, whereby rinsing out the desired lipids into your kettle?

    I'm no expert, but that seems to be the middle-of-the-road approach to vorlaufing and hell-no-way-am-I-vorlaufing-my-wort.