A: Using a reverse-osmosis filter to remove all minerals from your brewing water might be a mistake.

Yeast requires trace amounts of many different minerals to grow and flourish. A very large brewery had fermentation problems that were traced to a copper deficiency in the wort. Zinc deficiencies can cause the same trouble, and so can the lack of other minerals. These problems cannot be corrected by adding regular brewers' salts (gypsum, Epsom salts, and so forth) to the wort, because the salts do not contain the right minerals. Unless your water supply has iron in it, you probably don't need to demineralize it for brewing purposes. I suggest boiling your brewing water as an alternative to reverse-osmosis filtration. This will remove chlorine and excess alkalinity but leave the trace minerals.

A: In some places, it may be possible to get away with this. Most water supplies, however, are better suited to one type of beer than another. For example, here in Middle Tennessee our surface water is moderately alkaline -- about 60 ppm total alkalinity. You can brew just about any kind of beer using this water, and even with very light beers the mash pH will not be so far off that you don't get conversion. For maximum extract, however, adding calcium chloride to the mash (which lowers the pH) definitely helps. Also, the beer will be smoother if you adjust the sparge water pH with acid. I have been to brewpubs that make no attempt to control pH, and in almost every case I found that some of their beers -- usually the darker ones -- were better than others.

My experience coincides with what George Fix pointed out in a talk at the 1995 IBS National Microbrewers and Pubbrewers Conference in Austin, Texas. He said that what he often finds is that beers with a high pH (the most common deviation) are not undrinkable, but they are not as good as they could be.

pH measurement and adjustment are time-consuming, especially for the first few batches. Nevertheless, I think all-grain home brewers who take the time and trouble will find it worthwhile. A batch of all-grain beer takes at least 6 or 7 hours to make. An extra 15 minutes is not that big a deal. As far as cost goes, a bargain-basement pH meter or even a box of Merck pH strips is accurate enough if used carefully. Again, compared to the value of your time and the cost of your whole brewing kit, it's not that big a deal, and you may find it worth the effort.

Q: When should we check pH (mash, boil, fermentation, bottling?), and what values should we aim for? (July/August 1994, p. 22)

A: The most critical stage for measuring pH is the mash, especially during starch conversion. The malt enzymes alpha- and beta-amylase require a slightly acid pH to do their work. Values in the 5.0-5.7 range are alright, although values toward the lower end (5.1-5.3) are usually considered optimum. It is important to measure pH at room temperature; a phenomenon called displacement will cause pH to read lower at mash temperatures than at room temperature. Cool the mash liquid sample before reading.

The pH of wort in the kettle is also important for a good break reaction and is worth checking. The best range is the same as that for the mash. Wort pH and mash pH are usually similar, but if your sparge water is alkaline the wort pH may be higher. The best way to correct this difference is to adjust the pH of the sparge water with acid before sparging. I prefer phosphoric acid for pH adjustments. It is safer than other mineral acids (such as hydrochloric acids) and more stable than organic acids (such as lactic acid).

A: Sorry to confuse you, but live and learn, as they say. I was dragged down the single-infusion path kicking and screaming, and nothing but money could have done it. When you work in a brewpub, you work with equipment that, although very flexible and refined in some ways, is in other respects more limited than the average home brewery. Our brewing system uses a combination mash/lauter tun which has some insulation but no means of being heated. It is therefore limited to single-infusion mashing. To fit it with steam coils or jackets would have added many thousands of dollars to the price. We went with the basic design, which is similar to what you will find in the majority of pub breweries.

Since I began working at the pub, I have run across a lot of discussion about the merits of step vs. infusion mashing. Dr. Lewis at UC-Davis, long a proponent of single infusion, now seems to believe that the advantage of step mashing is that it allows one to get a higher extract yield without resorting to high mash temperatures (such as 158° F [70° C]) (1). Such high temperatures give the best yield in single-infusion mashing but have the undesirable side effect of producing a wort high in unfermentable carbohydrates.

Other research suggests that mash thickness is a critical parameter.

Two-row malt is preferred for single-infusion mashes because it is lower in protein than six-row malt and generally causes fewer problems with colloidal (haze) stability. Two-row malt is also lower in enzymes (hence the preference for six-row when using adjuncts).

We use domestic two-row malt as the basis for all our recipes. This choice is based on a number of factors, including cost and suitability to our brewing system.

American two-row malt stands somewhere between six-row and European two-row in its properties. Its protein content is higher than the best European two-row malt but lower than six-row malt; conversely, its enzyme content is lower than six-row malt, but much higher than many European two-row malts. Price is a bit higher than six-row, but considerably lower than that of imported malts.

Does it work? Well, our beers are good. I think that we might be able to get more colloidal stability by using the European pale malts, or, alternatively, by using a step mash process. I have done a few batches with imported pale malts, but not enough to draw any definite conclusions about how much difference they would make. Step mashing is impossible with our mash/lauter tun. But stability is not that critical for a brewpub. The beer is always drunk quickly, and it is not subjected to cycles of warming and cooling. It is pretty hazy coming out of the unitank, but Celite 512 covers a multitude of sins.

One other advantage sometimes touted for step mashing is that it increases the amino acid content of the wort. Although this is true, in practice, worts made from all-malt grists will always have plenty of amino acids for the yeast to use if one is using modern, fully modified malt.

I guess I've answered your question about the advantages of step mashing. Disadvantages? Lower foam stability, primarily. Possibly less body, if the rest goes on too long. Other than that, time and trouble -- and money, in a commercial operation. Again, the lower foam stability is most obvious in beers of low gravity or in those brewed with a high proportion of corn or rice.

Step-mashing is certainly preferable for six-row malts, because of their high protein content. Nonetheless, I have a sneaking suspicion that you could probably do without it, at least in a brewpub or home brewing situation.

I can tell you from first-hand experience that Belgian malts definitely do not require step mashing. Also, a growing number of German breweries are using single-infusion mashing to produce their pale lagers, mostly because single infusion is the quickest mash method and has the lowest energy costs. Even in Germany, money talks. Again, the uniform modification of modern malt is what makes this feasible.

As far as I can see, the big issue these days is not step vs. single-infusion mashing. It is infusion vs. decoction. Although it is possible to brew the majority of beer styles successfully using an infusion mash, there are some styles for which decoction is preferable. Examples include German wheat beers and dark German lager styles including bocks, dunkels, and Murzen beers.

Reasons for the advantage all center on the boiling of the mash, which liberates undermodified starches (this helps a lot with wheat malt) and extracts more of the flavor and color from dark malts such as Munich and caramel malts. Although I have been able to brew good Murzen and Doppelbock at my brewery, the beers lack the utter smoothness of the best German examples. I believe that the reason is that, in order to get the color, flavor, and aroma of the style, I have to use relatively high proportions of dark grains such as Munich malt. Using a decoction mash, I would be able to get the characteristics I want with lower proportions, and avoid the roughness these grains can impart. It also seems to be the case that, given a similar grist, decoction will usually give a smoother finish than infusion mashing. This seems counterintuitive -- you would think that boiling the mash would extract more tannins and rough, sharp flavors from the husks -- but the opposite appears to be the case.

I welcome comments on this issue from brewers with more decoction experience than I have.

A: The first thing to try with a set mash is cutting the bed. By cutting a crosshatch pattern with a paddle or spatula, you can break up the top part of the packed grain bed, leaving only the bottom few inches to act as a filter. If the bed is packed tight, that is all the filtration you need. Be aware, though, that you cannot cut the bed all the way to the bottom; if you do, the wort will run cloudy. Also be aware that a set mash will usually try to reset itself, so cutting the bed may have to be repeated regularly during the runoff and sparge.

For a really bad case -- one where cutting has little or no effect -- the usual remedy is to stir the mash thoroughly to break up the entire packed-down filter bed. Add some hot water if necessary to make the mash loose enough to stir. Then let the mash sit for at least 15 minutes before starting over again with your recirculation. While you wait, try to figure out what caused the set mash. Maybe you just ran the wort out too fast. Maybe your malt is crushed too fine. Or maybe you used a problematic grain in your grist; both rolled oats (not brewer's flaked oats) and malted rye have given me trouble. In any case, your best hope for avoiding a repetition is to run the wort off slowly to avoid packing the filter bed too tight.

One equipment problem that often contributes to set mashes is having an unsuitable runoff valve on the lauter tun. Any valve can get blocked with grits and husk pieces, but some types are more prone to this malady and are harder to flush out than others. With a butterfly valve, a quick flick open then shut again is all it takes to clear the blockage. The momentary surge does not pack the grain bed appreciably. Ball valves are also easy to clear. Try one of those valve types if you have trouble getting a steady, slow runoff.

A: My answer is based primarily on my own experience. My first batches of all-grain homebrew were made using primitive lautering equipment. The result was very hazy wort in the kettle and finished beer with what I later learned to identify as typical starchy and astringent/grainy off- flavors.

When you argue about clarifying wort, the first thing to keep in mind is that more than one component of the mash is being carried into the kettle. First, in the case of an infusion mash at least, the mash will always contain some unconverted starch, and clarifying the wort will minimize the amount of starch that finds its way into the kettle and, ultimately, the beer. On this point there is little debate. Except for some extraordinary beers such as lambics, which are made using mixed or wild fermentations, starch is not desirable in wort or beer. It is of no use to brewer's yeast and imparts a starchy off-flavor.

Second, cloudy runoff always contains grain husk fragments. They are particularly prevalent in small brewery mashes because of our simple malt mills. Husks that are carried over into the kettle will be boiled, which extracts tannin from the husks. Again, not much argument in the brewing literature about this. Tannic astringency is not desirable in beer.

So far, we've got two components in cloudy wort that are on the Not Wanted list. If that were the whole story, we would all be trying to make our wort as clear as our finished beer.

The case would be as clear as we want that beer to be.

But then there are lipids, which are complex fatty substances derived from the malt. Their case is not as simple. On the one hand, they are widely suspected of being the precursors of some notorious staling compounds (aldehydes, of which trans-2-nonenal is one) that are well known to be the source of undesirable aromas and flavors in old beer. On the other hand, they may be beneficial to yeast nutrition. However, recent research into this issue suggests that fermentation problems with clear worts are not due to inadequate lipids, but lack of nucleation sites for CO2 bubbles to form.

This leads to fermentation problems because CO₂ is toxic to yeast.

Other arguments about lipids remain, such as whether they help or hurt foam stability. Various researchers have reported different results. I suspect it depends on which lipids you're talking about. Obviously, the wort for a premium American lager will have a very different lipid profile from the wort for a microbrewed oatmeal stout (to take extreme cases), owing to the differences in grist composition.

The one thing I know for sure is that at least one large American brewery found it got better fermentations by cutting back the vorlauf (recirculation) so as to leave the first runnings slightly hazy rather than "as bright as the finished beer," as one of the brewers put it to me.

Based on all the evidence, including my own experience, I have concluded that clarifying the wort before running into the kettle is a good practice, one that has helped my own beer substantially. I also have to admit, however, that it may be possible for some brewers to clarify their wort too much, to the detriment of fermentation. While I doubt that it is possible for home or microbrewers to clarify their wort as much as the "big guys" can (at least, I know I have never been able to), I can't say so for sure in every case.

So my recommendation is: If you encounter persistent difficulties with fermentation, and those difficulties are not resolved by addressing the usual causes (underpitching, underaerating, and so forth), it is simple to make the experiment of cutting back on the vorlauf to get more particulate matter into the kettle. But to anyone who is not having problems with fermentation, I say that the benefits of clarifying wort make it well worth the effort.

A: These questions point out one of the biggest dilemmas that brewers face. On the one hand, anytime you expose cold wort or beer to air, you risk infection. On the other hand, you sometimes have to move the beer around to accomplish something important.

Racking: The main reason for racking beer after primary fermentation is not to clarify it but to separate the beer from the layer of sedimented yeast on the bottom of the fermentor. When fermentation is drawing to a close, the yeast cells sense that their sugar supply is dwindling. They quit fermenting sugar and instead concentrate on building up their reserves of glycogen, looking to survive the lean time ahead. Many of them also flocculate at this time and drop out of suspension. They lie dormant at the bottom of the vessel.

Even in this dormant phase, however, metabolic activity continues, albeit slowly. Eventually, the yeast cells use up their glycogen reserves and face starvation. At this point they resort to what can only be called cannibalism. They excrete enzymes that dissolve the walls of neighboring cells, thus making available the nutrients that those cells contain. This process is called autolysis. It is easy to identify autolysis by examining the yeast slurry. Autolyzed yeast darken and take on a red or orange tinge. Autolyzed yeast also give off a sulfury odor that is much stronger and less pleasant than the clean, yeasty smell of a healthy yeast crop.

How long does it take for autolysis to begin? That depends on temperature and the strain of yeast. The colder the yeast layer, the longer it will stay in good condition. At the Saint Louis Brewery, we crash cool our ales (drop the temperature from 70° F (21° C) to 34° F (1° C) over 24 hours) as soon as fermentation is over. The yeast drop to the bottom and are usually good for repitching for about a week. It takes at least three weeks for autolyzed flavors to noticeably taint the beer. If we were unable to crash cool, however, autolyzed flavors would develop much more rapidly -- most likely in less than a week.

Because most home brewers lack the facilities to crash cool their beer after fermentation, I generally recommend racking as soon as most of the yeast has settled to the bottom, three to four days after the end of primary fermentation. If you exercise caution and thoroughly clean and sanitize all equipment that touches the beer, the risk of picking up an airborne infection during transfer is minimal. Let experience be your guide. If your friends are having no problems with infected beer, then I would recommend they stick with racking.

Wort aeration: It is absolutely vital that the wort be saturated with air immediately before or after pitching. Yeast need oxygen to grow, and a strong growth of young, actively fermenting yeast cells will rapidly choke off most competing organisms (infections, from our point of view). They do this by creating conditions that make it difficult for their competitors to survive and by using available nutrients for their own growth.

Any method you can use to ensure complete aeration of the wort will almost certainly produce a cleaner flavored beer than you would get without it. The test here is your lag period. Assuming you pitch a large enough yeast slurry or starter, ale yeast should show vigorous fermentation in 8 hours or less. Lager yeast may take longer (as much as 16 hours) because of the cooler temperature.

Having established that aeration is vital, I would add that a system that is capable of forcing more air through the wort in a shorter period of time, and that can do so without requiring exposure to airborne dust, is preferable to the less certain and riskier method of pouring wort back and forth between two containers. In my own home brewing, I was never able to get as good aeration by your method (judging by lag times) as I was with my aerating stone setup (2,3). I don't want to exaggerate the risk of infection that your method poses, but because the stone works better and is less dangerous, why not try it?

And so back to where I started this reply. In working out a brewing method -- which includes putting together a set of equipment -- a brewer faces a lot of choices. Often, no answer is perfect. To minimize one danger, you may have to incur another. But experience and understanding will enable you to weigh the risks that each choice poses, and good techniques and equipment can greatly increase your chances of success.

Q: ...and you're supposed to avoid aeration on the "hot side," right? I use a 10-gallon stainless steel pot with a perforated stainless steel false bottom for a mash/lauter tun. The false bottom is elevated about 2 in. from the bottom of the pot.

When I mash, I find it difficult to maintain or increase temperatures because I can't stir the hot liquid that is under the screen into the mash. I am considering using another pot without a screen or an insulated cooler to mash in. To sparge, I would have to transfer the hot mash back to the lauter tun with the screen. Should I risk the hot-side aeration that I may get from transferring (pouring) the mash from a mash tun to a lauter tun, or should I put up with difficult temperature maintenance? (March/April 1996, pp. 41-42)

A: Any time you move the mash around you will get some aeration, but if you do it carefully and gently, the amount of air you pick up in moving the mash from one kettle to another should be small. Most hot-side aeration takes place during the transfer of wort from the lauter tun into the kettle and to a lesser extent during the vorlauf before runoff begins. Moving hot wort from the kettle to another vessel (a hop back, for example) before cooling can also cause a lot of air to be picked up. When the trade-off is between a small amount of air pickup and a large risk of scorching, incomplete conversion, or other problems that can have a major effect on wort quality, the choice seems clear. If you want to do step mashing, do it in a separate mash kettle and transfer the mash to a separate, dedicated lauter tun for sparging. If you are content with a single-infusion mash and your only concern is the temperature drop during the mash stand, you can insulate the mash/lauter tun.

A: Pitch the yeast as soon as the wort is cool. If you choose to try to separate the cold trub from the wort, do it after pitching. You should pitch the yeast and aerate the wort immediately after chilling to fermentation temperature. An in-line aeration setup is ideal. Next morning, your wort should be starting to ferment. Now is the time to rack it off the trub (break material) and into the primary fermentor.

A: Judging by the number of different yeasts you have used, it seems that a bad yeast culture is not the cause of your problem. Sounds like your yeast starter is sufficient as well (underpitching is one of the biggest problems home brewers face -- it's very important to make up a healthy, vigorous yeast starter for pitching). There are two other prime suspects in this case.

The first is insufficient aeration of the chilled wort. (See the question about aeration "When is oxygen Okay?".) Yeast use oxygen in their early stages of growth for healthier growth, and it's hard to overestimate the importance of thorough aeration for a healthy fermentation.

I also wonder about your RO water. I'm not sure what your reasons are for using RO water -- perhaps you have iron in your water, which would certainly be unwelcome in any beer. If not, and if more aeration doesn't do the trick, you might try changing your treatment regime. As mentioned above, some nutrients typically found in water are necessary for proper yeast growth (see the answer"Water- the main ingredient"), and even though you say you've tried adding nutrients, you might try using tap water for a batch instead to see if it helps.

Q: First, let me say that longer recirculation will not entirely solve your problem. Some haziness will be present, but there should be few or no visible solid particles.

The best way to clear proteins (and yeast) from a finished beer is to filter it. But that may not be what you want, and you may not be equipped for it. If you can't or don't want to filter, read on.

Isinglass and gelatin primarily help to clear yeast. Of the two, isinglass is far more effective. Polyclar (PVP, or polyvinyl pyrrolidone) primarily removes tannins. Protein haze is actually a protein-tannin complex, so Polyclar tends to reduce protein hazes. Probably the best way to remove protein haze is to use a combined treatment of silica gel and Polyclar -- this seems to work better than either agent alone. Overdoing protein rests can affect head retention. Overdoing a sugar rest or finings will not. Overdoing clarifiers such as silica gel may.

Now to troubleshoot your problem. Your problem is occasional; this is where a good log book can help.

If you have one, go through your brewing records and see if you can find any common factors, in either your ingredients or procedures, that seem to correlate with the appearance of haze. Some yeasts, for example, are much more reluctant to drop out than others, so if you use more than one ale yeast strain your haze problem could be caused by yeast and not protein. Similarly, different brands or types of malt and adjuncts will greatly affect the tendency to haze. Wheat malt is notorious for this. Process differences, such as skimming the yeast crop, can also affect haze greatly. Don't forget that infections are usually accompanied by haze.

If you use British ale malt, you should not need a protein rest to get a clear, unfiltered beer. Isinglass finings are helpful for removing yeast haze, but other clarifiers should not be necessary.

A: First of all, you can fill your bottles while they are still wet. You should let them cool to room temperature before filling, though. To speed up the cooling, open the dishwasher door when the heat-dry cycle is finished, and just leave the bottles standing upside down in the racks with the door open. I know somebody is going to object, but I did this for years and never had a problem -- and my kitchen was no cleaner than yours.

Second, I suspect with the bigger bottles you are getting more splashing at the beginning of the fill. It sounds like you have one of those fillers with a spring-loaded valve in the tip. They tend to cause a lot of splashing. This is bad because it aerates the beer.

I suggest you get rid of the filler and just use a plastic hose to fill the bottles. To control the flow, use your thumb or one of those plastic tubing crimpers (many homebrew supply stores now carry them). With a little practice you will get a lot less agitation and aeration than you have now. Also, by using the hose, you can fill the bottle more because, as the beer level rises, you can raise the end of the hose too, keeping it just below the surface of the beer.

Third, the recent thinking on bottle headspace is that you don't need it - at least, not any appreciable amount. Filling them as much as you can, you will still have a few milliliters of headspace under your bottle caps, and that is plenty. It used to be thought that a certain minimum amount of headspace was needed, for various reasons, but I've seen a number of homebrews that were bottled with no headspace, and the brewers reported no problems.

ESPECIALLY FOR THE PROS

Recipe scale-up

A: You are right, recipes don't scale up well. This is especially true with regard to hops. Generally, you get more hop utilization from a big kettle, but many variables are involved, and utilization is hard to predict.

For your late and finish hops, an awful lot depends on how long you whirlpool after throwing in the hops. I assume you will be using pelletized hops exclusively -- most micros do because they are much easier to remove after the boil. If you have been using whole hops in your home brewing, you should switch to pellets to get some idea how they behave physically. I can't tell you what you will get with your system, but at the 15-bbl brewery I worked with in St. Louis I got about 33% utilization from hops that were added 45 minutes before the end of the boil. Hops added at the beginning of whirlpool (1/2 hour before starting knock out) yielded about 18% utilization.

Your numbers for water use seem low -- your grain- to-water ratio will produce a very stiff mash. You will find it much easier to stir an 8-bbl mash if you use more water. I suggest measuring the foundation water needed for your mash/lauter tun. For a trial brew, use 1 bbl (31 gal) of water for every 100 lb of grist, plus the foundation water. This assumes, of course, that you will be using a conventional mash/lauter tun and doing single-infusion mashes. That being the case, you should expect to get ~30 points specific gravity/lb/gal for an average recipe (original gravity = 1.048, 20% specialty malts).

Efficiency is reduced for higher gravity worts -- assuming you continue sparging until you have collected the desired final quantity of wort. If you cut off sparging at a fixed point, such as a runoff gravity of 1.012, you may get lower extract from your low-and normal- gravity beers as well.

Total water usage -- mash plus sparge -- is usually about 1.4 times greater than the volume of wort collected in the kettle (not the volume after the boil). In addition to this water, I always cool my 15-bbl batches by spraying about 150-200 gallons cold water on the mash and letting it drain before shoveling the spent grains out of the kettle. This practice may be considered a waste of water, but it makes handling the spent grain safer and more pleasant and will help the grain keep better if it cannot be disposed of immediately.

The really tricky part of scaling up recipes is not calculating water-to-grain ratios, though, it's trying to predict color and flavor contributions from your specialty malts. All I can say about this is "Be prepared for surprises." Depending on the malts, the mash system, and the equipment you have been working with, you may find that you have to make some major adjustments to your proportions to replicate the color and flavor of your home-brewed batches. Some people have been able to scale up pretty easily, but others have not.

By way of example, I use about 13% British crystal malt in my American Red ale recipe. This is a fairly dark caramel malt, rated at about 55-65° L. The beer is definitely on the light side of the spectrum for the style. When I was home brewing, I never would have used anywhere near that proportion of crystal malt, even in much darker amber ales, yet that is what it takes with my current system.

A: What you were told is basically true. We use Wyeast #1056 (Wyeast Labs, Hood River, Oregon) for most of our ales. The reasons are purely pragmatic, and they illustrate the kinds of compromises you have to make when you get involved in commercial brewing.

The first reason is the difficulty of maintaining a number of yeast strains. Most brewpubs do not have the equipment needed to propagate yeast outside the fermentors. Their basic method of yeast maintenance is to repitch yeast from the bottom of one tank into another. With unitanks, this is easy to do, and the yeast is being held under a layer of cold beer, which is the best way to store a yeast slurry. Even this storage method has its limits, though; you always want to pitch a slurry that is as fresh as possible. Personally, I would never pitch yeast from a beer that had been brewed more than two weeks ago, and 10-day-old yeast is better.

Unless you have a lot of fermentors, using several strains of yeast for different styles of beer can pose problems, particularly if one or more of your strains is used only for a slow-selling beer style. It simply won't be repitched frequently enough to maintain its viability. Sometimes your only recourse is to "rouse" the yeast (basically, feed it a charge of sterile wort) to reinvigorate it. This is tedious and costly if it has to be done repeatedly, and if you are using malt extract for your wort charges, the flavor of the beer will be affected.

For this reason, it is generally better for a brewpub or microbrewery to settle on a single strain of yeast that, although it might not be optimal for every one of your regular beers, will be "user-friendly"; that is, it will settle well, be stable, resist mutation, pick up relatively little trub, and so on. Wyeast #1056 is an excellent all-purpose ale yeast, and although it may not be as estery as one would like for a nut brown ale, or as sulfury as one would like for an Alt, it is still capable of producing good results with both of those styles and many others.

Most brewmasters have a second reason for accepting the general principle that you should have only one yeast in a brewery: the threat of cross-contamination. If you are using three yeasts for different styles of beer, two of them represent a potential infection in every batch you brew. You have to be very careful with cleaning and sanitization, especially on the cold side of the process.