This month, our intrepid troubleshooter takes on a variety of problems, from periodic haze formation, ring around the bottle, and foaming bottling operations to a 1.109 beer that got stuck at 1.060. In addition, a new microbrewer gets answers to questions about pasteurization and filtration.

HAZE PROBLEMS

DM: First, let's go through your specific questions, then we'll talk about troubleshooting your problem. First, recirculation. It is almost impossible, with home or microbrewing equipment, to get your first wort as bright as filtered beer. Some haziness will be present, but there should be few or no visible solid particles. From your description, it sounds like your recirculation (vorlauf) is fine. Just be sure to maintain suction on the grain bed during your runoff and sparge so the bed does not "open up" and release fine material that was trapped during the vorlauf. I have always found it harder to maintain wort clarity during the sparge than to establish it in the first place.

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. You say that you suffer from cloudy beer "every so often," which I take to mean not all the time; some batches are hazy, others bright. This is where a good log book can help. 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. If you keep good brewing records, you should be able to go back through them and identify the probable cause(s) of the problem. Then you can take corrective action.

BOTTLING BLUES

These bottles date from my first year of brewing, when I had a very heavy hand with hop additions - to say I was a "hophead" is an understatement. I believe that this residue is some sort of precipitate from the hops in solution. Can you confirm this? I have always worked hard at sanitation, but a wild yeast infection is not out of the question.

DM: At this distance I can't confirm that you have hop residue in those bottles, but I can give you some clues to help you find out.

First, how were the bottles cleaned before you stored them? If you just rinsed them out with water, then it's likely that a hop residue could have survived the rinse. One way to confirm this would be to retrieve a bit of the residue with a cotton swab and taste it. If it is sticky and tastes like hop resins, that's probably what it is. If it has a yeasty taste, then your suspicion about a wild yeast infection may be correct. But surely you would have noticed the phenolic off-flavor (usually described as medicinal or Band-Aid) when you drank the beer? Well, if you overhopped your beers as much as you say, maybe not.

Whichever it is, a strong chlorine solution should remove the residue, as you observed. You should be wary of this procedure, however, because chlorine can etch glass, leaving a rough surface that is impossible to clean. Odious as it is, scrubbing the bottles with a soft brush and detergent is safer.

Q: When I start to bottle I get a small amount of foam in the first four to six bottles. If I fill up to drive the foam out I lose beer. If I leave the foam in the bottle and then cap my head space is too large. Right now I fill the first 4 or 5 bottles up to the shoulder and let them sit until the foam subsides, which it does in a few minutes, then I fill the rest of the way and cap. Is there a better way to handle this nuisance, or is there a way to eliminate the foaming? Or is this the price I pay for the great head and head retention I am able to achieve? My bottling setup is a simple gravity feed with a siphoning cane and bottling wand.

DM: The best way to reduce foaming with a siphon bottling system is to minimize splashing as much as possible. If your bottling wand has a spring-loaded valve, it is probably agitating the beer severely as it flows out. I suggest eliminating the wand and simply filling the bottles with a piece of vinyl hose attached to your siphon tube. You can control the flow by crimping the hose, either with your thumb or with a little plastic device made for this purpose (these are available at most homebrew supply stores).

Foaming is not just a nuisance - in a siphon bottling system like yours, it means air is being dissolved into the beer, which can lead to oxidized off-flavors later on. Even though your beer is bottle conditioned, and the live yeast in the bottle are potent antioxidants, oxidation is still possible if too much air gets into the bottle. I have tasted oxidized, bottle-conditioned homebrews.

PITCHING HIGH-GRAVITY WORTS

I am aware that many brewers pitch additional yeast to remedy a stuck fermentation (or sometimes by design). That practice, however, raises some questions (I posed the question to the internet mailing list Home Brew Digest and still had some unanswered questions). Although vigorous aeration is appropriate for pitching unfermented wort, in a partially fermented beer it is just asking for trouble because of oxidation. It would seem, then, that the volume of additional yeast would need to be large, but how large? What about aerating the starter before pitching the additional yeast into the secondary? Is that introduction of oxygen going to be a problem, or will the yeast consume it without ill effect? If you don't aerate the starter, will the largely anaerobic conditions lead to off-flavors when the new yeast gets to work?

Obviously, I have already done something long before this ever makes it into print, but I imagine that many readers will find your response useful. (I pitched an aerated 750-mL starter of the same Chico yeast into the unaerated 1.060 beer and will have to wait for the results.)

DM: I have no first-hand experience with worts as heavy as yours. The strongest ales I have ever made were barley wines with original gravities in the mid-1.080s. I pitched these with Chico ale yeast (Wyeast #1056, the same strain you are using) and fermented to a terminal gravity of about 1.020. This experience would indicate that you are right in assuming that there is a problem with your fermentation; your wort dropped only (!) 49 points before the yeast pooped out, whereas mine dropped at least 60.

The usual problem with using brewing yeasts for very strong beers is that many of the brewing strains have limited alcohol tolerance. I have heard tales of ale yeasts that cannot take more than 5% alcohol before they pass out like a giddy maiden. However, as my experience proves, Chico is not one of these faint-hearted yeast strains. It should have been able to ferment your wort down farther.

No question, though, that a strong fermentation demands young, healthy yeast cells in top physical condition. This is why wort aeration is so important. Your yeast needs to grow before it starts to ferment. Most of the cells in the wort need to be young and fresh - not old cells that are already tired from having gone through a fermentation before.

Several factors can lead to a weak fermentation. Note that the effect of these factors will be magnified when you work with heavy wort. In a normal-gravity wort, they might pass unnoticed or manifest themselves only in a slightly prolonged fermentation.

The first factor is wort aeration. You sound like a person who is very concerned about oxidation and may be reluctant to aerate your wort. Don't be. Wort must be saturated with air either before or immediately after pitching. If you get a stuck fermentation and decide to repitch, aerate again - the wort as well as the starter. The most likely result of reaeration will be an increased level of diacetyl in the finished beer, but at this point you're doing a salvage operation and your choice may be between flawed beer and no beer. Besides, diacetyl is not necessarily a fault in barley wine.

A second factor in weak fermentations is over- or underpitching. Most home brewers by now are aware of underpitching, but overpitching can also lead to similar problems. If you overpitch, the yeast does not grow as much, so you end up with more old, tired cells and fewer young, healthy ones. This may pass unnoticed in beers of normal gravity, but in a wort as heavy as yours, it may easily lead to a stuck fermentation; remember, normal-gravity worts, in fermenting out, don't drop as far as your wort did before it stuck. You don't state your batch volume, but if it is 5 gal, then a 1.5-L starter, depending on how it was made, may be too much.

A third factor in weak fermentations is the Crabtree effect, which was first brought to the attention of home brewers by George Fix. Yeast has such an affinity for glucose that, if a solution (such as wort) contains more than about 1% of it, the cells will immediately begin to ferment it - even if oxygen is available for respiration and growth. In other words, the practical effect of high glucose levels is to short-circuit the normal growth of the yeast in the pitched wort. A very high gravity wort is more likely to have a lot of glucose in it - especially if it is made up entirely or partly from high-glucose malt extract or if sugar has been used to boost the gravity. You don't say how your wort was made, but you can judge for yourself how likely the wort composition is to be a factor in your problem.

For the sake of completeness, I should mention that lack of yeast nutrients is another cause of stuck fermentations, but a wort of such high gravity is almost certain to contain enough amino acids, vitamins, and minerals for good yeast growth.

Good luck with your repitch. Let me know how you make out.

PASTEURIZATION AND MICROBIOLOGICAL STABILITY

DM: Any type of pasteurization is a process of heating beer to kill off or stun yeast or bacteria that may be living in the bright, filtered beer. If done correctly, it renders the beer microbiologically stable, which means it will not spoil even if stored for several months at room temperature. This is important for bottled beer. The alternative to pasteurization is sterile filtration, which means running the beer through a filter so tight that it traps all microbes that were in the beer. This also results in a microbiologically stable product.

Tunnel pasteurization involves passing bottles or cans of beer through a pasteurizing tunnel on a conveyor belt. Inside the tunnel, the bottles are sprayed with hot water until the contents are heated to 140 °F (60 °C) and then held at that temperature for 10 min. Then the bottles are sprayed with cold water to cool them down.

Flash pasteurization involves basically passing beer through two heat exchangers. The first one operates in the reverse manner from a counterflow wort chiller - instead of cold water, hot water is pumped in a flow that runs counter to the cold beer, heating it very rapidly to about 160 °F (71 °C). It is held at that temperature for only about 20 seconds before going into the second heat exchanger, which cools it back down.

All three methods have advantages and disadvantages. All of them can and do damage the flavor of the beer. The question is "How much?" and "In what way?"

Sterile filtration strips body, flavor, and even color from beer. A filter tight enough to trap all bacteria also traps large molecules such as proteins, dextrins, and melanoidins. These substances are responsible for the mouthfeel, head retention, color, and in part the flavor of beer. Thus, sterile filtration is fundamentally more compatible with light-bodied pale beers (such as the products of the major American breweries), than it is with the darker, fuller bodied craft-brewed beers.

I have heard a microbrewery owner call stripping "a home brewer's term." Let me assure you the Big Guys are quite familiar with the word - and the phenomenon. In fact, one of the major brewers filters its "bottled draft" products using only 0.65-µm rated filters rather than the 0.22-µm filters required for 100% effectiveness. They do this to minimize the damage caused by stripping. In effect, they have chosen to accept the risk of a few rod-shaped bacteria slipping through the filter in exchange for more body and flavor in the finished beer.

Pasteurization damages beer by greatly accelerating oxidation. Obviously, the degree of damage depends on both the time and temperature of the pasteurization cycle and on the oxidation potential of the beer itself. Beer oxidizes in the bottle because of oxygen dissolved in the finished beer (mostly during filling) and because of oxidized tannins and melanoidins that are created by hot-side wort aeration. Clearly, the lower the dissolved oxygen in the bottle ("package air" in trade lingo) and the better the hot wort was handled, the less pasteurization will damage it. Nonetheless, pasteurization always does some damage, though it is not always immediately noticeable.

Flash pasteurization is less damaging, in terms of oxidation, than an equivalent degree of tunnel pasteurization. Though the temperature is higher, the time is far shorter. Also, flash pasteurization takes place before the beer is bottled, so the dissolved oxygen level is much lower when the beer is heated. Flash pasteurization, however, shares with sterile filtration the serious drawback that it requires aseptic filling. Aseptic filling means filling the package under sterile conditions. The beer may be stable when it leaves the flash pasteurizer or sterile filter, but if the filler or capper is contaminated it will not be stable in the bottle.

An aseptic filling line and the room that houses it must be kept as clean and sanitary as a hospital operating room and its equipment. If you have ever taken a close look at a bottle filling machine, you will appreciate what a challenge this is. Older breweries with older equipment, which were not built with the requirements of aseptic filling in mind, often have a lot of trouble trying to produce "cold-filtered draft" (sterile-filtered, aseptically filled) bottled beers.

If I were trying to do what you are doing I would accept the method of stabilization recommended by the brewmaster. He or she knows best what the plant's capabilities are. But I would also try to do a real-world assessment of the beers produced there. I assume they are turning out microbiologically stable beers. Because they use pasteurization, you need to try to assess the oxidative stability of the products. Try to get hold of some of their bottled beer of various ages - one month, two months, three months - and compare them with freshly bottled and fresh draft examples of the same brands. That should give you some idea of how much damage pasteurization will do to your beer.

In my opinion, most micros opt for sterile filtration because of the lower initial cost. Note, however, that filter cartridges are expensive, and replacement represents a large ongoing expense. Pasteurization can actually be cheaper over the long run.

It sounds like you hope to eventually build your own brewery. If or when you reach that stage, then you should seriously look at all three options in terms of both initial and long-term cost. I would also recommend that you talk to brewers working with all three methods to get an idea of their ease of operation and maintenance requirements. Also, do some critical taste evaluations of products that are similar to the one you want to make and that have been treated by each method. Any of these methods can give you good stable beer, but none of them is flawless or foolproof.