Cultured Dregs, Challenging Infections, and Home-Kilning Malt


Q and A with David Miller (Brewing Techniques)
Caustic soda is needed in commercial breweries

Cultured Dregs, Challenging Infections, and Home-Kilning Malt 

One brewer’s efforts at fermenting with cultured Oberdorfer Weizen yeast yielded a beer that tasted nothing like the original. Another home brewer with a persistent infection problem cleaned or replaced everything in his brewery in pursuit of the offending bug. The Trouble-shooter David Miller takes on these issues and offers advice about home-kilning specialty malts. 


Question: You have written about starting a yeast culture from the dregs of a bottle-conditioned beer. I decided to try this with a bottle of Oberdorfer Weizen. The culture grew up just fine, and I was very careful with my sanitization. I used an authentic weizenbier recipe, 50% wheat malt. The beer tastes OK, but it doesn’t taste like Oberdorfer. What did I do wrong? 
David Miller: Probably nothing. The yeast in your Oberdorfer bottle was not, most likely, the yeast that fermented the beer. Let’s go back and look at the yeast connection in Bavarian Weizenbier.
First, the typical clovelike or spicy aroma and flavor of Weizenbier is almost entirely due to the yeast. Malted wheat does have a distinct flavor that is different from malted barley, but the distinction is subtle. If you want to know how subtle, stop by the Saint Louis Brewery sometime and try a pint of our wheat ale. This beer is fermented with a very clean ale yeast (Wyeast #1056), and it has 13 units of bitterness. It doesn’t taste exactly like American lager, but it is close enough to please our less sophisticated customers. The wheat flavor is a very light sort of bready taste.
The weizenbier flavor, on the other hand, is quite unsubtle and can easily get raunchy if the fermentation is mismanaged. The flavor arises from 4-vinylguaiacol, a phenolic compound produced by the weizenbier yeast, Saccharomyces delbrueckii. Phenolic compounds are typically by-products of wild Saccharomyces strains, and Weizenbier can be considered (and is by many) a spoiled beer. The trick is to keep the spoilage under control — to get enough of that clovelike character to make the beer interesting, but not enough to make it unpalatable.
One of the things you will find if you’re ever fortunate enough to experience a wild yeast infection is that it continues to get worse the longer the beer sits in contact with the yeast. You may barely be able to detect a phenolic note in the beer at bottling, but a month later the stuff will be undrinkable. The yeast has finished its main metabolic process (changing sugar to alcohol), but it just keeps cranking out those phenolics.
One way to make sure this doesn’t happen is to filter your Weizenbier as soon as you can. Once the yeast is removed from the beer, the flavor should, in respect to this phenolic character, be relatively stable. However, if you have a large number of health-conscious customers demanding natural, bottle-conditioned beer, you have to put some yeast back in at bottling time. Often the German breweries use their regular lager yeast for this duty, because it settles out nicely and is unlikely to wreak havoc with the beer’s flavor.
So, as I suggested, I suspect what you grew up in your home culture was Oberdorfer’s production lager yeast. If you want that authentic weizenbier flavor from your next batch, I suggest trying Wyeast Labs #3056, which is a mixed culture of S. delbrueckii and S. cerevisiae strains. It has worked well for a lot of my homebrewer friends. 

A Challenging Sanitization Problem

Q: My brewing has been plagued by infections that I can’t seem to cure. I clean my pots and fermentors thoroughly, and I sanitize everything with chlorine solution. Somebody told me about plastic being a potential problem, so as a last resort I replaced all my plastic tubing and other small plastic items (I have always used glass fermentors). I just brewed another batch, after an extra-careful cleaning and sanitizing session, using all new plastic equipment. Same result! Where could this infection be coming from? Is my house so infested with bacteria that even momentary exposure to air contaminates my beer? I have always taken every step to minimize air exposure, including using a counterflow wort chiller. I even tape gauze around the racking hose when I run the cold wort into the carboy. I don’t see what else I can do. Any suggestions?
DM: I doubt the air in your house is any more laden with bacteria than the air in my brewery. The most probable cause is an infected piece of equipment. You did the right thing in replacing all your plastic, because the soft nature of the material makes it highly susceptible to scratches, which can then trap sludge.
In most breweries, the two pieces of equipment most likely to harbor infections are the heat exchanger (wort chiller) and the filter. If you look at these items, it’s pretty obvious why they are so infection-prone — both take the product (wort or beer) through a lot of small passageways that are difficult or impossible to scrub out. I assume you do not filter your beer; if you do, you can test the cleanliness of your filter by bottling some of your next batch in the conventional home brewing way and not running it through the filter.
I suspect, though, that your counterflow wort chiller is the culprit. Most people treat these things by flushing them out with water and then siphoning sanitizing solution (chlorine solution or whatever) through it. This is really not good enough.
The reason I have always recommended immersion wort chillers for home brewing is that the wort is in contact with the outer surface of the tubing, which is easy to see, easy to clean, and easy to sanitize. You can take care of any “big problem” by using heat — just set the wort chiller in the kettle 10–15 min before the end of the boil. Granted, counterflow chillers have some advantages. You get a better cold break, because the wort drops from near boiling to fermentation temperature in the few seconds it takes to flow the length of the tubing. They are enclosed, so there are no worries about exposure to airborne bacteria and yeast. Finally, they are much slicker and more professional.
All true, but in my judgment largely irrelevant to home brewers. I have no ideological bias on this issue, and I encourage any home brewer who wants to use a counterflow chiller to go right ahead. But it is important to consider how the thing works — the wort flows inside a small-diameter metal tube whose inner surfaces are invisible and impossible to scrub. That rapid cold break means the deposition of protein-laden sludge on the walls of the tubing, and you cannot sanitize a surface until it is perfectly clean.
This means that if you want to cool wort like the big boys do, you also have to clean your wort chiller the same way. At the Saint Louis Brewery, we follow a clean-in-place (CIP) schedule that takes about 1¼ h to clean and sanitize our plate-and-frame wort chiller. To adapt this procedure to home brewing, you need to first obtain a small pump whose impeller and body are made of stainless steel or heat-resistant, nonreactive plastic. Run a racking hose from the output end of the wort chiller to the output side of the pump. Run a second piece of hose from the input end of the wort chiller to the reservoir. This arrangement will allow you to backflush cleaning solution through the wort chiller — that is, run it through in the direction opposite from that of the wort flow. The pump must have enough muscle to move the solution at several times the flow rate of the wort; if it takes 15 min for you to siphon 5 gal of wort through your heat exchanger, make sure your pump can push 5 gal through in 5 min or less.
Don’t panic — you won’t need to use 5 gal of cleaning solution for backflushing; 1 gal should do fine. You keep recirculating the solution over and over again. The toughest trick is liable to be getting the pump primed. Usually the easiest way to deal with this is to put the reservoir above the pump and to have a spigot near the bottom, to which you can attach the hose that runs to the suction side of the pump. The hose that returns cleaning solution to the reservoir can just hang over the rim. 

Example microbrewery cleaning regimen 

1. Preliminary tap water rinse (backflush) until the water runs clean
2. Hot caustic (sodium hydroxide) solution (2.5 % w/w), 140 °F (60 °C) minimum, 40 min
3. Tap water rinse 5 min
4. Room-temperature phosphoric acid solution (1% w/w) 10 min.
5. Tap water rinse 2 min
6. Room temperature iodophor solution (25 ppm iodine) 10 min; unit left filled with this solution until next use. 


If you need a small pump, a recent issue of Zymurgy has a couple of interesting articles. After you get your equipment in order, you need to decide on a cleaning regimen. The box above shows what we use at the Saint Louis Brewery.

If you want to try this at home, be warned that caustic soda (which is sold as lye) is one of the nastiest chemicals around. Wear rubber gloves, goggles, and a mask and mix it up slowly. For each gallon, use 3.2 oz of lye.

If you get caustic soda on yourself, don’t wait for it to start hurting. Flush the affected area with tap water for 15 min. If you get it in the eye, flush immediately for at least 15 min with copious amounts of water and get help immediately. You will need to be examined by a doctor. If you insist on using caustic, always be sure there is someone within earshot who can come to your aid in case of an accident.

Besides being nasty, caustic is almost impossible to rinse clean with water. The acid wash step is used mostly to neutralize the caustic residue and ensure that you don’t leave mineral deposits in the tubing. Phosphoric acid from homebrew supply stores is really too expensive for this use. You could try using citric acid instead.

Gary Bauer, a chemist by training, tells me that caustic is too dangerous for home brewers. He is probably right. A less dangerous cleaning compound could be substituted, such as B-Brite (Crosby & Baker, Weston, Connecticut). Dishwasher detergent that include chlorine are less suitable because chlorine corrodes most metals, including stainless steel. However, they are about as effective as B-Brite and, if you rinse them thoroughly, don’t seem to do much damage. I have been washing stainless flatware in a dishwasher for years using a chlorinated dishwasher detergent. Copper might be another story, though. These agents also rinse cleaner, allowing you to dispense with the acid wash step. 

Caustic soda, however, for all its faults, is the most powerful protein solvent known, which is why almost all commercial breweries use it. If you have a chronic infection problem and your wort chiller is the prime suspect, you might decide that it’s worth the risk to try to salvage a pretty expensive piece of equipment. Nonetheless, caustic is a drastic step, which is why I recommend B-Brite or another detergent for routine use by home brewers. It is also why I prefer immersion wort chillers. 

Home-Kilned Malts

Q: In The Complete Handbook of Home Brewing, you talked about making your own Munich malt by “kilning” pale malt in an oven. But in your new book, Brewing the World’s Great Beers, you don’t mention this. Why? Have you given up on home-roasted malt?
DM: There are two questions here. First, “Have I personally given up on home roasting?” Yes. On the scale that I am brewing now (14-bbl batches), it would be hard to find a kiln large enough to handle the amount of grain I would require.
Also, the reason I got interested in doing my own kilning was that I wasn’t completely happy with some of the specialty grains available to me — especially the Munich and Vienna malts. Fortunately, I now have more choices in this area, including some excellent high-kilned malts from Germany and Belgium. Right now I am using Munich malt from DeWolf-Cosyns Maltings (Brussells, Belgium). It is considerably paler than domestic Munich malt, but it is made from Prisma two-row barley. You can use very large proportions of it in dark and amber beers, and the resultant beers are wonderfully smooth and flavorful. DeWolf-Cosyns also makes a darker high-kilned malt called Aromatic (about 25 °L), which gives an intense malty aroma. In contrast to the Munich malt — which you can use for up to 75% of the grist — I suggest trying about 5% of the Aromatic, and certainly not more than 10%.
The second question is, “Have I changed my mind about home kilning malt?” No. But I think you have to have reached a certain level of expertise before attempting it. It’s not the sort of thing you should be trying with your first, or even your tenth batch of all-grain beer. For that reason, I did not think it was something worth mentioning in a book aimed primarily at beginning and intermediate home brewers.
Once you have a couple of dozen all-grain batches under your belt, you probably know what kind of brewer you are. There are a lot of real adventurers in the ranks, those who are looking to create new and unique flavor profiles in their brews and who find the range of recognized beer styles limited and even a bit boring. For them, creating a unique malt is one more way to stretch the limits of beer tastes. On the other hand, there are also the dull, unimaginative types like me, who never really wanted to do more than match the taste of Schlitz (when I first started out) or Spaten (when I had done a little more drinking). For them, the range of commercially available malts is more than sufficient.
If you are the adventurous type, I suggest that you start by reading Randy Mosher’s articles on home kilning malt. Also, no matter how creative you are, you undoubtedly have an idea of what you’re looking for, so keep good records and standardize your procedures. Otherwise you won’t be able to duplicate or improve upon your results. Finally, be patient. Randy tells me that freshly roasted malt has a tough, burnt character, and that certainly agrees with my experience. You have to let it sit for a couple of months to allow the grain to mellow out. 

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