Dear Mr. Wizard,
I have a brewing problem that I have not been able to solve. I am an extract brewer and occasionally add grain. I have brewed approximately 60 batches of beer over the past four years. My problem: About a year ago I suddenly started to get beer that was thick, syrupy, and very disgusting. It seems to take two or three weeks after bottling to start to show up, a little at a time. I suspected sanitation, but I have been extra careful and it still happens. I now suspect my water, which is from a well. I also add a little extra water to a typical five-gallon batch, usually ending with 5.5 gallons.
Mr. Wizard replies:
The problem you describe sounds like the phenomenon called "ropiness" or the development of a complex polysaccharide slime in beer produced by certain bacteria. The slime produced by rope-forming bacteria is thixotropic in nature, which means the viscosity of the beer will drop when it is stirred or shaken and will increase once the beer is left still. The famous Belgian brewing scientist Jean De Clerck wrote in his Textbook of Brewing, published in the 1940s, that ropiness is "the most unpleasant infection which can be encountered in beer."
Ropey beer is caused by two different kinds of bacteria. The aerobic, vinegar-forming Acetobacter are known to secrete slime — that has such a nice sound to it! Ropiness from the Acetobacter species is only common in beer exposed to oxygen, like cask ale and beer left in beer taps. Your bottled beer does not have enough oxygen for Acetobacter to grow and form rope.
The other bacteria known to form rope in beer are the varieties viscosus and limosus of Pediococcus damnosus. Unlike other strains of Pediococcus, these guys do not produce diacetyl (buttery or butterscotch flavor). Pediococcus is a common spoilage organism in beer and grows best under anaerobic conditions like those found in a bottle. Like other beer-spoilage bacteria, Pediococcus is commonly found in the environment and is often carried into beer through yeast or other ingredients added after the boil.
In general your problem is most likely a result of insufficient sanitation. This does not necessarily mean that you are using "dirty" brewing practices, rather it simply means that you are contaminating your beer somehow. Good sanitation after the boil requires all implements that touch beer or wort to be cleaned with a detergent and sanitized before use. Make sure you are using a recognized sanitizer and that its concentration is correct. If you are using hot water, make sure the water is hotter than 180° F and that you allow at least 20 minutes at this temperature before considering your tools sanitized. This includes carboys, hoses, spoons, bottles, and bottle caps.
Good sanitation also means that any ingredient added to beer should be properly treated before its addition. If you are adding well water to beer after fermentation, the water should be boiled. This rule also applies to priming sugar and other post-boil additives. This is the first time I have had a ropey beer question, or at least a problem that sounds like rope. If your problem persists, write back with more details and a sample. Good luck!
Dear Mr. Wizard,
In using specialty grains with extract homebrewing, what is the best method to get the most flavor and color out of the grains but still reduce tannins? Some recipes say to steep grains until water comes to a boil and remove, while others say to bring water to 150° F and steep for 30 minutes. I just made a Belgium ale in which I steeped the grains in 170° F water for 30 minutes and then sparged with 170° F water. Was this temperature too high for the steep and did it release unwanted tannins?
Mr. Wizard replies:
The two most influential factors affecting the extraction of tannins from malt into wort are pH and temperature. All-grain brewers are very careful not to allow wort pH to reach more than about pH 6 during sparging because tannin extraction increases with pH. In all-grain brewing wort pH typically rises during the last stages of wort collection and is one of the factors letting the brewer know that wort collection should be stopped.
When a relatively small weight of specialty grains is steeped in a large volume of water, the result is a very thin mixture. The pH is only slightly affected by the malt (pale malts tend to lower the mash pH during all-grain mashing to about 5.4 pH). This means the pH of the solution during steeping will be higher than the pH of a normal mash, which has an oatmeal-like consistency.
To combat this problem the pH of the steep can be adjusted to around 5.4. Although all-grain brewers typically use calcium sulfate (gypsum) or calcium chloride to lower mash pH, these salts lower pH by reacting with phosphates from the malt. Steeping mixtures don’t contain much malt and lowering the pH with water salts can be difficult. Food-grade lactic or phosphoric acid are alternatives to water salts; both of these acids are sold in homebrew stores.
The key to adding acids is to add them slowly with continual stirring and monitoring with a pH meter or pH paper. I recommend adding a small amount while stirring the pot, checking the pH, and continuing until the pH is around 5.4.
Temperature also affects tannin extraction. This relationship is pretty simple. If you don’t want to run the risk of getting too much tannin in your wort, keep the temperature just below 170° F.
This is where the answer to your last question begins. You ask whether steeping and sparging released "unwanted tannins" in your beer. For starters, all beer contains tannins. Some tannins are implicated in haze and some lend astringent flavors to beer.
The type most homebrewers are concerned about are those affecting flavor. In any case, it is up to the brewer to decide if the level of tannins in their beer is too high. The (in)famous decoction mash is frequently recommended when a brewer is in search of more malt flavor. Decoction mashes boil malt and — among analytical brewers who are not afraid of rocking the boat with unpopular ideas — are known to increase the astringent character associated with tannins. In general I wouldn’t consider 170° F dangerously high with respect to tannin extraction. However, if you believe your beers may suffer because of too much astringency, consider adjusting your steep pH and lowering the temperature a few degrees.
Mr. Wizard, BYO's resident expert, is a leading authority in homebrewing whose identity, like the identity of all superheroes, must be kept confidential. To see more of Mr. Wizard, check out the latest issue of Brew Your Own available at better homebrew shops and newsstands.