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10 Good Brewing Questions, Answers Included

How Long Should Beer Ferment?  

This is the most common question of all, and many homebrewers are confused by books and recipes that give definite times for fermentation. There are too many variables to say that a batch of beer will ferment for only three days or for exactly seven days. Beer usually doesn’t follow a printed timetable and when it doesn’t, folks get worried. Fermentation time is affected by temperature, the yeast strain used, the amount of yeast pitched, the specific gravity of the wort, water chemistry, and many other factors. The proper answer to this question is: Beer should ferment until it’s done!
Here are two guidelines for determining fermentation time. First, beer is ready to rack (siphon) into a secondary fermenter when the active primary fermentation is done. Primary fermentation is done when the foam (kraeusen) has dropped from the surface of the beer. Pull the stopper and airlock, then squint through the hole. If you can see the surface of the beer instead of solid foam, it’s ready to move to the secondary. Second, beer is ready to bottle when it looks as clear as iced tea. At bottling time it should be still, flat, and clear.
You can check the beer with a hydrometer to make sure it’s done, but at room temperature it is easy to tell whether beer is finished by its appearance in the carboy.
Temperature has the biggest effect on the length of fermentation. The temperature of the liquid is much more important than the temperature of the room the beer is in, because it takes a long time for five gallons of liquid to assume the temperature of its surroundings. If you pitch yeast into wort that is 85° F (not recommended), you may miss seeing the entire fermentation. At that temperature the fermentation may be done overnight, and the brewer often thinks his yeast never started. Those little yeasties get excited when they’re warm!

Why Can’t I Pitch Yeast at a Higher Temperature? 

Homebrewers often misunderstand the relationship between yeast and temperature. It is not true that ale yeast “like” room temperatures and that lager yeast “like” the cold. All beer yeast really “like” to be about 90° F for their own metabolism. At that temperature the yeast really go crazy. They make lots of yeast, eat lots of sugar, and make really bad beer as a by-product. A hot fermentation will be finished in a few hours, but the yeast get too excited when it’s hot and put all kinds of strange-tasting compounds in your beer. That’s why a hot fermentation is to be avoided.
Both ale and lager yeast make good beer when they are forced to work much colder and slower than they want to. Both kinds of yeast can make good beer at room temperature. Ale yeast will usually quit working below 55° F, but lager yeast has the additional property of making extremely clean-tasting beer at refrigerator temperatures.

Did I Get an Accurate Starting Gravity Reading? 

If you boiled part of the wort then added cold water to the brewpot or fermenter to bring your batch up to volume, you may not have gotten an accurate reading of starting gravity. Water is less dense than wort, so the water stays near the top of the vessel. Since a hydrometer floats, this situation will cause a false reading of a low starting gravity every time.
To get an accurate reading, stir the water vigorously into the cooled wort. If you ferment in a carboy rather than a bucket, put the airlock on the carboy after you’ve added the water. Then rock the vessel back and forth for at least a minute to mix the liquids together.

How Much Yeast Should I Pitch? 

The proper answer to this question is “more.” Homebrewers underpitch their yeast. We do it because of published recipes and, perhaps, for economy. If homebrewers pitched their yeast at the same rate as commercial breweries, we would be using about a pint of yeast in five gallons of wort! That would virtually eliminate the lag time before active fermentation starts and would greatly reduce the risk of contamination.
Theoretically, if sanitation were perfect, one live yeast cell would be enough to pitch. Eventually that one cell would produce enough yeast to turn all of your wort into beer. However, it takes millions of yeast cells per cubic centimeter to create visible signs of fermentation. If you started from one cell, it would be a long time before enough yeast cells existed to create a vigorous fermentation.
Unfortunately, sanitation is never perfect, so some bacteria and wild yeasts are always present. During the lag time before your good yeast cells multiply enough to really get fermentation rolling, the bad organisms are also reproducing as quickly as possible. If too little yeast is pitched, the lag time may be long enough to let bacteria and wild yeasts form substantial populations. When this happens, their by-products rise above the flavor threshold and are detectable in the finished beer. In short, the beer at best develops off-flavors and at worst is completely spoiled.
Pitch as much yeast as you can (within reason). When using liquid yeast, make a starter in advance to increase the amount of yeast before you pitch it. There are a lot more cells in a pack of dry yeast than in liquid yeast, but the liquid yeast is a pure laboratory culture. Ideally, save the dregs from the bottom of a primary fermenter in a sanitized bottle with an airlock. Keep this in the refrigerator and use it to pitch in a later batch of an appropriate beer style. You will find that the larger volume of yeast greatly reduces the “lag time” and fermentation will start very quickly!

How Can I Avoid Losing So Much Beer During Fermentation?

This question generally arises if you use the so-called “blow-over” method of fermentation. That’s the one where five gallons of beer is started in a closed, five-gallon primary fermenter. There is little room for foam during active fermentation, so a blow-over tube is used to allow foam to flow into another container and be discarded. You may lose as much as a half-gallon using this method.
The idea here is that there are harshly bitter hop resins and cold-break trub in the foam, and the finished beer will be better if these are removed. However, the liquid walls of those foam bubbles are beer, and it’s wasted when it’s allowed to pump overboard.
One solution is to use open fermentation. If you’re making a five-gallon batch, use a six-gallon food-grade plastic bucket as your primary fermenter. Place the lid loosely over the bucket (but don’t seal it). The foam will rise, then decline. A lot of the beer gets a chance to settle back into the batch. When primary fermentation is completed, siphon the beer into a five-gallon carboy — leaving the condensed hop resin, yeast, and trub spooge (called braun-hefe in Germany) — and place an airlock on it for secondary fermentation. When you’re done, you’ll bottle a full five gallons.

Foam Is Coming Through the Airlock. Should I Be Worried?

This problem is related to the previous one, except it is usually caused by an unintentional blow-over. This happens often in the summer or when yeast has been pitched into wort that is too warm. Sometimes it just happens with a high-gravity beer, such as a porter or barleywine. A homebrewer comes home from work and finds that his beer in the primary fermenter is so foamy it is coming through the airlock. This is a bad situation because it often causes contamination of the whole batch.
When an airlock is standing full of foam, all the protection it is providing is lost. It creates a continuous liquid path from the outside air to the beer in the fermenter. Bacteria will start to grow in the foam at the top and will reproduce right down into the beer.
To avoid this be sure to use a primary fermenter that allows at least one gallon for foam. If foam starts to reach the airlock, move the fermenter to a cooler location — even into a refrigerator temporarily if that is necessary to control the foam. Use vodka in the airlock instead of water, as this will help prevent bacteria from moving downward into the beer.
If you can’t control the foam any other way, install a blow-over tube temporarily from the airlock hole of the fermenter into a container of sanitizer solution sitting next to the fermenter. This should be removed and the airlock replaced as soon as is practical.

Will Tap Water Contaminate Sanitized Equipment?

A lot more beer has been ruined by leaving a residue of sanitizer on equipment than by bacteria introduced when rinsing with tap water. Chlorine bleach is known to leave a residue on equipment. Even if you use iodophor instead of chlorine, you should give all equipment a good hot-water rinse after sanitizing.
Most drinking water is really very clean. Bacteria is present everywhere, of course, but the risks of a hot-water rinse are small. The truth is that all beer, including commercial beer, contains some bacteria. The important thing in brewing is to keep bacteria below the flavor threshold so it cannot be detected. This is done through good brewing practice, mostly by rapid and efficient wort chilling and by overwhelming a small amount of bacteria with a massive amount of yeast.
The risk of contaminating equipment through a good hot-water rinse is insignificant when compared with the benefits of removing any yeast-inhibiting chemical residue.

Is It Okay to Use Plastic? 

Replace plastic often because in time it will become a source of contamination to your beer. The softer parts, such as the siphon tubing, should be replaced most often. Harder plastic parts such as fermenter buckets and racking tubes may last for years, but watch them and replace them if there is any indication of bacteria problems with your beer.
Unlike glass or metal, plastic is porous. When plastic parts touch beer wort, some of the beer will soak into the crevices. Sanitizing is more difficult with plastic, and such parts may eventually harbor pockets of bacteria that will contaminate any beer wort they touch.
Smell is the best indicator of this problem. Check your used plastic homebrewing equipment before you use it for a new batch. If there is an odor of beer, especially if there is an odor of soured beer, replace it. Lacto­bacillus (a bacteria that sours beer by producing lactic acid) is not your friend, and siphon tubing is cheap to replace!
 

Can I Substitute Dry Malt Extract for Corn Sugar When Priming? 

Corn sugar and dry malt extract (DME) are not interchangeable when bottle conditioning. Although they both can be used to carbonate homebrew, the two ingredients are quite different.
Corn sugar is pure sugar and is 100 percent fermentable. This means that every bit that is used for conditioning is converted to alcohol and carbon dioxide by yeast. DME, on the other hand, is only 80 percent fermentable, at best. More DME (1.25 to 1.43 times more!) must be used compared to corn sugar to get the same carbonation level.
In addition DME contains protein that can cause haze in the beer if the priming mixture is not boiled, cooled, and clarified.
If you want to use DME, mix it with water (about two cups of water per cup of DME), boil the mixture for 15 minutes, cool it, and allow the hot and cold trub to settle. Decant off the clarified wort, and use it to prime your beer.

How Long Does Beer Have to Age in the Bottle Before Drinking?

Bottle-primed beer takes only about a week to carbonate. But carbonation is only one reason to bottle condition your beer.
Another reason is clarification. If your beer is cloudy, let it sit undisturbed for a few weeks.
Beer flavor often improves with aging, too. A little extra time in the bottle will help get rid of young or “green” flavors — the ones that smell like apples or butter. These flavors will mellow as long as there is yeast in the bottle.
Strong beers, such as barleywines and Scottish ales, will mellow considerably with aging. The aging process for these beers can continue for months and sometimes years.
In general, if your beer is of ordinary strength, taste it after seven to 10 days to see if its ready. If you are brewing a strong beer, hold out for at least three weeks. And don’t be shy about extending the aging time. Your beer will probably benefit.
Issue: March 1996