Dear Mr. Wizard,
If I wanted to use oak or beechwood chips in brewing a 5.5 gallon batch of beer, how would I go about it? How many ounces would I use and how would they be handled in the mash or fermentation containers? How long would they be left there? I realize that they would have to be steamed for 15 minutes before using.
Paul A. Borowski
via email
Mr. Wizard replies:
You have really asked two different questions here: How to add oak for flavor and how to add beechwood for aging. Beechwood does not not add flavor. Adding oak chips — which is done in the fermenter, not the mash tun — can add some interesting flavors to your homebrew as well as acting as a surface area to accelerate aging.
Whether using oak for flavor or beechwood to help with aging, the weight of the wood chip is not the most important consideration. Rather, the surface area is the key factor to consider. The flavor from the chip is released into the beer only where the beer and the chip are in contact. You could have a bag of thin oak chips and a bag of thick oak chips that both weigh the same, but the thin chips would have a greater surface-area-to-weight ratio. So the thin chips would add more flavor than the same weight of thick chips.
I recently made some oak-aged hard cider and got an incredible aroma from the wood during the aging process. The barrels I used are about three feet in diameter,
four feet long and contain 50 gallons of liquid. To put this in beer-geek terms, the barrels have about 149 square inches of oak area per gallon of contents. This statistic is the barrel’s surface-to-volume ratio. That’s a good number to keep in mind, since most barrels used for aging wine are in this size range. As the capacity of a barrel increases, its surface-to-volume ratio decreases and the time required for the oak to flavor the contents of the barrel increases.
When I decided to do an oak-aged cider, I had to make a few decisions. To begin with, I had to choose between new and used barrels. I wanted to flavor my cider with oak and nothing more, so I chose new barrels. I then had to choose among several different levels of “toast.” Toast refers to the firing the inside of the barrel receives during the manufacturing process, similar to the toasting or roasting of malt during kilning. I also had an option of interior surface roughness and could buy American or French oak.
I chose American oak, with a medium toast and a “normal” surface roughness. According to the barrel maker, this would give me nice vanilla notes from the toast level, an aroma consistent with American oak. The roughness of the interior would result in a faster release of oak flavors than a barrel with a more polished finish.
To be honest, I felt pretty ignorant when faced with all these options. So I asked, “What barrels are used by winemakers producing aggressively-oaked Chardonnays?” “Most of our customers use American oak with medium-plus toast with a normal roughness,” was the reply. “Very well,” I said, “I’ll buy two of those!”
Most of these same options are available when buying oak chips that are added to the aging vessel. You may also choose used barrels because used barrels may add more than oak flavors. There are many stouts available these days, for example, that have been aged in used bourbon barrels. As a result, these bourbon stouts have complex bourbon flavors. Sam Adams uses port and sherry barrels to age their triple bock family of beers. Used barrels open up a whole world of options that can be explored to create new and interesting beers. If the barrel contained whiskey, most brewers don’t worry about sanitation. Used wine barrels, however, can pose problems and must be sanitized prior to use.
Right now it’s summer, a good time to brew a big beer for the winter. Imagine a strong ale with assertive bitterness, low hop aroma and a full and clean malt backbone. This beer has just finished primary fermentation and the plan is to age it on oak to add further complexity to its flavor. A bag of oak chips with the desired toast has been purchased and the question is how much to add. If the chips are two inches wide, four inches long and 0.25 inches thick they will each provide 19 square inches of surface area (two sides at eight square inches, two edges at one square inch and two edges at 0.5 square inch). Eight of these chips per gallon of beer will give about the same surface-to-volume ratio (149) as an oak barrel. So set aside 43 of these chips for the 5.5-gallon batch of beer.
Chips will float and it is important to keep the entire surface of the chip in contact with the beer during aging. A hop bag weighted with some stainless steel bolts (or some other inert weight) will do the trick. Sterilize the bag, chips and weight with either steam or hot water. I chose to fill my barrels with 195° F water and let the barrels sit for several hours prior to use. Either method will work for sterilization. Some sanitizing solutions will damage the wood and perhaps flavor the beer. Burning sulfur is one method of sanitizing barrels used by winemakers, while using a dilute solution of KMS or Campden tablets is another. I like hot water because there is nothing added to the barrel other than water.
The next step is to place the chip bag into a vessel for the aging process. This poses a dilemma since the chip bag won’t fit into a carboy and a plastic secondary allows oxygen into the beer. The ideal container is a five- gallon Cornelius keg. Place the chips in the keg and rack the beer from the primary into the keg for aging. Try to minimize the amount of yeast carried into the secondary as excessive yeast will impart autolyzed flavors from yeast death over the aging period. The beer can be primed at this time or you can wait until later. Priming at this stage will be easy since the yeast viability is still excellent. If primed later, more yeast will most likely need to be added.
Now it’s time to wait. This is the most important step to oak aging. It is tempting to place the keg in a cool corner and to forget about it for several months. After all, if you pay attention to the beer during aging, the temptation to drink it early may get to you and you will have no beer left after nipping on it for several months. However, if you store the keg where it is too cool, the flavor takes longer to extract. Too warm and the beer suffers because of yeast autolysis. Cellar temperature (55° F) works well for the aging step.
Vigilance and restraint are required during aging. Sample the beer on a regular basis — say once every three weeks — to keep tabs on its progression. The purpose is to prevent the beer from becoming excessively oaky. The oak should add complexity to the beer, but not dominate its flavor. Once the flavor reaches the intensity you desire, you can rack the beer into a second keg or bottle it.
Another variation is to not worry about the oak intensity during aging and to blend the oak-aged beer with a batch of non-oaked beer to produce the desired oak intensity. This is how I treated my cider, which became so oaky after three months in a new barrel that it was hard to smell or taste anything else but oak!
You also mentioned beechwood in your question. Beechwood aging has absolutely nothing to do with wood flavor. The wood gives the yeast more surface area to cling to and helps the beer age. The one brewery I know that still uses beechwood aging goes to a lot of effort to cook all the wood flavor out of the chips prior to use. This process also renders the chips non-buoyant so that they lay on the bottom of the chip tanks during the lagering process. These long, curly chips add a tremendous amount of surface area that yeast settles on during lagering. Diacetyl and acetaldehyde reduction during aging requires yeast and beer to interact, and that is precisely what the beechwood chips do for the brewer. This reactive surface area is similar to the enormous surface area in the human intestine across which we absorb nutrients from food. If the intestine were smooth it would have a much lower surface area than it does with its microscopic convolusions. Beechwood chips give yeast a large surface area where they can hang around and interact with the aging beer.
Although I have no data to support my opinion, I bet any benefit to this practice would be very hard to quantify in a 5-gallon batch of beer. Most chip tanks in the United States are horizontal tanks containing about 60,000 gallons of beer. That’s a lot of beer!
Dear Mr. Wizard,
In the January-February issue, there was a question from John “Mick” Barns concerning mashing efficiency and undershooting the target gravity given in the recipe. I have also experienced this same problem and have adjusted the specific gravity using the ProMash software. I am now ending up close to the OG I want by adjusting the amount of base malt in my recipes. The question I have is, should I also increase the amounts of crystal and other non-base malts? It seems that I am getting the colors and flavors I desire from the crystal and dextrin malts, but I would like some advice.
James Stewart
Riverside, California
Mr. Wizard replies:
This is one of those questions that raise issues extending much further than simply hitting the target original gravity. In your case, you like the color and flavor intensity of the special malts, but you have had problems hitting the target gravity. Increasing the weight of the base malt is certainly the most direct way to deal with the issue and is the method that most commercial brewers use to hit their specified original gravity. If you are not too far off target, then this is the way to go.
Base malts are used for a number of reasons, yet the most important feature of base malts is their contribution to fermentable extract. If wort did not contain fermentable extract, there would be no beer. For this reason, one could argue that base malt is the single most important ingredient in beer. The point here is that, if you need more extract, adding more base malt is the most logical response. In doing so, however, questions arise about the similarity of the wort produced and the wort described by the recipe.
I have always figured that if I am not getting what I want from the base malt, I may be missing something from the specialty malts as well. Base malts change because of seasonal fluctuations in the barley crop and in the specifications used amongst maltsters. If the malt used has a lower laboratory yield than the base malt originally used in the recipe, then the weight of base malt should be increased to adjust for the difference. On the other hand, if the lab yields are the same, but the wort gravities are not, the difference most likely has to do with something in the brewing process. That could be milling, mashing, lautering or a combination of these steps. If this is the case, then it’s likely that the special malt color and flavor intensity is different from the original recipe as well. If I’m not getting all I am supposed to out of my base malt, I may not be getting it from my specialty malts, either.
Some brewers find this all very esoteric and only care about the qualities of the beer in their glass. If the color, flavor and alcohol level are satisfactory, they are happy with that particular batch of beer and this question is a moot point. Other brewers want to produce that same glass of beer indefinitely and the question becomes much more pertinent. These brewers will not only chart original gravity, but also wort/beer color and special malt-related beer flavors using highly trained taste panels. This data can then be used to determine which malt weights need to be adjusted to keep the beer within the defined specifications.
Most homebrewers or small craftbrewers do not go that far with fine-tuning their recipes. When I think of recipes in this manner, it reminds me of what a recipe really is to most brewers and cooks. A recipe is simply a way of describing something that was previously made. I routinely brew an American-style unfiltered wheat that contains three pounds pale malt, 2.5 pounds wheat malt and 0.75 pounds unmalted wheat per five-gallon batch to give an original gravity of 11.25° Plato (1.045 SG). I hop this beer with Perle hops to about 18 bittering units and use Liberty hops for aroma. This is my recipe and it merely defines the ingredients used in the beer. That’s all any recipe does. I would be surprised if another brewer used this recipe and made a beer that tasted just like mine.
In my opinion, if a brewer or a cook uses another person’s recipe, they should think of the recipe as a general description. The most important quality of the finished product to most homebrewers is how good the beer tastes, not how similar the beer is to that described by the recipe. Unless you have tasted the beer the recipe is based on, you have no idea how close you have gotten to the target. If you are more challenged by hitting your target than just making a great glass of beer, then you will need to invest in some lab equipment and recruit your friends and family to participate in your numerous taste panels.
Like all brewers, I grapple with this same issue. I personally prefer to “tweak” the weight of base malt if I am trying to stay focused on my target specific gravity. After all, that’s what the base malt primarily contributes to the wort. If, on the other hand, my color is off target or the flavor of the beer lacks the intensity of a particular malt, I change my focus. Color and flavor variances are best addressed by fine- tuning the specialty malt portion of the recipe. It is most important to remember that the brewer is not the only person faced with the challenge of consistency. Specialty malts are typically described with rather large ranges. For example, I use a crystal malt called “Crystal 135-165° Lovibond.” That’s one heck of a range of color. If I brew a beer today and the malt is on the lower end of that range, and the same beer is brewed later and the malt falls toward the upper range, then the finished beers will not be the same color unless the recipe is tweaked.
This is one doozy of a question. In my own opinion, you can’t really fine- tune the special malts unless you know what the target is. For these grains, I would view recipes as the historic log that they are. Specific gravity is a target, however, and I do adjust my base malts to hone in on that variable.
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