Perhaps it was sampling that delicious bourbon barrel stout that seduced you into contemplating a way to impart the taste of oak into a batch of homebrew. Maybe it was the scent of smoked grain mashing on brew day. Whatever your personal call to oak is, there are now a range of choices to give your beer that fabulous hint of complexity that oak imparts. After all, wood was the initial home to all things beer. From aging to storage, wooden casks were the only choice for brewers of old. The modern home brewer has a range of choices to bring back that taste of yesterday. Choosing your oak is a matter of beer styles, taste, and simplicity of use.
Oak is the wood of choice for many reasons, but for now, we’ll focus on the aspects of flavor and aroma. Oak is superior to other woods because elements found within the structure of oak add desirable flavors and aromas, while also transforming undesirable characteristics. Oak also lacks resins that could add unwanted elements to aging spirits, beers, or wines.
Oak chips in a carboy
There are several types of oak used for the aging process. American white oak, which is slightly more porous than the European oaks, European (French/Hungarian) “Sessile” oak, European white oak, and Japanese Mizunara oak, which is primarily used in Japanese whiskey production.
Despite the species, the characteristics vary somewhat with the area where the trees are grown, due to differences in growing conditions. Before we get to a general flavor profile for each variety, let’s take a quick look at the particulars of oak that result in flavor and aromatic additions. The choice of specie by a brewer is directly related to the ratio at which these elements are found in the wood.
Oak tannins: an astringent preservative compound.
Flavor/aroma addition: Tartness. This is more pronounced in wood that has not been toasted or charred.
Toasted or Charred: Toasting or charring oak results in chemical changes that develop flavors from these compounds, as well as toning down the addition of tannin and lending the taste of smoke.
Hemicellulose: simple sugars that break down when heated.
Flavor/Aroma Addition: Caramel aroma and flavor. It is also worth noting that hemicellulose adds body, due to the breakdown of wood sugars.
Lignin: a binding agent for cellulose that yields vanillin when heated.
Flavor/aroma addition: Sweet, smoky, spicy(clove), and vanilla.
Oak Lactones: lipids that multiply after toasting or charring.
Flavor/aroma addition: Wood, coconut.
American white oak is higher in lignin and lactones, which results in a higher concentration of vanillin. European (French) oak has refined tannins and more vanillin than European white oak. European white oak is higher in tannins. The white oak grown in Spain offers raisin and prune notes. The European Sessile oak grown in Hungary has a delicate spice and a similar flavor and aroma profile to French oak, but is offered at a lower price. Mizunara oak has a high coconut aroma and a hint of sandalwood.
With the differences in oak species firmly in mind, let’s move on to the aroma and flavor differences of toasting or charring oak. Toasting/charring is labeled in different ways. When purchasing barrels from a cooperage, they will likely provide a char number to indicate how much toasting is applied to the interior of the barrel. Char #3 is the standard char, but many cooperages offer Char #4 as well. New barrels can be custom charred. Tell the cooper the taste and aroma you are trying to achieve and they will suggest a char to accomplish that.
Char #3 flavor profile: Highest vanillin profile. Caramel and toffee.
Char #4 flavor profile: Smoke, coffee, chocolate.
Outside the world of barrels, there are other ways to add oak to beer. There is more information about all of these options below. For the sake of organization, this section covers the toasting of these other oak additives.
Light: Enhances the fruit notes in oak and adds a delicate coconut note.
Medium: Aroma and vanilla.
Medium Plus: Honey and roasted nuts. Hints of coffee and spice.
Heavy: Caramelized wood, smoke, bread
After fermentation is complete, aging the beer in or with oak for a projected flavor profile can be as simple as moving it to a barrel or adding one of several oak options to the carboy. Contact time is the key to achieve the flavor and aroma profile you seek, so make notes and taste regularly until you achieve the taste and aroma you desire. Suggested times and amounts for additives are included for a reference point.
5 gallon (or even 55 gallon) barrels take up the most room, but have relatively slower release rates.
This is the most expensive and cumbersome option, but the complexity of flavor and aroma makes a strong case to balance the downside. There are a lot of decisions in choosing a barrel. The first choice is new versus used. The surface to beer ratio in a barrel offers the most reuse potential. It also takes longer contact time to impart oak to the beer than the additive methods.
New barrels are significantly more expensive, and will have a more profound impact on the flavor of beer than barrels that have held some type of spirit. Cooperages make barrels in a variety of craft distillery sizes, 5, 10, 15, and 30 gallon, as well as larger sizes for the volume spirit business.
Choosing a used barrel presents a need for additional decisions, including the flavor profiles that spirits will impart. Used barrels offer a significant price break. Bourbon barrels are the most widely available used barrel, because bourbon can be stored only in new barrels. At that point, bourbon makers pass the barrels on to breweries and distilleries making other spirits that use the residual flavor profiles of bourbon to enhance their beers and liquors. One of the downsides to used barrels is size unless you can get them from a craft distillery. Bourbon barrels average 42 to 53 gallons per barrel, take up a lot of space, and represent a storage capacity that is more than the average home brewer is likely to make at one time.
Craft spirit distilleries may offer smaller barrels that have housed bourbon or other sprits that could add to a beer’s overall flavor profile. Bourbon would be the most widely available, but there are other spirits that have limited barrel life.
Mini barrels are available in the 1-3 liter range (that’s 31-102ish ounces) and offer improved storage options, but limit you to a smaller brew, buying more minis, or using an oak additive in the leftover beer.
Keep in mind that wood makes a great home for bacteria and yeast, so sanitation becomes a concern with the lower alcohol content of beer. Used wine barrels seem to create an ideal environment for Brettanomyces, which could be considered a plus for certain styles of beer, but definitely the author of off tones for others.
Getting the oak notes in your aging beer will take six to twelve months, though if you are using a spirit barrel and primarily want to capture the spirit and its oak notes, one or two months may produce the results you seek. Since patience isn’t a virtue when you’re thirsty, there are, thankfully, faster methods to get your oak on.
Top Left to Bottom Right: Spiral, Honeycomb, Staves, Essence, Cubes, Powder, and Chips
Staves are the oak pieces that are used to make a barrel. Staves are available from used barrels, which offer the added complexity of spirit residue to accompany the oak. Fresh staves may be available from some cooperages. You can control the amount of oak with contact time, but staves offer a complex flavor profile only rivaled by barrel aging. Suggested application is one eight-inch stave per five gallons, with extraction over two to three months in the carboy.
Spirals are a great alternative for adding oak to the carboy. Like chips or cubes, they add flavor quickly, but it’s more refined and complex. The spirals provide an infusion of oak properties for a longer period than cubes or chips because of a reduced surface to beer ratio, so they can be used for multiple brews. Like all oak additives, the characteristics diminish with each use, but that makes them ideal for beers where less oak profile is wanted. Spirals are available in a number of toast choices. Spirals can be used whole or they can be broken into pieces, but again, contact time offers the most control. The downside to using spirals is they take more alcohol should you choose to soak them for spirit characteristics; however, they fit nicely in a fourteen-inch hydrometer test jar. Suggested application is one stick per three gallons with complete extraction in six weeks.
Similar to spirals, these are oak rectangles with drilled holes to increase the surface ratio. Suggested application is one inch per gallon of beer with complete extraction in six weeks, but at present, they are only available in an unspecified single toast profile, though toasting it on your own is an option. They are available in batch size lengths, however, ranging from bottle inserts to 30 barrels and offer a similar complexity to spirals.
Oak cubes are also available in a variety of woods and toasts. The aroma and flavor profile is not as complex as with any of the previous additives, but does provide some complexity as the thicker surface results in uneven toasting. Reusing them is possible, but the result is less character over more contact time, as the high surface area-to-beer ratio leeches most of the oak characteristics after initial use. This feature potentially makes them more useful for beers where only a hint of oak is preferred. Cubes are also easy to soak in spirits, if that component is key to the recipe. They make great additives to the smoker box if not reused.
Chips offer a greater surface area-to-beer contact ratio, which means less contact time is needed to achieve the effects of oak. Chips toast more evenly, reducing the complex flavors and aromas available from other oak additives, but the simple profile may suit the beer style. Another disadvantage to chips is that they can get sucked into the keg or bottling rig when siphoning, but that can be alleviated by placing a sanitized hop bag over the end of the siphon. Suggested application is 5 oz. with extraction complete in one week.
Powder offers the least contact time of the wood products because of the great surfacearea-to-beer ratio, so if you’re in a hurry, it’s the way to go. On the other hand, it's more difficult to separate from the beer. Again, use the sanitized hop bag, but this time applied to the hose end, letting the wood shavings collect in the bag as it empties into the keg or bottling bucket. Added complexity can be achieved by mixing toasts, but the flavor and aroma profiles won’t rival any of the other additives. Suggested application is an eighth to quarter of an ounce for one to two days.
The imitation vanilla of the oak world, oak essence does have a scent (think woody vanilla) and flavor that loosely resembles medium toast oak (bitter liquid smoke and watered down vanilla undiluted). It lacks complexity, but ranks number one in ease of use. It can be added to the keg or at bottling. There are at least a couple of different strength concentrations, so read the bottle for recommended usage. Unlike other methods, there’s no wait time at all. Even if you’d never forego wood for a flavoring, it is useful to see if oak enhances or clashes with a particular recipe you might long to oak without sacrificing a whole batch to experimentation.
With all these readily available choices at hand, it’s time to try oak with a favorite recipe.
Oak is the wood of choice for many reasons, but for now, we’ll focus on the aspects of flavor and aroma. Oak is superior to other woods because elements found within the structure of oak add desirable flavors and aromas, while also transforming undesirable characteristics. Oak also lacks resins that could add unwanted elements to aging spirits, beers, or wines.
Types of Oak
Oak chips in a carboyThere are several types of oak used for the aging process. American white oak, which is slightly more porous than the European oaks, European (French/Hungarian) “Sessile” oak, European white oak, and Japanese Mizunara oak, which is primarily used in Japanese whiskey production.
Despite the species, the characteristics vary somewhat with the area where the trees are grown, due to differences in growing conditions. Before we get to a general flavor profile for each variety, let’s take a quick look at the particulars of oak that result in flavor and aromatic additions. The choice of specie by a brewer is directly related to the ratio at which these elements are found in the wood.
Untoasted or Uncharred
Oak tannins: an astringent preservative compound.
Flavor/aroma addition: Tartness. This is more pronounced in wood that has not been toasted or charred.
Toasted or Charred: Toasting or charring oak results in chemical changes that develop flavors from these compounds, as well as toning down the addition of tannin and lending the taste of smoke.
Hemicellulose: simple sugars that break down when heated.
Flavor/Aroma Addition: Caramel aroma and flavor. It is also worth noting that hemicellulose adds body, due to the breakdown of wood sugars.
Lignin: a binding agent for cellulose that yields vanillin when heated.
Flavor/aroma addition: Sweet, smoky, spicy(clove), and vanilla.
Oak Lactones: lipids that multiply after toasting or charring.
Flavor/aroma addition: Wood, coconut.
American white oak is higher in lignin and lactones, which results in a higher concentration of vanillin. European (French) oak has refined tannins and more vanillin than European white oak. European white oak is higher in tannins. The white oak grown in Spain offers raisin and prune notes. The European Sessile oak grown in Hungary has a delicate spice and a similar flavor and aroma profile to French oak, but is offered at a lower price. Mizunara oak has a high coconut aroma and a hint of sandalwood.
Levels of Toast or Char
With the differences in oak species firmly in mind, let’s move on to the aroma and flavor differences of toasting or charring oak. Toasting/charring is labeled in different ways. When purchasing barrels from a cooperage, they will likely provide a char number to indicate how much toasting is applied to the interior of the barrel. Char #3 is the standard char, but many cooperages offer Char #4 as well. New barrels can be custom charred. Tell the cooper the taste and aroma you are trying to achieve and they will suggest a char to accomplish that.
Char #3 flavor profile: Highest vanillin profile. Caramel and toffee.
Char #4 flavor profile: Smoke, coffee, chocolate.
Outside the world of barrels, there are other ways to add oak to beer. There is more information about all of these options below. For the sake of organization, this section covers the toasting of these other oak additives.
Light: Enhances the fruit notes in oak and adds a delicate coconut note.
Medium: Aroma and vanilla.
Medium Plus: Honey and roasted nuts. Hints of coffee and spice.
Heavy: Caramelized wood, smoke, bread
Bringing Oak to Homebrew
After fermentation is complete, aging the beer in or with oak for a projected flavor profile can be as simple as moving it to a barrel or adding one of several oak options to the carboy. Contact time is the key to achieve the flavor and aroma profile you seek, so make notes and taste regularly until you achieve the taste and aroma you desire. Suggested times and amounts for additives are included for a reference point.
Barrels
5 gallon (or even 55 gallon) barrels take up the most room, but have relatively slower release rates.This is the most expensive and cumbersome option, but the complexity of flavor and aroma makes a strong case to balance the downside. There are a lot of decisions in choosing a barrel. The first choice is new versus used. The surface to beer ratio in a barrel offers the most reuse potential. It also takes longer contact time to impart oak to the beer than the additive methods.
New barrels are significantly more expensive, and will have a more profound impact on the flavor of beer than barrels that have held some type of spirit. Cooperages make barrels in a variety of craft distillery sizes, 5, 10, 15, and 30 gallon, as well as larger sizes for the volume spirit business.
Choosing a used barrel presents a need for additional decisions, including the flavor profiles that spirits will impart. Used barrels offer a significant price break. Bourbon barrels are the most widely available used barrel, because bourbon can be stored only in new barrels. At that point, bourbon makers pass the barrels on to breweries and distilleries making other spirits that use the residual flavor profiles of bourbon to enhance their beers and liquors. One of the downsides to used barrels is size unless you can get them from a craft distillery. Bourbon barrels average 42 to 53 gallons per barrel, take up a lot of space, and represent a storage capacity that is more than the average home brewer is likely to make at one time.
Craft spirit distilleries may offer smaller barrels that have housed bourbon or other sprits that could add to a beer’s overall flavor profile. Bourbon would be the most widely available, but there are other spirits that have limited barrel life.
Mini barrels are available in the 1-3 liter range (that’s 31-102ish ounces) and offer improved storage options, but limit you to a smaller brew, buying more minis, or using an oak additive in the leftover beer.
Keep in mind that wood makes a great home for bacteria and yeast, so sanitation becomes a concern with the lower alcohol content of beer. Used wine barrels seem to create an ideal environment for Brettanomyces, which could be considered a plus for certain styles of beer, but definitely the author of off tones for others.
Getting the oak notes in your aging beer will take six to twelve months, though if you are using a spirit barrel and primarily want to capture the spirit and its oak notes, one or two months may produce the results you seek. Since patience isn’t a virtue when you’re thirsty, there are, thankfully, faster methods to get your oak on.
Staves
Top Left to Bottom Right: Spiral, Honeycomb, Staves, Essence, Cubes, Powder, and ChipsStaves are the oak pieces that are used to make a barrel. Staves are available from used barrels, which offer the added complexity of spirit residue to accompany the oak. Fresh staves may be available from some cooperages. You can control the amount of oak with contact time, but staves offer a complex flavor profile only rivaled by barrel aging. Suggested application is one eight-inch stave per five gallons, with extraction over two to three months in the carboy.
Spirals
Spirals are a great alternative for adding oak to the carboy. Like chips or cubes, they add flavor quickly, but it’s more refined and complex. The spirals provide an infusion of oak properties for a longer period than cubes or chips because of a reduced surface to beer ratio, so they can be used for multiple brews. Like all oak additives, the characteristics diminish with each use, but that makes them ideal for beers where less oak profile is wanted. Spirals are available in a number of toast choices. Spirals can be used whole or they can be broken into pieces, but again, contact time offers the most control. The downside to using spirals is they take more alcohol should you choose to soak them for spirit characteristics; however, they fit nicely in a fourteen-inch hydrometer test jar. Suggested application is one stick per three gallons with complete extraction in six weeks.
Honeycombs
Similar to spirals, these are oak rectangles with drilled holes to increase the surface ratio. Suggested application is one inch per gallon of beer with complete extraction in six weeks, but at present, they are only available in an unspecified single toast profile, though toasting it on your own is an option. They are available in batch size lengths, however, ranging from bottle inserts to 30 barrels and offer a similar complexity to spirals.
Cubes (Beans)
Oak cubes are also available in a variety of woods and toasts. The aroma and flavor profile is not as complex as with any of the previous additives, but does provide some complexity as the thicker surface results in uneven toasting. Reusing them is possible, but the result is less character over more contact time, as the high surface area-to-beer ratio leeches most of the oak characteristics after initial use. This feature potentially makes them more useful for beers where only a hint of oak is preferred. Cubes are also easy to soak in spirits, if that component is key to the recipe. They make great additives to the smoker box if not reused.
Chips
Chips offer a greater surface area-to-beer contact ratio, which means less contact time is needed to achieve the effects of oak. Chips toast more evenly, reducing the complex flavors and aromas available from other oak additives, but the simple profile may suit the beer style. Another disadvantage to chips is that they can get sucked into the keg or bottling rig when siphoning, but that can be alleviated by placing a sanitized hop bag over the end of the siphon. Suggested application is 5 oz. with extraction complete in one week.
Powder
Powder offers the least contact time of the wood products because of the great surfacearea-to-beer ratio, so if you’re in a hurry, it’s the way to go. On the other hand, it's more difficult to separate from the beer. Again, use the sanitized hop bag, but this time applied to the hose end, letting the wood shavings collect in the bag as it empties into the keg or bottling bucket. Added complexity can be achieved by mixing toasts, but the flavor and aroma profiles won’t rival any of the other additives. Suggested application is an eighth to quarter of an ounce for one to two days.
Essence
The imitation vanilla of the oak world, oak essence does have a scent (think woody vanilla) and flavor that loosely resembles medium toast oak (bitter liquid smoke and watered down vanilla undiluted). It lacks complexity, but ranks number one in ease of use. It can be added to the keg or at bottling. There are at least a couple of different strength concentrations, so read the bottle for recommended usage. Unlike other methods, there’s no wait time at all. Even if you’d never forego wood for a flavoring, it is useful to see if oak enhances or clashes with a particular recipe you might long to oak without sacrificing a whole batch to experimentation.
With all these readily available choices at hand, it’s time to try oak with a favorite recipe.
