Home » Chemical composition of Rum, Comparison with Burbon-Whiskey-Cognac/Brandy

  • Chemical composition of Rum      Part 3.
  • Heads and Tails 
  • Charcoal and Wood flavoring 
  • Wild Turkey style flavor 
  • Identification of components in Liquors and distilled Spirits 
  • Whiskey 
  • Cognac / Brandy 
  • Bourbon 
  • Scotch Malt Whisky and Irish Whiskey 
  • Rum 
  • Shortcuts and tricks 
  • American “Bourbon” made from essences 
  • Flavorings to Whiskey 

Chemical composition of Rum and comparison to American Bourbon Whiskey

The following figures were found for light bodied Rum that had been aged in charred oak barrels (previously used for aging bourbon)

 

Composition of Rum and American Bourbon Whiskey

 

Jamaican Rum

American Bourbon

Age (years)

0

3

0

3

Constituents

Concentration g/100L

Concentration g/100L

% alcohol

80.1

78.2

77.5

75.5

total solids (extract)

0

87.6

0

136

fixed acids

0.9

8.8

0

12

volatile acids

1.1

20.9

3.2

50

Total acids

2.0 (pH=4.9)

29.7 (pH=4.5)

(3.2)

(62)

esters (for years, erroneously called ethers)

9.7

37.5

9.6

42.0

aldehydes

1.9

4.7

0.6

5.6

fusel oils (higher alcohols)

48

66

250

298

furfural

n/d

1.6

0.12

1.42

tannins

n/d

     

Heads and Tails

Whenever you distill something, the most volatile products come out first.  So when you distill a mash, the low boiling point compounds in it (in general the Nitrogenous Substances, Aldehydes, and Esters) will appear in the first distillate. This part of the distillation is commonly called the “Heads”. You can prevent them from contaminating the product you are attempting to separate by watching the temperature and discarding (or saving for addition to the next batch) everything that boils off before you reach the boiling point of the target component.

But, depending on the nature of the wash, it’s sometimes difficult to isolate the heads by simply monitoring the temperature.  It’s easy to miss the boiling points of those compounds that vaporize below 70º C when there is an excess of heat input, and the vapors rise up the column quickly to reach the thermometer bulb.  Many experienced distillers carefully monitor the taste and smell of the first distillate from the still to ensure that all the heads are boiled off before they begin the collection of the body of the spirits.  Others simply discard a small (say150 ml) fixed amount, before beginning the collection of the ethanol.

A similar distillation cutoff point is also encountered as the ethanol nears depletion from the distillation.  This phase is commonly referred to as the “Tails”.  The tails contain an increased amount of the higher boiling point compounds, such as the higher alcohols and furfural. 

These compounds can also spoil the taste of the spirits if the collection is carried on too long.  A cutoff similar to that of the heads should be made.

Again, you can recognize this point by monitoring either the temperature or the taste and smell of the distillate.  Many distillers simply limit the collection of the pure spirits to a narrow range of temperatures (78.3 – 80 C), and then make the cut.  Others sample the specific gravity of the distillate as it nears the end of the run.  Still others use the smell and taste indicators.

In any event, there usually is considerable ethanol that can be recovered from that remaining after the tails have been cut.  Commonly, the tail collection is saved for inclusion in the next batch.

http://homedistiller.org/graphics/oak_aromatoast.gif

Charcoal and wood flavoring

When aging your spirit, it is best done between 58 – 70% alcohol.  It can be done using: woods – e.g. Natural or toasted oak. The temperature of the toasting will affect the flavor that develops.

 

Toasting the Oak: 148 C gives the most sweet aromas at 204 C is Vanilla at maximum and 270 C gives Almond taste – over this it will be very bitter, just bitter.

It is estimated that around 80% of the flavor of bourbon and whisky comes from the oak barrels used to store them in. We can replicate those flavors by soaking our spirits with oak chips or shavings. Start by using one teaspoon of oak per liter of alcohol, and let it soak for a week. Taste test frequently to find the level of flavor intensity that suits you – e.g. maybe a little more oak, or longer, or different % alcohol, or 

Different levels of oak toasting.

Oaking – Several different flavors can come from a single type of oak if alcohol strength is adjusted during maturation. 55%-53% will give vanillins, 40%-50% will give a mix of vanillins and sugars, 40%-49% will give sugars.

Start at 55%-53% for the first phase (1 to 12 months) then dilute to 40% (3- 12 months). In this manner sugar is added from the cells of the wood while marrying the dilution water to the whiskey. This results in a rich vanilla oak character with silky legs that cling to the side of the glass. The procedure works well with all types varieties of Oak.

Consider the size and shape of the barrels that are used to age the spirits you are trying to emulate. Calculate the ratio of the inner surface area to the volume of the barrel. Based on some whisky barrels – add about 70 square centimeters of oak per liter of 55% spirit. Keep in mind that one “strip” of oak has two surfaces that interact with the spirit. I age spirits in 4 liter glass bottles and add thin strips (<1mm) of oak that I had wrapped in aluminum foil and lightly charred on the stovetop. So if my oak strips are 2 cm wide I cut a total length of 70 cm, but I usually break such a strip into a few pieces before charring and adding them to the jug. This gives nice colors and flavors and generally a smoother drink.

Wood-essence can be made by soaking the shavings or toasted wood in 70% alcohol for a couple of weeks, then strain them off.  

 

Oak chips in Australian home brew shops anyway are usually American White Oak and are applied as per the label. Some prefer to use a natural essence as not only is it more accurate, but is actually “less harsh”. To make this infusion yourself, take equal proportions (by volume) of chips and neutral spirit at about 70% and soak for approximately one month, agitating as often as possible or percolate using a pump, then separate the two and apply solution (tincture) at a rate of about 10/15 ml per liter, or to taste of spirit at 40%. Or if you want to be really upmarket, take the tincture and simmer it very slowly until the volume is 75% less than original and you should have a fairly concentrated essence. In processing, remember it’s frightfully volatile!!!

It is quite possible to overdo the toasted oak but not so much with the plain oak.

The changes in the spirit during wood aging are caused by 3 types of reactions occurring simultaneously and continuously in the barrel.


1)  Complex wood constituents are extracted by the liquid
2)  Oxidation of components originally present in the liquid as well as of material extracted from the wood
3) Reactions between various organic substances present in the liquid, leading to the formation of more and new congeners

As with wine, the type of wood is very important and most of the major spirits have strict requirements. Bourbon whiskey regulations require that the barrels be new, and that the insides be charred. This is done by setting the inside of the barrel on fire until a layer of char is developed. Most other whiskies and other spirits do not have to be aged in new, unused wood, nor do the barrels have to be charred. Charring improves and softens the taste of the spirit and provides both body and color.

If you can’t buy the commercial toasted/natural oak chips for flavoring and aging, you can try making your own. Make sure you use oak or non-resinous wood – using a soft resinous pine will only give you an off taste. Be ingenious when looking for old oak – some even use bits of old furniture etc. (after shaving off the varnishes etc.). Smoked manuka timber seems particularly good.

To make your own toasted timber, find a tin with a push on lid of 1-2L. Split your timber into thin enough strips to fit your bottles. Light the pieces, and when well charred, place in the tin. Place the lid on lightly to snuff out the flames. Add more wood as it becomes ready, replacing the lid each time. When cooled, push the lid on tightly to retain the smoky aroma until ready to use.

Another way is to wrap the oak chips/shavings in aluminum foil, and bake them in your oven for a while.

Jack Daniels is 70 % clear grain whiskey when it goes into the barrel. The barrel is made from American white oak from Missouri. Each barrel is roasted at 232 C degrees for four hours then flash charred over an 800 C degree gas flame for 4 minutes. It is then steam quenched to “activate” the carbon (and put out the fire!). The roasting caramelizes the sugar in the wood before the flash burn creates the charcoal. The steam treatment not only puts out the fire, but it causes the charcoal to expand like popcorn creating trillions of tiny bubbles. This GREATLY expands the surface area of the carbon. A fresh barrel will have approximately 1/3 inch of char on the inner surface. 

Jack Daniels Whiskey is aged in the barrel for four years. During this time the barrels are racked in wooden barns. There is no heating or cooling in the barrel houses. The heating and cooling of the natural weather cycle in central Tennessee causes the whiskey to expand and contract with temperature. As the whiskey expands it is forced into the wood. In the wood it dissolves caramelized sugars, and tannins. As it contacts, it moves out of the wood and back into the barrel. The caramelized sugars give the whiskey it’s red-brown color. The whiskey will penetrate approximately 3/4 of the thickness of the barrel stave. The penetration line is easy to see on an old barrel stave. Jack Daniels uses each barrel only once. 

After ageing the whiskey is diluted to 40 % before bottling. Charring is actually burning the surface of the wood to create charcoal. For hobbyists, it is easier to use toasted chips for flavor, and activated charcoal filtering for clarifying. These two processes are combined into a single stage process in barrel ageing.

Charcoal that can be used to smooth the flavor of bourbons and rums may be made at home like this: use hickory, oak, or sugar maple wood (buying it from a lumber supplier is easy enough) as these are proven to be nontoxic.

Split the wood into finger-width sticks about 10 to 15 cm long and then pack them into an old coffee can that has no more of that coffee smell or any rust. Pack them in standing upright so there isn’t much space between them. Once the can has a solid layer of these sticks crammed in together like sardines standing upright, cover the top of the can with a layer of heavy tinfoil that has a pencil sized hole in the middle of it. Place this arrangement on your propane burner (this is not to be done inside!!), and set the heat on high. After a bit of heating up, some steam, then other various flammable organic gases will evolve off (if the foil swells up, make the hole a bit larger- try not to burn yourself).

 Once there is no more gas/steam coming out, turn off the heat and let the can sit outside to cool on its own with a cover to exclude any air from getting in. Once cool, rinse any ash off in some cold water and use however you wish. Do not make any holes in the coffee can – that will allow air into the mix and turn all of the wood into ashes, instead of turning it into charcoal.
Using a pressure cooker to inject steam could also be attempted to try making activated carbon.

To duplicate Jack Daniel’s Tennessee Whiskey ( NOT bourbon – the charcoal filtering procedure was legally recognized as producing a separate type of whiskey after World War II) the essential step is to filter the un-aged spirit through charcoal (not activated carbon) that has been made out of sugar maple wood

 

The residual sugars in the charcoal give a slight sweetness to the finished spirit, and the limited absorbing ability of the charcoal only makes the product smoother, but doesn’t strip the entire flavor out. Tasting homemade whiskey and rum made and filtered in this method, even at “barrel strength” (75%) they were very smooth – no ice was even needed.

For a “Wild Turkey” style flavor

Not a recipe, but here are some quotes that might give a lead:
1) Aging technique. “Wild Turkey is distilled and put into new barrels at a much lower proof than most Bourbons – a costly method that results in less of the flavor being cooked out. The barrels are made of the finest new oak with the heaviest char available, imparting a smoother flavor and a deep amber color.”


2) Taste. “Best flavors of our premium bourbon, but with real honey to give it sweetness….” real honey “obvious notes of vanilla and citrus” (this could come from the heavily charred American oak barrels).”Wild Turkey Liqueur is a sweetened cordial with honey” – 30% abv.
3) Wild Turkey Liqueur was introduced in 1976 – (possibly it was introduced to compete with honey based Scottish whisky liqueurs).

 

It appears that a starting point would be to age your raw whiskey distillate in heavily charred American oak, and then add a pure honey to say 25% sweetness (start with a 250 ml cup/l). Some orange peel might have been added to imitate Southern Comfort. The vanilla would probably come from the American oak which has that characteristic.

Identification of Components in Liquors and Distilled Spirits

Distilled Spirits contain a range of flavors that can be identified by GC-MS.  Not only can an analyst tell what type of liquor is present (i.e. gin versus whiskey) but they can also compare the presence and abundance of select flavor compounds between different brands of a given type of liquor.

It is relatively easy to distinguish between most types of liquors.  However, pure liquors (unsliced) such as rum and vodka produce similar chromatograms and only contain ethanol, water, and a few trace longer chain alcohols.  Other liquors, as shown below, are easily distinguished.

All of the compounds identified in the chromatogram below were conclusively identified by the spectral library (typically 99 percent confidence/probability) and are known to be present in the liquors based on a scientific literature search or from common information found on company web sites or web searches.  An interesting project is to Google some of the compounds identified in the spectra and research their origin and why they are added to specific liquor.                                                         

Whiskey

Whiskey from its origin with Irish monks) refers to a broad range of alcoholic beverages that are distilled from fermented grain mash and aged (matured) in oak barrels (casks).  The age of a whiskey refers to its time in the cask (between fermentation and bottling) and the length of aging greatly affects its chemical makeup and taste from the extraction of wood components from the cask.  These components include lacone (3-methyl-4-octanolide) that has a coconut aroma, and numerous phenolic compounds.  Grains of choice include barley, malted barley, rye, wheat, and corn, and it may be fermented from single or blends of grains.  Published flavoring chemicals include carbonyl compounds, alcohols, carboxylic acids and their esters, nitrogen- and sulphur-containing compounds, tannins and other polyphenolic compounds, terpenes, and oxygen-containing heterocyclic compounds and esters of fatty acids. The nitrogen compounds include pyridines, picolines and pyrazines.  After distillation, the flavoring compounds that are common among different brands of whiskey include fusel oils that are higher alcohols that are actually mildly toxic and have a strong disagreeable smell and taste in high concentrations. Hence, these are commonly removed by charcoal and linen filtration.  Other common flavor agents in whiskey are acetals, such as acetaldehyde diethyl acetal (1,1-diethoxyethane), the principal flavor agent in sherry.  The presence of a buttery aroma is due to diketone diacetyl (2,3-butanedione).  Some whiskey blends contain specific flavor agents.  Use the chromatograms given below to confirm the presence of these known whiskey components http://people.whitman.edu/~dunnivfm/C_MS_Ebook/CH7/Figs/Fig7-18.gif

 

 

 

 

 

 

 

 

 

Figures 7-15, 7-16, and 7-17 below are chromatograms for Bacardi Gold, http://people.whitman.edu/~dunnivfm/C_MS_Ebook/CH7/Figs/Fig7-16.gif

Captain Morgan, and http://people.whitman.edu/~dunnivfm/C_MS_Ebook/CH7/Figs/Fig7-17.gifCitrus Rum, respectively.  Note the lack of compounds in the relatively pure Bacardi Gold rum, only 3-methyl-1-butanol and acetic acid are present in measurable quantities.  Bacardi Gold has little presence of the oak flavor compounds such as those found in the other two rum beverages.  Captain Morgan’s flavor is characterized by additional compounds, most notably oak flavors and vanilla.  Citrus Rum contains almond, orange, cocoa, fruit, and lemon flavors, as well as extracts from the oak barrel aging process.                   

Figure 7-15.  Chromatogram of Bacardi Gold.

Figure 7-16.  Chromatogram of Captain Morgan Rum

Figure 7-17.  Chromatogram of Citrus Rum.   

As a side note, most of the components shown in these figures    are in the range of concentrations parts per million. 

 

Cognac cannot be distilled over 72% abv
Rum is distilled at 85-96% abv
Scotch malt whiskey is distilled at 70-71% abv
Canadian whisky is distilled at 70-90% abv

The congeners, those secondary products produced during alcoholic fermentation, consist of acids, esters, aldehydes, fusel oils, extracts of mineral salts and solids in minute quantities. Collectively, they do not amount to much from a percentage standpoint, but they are determining factors as regards product character.

Esters are volatile substances which give aroma to the spirits Aldehydes are produced from alcohol/air reactions and contribute to the character of the spirit.
Fusel oils are higher alcohols and form complex mixtures. Not all these compounds are desirable, and even those which are, should be present in specific amounts.

Cognac/Brandy

The use of copper stills is important because the contact between copper and liquid traps fatty acids and sulphur elements. Cognac regulations permit French oak only. The barrels are not charred. Freshly distilled cognac is placed in new barrels perhaps for 16-18 months. Barrels are considered new the first 3 times they are used. The first of the 3 will be for only a few months since the wood will impart excessive tannin to the spirit. The second use may be for up to 2 years and the third even longer. The barrels are kept filled unlike bourbon and malt Scotch whisky. Blending is a key factor. Both caramel and sugar syrup are legal and regulated additives. 

An unregulated practice is the use of oak chips soaked in old cognac and left in cask for months or years. The purists regard that the character from this is rather hard and tannic.

Bourbon whiskey

Charred barrel aging is said to impart the characteristic vanilla and caramel flavor of Bourbon. There are 4 grades of char and each distiller has their preference. Charring produces a layer of partially caramelized sugars below the char. Charring imparts color to the spirit and whiskey stored in new, charred white oak develops the distinctive red-amber color. Additives are not permitted. The used barrels are sold to distilleries in Ireland and Scotland.

Scotch malt whisky and Irish whiskey


Most malt whisky is matured in Bourbon barrels; only 4% is in sherry barrels. One difference between American oak and Spanish oak is that the American species is harder and consequently matures whisky more slowly. Spanish oak contains more resin which affects the flavor. Sherry and bourbon leach out the stronger tannins and oak extracts, creating a lighter product.

Rum


Maturing is done in previously used barrels which may or may not have been charred. Puerto Rican law requires a minimum of 1 year in wood. Fuller and more distinctive rums result from increased wood aging of a minimum of 3 years. Caramel is used to adjust the color. The typical dark color of Jamaican rums is due to the caramel added. The coloring is produced by heating sugar solutions to about 82C to evaporate the water and caramelize the sugars.

 Shortcuts and tricks

Other little tricks to help round out/ mature your Rum or Whiskey include adding:

  • A tad of orange flavor [essence], and/or
  • A bit of sherry (at 1-5% by volume, and Cream Sherry is said to be best), and/or
  • A bit of port, and/or
  • A smidgeon of bourbon, and/or
  • A tiny tiny amount of honey.
  • Or Rum:

Honey: Some use a lot of this! As much as half a liter per 190 liter barrel (in top of the line rums) so don’t spare it.

Black peppercorns: as in whiskey they give a bigger “woody” touch and more complexity, several drops.

Lemongrass: some fresh leaves in 90-96% from molasses. Not more than a few drops, give a nice citric flavor.

Coriander seeds: cover some dried whole corns in 60-70% neutral. Watch out because it has a lot of orange flavor but it gives richness and complexity, a “tropical” like flavor.

  • The ones recommended for rum: cinnamon, cloves and nutmeg. Sorry I can’t be more specific and exact on quantities but extract making,
  • And the last recommendation for both liquors is to make a nice collection of small oak barrels in which you can forget your rum or whiskey experiments and let age, because there’s really no good substitute to the old regular ageing. Thoroughly aerating your recently spiced spirits helps fix the flavor/aroma and gives you a better idea of what it would taste like when more mature. 
  • In the case of artificial oaking, it is essential to impart the whole range of it’s flavors to oxidize the spirit just after (or preferably during) spicing. 

In France four additives are allowed for Cognac and Armagnac

Water to cut excessive alcohol. But vintage cognacs/ Armagnac achieve their 40% abv by slow evaporation (3% a year), so dilution has an effect on flavor and for traditionalists reduction is a bad word. 

Boise A boise essence is made by boiling chips in water and then removing the chips and slowly reducing the remaining liquid. What one is left with is a dark brown liquid that is replete with wood flavor and tannin. Another source mentions infusing shavings in cognac. Charred French oak chips are also available which act like charred white American oak chips – more caramelised sugars and vanillin i.e. softer flavors.

Sugar Syrup used to add sweetness. Normally added if a cognac/armagnac is too tannic, or to remove any rough edges. It is viscous, and can either be dark or light. Legally 2% can be sugar syrup. 1 tsp/1 liter is a good starting point.

Caramel A liquid from burnt sugar. It is dark in color and slightly bitter in taste. It is used to adjust color and establish consistency or give the spirit the impression of being older and therefore smoother.

Discussion:


American whiskey can get flavors only from the charring of American white oak staves. American white oak contains less tannins and more vanillin than French oak. Filtering through maple charcoal is also practiced, and this has an effect on flavor due to caramelised sugars in the maple charcoal. A Bourbon essence could possibly be made by soaking charred American oak chips in Bourbon.


Rum is aged generally in used Bourbon barrels. Reusing the chips from making a Bourbon essence and soaking in aged rum (in effect diluting the wood character) would emulate a used Bourbon barrel.

Scotch and Irish whiskies are aged by reusing Bourbon or Spanish sherry barrels. Irish whisky is usually triple distilled (90%abv) as opposed to the double distilled peated malt Scotch whisky. So the amount of distilled congeners is different in the two styles. An essence could be made by soaking in aged whisky for a second time, American oak chips that were soaked previously in Bourbon, or European oak chips previously soaked in Spanish dry oloroso sherry.

The use of sugar and caramel is practiced in all the above liquors except Bourbon and Tennessee whiskies, and a starting quantity to achieve smoothness would be 1 tsp./liter. The amount of caramel (burnt sugar) used would depend on the style required.

  • smoothing agents – e.g. glucose or glycerine syrups.

Glycerine is a naturally occurring organic molecule that is manufactured by all animals. It is a major part of the animal fats known as triglycerides. Almost all animal fats such as lard, beef fat (tallow), mutton fat and other hard fats are triglycerides. These fats are called triglycerides because each molecule is made up of one glycerol molecule to which is attached three fatty acid molecules. A mono, or di glyceride fat such as is found in vegetable fats contains either one fatty acid molecule, or two fatty acids respectively. 

Glycerine itself is a molecule made of three connected carbon atoms, with an OH or hydroxyl group at one end. This makes it an organic alcohol by classification. This also gives glycerine it’s other name of glycerol. Either name is valid.

Glycerine is a natural byproduct of the soap making process. When a triglyceride fat is reacted with lye, the fatty acids are broken away from the glycerol molecule. The end product is three molecules of soap and one leftover molecule of glycerine. 

This glycerine molecule is valuable so it is recovered from the soap and used in many ways.

Pure glycerine is a clear, oily liquid with a very sweet taste. Think of mineral oil that tastes like honey

Moonshiners in the mountains of the USA called glycerine “Beading oil”. A few drops of glycerine added to low proof moonshine would cause the moonshine to form “beads” around the edge of the jar like those created when high proof liquor is shaken. The sweet taste also concealed the harshness of poor quality moonshine. Glycerine is available from most brewing shops as a finishing agent for wines. It is also available at pharmacies for use as a sweetener or in compounding medicines.

Glycerine is a completely safe and 100% natural compound.

Using a non-sweet aging syrup can mellow out your spirit, without having to store it away for years. Just don’t use too much to kill the character of whiskeys.

Try 20g/L of glucose, or 5 mL per liter of glycerine as a starter.

Caramel, a nice name for burnt sugar, is legally added to brandy, Scotch whisky and rum but by law not to American whiskey. How much is used?  

For Georgian brandies give sugar contents ranging from 0.7%, 1%, 7%, and 12% i.e. from 1 tsp (6 grams) to 20 tsp (120 g). Start with 1 tsp. /liter and add extra to taste or color. 

I’ve been doing some more reading on how commercial spirits are produced and I think I may have found something that Nixon/Stone still owners may find useful. As you may already know, not too many large producers of spirits just distill, age and then bottle. 

Somewhere in between these stages is where blending takes place. For spirits like rum, instead of just distilling to a high proof then cutting it back with water to make a light style, many distilleries either make (or buy) a 95% “base blending spirit” that has no flavor, they then add certain amounts of a spirit distilled to a lower proof, say, 50-70% alcohol. If they add a lot of the low proof spirit they get a “dark rum”, if you only add a little you get a “light rum”.

If someone were to run a batch of sugar alcohol through a good reflux still, and get it up to 95% pure, they could set this aside (undiluted), and then using a pot still (or with the collection valve wide open on an NS still), they could run of a 10% mash of grain (for whiskey) or molasses (for rum), and only distill it to about 50%. Then by adding various amounts of 95% spirit you could get a dark, heavy rum/whiskey, or a light version of the same drink (how much water you add is up to you).

Rum is produced from sugar cane by fermentation by yeast. The resultant “wash” has approximately 6% alcohol which after distillation produces rum as a clear, colorless liquid with about 80% alcohol and a sharp taste. White rum is essentially this product diluted to 40% alcohol. Gold rum is best aged in small 150 liter oak barrels. The process of aging is very complex, involving evaporation of some of the pungent volatile components, reaction of the rum with the oak wood and perhaps even the absorption of oxygen through the barrel to convert some of the alcohol to aromatic esters.

The total level of flavor components rarely exceeds 1% of the total weight (and is normally much lower) in a base of ethanol. This high concentration of ethanol presents particular problems in both sensory and analytical studies. Furthermore, the advent of gas chromatography has shown that most of the components found in potable spirits are the same and that the nuances of flavor are essentially attributable to small differences in the relative proportions of these components.

Note however that expert tasters have been known to name the district and frequently the actual estate, from which the rum originated, just by the sense of taste and flavor. In Jamaica, gold rum is generally bottled at 57 Volume % alcohols. 

American “Bourbon” made from essences.

  • Soak 2.25 liters 40% in 1 bag of Jack Daniels chips and 50 ml of flavor from Classic American Bourbon Sachet and age for 3 weeks 
  • Soak spent JD’ chips ( from above) in 1.125 liters of 40 % and flavor with 15ml of Spirits Unlimited premium bourbon mix Allow this to soak for 3 weeks 
  • Soak 1.125 liters of 40% in 1 heaped Tablespoon of virgin oak sawdust, add 1/2 a sachet of Classic Tennessee Flavoring and allow to soak for 3 weeks 
  • Combine in the same ratio 
    • 2 x 1125mls on chips and American Bourbon 
    • 1 x 1125mls on spent chips and premium bourbon 
    • 1 x 1125mls on oak and Tennessee flavoring 
  • Age for another 4 weeks

The best thing is to put down a couple of liters a week. Once the ball is rolling you will have a steady supply of quality Bourbon.

Allowing for a clean starting spirit this will give you Bourbon that is best served on its own with just a dash of water to bring out the flavor. 

Don’t forget most of that classic bourbon taste is vanillin, so you may need to add some American white oak, liquid oak or some toasted “quercus alba” (American white oak) chips to truly get wood/vanillin effect

Some like to throw in a handful of oak chips in about 2 weeks before distilling. Then transfer the wash and the chips into the still and go to town. It is found that the oak absorbs some of the fusels that we try to cut. The chips also quicken the distillation times. The oak also adds some interesting flavor when using it this way.

The process is fairly simple – get whatever you want as flavoring, soak it in alcohol, and distil it.
For the sake of consistency, I use 500mls of base material (corn, rye, barley etc.) and 2.5 liters of 40% alcohol. It sits for a week, and then I add water to make 4.5 liters and distil it.
OK, for the purists out there, I admit it’s not the real thing, but it’s getting close. And it’s better than anything I have ever tasted that wasn’t from a bottle shop.


After some research on bourbon to figure out where its characteristic flavors come from:
It is primarily made from corn, but rye is used to give it body. Much of the flavor, however, is obtained from the barrel. Unlike whisky, bourbon is aged in virgin oak. Bourbon barrels are charred with an intense flame that caramelizes the sap producing the characteristic vanilla/caramel flavor.


Set about combining corn, rye, oak, vanilla, caramel and smoke. Distill separate batches of corn and rye as detailed above and watered each back to 40%.


Have some 60% alcohol that has been in a 15 litre barrel with 2 kg of toasted oak staves. It is black as night and has the warm smell of dark rum. Distilled some of it (1.6litres at 60% watered back to 4.5litres volume) to produce a clear liquid with an oak flavor.
Distill 50ml of liquid smoke (purchased from the supermarket) in the same alcohol/water proportion as above.
Add 50ml of concentrated natural vanilla extract (the expensive stuff) with 40% alcohol to make a total volume of 500mls.
Caramelize 1 cup of sugar (on the stove) to a rich red/brown color and dilute it back with 60% alcohol to a volume of 500mls.


Dilute a bottle of Spirits Unlimited Bourbon to 500mls with 40% alcohol. Don’t substitute the Premium Bourbon, as it doesn’t have the same perfume taste. 

Combine the ingredients in the following ratio: 

Corn

600 ml

Rye

300 ml

Oak

150 ml

Caramel

80 ml

Vanilla

60 ml

Smoke

30 ml

S/U Bourbon

30 ml


The result is quite pale, but it lets you barrel age it without it getting to dark. It can also be darkened with some concentrated (un- distilled) oaked alcohol.
It involves some effort but the cost of the flavoring is very low. 

Flavorings for Whiskey

Raisin extract: cover with 90-96% neutral spirit for a week, then strain. Use more of this in rums than in whiskey but it gives both a taste I can just describe like “authentic”. 


Palisander extract: (deep brown, almost black precious wood, quite similar to ebony -but more expensive- used in making violin “souls”, sometimes in guitar’s neck the dark wood strips they sometimes use to decorate the cord this and sometimes other parts as well are made from this wood) cover with 60-70% alcohol from beer, more than a month is better. The wood that smells  like vanilla. 


Vanillin: It’s an artificial thing but it smells and tastes quite different from the real naturals and gives complexity to the oaky flavor, from powder, with 60-70% neutral spirit. 


Neutral spirit composition for blending: don’t use just one type of alcohol (grain, sugar or corn). Using a large part of molasses spirit refined to over 90% gives a lot of complexity. In a blind tasting by a seasoned whiskey drinker, the one blended mostly with molasses spirit over the one with predominantly grain (rice + malts) spirit in the blend.

Water for blending: Please do use distilled water for diluting rum.
Thyme: from 90-96% neutral. Cover for a week some fresh garden variety then strain. Use several drops in 10 liter. For trying in bottle (700 ml) sizes 3 drops aid a lot in complexity.
Strawberry seed extract: from 90-96% from beery or neutral. Make some extract mostly from the seeds that were left after making some strawberry pulp and straining it with a very fine mesh. Several drops of this help enhance and give complexity to the oaky flavor

INTRODUCTION Wood´s (Oak) meaning to Wine & Spirits

Wine and Spirits is progressively becoming more and more of a consumer-driven product. The current global wine glut is driving down prices, forcing wine producers to look carefully at input costs and innovative ways of producing quality wine while still managing to make a profit. Global consolidation of the market means fewer and fewer people are responsible for buying bigger and bigger shares of the total wine production. In the UK market, South Africa’s largest market for wine, this centralization of power means that supermarket buyers are able to not only determine styles of wine produced, but also to negotiate cut-throat prices. refers to the fact that there are only a handful of the same specific buyers who are purchasing 8 out of every 10 bottles of wine sold in the UK. Another phenomenon in the UK market is the demand for early release of young wines after harvest.

Winemaking methods therefore have to be able to produce early-drinking wines at consumer-friendly prices.

When scrutinizing all the extras that get added to the basic cost of the grape, wooding stands out as one of the larger expenses. Although the international appetite for the flavor of wood has paused to take a breath, the trend is, nevertheless, for subtler and better integrated wooding. The significant cost of wooding wines by traditional methods lends itself to scrutiny as a means of reducing input costs. Not only is a barrel an expensive item to manufacture, it is also an expensive item to manage. Barrels occupy a lot of space and require a lot of labor to manage. Winemaking utilizing barrel ageing is a slow process in the hurly burly of modern life, particularly with an ever-growing demand for early release of young wines. This study will examine the growing practice of wooding wines using alternative methods, as well as looking at whether the results thereof are comparable to the tried and tested methods of using oak barrels.

With the demand for the world’s natural resources growing, it is becoming imperative that those resources are sustainable and are utilized in an efficient way.  Barrel manufacturing wastes a significant amount of the best part of the tree, whereas alternative oak products (AOPs) minimize wastage and are much more labor efficient to produce. The number of barrels being sold globally is diminishing, but the

Volume of wooded wine is increasing, suggesting that alternative oak products are playing an ever more important part in modern wine production.

One of the clues to this trend is the recent relaxation of European Union legislation, allowing the use of oak chips and other alternative oak products in the production of “Vin de Paye” wine. The embattled French wine industry has been forced to allow the use of alternative wooding methods in its ever-growing fight to prevent loss of market share to New World wine producers. The use of AOPs in New World countries is widespread, especially in California, Australia and Chile. In South Africa, Distell has set up its own production of AOPs, and it is rumored that the majority of their bulk label brands will never see the inside of a barrel in the near future.

HISTORY OF WOOD,  AND WINE & SPIRITS

Types of wood used traditionally

According to Herodotus, merchants in Ancient Armenia shipped wine down the Tigris River in palm-wood casks in the seventh century BC. Eventually amphorae were succeeded by wooden barrels for shipping and storing wine in the 3rd. Century AD.

It was not until the 20.th Century that more inert materials, i.e. glass bottles, began to replace wood for shipment.

Although oak is currently the most predominant wood type used in conjunction with wine, over the years, many different types of wood have been used to make small barrels, vats and casks. In Europe, particularly in the Rhone, Beaujolais and parts of Italy and Portugal, chestnut was long used for the manufacture of large oval casks. Other wood types used include pine, eucalyptus, acacia, ash, redwood, cypress and poplar. Some of these woods, in particular pine, eucalyptus and acacia, produce wines with odd flavors, especially if the wood is not well seasoned. In North America, redwood was commonly used for the manufacture of large upright wooden tanks, but lost favor in the early 1970s when inert materials such as stainless steel made an impact. Redwood is also difficult to bend and tends to produce strong flavors.

There are several reasons that resulted in the barrel as we know it today. One of the main reasons was the fragility of amphorae and the impracticality of transporting them. Barrels are sturdy and easy to roll or pivot without being broken. Pliny (27-29 AD) said “We owe gratitude to the neighbors of the Alps, the people of Piedmont, for the invention of the barrel and we would admire this industry if ever we saw it. It demands a great deal of care to construct a barrel formed from several planks, held together only by wood, which contains a certain quantity of liquid, in a shape which is easily transported and which can withstand quite heavy shocks without losing the liquid” 

Over time, barrels came to be recognized as valuable aids to the winemaking process. For white wines, primary fermentation in oak barrels not only increases the range of flavors, but also prepares the wine for lees stirring, which softens and integrates the flavors from the wood and lightens the color, for both red and white wines. Also for the secondary fermentation that converts malic acid to softer lactic acid in barrel, or in contact with oak, adds richness and length of flavor on the palate, while softening the oak influence. The small aperture of the barrel allows for a limited amount of oxygen exposure that softens wine tannins and introduces further complexity through oxygen’s reaction with the wood tannins. The controlled amount of oxygenation also allows for stabilization of wine color. 

In the middle of the last century, by which time the use of barrels was limited almost solely to the storage and transportation of wine, winemakers also began to value the qualitative virtues that oak bestowed – flavors such as vanilla, spice, smoke, cedar and nut qualities – enhancements that added to a wine’s depth and complexity.

Wood management in Whisky and Bourbon 

This is a recent discipline. The benefits of oak ageing have long been appreciated, rather than understood, but it´s only since the 1970 -80´s that technical knowledge has supplanted anecdotal theories. With the continual advance of analytical techniques revealing the extent of oak´s influence during maturation, the growing focus on malts, as well as longer maturation terms, wood management has become the key. The maturation mandate is to reach a balance between the beneficial characteristics gained from the oak, while also retaining and developing the individual distillery’s character. Embodied in a new made spirit. Oak ageing accounts for up to 60 to 70% of a malty flavor, or around 40% in the case of heavy peating. 

It´s really a variable balancing act. Because different malts have varying ageing potential, longer maturation does not guarantee finer malt. It’s a case of variations on a theme: yielding different expressions at different ages, as the oak influence intensifies. Moreover, the appeal of malt may be a case of less is more, or more is more. The right age depends on your own palate.

Younger whiskies can have great enthusiasm, then after about 10 years you start to get a real mellowing out and balance; the balance is complete within 15 to 20 years. At 20 years the oak starts to really exert its influence, and at 25 years have a different, really good character, being mellower, rounder, slightly drier, and the heat drops into the chest, not the palate. Between 25 to 30 years the oak, and where the malt is matured, start to play a very important role. Thirty years and onwards there is a huge concentration of oak in the spirit.

Oak-derived flavors, for example, can be evident within the spirit from around six months; though losing immaturity may take a couple of years, or even extend over several. Similarly, filling a barrel with spirit can be said to initiate a form of interactive maturation. This reflects the fact that 2 to 3% of the new make spirit is drunk in. by the staves, possibly even within 48 hours, and subsequently begins to mingle with the .wood extractive liquid. Of the cask´s previous contents (although the full effect will, of course, take years to complete). In fact, specific flavors can be attributed to interactive maturation, due for example to the formation of esters.

While The Matalan’s citrus and floral notes originate from the new make spirit, the dried fruit notes derive from esters that have been created during interaction with the cask, and also from oxidation, according to the Matalan’s Master Distiller. An initial consideration is the difference between using bourbon barrels, fashioned from American oak, and sherry casks, which are usually produced from European oak, though American oak casks can also be seen in action at sherry bodegas.

European oak, typically harvested from 60 to 150-year-old trees, comprises a looser, more open and porous grain than American oak. This enables the spirit to penetrate the oak more readily than American oak, usually harvested from 40 to 100-year-old trees, which comprises a straighter, tighter grain. The level of tannins, promoting astringency, balance and structure, is also far higher in European oak than in American oak. However, charring bourbon barrels on the inside, while sherry casks are merely toasted, makes the interior of a bourbon barrel more accessible to the spirit.  Bildresultat för 225 liter oak barrel  

These technical differences also promote a varying range of characteristics. In terms of color coordination, sherry casks lend an orangey, amber hue, which is distinct from the lighter, golden, straw tint of bourbon barrels. The flavor profile also varies significantly with sherry casks contributing rich fruit (such as raisins, prunes, dates, figs, apricots), fruitcake, fortified wine, almond and walnut notes, spices such as nutmeg, ginger and cloves, not to mention crème caramel, chocolate, and a (positive) sulphurous note, delivered within a rich sweetness.

Bourbon barrels lend a lighter, drier sweetness, with a palate thriving on a medley of flavors: vanilla, honey, various fruits, almonds, hazelnuts, coconut, crème Brule, sherbet, and spices such as cinnamon, as well as mint and eucalyptus notes.

The influence of bourbon barrels can be further subdivided according to the degree of charring. The scale ranges from one to four, beginning with a .burnt toast effect and culminating in an “alligator char”. The popular term as the surface resembles alligator hide. Various malt distilleries have an inventory of bourbon barrels with a range of char levels, with a heavier char typically giving greater amounts of vanilla, crème caramel, toastiness and hint of smoke, not to mention more intense color. Alternatively, a milder char promotes greater sweetness, honey and vanilla, while also endowing the spirit with more body.

 

The “fill” (referring to the number of times the cask has been filled with spirit) is another important consideration, with many distillers using a .recipe. Of different fills to help achieve consistency, or a particular flavor profile. Each fill of a cask results in its degree of influence on the spirit diminishing, until the Master Distiller deems it to be exhausted. If a first-fill cask is said to contribute 100% of its available characteristics, a second-fill will contribute around 60%, with a third-fill (when relevant) dropping to around 35%. Consequently, a second- and third-fill require a longer time-frame than a first-fill to complete subtractive maturation. For example, spirit maturing in a second- or third-fill could require about 10 and 15 years respectively, in order to reach the same degree of maturity as a spirit aged for seven to eight years in a first-fill cask.

However, this does not mean that each successive fill also delivers the same flavor profile, in a progressively milder format. It’s actually a case of obtaining varying, rather than subtler flavors from different fills. Then again, it’s also a case of imparting an appropriate. Influence on the particular house style of the spirit. Lighter, un-peated malt, for example, may principally be aged in second-fill sherry casks, to ensure that the oak influence doesn’t predominate.

 


.The first-fill of Spanish oak sherry casks gives a dark mahogany whisky, with rich, woody spices such as cloves and ginger, toffee sweetness and dried fruits. When refilled there is a less robust oak influence and more new-make spirit character coming through, together with more apples, esters and floral notes, while the tannins manifest themselves as light spices (such as cinnamon) rather than oak..

Similarly, a first-fill bourbon barrel offers a different influence to products further down the line. .A first-fill bourbon barrel has more natural sweetness and body, the second-fill allows more products of oxidation to shine through and gives more of a floral top note, though greater oxidation also reflects the damper ageing conditions of a traditional warehouse, says the whisky company Glenmorangie´s Head of Distilleries and Maturation.

Spirit within a first-fill bourbon barrel also has optimum contact with the charred layer, though the char active influence does diminish during maturation, not to mention physically breaking down within the cask. (Consequently, when the spirit is emptied after the first-fill, some charcoal also leaves the barrel, reducing the level of char available during the second-fill, which is also less active anyway). 

This gives a lower level of vanilla and .burnt heather, notes which stem from the char, while simultaneously increasing the level of oak influence. Another principal difference between successive fills is the level of wood extractive liquid remaining within the staves of the cask. Not simply a case of residue bourbon or sherry, this liquid also incorporates additional wood-derived compounds, which could total around 75 cl in a 200-litre bourbon barrel, or 10 liters in a 500-litre sherry barrel.

The largest amount of wood extractive liquid is present within a first-fill, and released during the first few years, with some wood extractive liquid remaining in the second, but only a minimal amount is released from a third-fill. Traditionally this residue was considered an important element, though the nature of the oak, European or American, is now established as the primary influence during maturation, and the wood extractive liquid a supplementary influence. 

WOOD AND GRAPE WINE

Nature of Volatile Substances released by Wood

Wood has a profound influence on the flavor profile and characteristics of a wine. There is an interaction between the wood and the spirit, and certain substances are extracted directly from the wood to the spirit, while other substances interact with yeasts and bacteria in the wine to form flavors different to the original flavors. The organoleptic properties of the wine may be influenced by some substances that are extracted in large amounts. Some of the extractives can influence the bouquet, while others may influence the mouth feel.

The principal substances extracted from oak (the most commonly used wood), are as follows: 

Oak Lactones

These compounds are responsible for the wood aromas or what is commonly called “oakiness”. The CIS – and trans-methyl-g-octalactones, commonly referred to as “whisky lactones” are responsible for the oakiness of wines. Figure 1.1 shows the chemical structure of the various isomers of β-methyl-γ-octalactone. The levels of toasting of the wood will also affect these flavors. Open-air seasoning of the wood, prior to use, generally decreases these flavors. Lactones can easily overpower wine’s natural fruit aromas. The cis-isomer, with a threshold 12 times lower than that of the trans-isomer, possesses odors of coconut, celery and sawdust and is regarded as the most important of the volatile compounds in oak wood that are extracted into wine and spirits during barrel maturation. Staves which have been naturally seasoned by air result in wines with higher quantities of the β-methyl-octalactone than wines matured in barrels produced from artificially seasoned staves. The white oak, Quercus alba, contains significantly more β-methyl-octalactone than the European species.

Figure 1.1 The chemical structure of various isomers of β-methyl-octalactone of which the first three have been identified  

Volatile Phenols.

As a result of lignin degradation in oak, volatile phenols, based on guaiacol or syringyl nuclei are released. 

See Figure 1.3. The guaiacol derivatives have higher aroma and taste thresholds than the syringyl derivatives and impact wine flavor significantly more. In comparison to guaiacol, the syringyl derivatives have weak odors and little impact on wine flavor  

Vanillin is the most easily recognized member of this group. Levels of vanillin increase significantly with heating and toasting of oak .

Fig 1.2 The chemical structure of Vanillin

 

The aroma of vanillin is strengthened by other oak extracted compounds in the group, like acetovanillone, propiovanillone and propiosyringone.

 

 

 

Figure 1.3 The chemical structure of volatile phenols that occur in wine: some originates from oak wood and others from the wine.

Eugenol, the main aroma compound found in cloves, is also present in raw oak.

It´s levels decrease during open-air wood seasoning. It has been found that for untoasted wood, eugenol is found at its highest levels in green oak  described eugenol and isoeugenol as possessing a very similar, spicy clove aroma. As the toasting level is increased, so the release of eugenol and isoeugenol into wine is increased.

Figure 1.4 Above the chemical structure of Eugenol.

Terpenes

These essential oils, important in fruit, tea and perfume, are found in American oak and to a lesser degree in French oak. 

See Figure 1.5 a,b & c. Their role in wine flavor is yet to be established, but these terpene derivatives are very odorous with aromas of resins, violets, lemon and leather. A combination of oak lactones, eugenol and terpenoids thus must be responsible for the “oakiness” of wines. 

 Carbohydrate degradation products

The carbohydrates cellulose and hemicellulose are degraded during barrel toasting. The compounds furfural and 5-methylfurfural are produced from toasting wood sugars. They have sweet butterscotch, light caramel and subtle almond aromas. Maltol and cyclotene are also produced from the toasting process and not only have caramel-like flavors of their own, but also act as flavor potentiators. Like monosodium glutamate with food, these potentiators increase the perception of other flavors”. Other important compounds in extracts of toasted oak include lactones (sweet and fruity aromas), pyrazines, pyridines and isomaltol 

The chemical structures of common carbohydrate derived volatiles; furfural,  methyl-5-furfural, hydroxymethyl-5-furfural, cyclotene, maltol and isomaltol are a result of the heating process during cooperage that occurs in wines matured in barrels.  

Volatile Acids

The documented increase in volatile acidity is due to two reasons; Firstly the acidity that may originate from oak as a result of the toasting process, and secondly due to the metabolism of acetic acid bacteria in wine. Yeasts can produce esters of ethyl acetate from the extracted acetic acid, due to the large excess of ethanol.

Nature of Non-volatile Substances released by Wood

Tannins and other phenolics give wine color and astringency, but more importantly act as a reservoir to balance the oxidative/reductive reactions of the wine, protecting it from oxidation and lessening the chance of unpleasant reductive aromas. Phenols and more specific tannins are of great importance in wine. They play an important role in oxidation reactions, the maturation and ageing of wine, as well as the organoleptic properties.” Phenolics are derived from two sources, extraction and the oxidation of aromatic aldehydes. Aromatic aldehydes are considered to be degradation products of lignin.

4.2.1 Tannins.

Tannins can be divided into two groups: 1) condensed tannins or proanthocyanidins that originate from the grapes and 2) hydrolysable tannins that are extracted from wood. Ellagitannins are the only hydrolysable tannins that can be extracted from oak, while tannins may be added to spirit in the form of commercial tannin extractions from nutgall, oak or grapeseed. Wood in general tends to contain large percentages of ellagitannins, which are highly soluble in wine. These compounds contain many hydroxyl groups, which may serve as substrates for oxidative polymerization, and which are, together with oxygen, the reason for accelerated oxidation and polymerization of barrel maturing. Ellagitanins can thus affect the quality and taste of barrel- matured wine and spirits.

These tannins are easily hydrolyzed by enzymes or acid base conditions and can be classified as either gallotannins or ellagitannins, according to the type of acid formed. At the pH of wine, the hydrolysable tannins break down and generate gallic acid and mostly ellagic acid. 

See Figure 1.7.      

Five to ten percent of the dry weight of oak is composed of the hydrolysable tannins. These are a complex mixture of oligomers of gallic acid and glucose, bonded by oxidative couples and ester linkages.

Types of Oak and Influence of Wood Origin

Oak is a natural choice in the cooperage business, due to it being hard, supple and watertight. However, it also has other properties that have become sought after in the manufacture of quality wine – i.e. as a means of flavoring. The aim of using oak barrels and oak elaborated products is to flavor and to provoke a number of chemical and physical changes which are indisputable to the finished product.

There are three different types of oak commonly used in the winemaking industry. All three of them are white oaks, which are naturally more watertight than the more porous red oak varieties. Two of the varieties are grown in Europe, while the third is native to North America. All of them belong to the botanical genus Quercus.

The peduncle oak tree (Quercus pedunculata or Quercus robur) is the common oak. Thought of as the English or French oak, this grows all over Europe as far north as climate permits. Sweden is the northern limit, while it grows as far south as Turkey, Georgia and Portugal, and as far east as the Urals

.  

European oak ( Quercus robur) prefers fertile, damp soils. 

Quercus sessiliflora, also known as sessile oak, Quercus rouvre or Quercus petraea, is found in timber forests, especially around the center of France (and in the forests of Troncais) where it prefers sandy, silty soil with good drainage, but also thrives in a

Variety of other soil types. It is found throughout the United Kingdom, from France stretching east to Poland and the Baltic states, and as far south as Italy and Yugoslavia. The wood produced is “fine grain” and is harder and denser than Quercus pedunculata. Its growth is slower than robur, but is also regular (about 1mm per year). Due to the proximity of surrounding trees, in forests it tends to grow tall and straight, seeking the maximum amount of light. Its tannins are considered the lowest and supplest of the three types of oak used for cooperage and AOPs.

They are also the slowest extracting tannins of the three types of oak.

Quercus alba, also known as the American white oak, is originally from North America. The flavors imparted to wine from this particular oak type are much more obvious than the other two varieties. American oak imparts strong coconut, vanilla and dill flavors and can leave an impression of sweetness on the palate. American oak is also cheaper than French oak and is commonly used in North and South America, Spain and Australia. Because American oak typically has a more powerful flavor, it is generally used in conjunction with more powerful red wines such as Rioja and other Spanish reds, Australian and other New World Shiraz, and also warm- climate Cabernet Sauvignon.

Sustainability of Oak Forests

In the 19.th Century, Baltic and Slovenian oak were the most admired oaks, however French oak has since become the standard by which all other oaks are judged. Nearly a quarter of France or 14 million hectares (ha) is forest, which constitutes more than forty percent of all the forest in the European Union.

Part of the success of French forests is that a concerted effort has been made to sustain and protect them. Concern about their condition dates back to 1291, when scholars note the mention of “maistre de fôrets” in the Royal Ordinances. The most famous of these ordinances was written during the regime of Colbert in 1669 and he is commemorated in the Troncais forest, where he ordered systematic replanting of oak trees for use in shipbuilding. More recently, since the Second World War, around 2 million ha of the country has been reforested. Unlike some other countries where ancient forests have been cut down to provide for everyday commodities, France has done a good job of managing its forests since that period. Sylviculture is also actively practiced in France, so that trees in government-owned forests are not allowed to grow wild, but are carefully farmed to yield suitable wood, just like any other crop. Supplies of French oak should therefore hopefully remain abundant – barring unusual circumstances such as climate change.

The Influence of Origin

The characteristics or qualities of a wood tend to be influenced by its origin (refer to Table 1). High polyphenol content, as well as lower aromatic components can be found in Quercus robur and Quercus pedunculata, whereas Quercus petraea and Quercus sessilis are high in aromatic components and have smaller amounts of extractable ellagitannins. American woods tend to be high in aromatic flavourants, but low in levels of phenols. This is particularly evident when examining levels of β-methyl-octalactone (the so-called oak or whisky lactone), which gives wine a distinctive woody and coconut-like flavor: “Levels of between 0.5 and 16mg total lactones per gram of dry wood from Limousin have been found and 10.5mg per gram, for wood from Burgundy. For wood from the Vosges, 65mg per gram was obtained and for Troncais 77mg per gram. American wood gave levels of up to 158mg per gram. The cis isomer is more aromatic than the trans-isomer, so it goes without saying that the wood with more CISs oak lactone isomer will impart a stronger wood character to the wine. On the whole American wood also has more CIS isomer. 

American wood tends to also have higher levels of vanillin (vanilla flavor) than its French counterpart –that is to say 11 vs 6mg/g. Other flavorings, such as vanillin acid, sinapaldehyde, coniferaldehyde among others, are also found at higher levels in American wood. French wood does tend to have more eugenol (with its clove-like quality) and French Oak has higher levels of non-volatile components, especially phenolic compounds. Wood from Limousin in particular, has the highest extract and extractable polyphenols. In wood from this region, double the amount of total extracted tannins was measured than in wood from Central France and American wood. Wood from Limousin also contains more wood tannins than wood from the Central and Vosges regions of France. Second fill barrels have shown, however, that wood from Limousin did not impart much more phenolic components to the wine than American wood..

WOOD

SOIL

GRAIN

EXTRACTION

FLAVOUR

Limousin

Granite / Sub- soil, rich soil

Widest grain, rapid oxidation

Rapid, imparts color

Vanilla and lemon

Nevers

Tends to be rich and moist

Medium

Moderate

Buttery – slight citrus flavor

Allier

Deep fertile loam

Medium

Moderate, more subtle than Never

Flowery or perfumed character

Troncais

Deep fertile

Medium to tight

Moderate

Subtle with earthy character

Vosges

Chalky lime

Tight, slower oxidation

Subtle, prolonged

Most neutral

Burgundy

Clay, chalky, limey

Medium to open

Moderate

Soft and subtle

American

Various

Medium to tight

Moderate to rapid

Spicy, vanilla, oaky

Table 1. Influence of Origin on extraction and flavors imparted to wine by oak.

 

The Influence of Wood Grain

The quality of a spirit is not just affected by the origin of wood used, but also by the grain of that wood. The phloem and xylem of a tree comes from the cambium. Over time, xylem hardens and becomes pith wood – the key part of the tree from which barrels are constructed. Seasonal changes tend to affect wood growth, and subsequently the strength and grain too. In winter, the ducts found in wood are closed off by xyloses, but these reopen in spring and therefore the ducts in spring wood tend to be larger, making the wood lighter, softer, more flexible and also more porous. The important point with tyloses, wine would leak from the ends of the staves. 

Another aspect that affects the chemical composition of wood that is linked to annual growth rings is its age, as well as the rate at which it grows. 

The Influence of wood Seasoning

Before freshly cut oak can be used for cooperage it needs to be seasoned, in order to reduce the moisture content of the wood from around 50% to approximately 15%. The seasoning time outdoors is generally between 15 and 36 months (Swan et al, year unknown). However, in order to increase productivity, some cooperages dry the staves in a kiln at a controlled temperature and humidity. Kiln drying can speed up the seasoning process to as little as 28 days, although it is unusual for staves to only receive kiln drying with no outside seasoning. It was shown that due to fluctuations in climatic variations, natural seasoning outside is incapable of consistently providing the best conditions for the wood’s evolution. There is a large diverse population of microbes, including moulds, yeasts and bacteria present in the wood during seasoning. As a result of enzymatic action, these microbes easily assimilate the free sugars of the cellulose, hemicellulose and hydrolysable tannins to degrade the ellagitannins, but not to greatly affect the lignins. Comparing the effects of natural seasoning to artificial drying in a kiln it´s found that the kiln-dried wood possessed a higher level of extractable phenolic compounds and also a higher level of (trans) β-methyl-γ-octalactone. Reportedly a decrease in the ellagitannins, especially in the upper layer (1-3mm), and found that the kiln-dried wood has a higher content of astringent tannins and bitter coumarins. It also contained less eugenol, vanillin and (cis) methyl-octalactone. 

Wood dried naturally had much higher levels of total lactones than artificially dried wood. This was also the case for other important flavor compounds in which the concentrations of vanillin and eugenol were twice as high as wood aged artificially. On the whole, seasoning results in a reduction of tannins and the hydrolyzation of the bitter coumarins to aglycones (refer to Table 2).

 

Limousin Region

Central Region

Parameters

Natural Drying

Artificial drying

Natural drying

Artificial drying

Dry extracts(mg/g)

135 (7)

145 (7.5)

90 (15)

113 (4)

Total phenols (D 280)

30.4 (1.8)

31.2 (2.4)

22.4 (2.9)

27.2 (1.9)

Coloration (D 420)

0.04 (0.008)

0.038 (0.002)

0.024

(0.001

0.03 (0.005)

Catechins (mg/g)

0.59 (0.08)

0.56 (0.65)

0.3 (0.03)

0.6 (0.09)

Ellagitannins (mg/g)

15.5 (1.5)

17.2 (6.5)

7.8 (1.4)

11.9 (1.2)

Methyl- octalactone(cis)

12

0.85

77

25

Methyl- octalactone(trans)

4.5

0.22

10

124

Eugenol (μg/L)

2

0.3

8

4

Vanillin (μg/L)

11

0.5

15

0.3

( ): Standard deviation

Table 2 : The effects of the origin of oak wood and the seasoning method on the composition.

In seasoning tests done simultaneously in Australia and France, it´s found that that climate affects the extracts and aroma of oak wood in a significant way. The oak aged in Australia was found to contain higher levels of lactones than that aged in France.

The Influence of Toasting

The toasting process is one of the most critical phases in the making of a barrel. In France, toasting of barrels was traditionally done over an open fire, in order to bend the oak staves into the correct shape, while in the USA, the same job was performed with steam and a gas flame. Pyrolisys (heat treatment) of the oak degrades the wood components on the surface of the stave, resulting in the formation of many aromatic compounds.

As a result of the thermal degradation of polysaccharides, furan aldehydes such as furfural, methyl-5-furfural and hydroxymethylfurfural are formed. It´s found that the production of compounds with a carbohydrate origin, such as cyclotene, maltol and isomaltol, derived from hexoses in the presence of nitrogenated substances. These components could contribute to the caramel flavors of wine. The thermal degradation of lignin results in volatile phenols with spicy, smoky odors. At low to medium toast levels, vanilla and spicy flavors are obtained. At medium toast levels, maximum concentrations of vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde are reached, however, in heavily toasted wood, thermal breakdown leads to reduced levels of vanillin. At heavy toast levels the smoky and burnt aromas tend to dominate. Toasting therefore increases the complexity of the flavor profile of the wood.

The role of Oxygen in the Wooding Process

During storage, spirits come into contact with oxygen (O2) in various ways:  during racking, maturing in oak barrels, or via micro-oxygenation. 

The solubility of O2 at room temperature and atmospheric pressure is approximately 6 -8ml/ L. in wine.  An important aspect of wood maturation in barrels is the slow oxidation that takes place. Important by-products of the oxidation of ethanol are acetaldehyde and hydrogen peroxide. The acetaldehyde plays a pivotal role in the indirect polymerization (acetaldehyde mediated polymerization) of condensed tannins. This polymerization of flavonoids is responsible for the decrease in Gallic acid, coffee acid, ferulic acid, (+) catechin, epicatechin and trans-resveratrol concentrations. In wines which have had an O2 addition, the total phenolics are reduced, with a simultaneous increase in the red polymeric pigments. Thus with an addition of O2, whether it be by racking, micro-oxygenation or slow oxidation in barrel, an increase in color density and stability is expected. The presence of hydrolysable tannins (extracted from wood), in the wine can lead to increased acetaldehyde concentration. This happens because the hydrolysable tannins are more easily oxidized than condensed tannins. This oxidation of the hydrolysable tannins results in increased levels of peroxides, which in turn generate larger quantities of acetaldehyde.

LEGAL ASPECTS OF THE USE OF ALTERNATIVE OAK PRODUCTS IN WINE MANUFACTURING

The benefits of an overly regulated wine industry versus an under-regulated industry are often the subject of fierce debate. On the one hand, one has Old World producing countries such as France with their strict Appellation d’Origine Contrôlé (AOC) classifications, and on the other hand, New World countries like Australia, Chile, South Africa, New Zealand and China, are relatively free from prescriptive legislation. Old World legislation is generally aimed at preserving traditions established over hundreds of years and maintaining the identity of specific wines from specific areas, whereas the New World legislation is more concerned with health issues and the prevention of consumer deception.

In the Old World, wood was traditionally not seen as a condiment, or means of altering the flavor of the grape. It is only in relatively recent years that barrels and wood have taken on a new meaning in areas like Bordeaux and Burgundy. Many parts of France still shun the use of new wood to flavor the wine. They see it as being the antithesis of ‘terroir.’ In an article published it was pointed out that merely objecting to the use of wood in wine because it is not traditional is being reactionary. However, some feels that over-wooding is providing a simple, powerful flavoring with which the new wine drinker can readily associate”. The success of New World wines in the global market has forced the hand of the European lawmakers to make changes to European Union laws, governing the use of Alternative Oak Products. In 2006 European Union legislation was changed to allow the use of “pieces of oak wood.” Many journalists view this attempt to update European Union law as akin to ‘shutting the 

About wine-making additives and processes,” If comparing legislation between major 

(See Table 3). Australian and New Zealand legislation permit the addition of tannin as an additive and the use of oak as a processing aid, while South African legislation permits the addition of tannin, with the rider that it should not be foreign to wine, and the use of wood (type unspecified).

In the United States of America, “oak chips or particles in an untreated and uncharred state may be used to smooth wine. Tannin may be added to clarify or to adjust the tannin content of juice or wine, but it may not impart any color to the wine”. Thus we can see that all the major wine producing countries allow the use of alternative oak products.