Process for preparing an oak wood extract and distillate

A process for obtaining a blending and ageing additive from oak wood which comprises (a) mixing oak wood in subdivided or particulate form with water, alcohol or mixture thereof; (b) enzymatically digesting the mixture at elevated temperature; (c) adding wine or other alcohol to the digestion mixture after the digestion is completed; (d) refluxing the resulting mixture at elevated temperature until the wood changes color and the liquid phase no longer changes color; (e) separating the resulting liquid phase from the wood; and (f) distilling the liquid phase to obtain a clear or water-white distillate and solid extract. The distillate and/or extract may be added to wine or other beverage, or other composition such as vinegar, to improve properties thereof.

The present invention is concerned with blending agents derived from oak 
wood and the use of such agents for blending with alcoholic and 
non-alcoholic beverages such as wines or spirits or vinegar, sauces, 
dressings or the like. 
Oak wood and extracts thereof have an extensive history in the flavoring 
and/or ageing of wines. For example, U.S. Pat. No. 5,102,675 describes the 
use of toasted oak for use in ageing wine. The oak, in divided form, is 
soaked in water or ethanol to remove undesirable soluble flavors and the 
oak is toasted. The toasted oak is then added to the wine and the wine is 
aged. 
SU 1414866-A describes ageing blends of spirits distilled from wine and oak 
extracts. U.S. Pat. No. 4,350,708 discloses the preparation of oak flavors 
for ageing alcoholic beverages. Oak pieces are first extracted with 
alcohol and then extracted with demineralized water. The product is used 
for ageing wines, alcohols and other liquors. French 2,356,722-A also 
describes the production of an oak extract for use in ageing spirits, e.g. 
brandy. The extract is obtained by extracting finely divided oak with 
alcohol solutions. SU 1421767-A and SU 1291601-A also describe the 
addition of oak extracts to wines or alcoholic beverages. See also 
DD-212051-A,B and SU 1198115-A which disclose the addition of oak extracts 
to wines prior to ageing. 
Other disclosures relating to the addition of oak wood extracts to wine or 
other beverages to facilitate ageing and/or improve taste include: SU 
1033539-A; SU 962295-A; and U.S. Pat. No. 4,463,024. 
SU 247892-A discloses the use of an oak wood extract with alcoholic 
beverage to shorten the maturing time and improve quality. The extract is 
prepared by treating the oak wood with chemicals and heating after which 
the extract is passed through an anionic and cationic de-ionizer and then 
vacuum concentrated and dried. 
A study of the effect of various wood extracts to accelerate maturation of 
brandies, whiskey and other strongly alcoholic drinks, is described in 
Sadovodstvo, Vinogradarstvo i Vinodelie Moldavii, 25(12): 26-29, 1970. 
Extracts were obtained by treating oak wood with HCL, ammonia and heat 
with subsequent extraction. The results showed that the most effective 
results were obtained with an alcohol-water fraction with the basic 
tannins and in hydrocarbons with added aromatic aldehydes. 
A further paper in Vinodelie i Vinogradarstvo, 29(7): 13-16, 1969 describes 
the changes in carbohydrates of oak fibers in ethanol mediums and the 
migration of sugars from such fibers into brandy. 
It is also known to store or age wine or other alcoholic beverages in the 
presence of oak wood. See, for example, SU 753896-B; SU 734269-B; 
Australian & New Zealand Wine Industry Journal, 6(1): 69-72, 1991; Journal 
of the Association of Official Analytical Chemists, 73(4): 498-501, 1990; 
Connaissance de la Wigne et du Via, 21(3): 169-190, 1987; American Journal 
of Enology and Viticulture, 36(2): 148-155, 1985; American Journal of 
Enology and Viticulture, 34(4):211-215, 1983; Wines and Vines, 60(1): 
40-43, 1979; Bulletin de l'Office International du Vin, 44(482): 339-355, 
1971; Vinodelie i Vinogradarstvo SSSR, 31(2): 30-31, 1971. 
It will be evident from the foregoing that extensive efforts have gone into 
the use of oak wood and various extracts thereof for the purpose of 
improving the ageing and/or taste of alcoholic beverages including wines 
and for understanding the reasons for any such improvements. However, 
notwithstanding such efforts, there still remains considerable room for 
improving the rate of ageing and taste of wine and alcoholic beverages. 
There is also considerable interest in providing improved blending agents 
for use with non-alcoholic beverages as well as with flavoring agents such 
as vinegar, sauces and the like. 
SUMMARY OF THE INVENTION 
The purpose of the present invention is to provide certain improvements in 
oak wood extracts for use with wine and other alcoholic and non-alcoholic 
beverages as well as with such flavoring materials as vinegar and sauces. 
These extracts have been found to have a number of advantages including, 
for example, the shortening of the ageing time for wines and improvement 
in taste. Other advantages include, for example, the provision of a more 
complex character to wine and the ability to standardize organoleptic 
properties and batch-to-batch variations. 
An important aspect of the invention is the provision of a process which 
includes enzymatic digestion and distillation of oak wood in admixture 
with wine or other alcohol. 
Another feature of the invention is the use of the distillate obtained by 
the present process, or concentrate thereof, as an additive to wine, or 
the equivalent, advantageously mixed with a dark residue obtained by the 
present process, to improve taste and ageing characteristics. 
Other features of the invention will be evident from the more detailed 
description of the invention which follows. 
DETAILED DESCRIPTION OF THE INVENTION 
The present process for obtaining a blending or ageing additive from oak 
wood comprises (a) mixing oak wood in subdivided or particulate form with 
water or aqueous alcoholic liquid containing up to, for example, 50% by 
weight of alcohol, e.g. wine or spirit; (b) enzymatically digesting the 
mixture at elevated temperature; (c) adding wine or other alcohol to the 
digestion mixture after the digestion is completed; (d) refluxing the 
resulting mixture at elevated temperature until the wood changes color and 
the liquid phase no longer changes color; (e) separating the resulting 
liquid phase from the wood; and (f) distilling the liquid phase to obtain 
a clear or water-white distillate and a dark syrup-like residue 
(hereinafter called the "solid extract"). Both the distillate, and solid 
extract are suitable for addition to wine or other beverage to improve the 
flavor thereof. Preferably the distillate and solid extract are used 
together although either component, can be used alone. Significantly 
equivalent results are not obtained if the distillation step (f) is 
omitted. The reason for this is not understood but apparently the 
distillation or refluxing step tends to generate flavors thus improving 
the results obtained. 
Preferably the initial mixing (a) of the wood and alcohol, which is 
advantageously wine but not necessarily so, is carried out at ambient 
temperature although other temperatures may be used. However, the 
enzymatic digestion (b) is desirably conducted at an elevated temperature 
where the enzymes involved are most active, usually 50.degree.-60.degree. 
C., although lower and higher temperatures can also be used. The digestion 
will normally take from 4-8 hours. The course of the digestion is evident 
as the mixture turns into a smooth slurry with a brownish gray striation 
as the digestion proceeds. 
If the mixture becomes too viscous as the digestion proceeds, more wine or 
other alcohol can be added to give a viscosity suitable for mixing during 
digestion. After the digestion, the digested mixture is preferably allowed 
to cool to room temperature. Preferably the same kind of wine or alcohol 
is added to the digested mixture in step (c) as is used to form the 
initial mixture for digestion in (a). The amount of wine or the like added 
at this post-digestion stage can be varied but usually will be in the 
order of 50-200% by weight of the wine or other alcohol used in the 
beginning. 
Refluxing (d) of the mixture at, for example, 75.degree.-100.degree. C., is 
conducted in a closed vessel for from about 4-10 hours. The wood changes 
color during this refluxing and becomes progressively lighter. The 
refluxing can be discontinued with the color of the liquid present becomes 
dark and does not change significantly on further heating. At this stage, 
the colored liquid phase is separated from the wood, preferably by 
decanting or filtering in step (e) to give what is conveniently called a 
"pre-concentrate" liquid phase and the wood phase. 
The pre-concentrate is then distilled, preferably under vacuum, in step (f) 
at a temperature of, for example, 50.degree. to 100.degree. C., preferably 
about 80-85.degree. C., to give a water-white distillate, leaving a 
colored residual liquid in the distillation vessel. This colored liquid is 
further distilled, preferably in a roto-evaporator, to give more 
water-white distillate which can be mixed with the distillate earlier 
obtained for use in ageing and flavoring wine or other beverages. This 
distillation step leaves a solid extract or residue which is desirably 
used with the clear white distillate for purposes of the invention. This 
solid extract is, generally speaking, a sludge-like mass with a brix value 
of, for example, 60-90. This is soluble in wine or alcohol and, as noted 
is desirably used with the distillate for blending according to the 
invention. 
The alcohol content of the distillate obtained in (f) can be varied but 
usually will be in the range of 8-15% by weight. This distillate may be 
used directly as an additive to wine or the like, with or without the 
solid extract. Alternatively, the distillate may be even further 
concentrated by distillation, for example, by column or reverse phase 
chromatography or vacuum distillation, to give a further concentrate which 
is also suitable for use, as such or mixed with solid extract, as a 
blending or ageing additive to wine or the equivalent. 
Any available oak wood may be used for present purposes. Typically 
available oak woods include American White Oak; American medium toast oak 
chips; Medium toast French oak and dark toast French oak. These or other 
types of oak wood are used in subdivided or particulate form, e.g. as 
chips, dust or the equivalent. It may also be possible to use other types 
of wood, e.g. beechwood, as a replacement for oak wood. This depends on 
the nature of the liquid to be blended with the blending additive of the 
invention. For example, beechwood may be a useful replacement for oak wood 
when the additive is to be used with vinegar or beer. 
Advantageously, wine is used as the alcohol component in the various steps 
of the process. However, for example, aqueous alcoholic solutions, e.g. 
ethanolic solutions or other types of alcohol solutions may also be used. 
The enzymatic digestion may be carried out using any available type of 
biocellulase enzyme. Typical examples include BIOCELLULASE A20 and 
BIOCELLULASE TRI (Quest Bioproducts). Other enzymes consistent with the 
purpose of the invention can also be used. 
The invention can be used for improving the ageing and taste 
characteristics of any type of wine or alcoholic beverage. The invention 
is illustrated herein utilizing a Chablis Blanc type wine. However, other 
white or red wines may be used in the practice of the invention. 
Additionally, other alcoholic beverages, e.g. whiskeys, brandies, cognacs 
and the like may also be used. Vinegar may also be. Non-alcoholic 
beverages or flavors, e.g. sauces, may be similarly modified using the 
distillate described herein as such or in admixture with the solid extract 
.

The invention is illustrated, but not limited, by the following example: 
EXAMPLE 
412.50 grams of wine (Chablis Blanc with 11% alcohol content) at room 
temperature (about 25.degree. C.) was placed in a glass flask. Thereafter, 
82.50 grams of oak wood chips were gradually added to the wine with slow 
mixing. Mixing speed was escalated as the amount of wood in the wine 
increased. Care was taken to position the mixing blade so that all of the 
material was kept moving. 
Heat was then applied to the mixture to bring the temperature of the 
mixture to 60.degree. C. The vessel was kept covered as well as possible 
to minimize alcohol evaporation. 
5 grams of biocellulase (BIOCELLULASE A20) were then carefully added to the 
mixture of wood and wine. Mixing was continued with the temperature 
maintained at between 50-60.degree. C. to maximize enzyme effectiveness. 
The vessel was maintained covered throughout and digestion at 
50-60.degree. C. was allowed for 8 hours. The mixture turned into a smooth 
slurry and a brownish-gray striation appeared after about 4 hours of 
digestion. 
At the end of the digestion, when the enzyme has decreased in activity due 
to the acidic media and the presence of 11% alcohol, the reaction batch 
was allowed to cool to room temperature with mixing. 
500 grams of the same wine were then added to the digested mixture with 
mixing. Once the mixture reached homogeneity, the batch was transferred to 
a closed flask provided with a condenser column. 
The mixture was allowed to percolate with reflux at 80.degree. C. for 8 
hours while mixing. As the heating proceeded, the wine present became a 
progressively darker shade of amber-brown. The wood began to take on a 
lighter tan color as opposed to its original light-brown color. After 8 
hours of heating at 80.degree. C., the heating was discontinued and the 
flask allowed to cool to room temperature with mixing. 
The liquid (pre-concentrate) phase of the batch was then separated from the 
wood residue. This was done by decanting the amber liquid from the mass 
and filtering the liquid thus collected through filter paper at ambient or 
room temperature. The yield of liquid was about 700 grams (from a 1,000 
gram batch). The thus separated liquid was kept sealed and under 
refrigeration to avoid possible oxidative deterioration or microbiological 
contamination. Enzyme activity was shown analytically to be non-existent 
after the reflux heating step was completed. 
The filtered liquid, conveniently termed the "pre-concentrate", was then 
transferred to a distillation unit. Vacuum was applied as the temperature 
was raised to 80.degree. C. in a mantle-held flask. A stand pipe was used 
in the holding flask as a means of minimizing the risk of pulling over the 
colored residual liquid into the water-white clear fraction that was 
distilled off and collected. The heating to 80.degree. C. was gradual and 
an equilibrium was achieved which resulted in a 20 in. Hg vacuum with the 
contents of the holding flask at 75.degree. C. Approximately 1 kilogram of 
clear white distillate was obtained per hour. 
After about 90% of the original liquid mixture (pre-concentrate) had 
distilled over as the indicated clear distillate or concentrate, the 
remaining pre-concentrate was placed into a roto-evaporator and 
concentrated to 78 brix. The clear distillate from this step and the 
initial distillate from the pre-concentrate were then combined to provide 
the final blending product as a clear water-white liquid distillate. The 
alcohol content of this product was about 10.80% by weight. It was added, 
in the amount of about 2% by weight, to Chablis Blanc type wine which was 
then conventionally aged for about 4 days. The aged product had an 
excellent taste characterized by a smooth well-rounded body typical of 
wines which had been aged for longer periods of time. When compared with 
conventionally prepared "oaked" wine, i.e. wine aged for several weeks in 
the presence of added oak chips, and blends thereof with non-oaked wine, 
wine blended with the distillate of the invention, demonstrated better 
body and flavor characteristics among other desirable properties. 
It will be recognized that various modifications may be made in the 
invention exemplified above and as otherwise described herein. For 
example, in the foregoing example, the clear white distillate of the 
invention may be usefully added in amounts ranging from about 0.1-10% by 
weight, or even more or less, to the same or different wine. Additionally 
the wine, with distillate added, may be aged for other periods of time, 
e.g. 3-7 days or even more. An amount of the solid extract (e.g. 0.5-5% by 
weight) may also be usefully mixed with the distillate for addition to 
wine or the equivalent to obtain the advantages of the invention. Other 
variations will also be evident to those in the art. Accordingly, the 
scope of the invention is set out in the following claims wherein: