Low-temperature synergistic oxidation pretreatment process for barrel-making wood and application of low-temperature synergistic oxidation pretreatment process

Abstract

The invention discloses a low-temperature synergistic oxidation pretreatment process for barrel-making wood and application of the low-temperature synergistic oxidation pretreatment process. The process comprises the steps that (1) ozone oxidation treatment is conducted, specifically, a wood plate is placed in a closed space, and ozone is introduced; the ozone concentration is 60-100 mg / m < 3 >, and the treatment time is 12-48 hours; (2) ultrasonic-assisted tea polyphenol dipping treatment is conducted, specifically, the wood board obtained in the step (1) is completely dipped into a tea polyphenol solution with the concentration being 2%-5% by weight, and ultrasonic-assisted oscillation is applied; and (3) infrared gradient drying treatment is conducted, specifically, the impregnated wood board is sequentially subjected to low-temperature drying treatment, medium-temperature stable drying treatment and high-temperature conversion drying treatment, and finally the water content of the wood is controlled to be 12% + / -1%. The process operation is simple, the cost is controllable, the processed wood barrel is used for wine ageing, the wine body can be endowed with composite pleasant fragrance, the wine quality is remarkably improved, and the method is suitable for the field of storage of wine such as baijiu and whisky.

Description

Technical Field

[0001] This invention relates to the field of wood processing technology for wine aging, specifically to a low-temperature synergistic oxidation pretreatment process for wood used in barrel making and its application. Background Technology

[0002] In the field of wine aging, wooden barrels are the core flavor carriers. Traditionally, the wood needs to be toasted at 150-220°C before barrel making to degrade the lignin and generate aromatic components such as vanillin and eugenol, which impart complex flavors to the wine. However, existing technologies have significant drawbacks: Eucommia wood contains eucommia gum and flavonoids, which are easily decomposed at high temperatures to produce sulfur- and carbon-containing small molecule compounds, resulting in a pungent off-flavor in the wine. Cherry wood, apple wood, and other fruit woods contain natural volatile oils and anthocyanins. High temperatures can destroy their original floral and fruity aromas, leading to a loss of the wood's flavor value. High-temperature baking consumes a lot of energy, results in a wood loss rate of 10% to 15%, and easily produces burnt and bitter substances, affecting the taste of the wine.

[0003] Therefore, there is an urgent need for a low-temperature pretreatment process that can both preserve the characteristic flavor of special wood and generate sufficient aromatic components to meet the flavor requirements of wood barrels for wine aging. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature synergistic oxidation wood pretreatment process that achieves wood oxidation and aroma enhancement at ≤80℃ through the coupling effect of ozone directional oxidation, tea polyphenol modification and ultrasonic assistance, retains characteristic flavor, and reduces energy consumption and wood loss.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A low-temperature oxidation pretreatment process for wood used in barrel making includes the following steps: (1) Ozone oxidation treatment: Place the wooden board in a closed space and introduce ozone; the ozone concentration is 60-100 mg / m³. 3 The processing time is 12 to 48 hours.

[0006] In this step, the ozone oxidation potential is 2.07V, which can specifically break the CO bonds in lignin and oxidize the guaiac wood unit to generate vanillin intermediate, with the concentration limited to 60-100 mg / m³. 3 Within the range. When the concentration is below 60 mg / m³ 3 At that time, the oxidation efficiency was insufficient, and when the concentration was higher than 100 mg / m³, the oxidation efficiency was insufficient. 3 At this time, it can easily lead to the degradation of wood cellulose.

[0007] (2) Ultrasonic-assisted tea polyphenol impregnation treatment: The wooden board obtained in step (1) is completely immersed in a tea polyphenol solution with a concentration of 2% to 5wt%, and ultrasonic-assisted vibration is applied.

[0008] In this step, tea polyphenols (mainly catechins) form a hydrogen bond network with vanillin intermediates to generate vanillin-like derivatives, while inhibiting excessive oxidation; the ultrasonic cavitation effect increases the penetration depth of tea polyphenols by 30% to 50%, and the 400 to 500W power can avoid damage to the wood cell walls.

[0009] (3) Infrared gradient drying treatment: The impregnated wood boards are subjected to low temperature drying treatment, medium temperature stable drying treatment and high temperature conversion drying treatment in sequence, and the moisture content of the wood is finally controlled to be 12%±1%.

[0010] In this step, the combination of three processing techniques can avoid cracking caused by a sudden drop in wood moisture content (the cracking rate of traditional drying is 8% to 12%, while that of this process is ≤3%). The 80℃ high-temperature conversion stage can promote the further generation of aromatic components from precursor substances without destroying the characteristic flavor.

[0011] Furthermore, the wood includes Eucommia ulmoides, cherry wood, and apple wood.

[0012] Furthermore, the timber has the following dimensions: length of 1–1.5 m, width of 0.1–0.5 m, and thickness of 0.02–0.06 m.

[0013] Furthermore, the ozone concentration in step (1) is 80 mg / m³. 3 The processing time is 24 hours.

[0014] Furthermore, the tea polyphenols mentioned in step (2) are food grade; the ultrasonic frequency range is 30-60KHz, the power range is 400-500w, the processing time is 6-10h, and the processing temperature is 25-30℃.

[0015] Further, in step (2), the concentration of tea polyphenols is 3wt%, the ultrasonic frequency range is 40KHz, the power range is 450w, the treatment time is 8h, and the treatment temperature is 30℃.

[0016] Further, step (3) specifically includes: first, raising the temperature to 40℃ and holding it for 12 to 24 hours, then raising the temperature to 60℃ at a rate of 5 to 10℃ / h and holding it for 8 to 12 hours, and then raising the temperature to 80℃ at a rate of 5 to 10℃ / h and holding it for 4 to 8 hours.

[0017] Further, step (3) specifically includes: first, raising the temperature to 40℃ and holding it for 18 hours, then raising the temperature to 60℃ at a rate of 5℃ / h and holding it for 10 hours, and then raising the temperature to 80℃ at a rate of 10℃ / h and holding it for 6 hours.

[0018] Another objective of this invention is to cut and assemble the treated wood into wooden barrels for the storage and aging of Chinese liquor, whiskey, and other alcoholic beverages.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a combination of ozone treatment and tea polyphenol solution impregnation to achieve the technical effect of low-temperature oxidation to enhance aroma and retain characteristic flavor, which solves the industry pain points of high-temperature aroma loss and low-temperature aroma loss in the prior art. (2) The present invention has been processed by a specific process, which preserves the characteristic flavor of woods such as Eucommia ulmoides and cherry wood. The content of aromatic components is comparable to that of high-temperature baking, which reduces energy consumption and saves production costs. (3) The low-temperature process used in this invention avoids the burnt and bitter taste and irritating substances produced by high temperature. Tea polyphenols can also inhibit the "old taste" produced by excessive oxidation of the wine. The aged wine is smoother on the palate, with fruit and roasted aromas. The hangover after drinking is reduced, which meets the demand of high-end consumers for "low-burden" drinks. (4) The pretreatment process of the present invention is applicable to a variety of woods such as Eucommia ulmoides, cherry wood, apple wood, and pear wood, and can be used for aging of liquors such as baijiu, whiskey, and brandy, with broad prospects for industrial application. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain. If any definition stated in this section is contrary to or otherwise inconsistent with a definition stated in a patent, patent application, published patent application, or other publication incorporated herein by reference, the definitions listed here shall prevail over those incorporated herein by reference.

[0022] Unless otherwise specified, the methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0023] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0024] Example 1 This embodiment provides a low-temperature oxidation pretreatment process for wood used in barrel making, comprising the following steps: (1) Timber preparation: Select high-quality Eucommia ulmoides wood planks with a length of 1-1.5m, a width of 0.1-0.5m, a thickness of 0.02-0.06m, no tree holes, and a moisture content of 20%-30%.

[0025] (2) Ozone oxidation treatment: Place the oak planks in a sealed ozone treatment chamber, start the high-precision ozone generator, and stabilize the ozone concentration in the chamber at 80 mg / m³ for 24 hours. During the treatment, use an ozone concentration monitor to monitor in real time and automatically adjust the ozone generator to ensure that the ozone concentration is always maintained at the set value.

[0026] (3) Ultrasonic-assisted tea polyphenol impregnation treatment: Prepare a 5% food-grade tea polyphenol solution and completely immerse the ozone-oxidized wooden board in the solution. Turn on the ultrasonic device, set the ultrasonic frequency to 40kHz, the power to 500W, and the impregnation time to 8h. During the impregnation process, stir the solution every 2 hours to ensure uniform penetration.

[0027] (4) Infrared gradient drying treatment: The impregnated wood boards were transferred to an infrared drying chamber, and the initial temperature was set at 40℃ and maintained for 18 hours to allow most of the free moisture in the wood to evaporate. Subsequently, the temperature was gradually increased to 60℃ at a rate of 5℃ / h and maintained at 60℃ for 10 hours. The temperature was then gradually increased to 80℃ at a rate of 5℃ / h and maintained at 80℃ for 6 hours. During the drying process, the moisture content of the wood was monitored in real time using a high-precision humidity sensor. Drying was stopped when the moisture content dropped to 12%±1%.

[0028] (5) Barrel making and effect verification: The dried wooden boards are cut and assembled to make storage barrels. The whisky is stored in these barrels for 1 year.

[0029] Comparative Example 1 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality Eucommia ulmoides wood planks with a length of 1-1.5m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0030] (2) Barrel making and effect verification: Raw wood planks were cut into appropriate sizes, baked at 200℃ for 60 minutes, and then assembled to make storage barrels. The whisky was stored in these barrels for 1 year.

[0031] Comparative Example 2 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality Eucommia ulmoides wood planks with a length of 1-1.5m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0032] (2) Barrel making and effect verification: Raw planks are cut into appropriate sizes and directly assembled to make storage barrels. Whisky is stored in these barrels for 1 year.

[0033] The barrel-aged whiskies from Example 1, Comparative Examples 1 and 2 were filtered and subjected to sensory evaluation by 12 judges, all of whom were national judges specializing in spirits or baijiu. The sensory evaluation results are shown in Table 1. Table 1

[0034] The content of aldehyde compounds in the whiskies treated in Example 1, Comparative Examples 1 and 2 was determined by high performance liquid chromatography (HPLC). The determination method was carried out according to the study on the detection method of six aldehyde compounds in oak barrel-aged spirits published by Hu Yang et al. The results are shown in Table 2. Table 2

[0035] The results showed that in Comparative Example 1, the aroma of Eucommia ulmoides wood after high-temperature roasting was dull and strange. When used to make barrels for storing whisky, the whisky flavor changed, the aroma became unpleasant and unharmonious, and the whisky had a bitter taste, but the flavor compounds such as vanillin and eugenol increased. In Comparative Example 2, the aroma of raw wood was relatively light, and its contribution to the aroma of whisky after being made into barrels was small. The whisky mainly exhibited a malty aroma. After one year of storage, the wood slowly oxidized, resulting in a slight increase in flavor compounds such as vanillin and vanillic acid. In Example 1, the aroma intensity of Eucommia ulmoides wood increased after oxidation treatment according to the present invention. When used to store whisky, the woody and malty aromas of the whisky were harmonious, giving the whisky a richer layer and a delicate taste. After wood oxidation, the flavor compounds such as vanillin and eugenol in the whisky increased significantly, and their content was comparable to that of wood treated at high temperatures.

[0036] Example 2 This embodiment provides a low-temperature oxidation pretreatment process for wood used in barrel making, comprising the following steps: (1) Timber preparation: Select high-quality cherry wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m, no tree holes, and a moisture content of 20%-25%.

[0037] (2) Ozone oxidation treatment: Same as in Example 1, cherry wood boards were treated in an environment with an ozone concentration of 80 mg / m³ for 24 hours.

[0038] (3) Ultrasonic-assisted tea polyphenol impregnation treatment: Prepare a 3% food-grade tea polyphenol solution, immerse the wooden board in the solution, set the ultrasonic frequency to 35kHz, the power to 400W, and the impregnation time to 10 hours. During the impregnation process, a circulating pump is used to keep the solution flowing to enhance the penetration effect.

[0039] (4) Infrared gradient drying treatment: The initial temperature is set at 40℃ and maintained for 15 hours. Then, the temperature is gradually increased to 60℃ at a heating rate of 5℃ / h and maintained at 60℃ for 8 hours. The temperature is then gradually increased to 80℃ at a heating rate of 5℃ / h and maintained at 80℃ for 4 hours. Drying is stopped when the moisture content of the wood drops to 12%±1%.

[0040] (5) Barrel making and effect verification: The dried wooden boards are cut and assembled to make storage barrels. The whisky is stored in these barrels for 1 year.

[0041] Comparative Example 3 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality cherry wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0042] (2) Barrel making and effect verification: Raw wood planks were cut into appropriate sizes, baked at 220℃ for 50 minutes, and then assembled to make storage barrels. The whisky was stored in these barrels for 1 year.

[0043] Comparative Example 4 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality cherry wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0044] (2) Barrel making and effect verification: Raw planks are cut into appropriate sizes and directly assembled to make storage barrels. Whisky is stored in these barrels for 1 year.

[0045] The barrel-aged whiskies from Example 2, Comparative Examples 3 and 4 were filtered and subjected to sensory evaluation by 12 judges, all of whom were national judges of liqueurs or spirits. The sensory evaluation results are shown in Table 3. Table 3

[0046] The whiskies treated in Example 2, Comparative Examples 3 and 4 were analyzed by high performance liquid chromatography (HPLC) to determine the content of aldehyde compounds. The determination method was carried out according to the study on the detection method of six aldehyde compounds in oak barrel-aged spirits published by Hu Yang et al. The results are shown in Table 4. Table 4

[0047] The results showed that, in Comparative Example 3, the cherry wood suffered significant loss of fruit aroma after high-temperature toasting, but gained a toasted aroma. When used to store whisky, the whisky exhibited a distinct vanilla-creamy body, which was related to the oxidative degradation of lignin after high-temperature toasting, resulting in a significant increase in the content of vanillin, eugenol, vanillic acid, and eugenol in the whisky. In Comparative Example 4, the raw wood had a rich fruit aroma, and when made into casks, the whisky had a distinct fruit aroma and a relatively light fragrance, but a heavier bitterness, and the content of vanillin, eugenol, vanillic acid, and eugenol in the whisky was extremely low. In Example 2, the wood suffered less loss of fruit aroma after low-temperature oxidation and produced a toasted aroma similar to vanilla-cream. When used to store whisky, the whisky had a distinct floral and fruity aroma with a rich vanilla aroma, and the content of vanillin, eugenol, vanillic acid, and eugenol in the whisky was significantly increased, comparable to the whisky stored in high-temperature toasted casks.

[0048] Example 3 This embodiment provides a low-temperature oxidation pretreatment process for wood used in barrel making, comprising the following steps: (1) Timber preparation: Select high-quality apple wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0049] (2) Ozone oxidation treatment: Same as in Example 1, apple wood boards were treated in an environment with an ozone concentration of 80 mg / m³ for 24 hours.

[0050] (3) Ultrasonic-assisted tea polyphenol impregnation treatment: Prepare a 3% food-grade tea polyphenol solution, immerse the wooden board in the solution, set the ultrasonic frequency to 35kHz, the power to 400W, and the impregnation time to 10 hours. During the impregnation process, a circulating pump is used to keep the solution flowing to enhance the penetration effect.

[0051] (4) Infrared gradient drying treatment: The initial temperature is set at 40℃ and maintained for 10 hours. Then, the temperature is gradually increased to 60℃ at a rate of 5℃ / h and maintained at 60℃ for 6 hours. The temperature is then gradually increased to 80℃ at a rate of 5℃ / h and maintained at 80℃ for 3 hours. Drying is stopped when the moisture content of the wood drops to 9%.

[0052] (4) Barrel making and effect verification: The dried wooden boards are cut and assembled to make storage barrels. The whisky is stored in these barrels for 1 year.

[0053] Comparative Example 5 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality apple wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0054] (2) Barrel making and effect verification: Raw wood planks were cut into appropriate sizes, baked at 180°C for 50 minutes, and then assembled to make storage barrels. The whisky was stored in these barrels for one year.

[0055] Comparative Example 6 This comparative example provides a low-temperature oxidation pretreatment process for wood used in barrel making, which includes the following steps: (1) Timber preparation: Select high-quality apple wood boards with a length of 0.5-1.0m, a width of 0.1-0.5m, a thickness of 0.02-0.06m and no tree holes.

[0056] (2) Barrel making and effect verification: Raw planks are cut into appropriate sizes and directly assembled to make storage barrels. Whisky is stored in these barrels for 1 year.

[0057] The barrel-aged whiskies from Example 3, Comparative Examples 5 and 6 were filtered and subjected to sensory evaluation by 12 judges, all of whom were national judges specializing in spirits or baijiu. The sensory evaluation results are shown in Table 5. Table 5

[0058] The whiskies treated in Example 3, Comparative Examples 5 and 6 were analyzed by high performance liquid chromatography (HPLC) to determine the content of aldehyde compounds. The determination method was performed according to the study on the detection method of six aldehyde compounds in oak barrel-aged spirits published by Hu Yang et al. The results are shown in Table 6. Table 6

[0059] The results showed that Comparative Example 5 suffered significant loss of applewood aroma after high-temperature toasting, but gained a toasted aroma. When used to store whisky, the whisky exhibited a distinct vanilla-creamy body, which was related to the high content of vanillin, eugenol, vanillic acid, and eugenol in the whisky. Comparative Example 6 had a rich fruity aroma from raw wood. After being made into casks, the whisky had a distinct fruity aroma and a relatively light fragrance, but a heavier bitterness. The content of vanillin, eugenol, vanillic acid, and eugenol in the whisky was extremely low. In Example 3, the wood underwent low-temperature oxidation, resulting in less loss of fruity aroma and the production of a toasted aroma similar to vanilla-cream. When used to store whisky, the whisky had a distinct floral and fruity aroma with a rich vanilla fragrance. The content of vanillin, eugenol, vanillic acid, and eugenol in the whisky was comparable to that of high-temperature toasted casks, indicating that this process can effectively promote the oxidation of lignin in the wood and preserve the original fruity aroma of the wood.

[0060] The above embodiments are merely illustrative examples of preferred embodiments of the present invention and do not encompass all possible implementations. Any modifications and refinements made by those skilled in the art without departing from the spirit and scope of the present invention are considered to fall within the protection scope of the claims.

Claims

1. A low-temperature oxidation pretreatment process for wood used in barrel making, characterized in that, Includes the following steps: (1) Ozone oxidation treatment: Place the wooden board in a closed space and introduce ozone; the ozone concentration is 60-100 mg / m³. 3 The processing time is 12–48 hours; (2) Ultrasonic-assisted tea polyphenol impregnation treatment: The wooden board obtained in step (1) is completely immersed in a tea polyphenol solution with a concentration of 2% to 5 wt%, and ultrasonic-assisted vibration is applied; (3) Infrared gradient drying treatment: The impregnated wood boards are subjected to low temperature drying treatment, medium temperature stable drying treatment and high temperature conversion drying treatment in sequence, and the moisture content of the wood is finally controlled to be 12%±1%.

2. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 1, characterized in that, The woods mentioned include Eucommia ulmoides, cherry wood, and apple wood.

3. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 1, characterized in that, The timber has the following dimensions: length 1–1.5m, width 0.1–0.5m, and thickness 0.02–0.06m.

4. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 1, characterized in that, The ozone concentration in step (1) is 80 mg / m³. 3 The processing time is 24 hours.

5. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 1, characterized in that, The tea polyphenols mentioned in step (2) are food grade; the ultrasonic frequency range is 30-60KHz, the power range is 400-500w, the processing time is 6-10h, and the processing temperature is 25-30℃.

6. The low-temperature oxidation pretreatment process for barrel-making wood according to claim 5, characterized in that, The concentration of tea polyphenols in step (2) is 3wt%, the ultrasonic frequency range is 40KHz, the power range is 450w, the treatment time is 8h, and the treatment temperature is 30℃.

7. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 1, characterized in that, Step (3) specifically includes: first, raising the temperature to 40℃ and holding it for 12-24 hours, then raising the temperature to 60℃ at a rate of 5-10℃ / h and holding it for 8-12 hours, and then raising the temperature to 80℃ at a rate of 5-10℃ / h and holding it for 4-8 hours.

8. The low-temperature oxidation pretreatment process for wood used in barrel making according to claim 7, characterized in that, Step (3) specifically includes: first, raising the temperature to 40℃ and holding it for 18 hours, then raising the temperature to 60℃ at a rate of 5℃ / h and holding it for 10 hours, and then raising the temperature to 80℃ at a rate of 10℃ / h and holding it for 6 hours.

9. The application of wood obtained through the low-temperature oxidation pretreatment process according to any one of claims 1-8 in barrel making, characterized in that, The wood is cut and assembled into barrels for the storage or aging of spirits, whiskey, brandy, and rum.

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