A processing technique for flavoring roasted stems

Abstract

This invention discloses a processing technique for enhancing the aroma of roasted stem shreds. The technique includes: rolling the stem shreds using a toothed roller to obtain microporous stem shreds; applying a protease solution to the microporous stem shreds for enzymatic hydrolysis, causing the stem shred proteins to hydrolyze in situ into free amino acids, primarily valine and proline; subjecting the hydrolyzed stem shreds to a directional aroma-enhancing reaction under controlled temperature and humidity conditions, allowing the free amino acids to undergo a Maillard reaction with the natural reducing sugars in the stem shreds, directionally generating aroma compounds such as 2-acetylpyrrole and 2-methylpropionaldehyde; and subjecting the reacted stem shreds to vacuum fixation treatment to efficiently retain the aroma compounds within the stem shreds, resulting in the finished stem shreds. This technique, through the synergistic effect of four steps—microporous rolling, protease hydrolysis, directional aroma-enhancing reaction, and vacuum fixation—gives the resulting stem shreds a distinct roasted and nutty aroma profile, with reduced off-flavors and a sweet aftertaste.

Description

Technical Field

[0001] This invention relates to the field of tobacco processing technology, and more specifically to a process for roasting and flavoring tobacco stems. Background Technology

[0002] Tobacco stems are a byproduct of cigarette processing after the separation of leaves and stems, accounting for approximately 25% of the weight of tobacco leaves. Because their price is much lower than that of tobacco leaves, and their chemical composition is not significantly different from tobacco leaves, they are often processed into stem shreds and incorporated into cigarette blends to reduce costs, increase efficiency, and decrease tar and harmful substances. However, stem shreds are not as chemically balanced as tobacco leaves, often resulting in a stronger off-flavor, weaker aroma, poorer aftertaste, and higher irritation when smoked, limiting their usage and scope in cigarette blends.

[0003] To improve the smoking quality of tobacco stems, current research employs enzymatic hydrolysis or microbial fermentation techniques to degrade macromolecules in the stems. For example, Chinese patent application CN120036523A discloses a stem fermentation process that enhances the sensory quality of the stems by adding compound bio-enzymes. However, these enzymatic fermentation techniques have limitations. Enzymatic hydrolysis is limited to degrading various macromolecules, resulting in uncontrollable product composition and difficulty in achieving precise aroma modulation. Furthermore, bio-enzymes are expensive, hindering large-scale application by cigarette manufacturers.

[0004] Therefore, in view of the shortcomings of existing technologies, there is an urgent need to develop a processing technology that can directionally accumulate and efficiently retain aroma-producing substances inside the stems in a low-cost and industrially feasible manner. Summary of the Invention

[0005] To address the problem that existing enzymatic fermentation technologies cannot accurately modulate the aroma of stem shreds, and more specifically, to increase the content of characteristic aroma compounds with roasted and nutty aromas in the treated stem shreds, this invention provides a processing technology for modulating the roasted aroma of stem shreds.

[0006] The specific technical solution of this invention is as follows:

[0007] On one hand, the present invention provides a processing method for flavoring roasted stems, which includes the following steps:

[0008] Step S1: Use a toothed roller to roll and press the stem wire to obtain microporous stem wire;

[0009] Step S2: Apply the protease solution to the microporous filaments for enzymatic hydrolysis.

[0010] Step S3: The stems obtained in step S2 are subjected to a directional aroma-enhancing reaction. The directional aroma-enhancing reaction is carried out by placing the stems in an environment with a temperature of 120~140℃ and maintaining the moisture content of the stems at 30%~45% during the reaction.

[0011] Step S4: Perform vacuum fixation treatment on the stems obtained in step S3. The vacuum fixation treatment is to place the stems under vacuum and high temperature conditions to dehydrate them, so that the moisture content of the stems is reduced to below 15%.

[0012] In the above-mentioned process of the present invention, the stem filaments are first rolled using a micro-toothed roller to obtain microporous stem filaments. Then, a protease solution is applied to the microporous stem filaments for enzymatic hydrolysis. Microporization of the stem filaments allows the protease to better adhere to the surface and interior of the stem filaments. Furthermore, under the action of enzymatic hydrolysis, the stem filament proteins are hydrolyzed in situ into free amino acids, mainly valine and proline. Next, the enzymatically hydrolyzed stem filaments are subjected to a directional aroma-enhancing reaction at a temperature of 120-140°C and a stem filament moisture content of 30%-45%. This allows the free amino acids to undergo a Maillard reaction with the natural reducing sugars in the stem filaments, directionally generating aroma compounds such as 2-acetylpyrrole, 2-methylpropionaldehyde, and furfural. Finally, the reacted stem filaments are subjected to vacuum aroma-fixing treatment at 85-100°C. This rapidly dehydrates the stem filaments to a moisture content of less than 15%, terminating the Maillard reaction, while efficiently retaining the aroma compounds inside the stem filaments, resulting in the finished stem filaments.

[0013] The above-mentioned process of the present invention, through the synergistic effect of four steps—microporous roller pressing, protease hydrolysis, directional aroma-enhancing reaction, and vacuum aroma fixation—gives the processed stems and shreds distinct roasted and nutty aroma characteristics, reduces off-flavors, and leaves a sweet aftertaste.

[0014] Preferably, in step S4, the endpoint of dehydration is to make the moisture content of the stem filaments 12.5%~13.5%.

[0015] Preferably, in step S4, the vacuum level is -0.06MPa to -0.15MPa.

[0016] Preferably, in step S4, the temperature of the high-temperature condition is 85~100℃.

[0017] Preferably, in step S3, the relative humidity of the environment for the directional aroma-generating reaction is 70%~80%.

[0018] Preferably, in step S3, the reaction time for the directional aroma-generating reaction is 30 to 90 minutes.

[0019] Preferably, in step S2, the amount of protease added is 0.05~0.2kg per 100kg of stem fibers; the protease is an acidic protease.

[0020] Preferably, in step S2, the enzymatic hydrolysis treatment is as follows: the moisture content of the stem filaments to which protease solution has been applied is adjusted to 35%~45%, and then placed in a fermentation chamber at a temperature of 35~50℃ for 4~8 hours.

[0021] On the other hand, based on the above processing technology, the present invention provides a type of stem filament. The stem filament undergoes its own transformation to form aroma-producing substances such as pyrazines and furanones, resulting in increased aroma, reduced off-flavors, and a sweet aftertaste. Most importantly, it possesses the aroma characteristics of roasted and nutty notes.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] 1. This invention significantly increases the content of 2-acetylpyrrole and 2-methylpropionaldehyde in stems through a four-step synergistic effect of microporous roller pressing, protease hydrolysis, directional aroma-enhancing reaction, and vacuum aroma fixation. This results in stems with distinct roasted and nutty aroma characteristics, reduced off-flavors, and a sweet aftertaste.

[0024] 2. The process of this invention can significantly improve the sensory quality of stem shreds without requiring major modifications to existing production lines; at the same time, the protease used is inexpensive, resulting in low overall process cost, and this invention has strong industrial applicability. Attached Figure Description

[0025] Figure 1 The results show the protein degradation rate under different enzyme addition amounts. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0027] In one embodiment, a processing method for preparing roasted stalks for aroma blending is provided, which includes the following steps:

[0028] Step S1: Use a toothed roller to roll and press the stem wire to obtain microporous stem wire;

[0029] Step S2: Apply the protease solution to the microporous filaments for enzymatic hydrolysis.

[0030] Step S3: The stems obtained in step S2 are subjected to a directional aroma-enhancing reaction. The directional aroma-enhancing reaction is carried out by placing the stems in an environment with a temperature of 120~140℃ and maintaining the moisture content of the stems at 30%~45% during the reaction.

[0031] Step S4: Perform vacuum fixation treatment on the stems obtained in step S3. The vacuum fixation treatment is to place the stems under vacuum and high temperature conditions to dehydrate them, so that the moisture content of the stems is reduced to below 15%.

[0032] The above process, through the synergistic effect of four steps—microporous roller pressing, protease hydrolysis, directional aroma-enhancing reaction, and vacuum aroma fixation—significantly increases the content of 2-acetylpyrrole and 2-methylpropionaldehyde in the stems, resulting in stems with distinct roasted and nutty aromas, reduced off-flavors, and a sweet aftertaste. In one embodiment, comparative verification showed that the absence of any one of the steps—microporous roller pressing, protease hydrolysis, directional aroma-enhancing reaction, or vacuum aroma fixation—leads to a significant decrease in the content of 2-acetylpyrrole and 2-methylpropionaldehyde in the treated stems, resulting in insufficient roasted aroma.

[0033] In step S1, the stem fibers are rolled using a micro-toothed roller to create microcracks on and inside the fibers. This microporous treatment allows the subsequently added protease to adhere better to the surface and interior of the stem fibers, enabling the enzymatic hydrolysis reaction to occur in the three-dimensional space inside the fibers. The free amino acids generated from protein hydrolysis are then evenly and more firmly distributed within the structure of the stem fibers, creating a stable and uniform amino acid substrate pool for the subsequent Maillard reaction.

[0034] Compared to the microporous stem filaments formed by the toothed roller, other methods of promoting or not promoting the enzymatic hydrolysis of the stem filaments have varying degrees of impact on the formation of the roasted aroma characteristics of the stem filaments. In one embodiment, step S1 was omitted, and enzymatic hydrolysis was performed directly. The internal protein hydrolysis of the stem filaments was insufficient. Furthermore, the stem filaments were dense and smooth, making it easy for the enzyme solution to slip off, resulting in a decrease in the amount of enzyme solution adhering to the surface. Therefore, the yield of free amino acids was significantly reduced, leading to insufficient substrate concentration for the aroma compounds generated in step S3, and ultimately, the roasted aroma characteristics of the finished stem filaments were not obvious. In another embodiment, cellulase, pectinase, and protease were added in a 1:1:1 ratio and applied to stem filaments that had not undergone microporous treatment. The degradation of the stem filament cell walls by cellulase and pectinase promoted the entry of protease into the stem filaments. However, the results showed that compared to microporous stem filaments, the stem filaments treated in this embodiment showed a slightly better reduction in irritation, but the valine and proline content of the stem filaments treated in this embodiment was reduced, resulting in a decrease in the roasted aroma characteristics. In another embodiment, by using a vacuum pressure change method, steam explosion creates pores in the stems, followed by enzymatic hydrolysis with protease, directional aroma reaction, and vacuum aroma fixation, resulting in a decrease in the roasted aroma characteristics of the obtained stems.

[0035] Microporous filaments are formed by rolling with micro-toothed rollers, for example, using a double-roller micro-toothed roller press. In one embodiment, the rolling pressure of the micro-toothed roller press is 0.1~0.5 kN / m, and the tooth structure of the micro-toothed roller is selected with a tooth height of 0.3~0.8 mm and a tooth profile angle of 15~25°. The micro-toothed rollers apply local shear stress to the filaments, generating microcrack structures with a depth of 20~200 μm on the surface and inside of the filaments.

[0036] In one embodiment, in step S2, the protease used for enzymatic hydrolysis was screened and optimized. The results showed that the selected protease was an acidic protease, which had significant advantages in terms of degradation rate and cost of stem fibers. The acidic protease was purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd., with production batch number 22410075. This preferred acidic protease was subsequently used in the implementation of this invention. Specifically, the screening and optimization of the protease involved selecting several mature commercial proteases, taking into account cost and commercial availability. After calibrating the enzyme activity, the prepared protease solution was evenly sprayed onto the stem fibers at an application rate of 15 U / g of stem fibers. The moisture content of the stem fibers was adjusted to 40% with purified water. Subsequently, the stem fibers were placed in a sealed leaf storage cabinet and enzymatically hydrolyzed for 6 hours under controlled temperature and humidity (temperature 40℃, relative humidity 75%). Then, the temperature was adjusted to 130℃ and the humidity was maintained at 75% for 30 minutes before the treatment was completed. The total protein content and soluble protein content of the stem fibers were measured. During the temperature adjustment period, the moisture content of the stem fibers was maintained at 35% ± 2%. For example, three of the proteases were purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd., and the results are shown in Table 1. In another embodiment, using the content of roasting aroma compounds in tobacco leaves as a screening index, this acidic protease also showed superior enzymatic hydrolysis performance compared to other proteases.

[0037] Table 1 Screening of four mature commercial enzymes

[0038]

[0039] The targeted modulation of roasted aroma in stem fibers using this process requires, firstly, the selective accumulation of valine and proline in step S2, and secondly, the selective Maillard reaction in step S3 to form 2-acetylpyrrole and 2-methylpropionaldehyde. Therefore, the selection of acidic protease to degrade stem fiber proteins in step S2 is not a random choice of any enzyme, but rather a selection based on the target aroma of roasted and nutty flavors. Acidic proteases exhibit higher selectivity for valine and proline peptide bonds than alkaline and neutral proteases, maximizing the release of target amino acid precursors and providing a specific reaction substrate for step S3. If step S2 lacks this specific substrate match, the targeted aroma-generating reaction in step S3 will degenerate into a simple, non-selective Maillard reaction, resulting in uncontrollable product composition and preventing the targeted modulation of roasted aromas.

[0040] In one embodiment, in step S2, the amount of protease added is optimized, and the results show that, as Figure 1As shown, the total protein degradation rate reached its highest when the amount of protease added per 100 kg of filament was 0.06 kg. Within the range of 0.005 kg to 0.06 kg of protease addition, the total protein degradation rate increased with increasing protease addition, then decreased, but remained higher than when the protease addition was 0.05 kg. After enzymatic hydrolysis, the incremental amino acids were mainly valine and proline. The amino acid content of filaments obtained after enzymatic hydrolysis when the amount of protease added per 100 kg of filament was 0.06 kg is shown in Table 2. Therefore, considering both cost and hydrolysis efficiency, the amount of protease added per 100 kg of filament should be 0.05–0.2 kg. The protease was dissolved in water to prepare a protease solution, which was then added to the filaments, and the moisture content of the filaments was further adjusted to the target moisture content.

[0041] Table 2. Effects of acidic protease hydrolysis on amino acid content of stem fibers

[0042] Amino acid content (mg / g) Untreated stems Enzymatic hydrolysis with protease (enzyme addition 0.06%) Total free amino acids 5.425 5.878 Aspartic acid 0.808 0.766 glutamic acid 0.684 0.649 Serine 0.056 0.049 Histidine 0.061 0.050 glycine 0.045 0.038 threonine 0.068 0.059 Arginine 0.461 0.278 alanine 0.588 0.538 Tyrosine 0.166 0.139 Cysteine 0.004 0.028 Valine 0.389 1.037 Methionine 0.006 0.005 Phenylalanine 0.182 0.211 Isoleucine 0.050 0.055 Leucine 0.064 0.062 Lysine 0.020 0.021 proline 1.073 1.895

[0043] In one embodiment, in step S2, the enzymatic hydrolysis treatment is as follows: the moisture content of the stem filaments to which protease solution has been applied is adjusted to 35%~45%, and then placed in a fermentation chamber at a temperature of 35~50°C for 4~8 hours.

[0044] Following enzymatic hydrolysis, the hydrolyzed stems are then subjected to a directed aroma-generating reaction at a temperature of 120–140°C and a moisture content of 30%–45%. This reaction causes the free amino acids to undergo a Maillard reaction with the natural reducing sugars in the stems, resulting in the directed generation of aroma compounds such as 2-acetylpyrrole, 2-methylpropionaldehyde, and furfural. Step S3 is the core aroma-generating step of this invention. Within the temperature range of 120–140°C, the conversion rates of valine to 2-methylpropionaldehyde and isobutyraldehyde, and the conversion rates of proline to 2-acetylpyrrole, both reach their highest levels. When the temperature exceeds 140°C, the Maillard reaction enters the caramelization stage, leading to excessive polymerization of pyrazine compounds and the production of unpleasant burnt and bitter substances. Therefore, 120–140°C is the preferred temperature window for balancing the reaction rate and product composition.

[0045] In one embodiment, in step S3, the relative humidity of the environment for the directional aroma-generating reaction is 70%~80%, and the reaction time is 30~90 minutes.

[0046] Finally, the reacted stems are subjected to vacuum fixation treatment at 85-100°C. While rapidly dehydrating to a moisture content of less than 15% and terminating the Maillard reaction, the aroma compounds are efficiently retained inside the stems to obtain the finished stems.

[0047] In a vacuum environment with high temperature, instantaneous dehydration is beneficial for the efficient retention of aroma compounds within the stem fibers. Low moisture content in the stem fibers also facilitates the storage of these aroma compounds. Achieving the target moisture content of the stem fibers in a short time through vacuum and high temperature conditions prevents the loss of aroma compounds during drying and firmly locks them inside the stem fibers. Furthermore, the high temperature under vacuum causes the fibers on the surface of the stem fibers to dehydrate rapidly, forming a low-permeability aroma-locking layer, further inhibiting the escape of internal aroma substances. Therefore, the aroma compound content of the finished stem fibers is increased. In one embodiment, comparative verification showed that after vacuum aroma fixing treatment, the retention rate of 2-acetylpyrrole was increased by 40%–80% compared to stem fibers dehydrated to the same moisture content under normal pressure and high temperature, and the total retention rate of pyrazine compounds was increased by 30%–50%.

[0048] In one embodiment, in step S4, the vacuum level is preferably -0.06 MPa to -0.15 MPa, and the endpoint of dehydration is preferably that the moisture content of the stems is 12.5% ​​to 13.5%. In another embodiment, the content of aroma compounds 2-acetylpyrrole and 2-methylpropionaldehyde in the finished stems can be increased by adjusting the vacuum level, temperature, and moisture content of the stems after dehydration during instantaneous dehydration.

[0049] The finished stems obtained from the above processing technology have formed aroma-producing substances such as pyrazines and furanones through the transformation of endogenous substances. The aroma is increased, the impurities are reduced, and the aftertaste is sweet. Most importantly, it has the aroma characteristics of roasted and nutty aroma.

[0050] The present invention will now be described more clearly with reference to specific embodiments.

[0051] Example 1

[0052] A processing technique for flavoring roasted stems includes the following steps:

[0053] S1. The stem wire is rolled using a micro-toothed roller to create microcracks with a depth of less than 200 μm, resulting in microporous stem wire. The rolling pressure of the micro-toothed roller press is 0.2 kN / m, the tooth height of the micro-toothed roller is 0.5 mm, and the tooth angle is 20°.

[0054] S2. Dissolve the acidic protease in water to prepare a protease solution. The amount of protease is determined by adding 0.08 kg of protease per 100 kg of stem fibers, and the amount of water is calculated based on the target moisture content of the stem fibers. The protease solution is evenly sprayed onto the microporous stem fibers obtained in step S1, and the mixture is allowed to equilibrate for 20 minutes. The moisture content of the stem fibers is measured to be 40%. The stem fibers are then placed in a sealed leaf storage chamber, and the temperature and relative humidity are adjusted to 40℃ and 75%, respectively, for enzymatic hydrolysis treatment for 6 hours.

[0055] S3. Place the stems obtained in step S2 in a leaf storage cabinet, adjust the temperature of the leaf storage cabinet to 130℃ and the relative humidity to 75% to carry out a directional aroma-generating reaction, and the reaction time is 45 minutes; during the reaction, maintain the moisture content of the stems at 35%±2%.

[0056] S4. Place the stems obtained in step S3 into an electric vacuum drying oven for vacuum treatment. Adjust the vacuum degree of the drying oven to -0.1MPa and the temperature to 90℃. Monitor the moisture content of the stems during the process until the moisture content of the stems is 13.0%. Then end the vacuum treatment to obtain the finished stems.

[0057] Example 2

[0058] A processing technique for flavoring roasted stems includes the following steps:

[0059] S1. The stem wire is rolled using a micro-toothed roller to create microcracks with a depth of less than 200μm, resulting in microporous stem wire. The rolling pressure of the micro-toothed roller press is 0.2kN / m, the tooth height of the micro-toothed roller is 0.5 mm, and the tooth angle is 20°.

[0060] S2. Dissolve the acidic protease in water to prepare a protease solution. The amount of protease is determined by adding 0.05 kg of protease per 100 kg of stem fibers, and the amount of water is calculated based on the target moisture content of the stem fibers. The protease solution is evenly sprayed onto the microporous stem fibers obtained in step S1, and the mixture is allowed to equilibrate for 20 minutes. The moisture content of the stem fibers is measured to be 35%. The stem fibers are then placed in a sealed leaf storage chamber, and the temperature and relative humidity are adjusted to 50°C and 70%, respectively, for enzymatic hydrolysis treatment for 8 hours.

[0061] S3. Place the stems obtained in step S2 in a leaf storage cabinet, adjust the temperature of the leaf storage cabinet to 120℃ and the relative humidity to 70% to carry out a directional aroma-generating reaction, and the reaction time is 90 minutes; during the reaction, maintain the moisture content of the stems at 32%±2%.

[0062] S4. Place the stems obtained in step S3 into an electric vacuum drying oven for vacuum treatment. Adjust the vacuum degree of the drying oven to -0.06MPa and the temperature to 85℃. Monitor the moisture content of the stems during the process until the moisture content of the stems is 12.5%. Then, end the vacuum treatment to obtain the finished stems.

[0063] Example 3

[0064] A processing technique for flavoring roasted stems includes the following steps:

[0065] S1. The stem wire is rolled using a micro-toothed roller to create microcracks with a depth of less than 200μm, resulting in microporous stem wire. The rolling pressure of the micro-toothed roller press is 0.2kN / m, the tooth height of the micro-toothed roller is 0.5mm, and the tooth angle is 20°.

[0066] S2. Dissolve the acidic protease in water to prepare a protease solution. The amount of protease is determined by adding 0.2 kg of protease per 100 kg of stem fibers, and the amount of water is calculated based on the target moisture content of the stem fibers. The protease solution is evenly sprayed onto the microporous stem fibers obtained in step S1, and the mixture is allowed to equilibrate for 20 minutes. The moisture content of the stem fibers is measured to be 45%. The stem fibers are then placed in a sealed leaf storage chamber, and the temperature is adjusted to 35°C and the relative humidity to 70%, for enzymatic hydrolysis treatment for 4 hours.

[0067] S3. Place the stems obtained in step S2 in a leaf storage cabinet, adjust the temperature of the leaf storage cabinet to 140℃ and the relative humidity to 80% to carry out a directional aroma-generating reaction, and the reaction time is 30 minutes; during the reaction, maintain the moisture content of the stems at 43%±2%.

[0068] S4. Place the stems obtained in step S3 into an electric vacuum drying oven for vacuum treatment. Adjust the vacuum degree of the vacuum drying oven to -0.1MPa and the temperature to 100℃. Monitor the moisture content of the stems during the process until the moisture content of the stems is 11%. Then, end the vacuum treatment to obtain the finished stems.

[0069] Example 4

[0070] A processing method for preparing aroma from roasted stems differs from Example 1 only in that, in step S4, the vacuum treatment ends when the moisture content of the stems reaches 14.5%. All other steps are the same as in Example 1.

[0071] Comparative Example 1

[0072] A processing method for preparing roasted stem fragrance is described, which differs from Example 1 only in that the reaction temperature in step S3 is 110°C. All other steps are the same as in Example 1.

[0073] Comparative Example 2

[0074] A processing method for preparing roasted stems and shreds for aroma blending differs from Example 1 only in that the reaction temperature in step S3 is 150°C. All other steps are the same as in Example 1.

[0075] Comparative Example 3

[0076] A processing method for preparing roasted stem fragrance is provided, which differs from Example 1 only in that: in step S3, the moisture content of the stem is maintained at 27% ± 1% during the reaction. The other steps are the same as in Example 1.

[0077] Comparative Example 4

[0078] A processing method for preparing roasted stems for aroma blending differs from Example 1 only in that: in step S3, the moisture content of the stems is maintained at 47% ± 1% during the reaction. The other steps are the same as in Example 1.

[0079] Comparative Example 5

[0080] A processing method for flavoring roasted stems differs from Example 1 only in that step S4 is atmospheric pressure dehydration. All other steps are the same as in Example 1. Step S4 in this comparative example is:

[0081] The stems obtained in step S3 are placed in an oven for normal pressure drying. The temperature of the oven is adjusted to 90°C. During the drying process, the moisture content of the stems is monitored. When the moisture content of the stems is 13.0%, the stems are removed to obtain the finished stems.

[0082] Comparative Example 6

[0083] A processing method for preparing roasted stems and shreds for aroma blending differs from Example 1 only in that step S4 involves vacuum dehydration. All other steps are the same as in Example 1. Step S4 in this comparative example is:

[0084] The stems obtained in step S3 are placed in an electric vacuum drying oven for vacuum treatment. The vacuum degree of the drying oven is adjusted to -0.1MPa and the temperature is room temperature (25℃). During this period, the moisture content of the stems is monitored until the moisture content of the stems is 13.0%. The vacuum treatment is then stopped to obtain the finished stems.

[0085] Comparative Example 7

[0086] A processing method for roasting and flavoring stems is provided, which differs from Example 1 only in that: in step S4, the vacuum treatment ends when the moisture content of the stems reaches 10%. The other steps are the same as in Example 1.

[0087] Process characterization

[0088] 2-Acetylpyrrole and 2-methylpropionaldehyde are the aroma compounds that give the stems of this invention a significant roasted / nutty characteristic aroma. The finished stems obtained from the examples and comparative examples were quantitatively analyzed using headspace gas chromatography-mass spectrometry (HS-GC-MS), and the results are shown in Table 3 below. 2-Acetylpyrrole is a key marker of roasted aroma, possessing aromas of toasted bread, roasted nuts, and a strong sweetness; 2-methylpropionaldehyde imparts a mild roasted, caramelized, and nutty aroma to the stems.

[0089] Table 3. Detection results of aroma compounds in baking.

[0090] 2-Acetylpyrrole (μg / kg) 2-Methylpropionaldehyde (μg / kg) Example 1 934 468 Example 2 762 390 Example 3 865 435 Example 4 810 424 Comparative Example 1 490 256 Comparative Example 2 562 215 Comparative Example 3 637 230 Comparative Example 4 574 241 Comparative Example 5 548 274 Comparative Example 6 677 330 Comparative Example 7 698 385

[0091] The test results show that this invention, through a four-step synergistic process of microporous roller pressing, protease hydrolysis, directional aroma-enhancing reaction, and vacuum aroma fixation, significantly increases the content of 2-acetylpyrrole and 2-methylpropionaldehyde in the stems. The content of 2-acetylpyrrole in the stems reaches 762–934 μg / kg, and the content of 2-methylpropionaldehyde reaches 390–468 μg / kg. The stems processed by this invention have distinct roasted and nutty aroma characteristics, with reduced off-flavors and a sweet aftertaste.

[0092] Comparative analysis of Comparative Examples 1 and 2 with Example 1 shows that in the directional aroma-generating reaction of step S3, if the temperature is 110℃ (Comparative Example 1), the Maillard reaction rate is insufficient, and the aroma-generating product is reduced by about half; if the temperature is 150℃ (Comparative Example 2), the temperature is too high, and the target product also decreases. Inhalation evaluation shows that the smoke produced a burnt and bitter taste, indicating that excessively high temperatures will cause the reaction to enter the caramelization stage, thereby producing bitter substances. Comparative Examples 1 and 2 demonstrate that 120–140℃ is the preferred temperature window for the directional aroma-generating reaction of step S3.

[0093] Comparative analysis of Comparative Examples 3 and 4 with Example 1 shows that in the directional aroma-generating reaction of step S3, a low (Comparative Example 3) or high (Comparative Example 4) water content of the stems is not conducive to the selectivity of valine / proline and reducing sugars, and the content of the target aroma-generating substances decreases.

[0094] A comparative analysis of Comparative Example 5 and Example 1 reveals that in Comparative Example 5, the finished stem shreds obtained through high-temperature dehydration at normal pressure had insufficient retention of aroma compounds; 2-acetylpyrrole was only 548 μg / kg, and 2-methylpropionaldehyde was only 274 μg / kg. This is likely due to the long drying time required to reach a moisture content of 13% under normal pressure. This indicates that short-time dehydration to the target moisture content is beneficial for aroma retention. Further verification was made with Comparative Example 6, which achieved dehydration to 13% using vacuum treatment of the stem shreds without heating. The aroma compound content in Comparative Example 6 also significantly decreased. This demonstrates that vacuum and high-temperature conditions play a crucial role in locking in the characteristic aroma of roasted / nut-like stem shreds.

[0095] As can be seen from the comparison between Comparative Example 7 and Example 1, the optimal dehydration endpoint is a final moisture content of over 10% for the stem fibers, which can maintain the 2-acetylpyrrole content at over 698 μg / kg.

[0096] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A processing method for flavoring roasted stems, characterized in that: Includes the following steps: Step S1: Use a toothed roller to roll and press the stem wire to obtain microporous stem wire; Step S2: Apply the protease solution to the microporous filaments for enzymatic hydrolysis. Step S3: The stems obtained in step S2 are subjected to a directional aroma-enhancing reaction. The directional aroma-enhancing reaction is carried out by placing the stems in an environment with a temperature of 120~140℃ and maintaining the moisture content of the stems at 30%~45% during the reaction. Step S4: Perform vacuum fixation treatment on the stems obtained in step S3. The vacuum fixation treatment is to place the stems under vacuum and high temperature conditions to dehydrate them, so that the moisture content of the stems is reduced to below 15%.

2. The processing technology as described in claim 1, characterized in that: In step S4, the endpoint of dehydration is to make the moisture content of the stem filaments 12.5%~13.5%.

3. The processing technology as described in claim 1, characterized in that: In step S4, the vacuum level is -0.06MPa to -0.15MPa.

4. The processing technology as described in claim 1, characterized in that: In step S4, the temperature under high-temperature conditions is 85~100℃.

5. The processing technology as described in claim 1, characterized in that: In step S3, the relative humidity of the environment for the directional aroma-generating reaction is 70%~80%.

6. The processing technology as described in claim 1, characterized in that: In step S3, the reaction time for the directional aroma-generating reaction is 30 to 90 minutes.

7. The processing technology as described in claim 1, characterized in that: In step S2, the amount of protease added is 0.05~0.2kg per 100kg of stem fibers; the protease is an acidic protease.

8. The processing technology as described in claim 1, characterized in that: In step S2, the enzymatic hydrolysis treatment is as follows: the moisture content of the stem filaments to which protease solution has been applied is adjusted to 35%~45%, and then placed in a fermentation chamber at a temperature of 35~50℃ for 4~8 hours.

9. The stems obtained by the processing method according to any one of claims 1 to 8.

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