Model for evaluating mildew degree of stored tobacco leaves based on characteristic atmosphere and application thereof

Abstract

The invention discloses a model for evaluating the mildew degree of stored tobacco leaves based on a characteristic atmosphere and application of the model. The model comprises the following steps: carrying out qualitative and quantitative analysis on volatile gases before and after mildew of the stored tobacco leaves by adopting an internal standard method, then classifying the volatile gases in the warehouse according to variable quantity, setting a variable quantity threshold value, screening characteristic atmospheres, and then carrying out continuous mildew test on the stored tobacco leaves under standard conditions to obtain the number of moulds and the content of the characteristic atmospheres. And S3, establishing a correlation relation model of the mould number and the characteristic atmosphere content, and checking the identity and universality of the model obtained in the step S3 under different environment factors according to the same model data set. Based on the excellent performance of the model, the model can be used for early warning and classification of tobacco mildew, online monitoring of the tobacco mildew process is achieved, mildew signs are found in time, and further development of mildew is avoided.

Description

Technical Field

[0001] The invention relates to a stored tobacco leaf mildew model, in particular to a model for evaluating the mildew degree of stored tobacco leaves based on characteristic atmosphere and application thereof, and belongs to the technical field of stored tobacco leaf research. Background Art

[0002] The problem of tobacco mildew is a common problem in tobacco storage in various cigarette companies, causing huge losses to my country's tobacco industry. Tobacco mildew is caused by the reproduction of mold in tobacco. The chemical composition of tobacco leaves is complex, containing necessary substances and nutrients for mold reproduction, such as carbon, sugar, starch, cellulose, pectin and organic acids. At the same time, tobacco leaves contain a large amount of protein and nucleic acid, which can also provide energy for mold, which become the internal factors for the occurrence of mildew. On the one hand, these substances undergo assimilation to synthesize the structural components of the mold body, and on the other hand, they produce energy through alienation, and also generate a series of complex metabolites.

[0003] The production pathways of common volatile metabolites (MVOCs) are divided into primary metabolites and secondary metabolites. For example, Aspergillus niger has a large number of specific proteins that participate in the metabolism of secondary metabolic pathways such as proteins, carbohydrates, fatty acids and isoprenoids, producing various alkanes, alkenes and ester compounds. In addition, existing studies have shown that mildew can promote the degradation of most complex alkane compounds and may generate some simple alkane organic molecules. Furan derivative MVOCs may be obtained through the biotransformation process of microorganisms using lignocellulose as raw materials. Some alcohol MVOCs can also be produced by the dissimilatory effect of amino acids, such as 2-methyl-1-propanol, 2-phenylhexanol and tryptophan, which can be produced by the dissimilatory effect of valine, phenylalanine and tryptophan, respectively. Isopropanol in MVOCs is mainly metabolized in the body through oxidation reactions, and it can be synthesized through biological reactions, such as using microbial fermentation of hemicellulose carbon sources. Benzoic acid degradation is one of the most abundant microbial biomass degradation and metabolic functions in tobacco leaves, and many volatile aromatic compounds may be produced by this pathway during tobacco leaf mildew.

[0004] Traditional tobacco mold detection methods mainly rely on sensory evaluation, physical and chemical analysis, and microbiological testing. Although these methods can reflect the mold condition of tobacco to a certain extent, they have the following limitations:

[0005] Sensory evaluation is highly subjective: sensory evaluation mainly relies on the experience and judgment of professionals. Due to individual differences among evaluators, the evaluation results are prone to volatility and inaccuracy, making it difficult to achieve standardized, quantitative determination of the degree of mold. Physical and chemical analysis has a long cycle and high cost: Physical and chemical analysis of chemical components related to mold in tobacco (such as mycotoxins) usually requires complex instruments and equipment and professional operation, a long test cycle, and high test costs, which is not suitable for large-scale tobacco mold detection needs. There are delays in microbial testing: Although the degree of mold is assessed by culturing mold colonies or detecting mold metabolites, the detection cycle is long and it usually takes several days to get results, which is not suitable for rapid testing.

[0006] With the rapid development of gas sensing technology and data analysis technology, the technology of using characteristic atmosphere (including common inorganic gases, volatile organic compounds, etc.) to evaluate the degree of tobacco mold has gradually attracted attention. During the mold process, tobacco will release specific volatile organic compounds (VOCs), and the changes in these gas components can reflect the mold condition of tobacco. Therefore, by monitoring the characteristic atmosphere components around tobacco and combining them with data analysis models, it is possible to achieve a rapid and accurate assessment of the degree of tobacco mold.

[0007] The existing mildew detection technology based on characteristic atmosphere still has some shortcomings, such as the detection accuracy needs to be improved, and the selection of gas sensors, signal processing and optimization of data analysis models are not mature enough. Therefore, there is an urgent need for a more efficient and accurate method to assess the degree of tobacco mildew, which can realize real-time monitoring and rapid evaluation of the tobacco mildew process. Summary of the invention

[0008] In view of the problems existing in the prior art, the first purpose of the present invention is to provide a model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere. The model uses the characteristic atmosphere components released by the monitored tobacco during the mildew process to construct a correlation model between the number of molds produced by mildew and the characteristic atmosphere content through the Boltzmann model, thereby effectively overcoming the technical problems of the prior art in that the detection process of the degree of mildew of stored tobacco is long and the experimental process is complicated.

[0009] The second purpose of the present invention is to provide a model application for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere. Based on the excellent performance of the above model, the present invention can be used for early warning and classification of tobacco mildew, realize online monitoring of the tobacco mildew process, timely discover mildew signs, and avoid further development of mildew. The invention has excellent universality and can be applied to a variety of scenarios, including tobacco production and processing, storage and transportation, and market terminals, etc., with strong versatility and flexibility.

[0010] In order to achieve the above technical objectives, the present invention provides a model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere, which is characterized by:

[0011] Step S1: using the internal standard method to conduct qualitative and quantitative analysis of the volatile gases before and after the stored tobacco leaves become moldy;

[0012] Step S2: classify the volatile gases before and after the tobacco leaves are moldy according to the size of the change, set the change threshold, and screen the characteristic atmosphere;

[0013] Step S3: Under standard conditions, continuously test the stored tobacco leaves for mildew, obtain the number of molds and the characteristic atmosphere content, and establish a correlation relationship model between the number of molds and the characteristic atmosphere content;

[0014] Step S4: Verify the identity and universality of the model obtained in step S3 under different environmental factors based on the same model data set.

[0015] As a preferred solution, the qualitative and quantitative process of the internal standard method is: adding a common VOC internal standard of known concentration to the sample to be tested, and directly extracting the sample through a Suma tank for GCMS analysis.

[0016] As a preferred solution, the temperature conditions for the GCMS analysis are: at room temperature, increase to 150-170°C at a rate of 3-5°C / min and maintain for 5-7 minutes, then increase to 180-200°C at a rate of 15-20°C / min and maintain for 3-5 minutes, the injector temperature is 230-250°C, and the transfer line temperature is 200-230°C.

[0017] As a preferred solution, the classification method of the change in the amount of volatile gas before and after the stored tobacco leaves become moldy is: the change in the amount of volatile products in the moldy process is classified as 0-30%, 30-50%, 50-100% and >100%.

[0018] As a preferred solution, the volatile products include organic volatile products and inorganic volatile products.

[0019] As a preferred solution, the organic volatile products include volatile products of alkanes, olefins, furans and aromatics.

[0020] As a preferred solution, the inorganic volatile products include carbon monoxide and / or carbon dioxide.

[0021] As a preferred embodiment, the volatile products with a variation of more than 100% include: ethylene, propylene, propane, 1-butene, n-pentane, isoprene, 3-methylhexane, styrene, acrolein, isopropanol, tetrahydrofuran, furan, 2-chloropropane and carbon dioxide.

[0022] As a preferred embodiment, the volatile products with a variation of 50 to 100% include: isopentane, 1-pentene, benzene, 2-methylfuran, 2-methyl-3-pentanone, 3-methyl-2-pentanone, n-undecane, n-dodecane, 1,1-dichloroethylene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene and vinyl acetate.

[0023] As a preferred solution, the standard conditions are a temperature of 25° C. and a humidity of 97%.

[0024] As a preferred solution, the process of the continuous mildew test is: 1 to 3 g of tobacco leaves are inoculated with 100,000 to 300,000 CFU / g spores and placed in a standard condition box, and the number of molds and characteristic atmosphere content are collected every 10 to 30 minutes.

[0025] As a preferred solution, the correlation relationship model between the number of molds and the characteristic atmosphere content is constructed by using the Boltzmann model with the highest relative fit.

[0026] As a preferred solution, the fitting equation of the correlation relationship model between the number of molds and the characteristic atmosphere content is:

[0027] Formula 1:

[0028] In formula 1, y is the number of molds, with the unit of CFU / g; x is the characteristic atmosphere content, x0 is the initial content of the characteristic atmosphere, with the unit of μg / m 3 ; A1 and A2 are characteristic parameters, dimensionless.

[0029] The present invention also provides an application of a model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere, which is characterized by being used for early warning and classification of tobacco mildew.

[0030] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are:

[0031] 1) The model provided by the present invention utilizes the characteristic atmosphere components released by tobacco during the mildew process, and constructs a correlation model between the number of molds produced by mildew and the characteristic atmosphere content through the Boltzmann model, thereby effectively overcoming the technical problems of the long process and complex experimental process of the mildew degree detection of stored tobacco in the prior art.

[0032] 2) In the technical solution provided by the present invention, by monitoring the characteristic atmospheric components released by tobacco during the mildew process, combined with sensor technology and data analysis models, real-time monitoring can be achieved in tobacco production, processing, storage and other links, thereby effectively preventing and reducing the impact of tobacco mildew on product quality and consumer health. Compared with traditional physical and chemical analysis and microbial detection methods, the present invention realizes real-time evaluation of the mildew process by monitoring the characteristic atmospheric components around the tobacco, without the need for complex experimental equipment and long-term cultivation process, and significantly shortens the detection cycle.

[0033] 3) In the technical solution provided by the present invention, the detection device based on the gas sensor replaces the expensive and cumbersome experimental equipment, reduces the cost of the detection equipment, and the method does not require professional technicians to operate, which is suitable for large-scale tobacco mold assessment needs, further reducing the detection cost in production.

[0034] 4) In the technical solution provided by the present invention, based on the excellent performance of the above-mentioned model, it can be used for tobacco mildew warning and classification, realize online monitoring of the tobacco mildew process, timely discover signs of mildew, and avoid further development of mildew. The invention has excellent universality and can be applied to a variety of scenarios, including tobacco production and processing, warehousing and transportation, market terminals and other environments, and has strong versatility and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The change of volatile gas components of alkanes after mildew in Example 1 of the present invention;

[0036] Figure 2 The change of olefin volatile gas components after mildew in Example 1 of the present invention;

[0037] Figure 3 The change of the volatile gas components of aromatic hydrocarbons after mildew in Example 1 of the present invention;

[0038] Figure 4 The change of heterocyclic volatile gas components after mildew in Example 1 of the present invention;

[0039] Figure 5 The corresponding relationship between carbon dioxide and the number of mold in Example 1 of the present invention;

[0040] in, Figure 5 A is the number of mold per gram of moldy tobacco, ranging from 0 to 2.5×10 8 Model diagram of range and carbon dioxide content, Figure 5 B is the number of mold per gram of moldy tobacco, ranging from 0 to 8×10 6 Model diagram of range and carbon dioxide content, Figure 5C is the number of mold per gram of moldy tobacco, ranging from 0 to 2.0×10 6 Schematic diagram of the model with respect to the rate of carbon dioxide generation within the range, Figure 5 D is the number of mold per gram of moldy tobacco, ranging from 0 to 8×10 5 Schematic diagram of the model with respect to the range and rate of carbon dioxide production. DETAILED DESCRIPTION

[0041] The following examples are intended to illustrate the present invention rather than to further limit the scope of protection of the present invention.

[0042] Example 1

[0043] The present invention provides a model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere, which specifically includes:

[0044] 1. Add known concentrations of common VOC internal standards to the sample, and use the Suma tank to directly extract the sample for GCMS quantitative analysis. The chromatographic column is DB-624 (30.0m×250μm, 0.25μm); the starting temperature is 35℃ for 5min, then it is increased to 170℃ at a rate of 5℃ / min and maintained for 7min, and then it is increased to 200℃ at a rate of 20℃ / min and maintained for 5min; the injector temperature is 250℃; the transmission line temperature is 230℃; the carrier gas is He; the carrier gas flow rate is 1.0mL / min; no split; the injection volume is 1mL. The column pre-pressure is 112.9KPa. Mass spectrometry conditions: EI source; electron energy 70eV; ion source temperature 230℃; quadrupole 150℃; scanning mode is Scan; the scanning mass range is 20~500u.

[0045] 2. 124 volatile and semi-volatile components were detected in the non-moldy tobacco samples, and 123 components were detected in the moldy tobacco samples. There are three volatile and semi-volatile compounds produced due to tobacco mold, namely: 1-hexene, 2,3-dimethylpentane, and vinyl chloride. There are four volatile and semi-volatile compounds that disappear due to tobacco mold, namely: m-diethylbenzene, 1,3-butadiene, 1,4-dioxane, and hexachloro-1,3-butadiene. Among them:

[0046] 2-1. The total amount of volatile and semi-volatile components in moldy tobacco leaves was 24702.17 μg / m3, compared with 17638.94 μg / m3 in the control tobacco leaves. 3 An increase of 40.04%;

[0047] 2-2. The content of alkanes in moldy tobacco leaves is 1488.93 μg / m 3 Compared with 884.11 μg / m 3 , the content increased by 68.41%;

[0048] 2-3. The content of olefins in moldy tobacco leaves is 469.15 μg / m 3 Compared with 98.78 μg / m 3 , the content increased by 374.93%;

[0049] 2-4. The furan content in moldy tobacco leaves is 1438.53 μg / m 3 Compared with 168.26 μg / m 3 , the content increased by 754.96%;

[0050] 2-5. The content of aromatic hydrocarbons in moldy tobacco leaves is 95.06 μg / m 3 Compared with 64.68 μg / m 3 , the content increased by 46.97%;

[0051] The characteristic compounds with content increase of more than 100% include: ethylene, propylene, propane, 1-butene, n-pentane, isoprene, 3-methylhexane, styrene, acrolein, isopropanol, tetrahydrofuran, furan, 2-chloropropane, 3-methylfuran, 2-methyl-1,3-pentadiene, 3-pentanone, 2-vinylfuran, 1-(2-furanyl)-ethanol, 3,4,4-trimethyl-2-cyclopentene-1-one, and the content of 3-methylfuran increased by more than 55 times, and the content of furan increased by more than 100 times; the compounds with content increase in the range of 50% to 100% include: isopentane, 1-pentene, benzene, 2-methylfuran, 2-methyl-3-pentanone, 3-methyl-2-pentanone, 3-methylene-1,5,5-trimethylcyclohexene.

[0052] The compounds whose contents were reduced in the range of 50% to 100% were: n-undecane, n-dodecane, 1,1-dichloroethylene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, vinyl acetate, ethyl acetate, carbonyl sulfide, dimethyl sulfide, and 1-butanol.

[0053] The three substances produced by mildew, 1-hexene, 2,3-dimethylpentane and vinyl chloride, have low contents (all less than 2 μg / m 3 ), so we used specific substances with large variations, high contents and easy detection, such as propane, 3-methylhexane, propylene, isoprene, styrene, 3-methylfuran or carbon dioxide as characteristic gases for subsequent modeling verification.

[0054] Table 1 Changes in volatile gas components of alkanes after mildew

[0055]

[0056]

[0057] Table 2 Changes in olefin volatile gas components after mildew

[0058]

[0059] Table 3 Changes in volatile gas components of aromatic hydrocarbons after mildew

[0060]

[0061] Table 3 Changes in heterocyclic volatile gas components after mildew

[0062]

[0063] Through the changes in the above-mentioned volatile atmospheres, the present invention chooses carbon dioxide as an example to explore the relationship between the characteristic atmosphere content and the tobacco mildew process. It should be noted that other characteristic atmosphere contents can also be used to establish a model for characteristic atmosphere evaluation of the degree of mildew of stored tobacco leaves according to the following method.

[0064] 2g of tobacco leaves were inoculated with 300,000 CFU / g spores and placed in a dryer at 25°C and 85% humidity. High-precision carbon dioxide and oxygen sensors were placed in the dryer to continuously monitor changes in carbon dioxide content for 14 days, and data was uploaded every 30 minutes.

[0065] We found that the relative equilibrium content of tobacco carbon dioxide was different under different mold levels. In order to quickly detect the number of tobacco mold and provide data support for mold early warning, we explored the correlation between the change of tobacco mold number and carbon dioxide content under standard conditions (25°C, 97%), and constructed a corresponding model between the number of mold (y) and carbon dioxide content (x) under standard conditions with the Boltzmann model with the highest relative fit ( Figure 5 A) Its fitting equation is:

[0066]

[0067] R 2 =0.9973.

[0068] In order to prove the universality of the model, that is, the model is identical under different environmental factors, we explored the Boltzmann fitting of carbon dioxide content and mold number at 25℃ and 85% humidity ( Figure 5 B) The Origin test of the same model data set showed that there was no statistical difference between the two data sets at the 0.05 significance level, and it was preliminarily determined that the model was universal.

[0069] In order to correct and simplify the judgment model, we explored the linear model of mold number and carbon dioxide generation rate during the exponential growth period of mold under different environments. Molds in the exponential growth period grow actively, rarely dormant, and have less interference. The model is as follows Figure 5As shown in C and D, the fitting effect is good, but the model is tested on the Origin data set with the same model, which shows that there are statistical differences between the two data sets at the 0.05 significance level and is not universal. This may be because the mold growth process is not long-term stable.

Claims

1. A model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere, characterized by: Step S1: using the internal standard method to conduct qualitative and quantitative analysis of the volatile gases before and after the stored tobacco leaves become moldy; Step S2: classify the volatile gases before and after the tobacco leaves are moldy according to the size of the change, set the change threshold, and screen the characteristic atmosphere; Step S3: Under standard conditions, continuously test the stored tobacco leaves for mildew, obtain the number of molds and the characteristic atmosphere content, and establish a correlation relationship model between the number of molds and the characteristic atmosphere content; Step S4: Verify the identity and universality of the model obtained in step S3 under different environmental factors based on the same model data set.

2. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1, characterized in that: The qualitative and quantitative process of the internal standard method is: adding a common VOC internal standard of known concentration to the sample to be tested, and directly extracting the sample through the Suma tank for GCMS analysis.

3. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 2, characterized in that: The temperature conditions for the GCMS analysis are: at room temperature, increase to 150-170°C at a rate of 3-5°C / min and maintain for 5-7 minutes, then increase to 180-200°C at a rate of 15-20°C / min and maintain for 3-5 minutes, the injector temperature is 230-250°C, and the transfer line temperature is 200-230°C.

4. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1, characterized in that: The classification method of the change amount of volatile gas before and after the stored tobacco leaves become moldy is: the change amount of volatile products in the moldy process is classified according to 0-30%, 30-50%, 50-100% and >100%; the volatile products include organic volatile products and inorganic volatile products.

5. A model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1 or 4, characterized in that: The organic volatile products include alkane, olefin, furan and aromatic hydrocarbon volatile products; the inorganic volatile products include carbon monoxide and / or carbon dioxide.

6. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 5, characterized in that: The volatile products with a variation of more than 100% include: ethylene, propylene, propane, 1-butene, n-pentane, isoprene, 3-methylhexane, styrene, acrolein, isopropanol, tetrahydrofuran, furan, 2-chloropropane and carbon dioxide; the volatile products with a variation of 50-100% include: isopentane, 1-pentene, benzene, 2-methylfuran, 2-methyl-3-pentanone, 3-methyl-2-pentanone, n-undecane, n-dodecane, 1,1-dichloroethylene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene and vinyl acetate.

7. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1, characterized in that: The standard conditions are a temperature of 25° C. and a humidity of 97%. The process of the continuous mildew test is as follows: 1 to 3 g of tobacco leaves are inoculated with 100,000 to 300,000 CFU / g of spores and placed in a standard condition box, and the number of molds and characteristic atmosphere content are collected every 10 to 30 minutes.

8. The model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1, characterized in that: The correlation relationship model between the number of molds and the characteristic atmosphere content is constructed by using the Boltzmann model with the highest relative fitting degree.

9. A model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claim 1 or 8, characterized in that: The fitting equation of the correlation relationship model between the number of molds and the characteristic atmosphere content is: Formula 1: In formula 1, y is the number of molds, with the unit of CFU / g; x is the characteristic atmosphere content, x0 is the initial content of the characteristic atmosphere, with the unit of μg / m 3 ; A1 and A2 are characteristic parameters, dimensionless.

10. The application of the model for evaluating the degree of mildew of stored tobacco leaves based on characteristic atmosphere according to claims 1 to 9, characterized in that: Used for tobacco mold warning and classification.

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