CN102507495A - Method for rapidly and nondestructively detecting green tea water content based on wavelet transformation - Google Patents
Method for rapidly and nondestructively detecting green tea water content based on wavelet transformation Download PDFInfo
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- CN102507495A CN102507495A CN2011103756089A CN201110375608A CN102507495A CN 102507495 A CN102507495 A CN 102507495A CN 2011103756089 A CN2011103756089 A CN 2011103756089A CN 201110375608 A CN201110375608 A CN 201110375608A CN 102507495 A CN102507495 A CN 102507495A
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Abstract
The invention discloses a method for rapidly and nondestructively detecting green tea water content based on wavelet transformation. The method comprises the steps of: obtaining a diffuse reflection spectrum of tea leaf samples within a short-wave near infrared spectrum range being 888-1007nm, conducting calculation and transformation to obtain an absorbance spectrum, adopting a db2 wavelet basis function to conduct discrete wavelet transformation, extracting a three-scale low-frequency wavelet coefficient to obtain nineteen wavelet characteristic coefficients and accordingly calculating the water content of the samples. The method for rapidly and nondestructively detecting the green tea water content based on the wavelet transformation can rapidly and effectively monitor the dynamic change of the water content during green tea processing and can realize the rapid, nondestructive and low-cost detection of the water content during green tea processing.
Description
Technical field
The invention belongs to the Tea Processing detection range, be specifically related to the method that a kind of quick nondestructive detects the green tea water percentage.
Background technology
Tea products is processed through a series of physics and chemical change by the new fresh and tender tip of tealeaves; The manufacturing procedure of green tea comprises and completes, kneads and operation such as drying; Water percentage has directly influenced the physical state of raw material and the process of chemical reaction in these manufacturing procedures, is the key factor that forms tea leaf quality.With the operation that completes is example, and the gordian technique that completes is to confirm fixation time and to complete temperature to the water percentage of blade.And the accurate measurement of tealeaves water percentage at present all is to adopt oven dry to claim mass method; This method Measuring Time is long; At least need 1～2 hour; And the hyperthermia drying process destroyed the nutritional labeling of tealeaves, caused test sample book not eat again, can't satisfy the needs that the Tea Processing process real-time detects.
Summary of the invention
The invention provides the method that a kind of quick nondestructive based on wavelet transformation detects the green tea water percentage, can fast and effeciently monitor the dynamic change of water percentage in the Green Tea Processing process, realize water percentage in the Green Tea Processing process fast, harmless, the low-cost detection.
A kind of quick nondestructive based on wavelet transformation detects the method for green tea water percentage, may further comprise the steps:
(1) obtains the diffuse reflection spectrum of green tea sample in the 888-1007nm scope; Obtain the diffuse reflection spectrum reflectivity of each wavelength in the 888-1007nm scope; And calculate the absorbance of said green tea sample based on formula A=log (1/R), obtain the absorbance spectrum of said green tea sample; Wherein, R is the diffuse reflection spectrum reflectivity, and A is an absorbance;
(2) select for use db3 (Daubechies 3) wavelet basis function that the absorbance spectrum of said green tea sample is carried out wavelet transform, extract 3 yardstick low frequency wavelet coefficients, obtain 19 wavelet character coefficients of said green tea sample;
(3), calculate the water percentage of said green tea sample 19 wavelet character coefficient substitution formula (I) of said green tea sample:
Y
Water percentage=0.206-10.718x
1-18.337x
2+ 29.155x
3+ 13.073x
4+ 5.081x
5+ 4.935x
6-12.903x
7-10.960x
8-3.334x
9-12.292x
10-2.915x
11+ 7.334x
12+ 5.165x
13+ 4.296x
14+ (I) 7.772x
15+ 5.366x
16-4.253x
17-5.163x
18-1.262x
19
Wherein, Y
Water percentageBe the water percentage of green tea sample, x
1... X
1919 wavelet character coefficients for said green tea sample.
In the step (1), described green tea sample can obtain through the spectrometer of shortwave near infrared range at the diffuse reflection spectrum of 888-1007nm scope.
Among the present invention; At first through gathering green tea at the diffuse reflection spectrum of 888-1007nm and calculate absorbance; Because 888-1007nm is the characteristic absorption wave band of characteristic key O-H in spectrum in the hydrone; Especially the combination absorption band 970nm etc. frequently that has comprised the antisymmetric stretching vibration of hydrone, therefore, the information of the water percentage of the absorbance spectrum at the characteristic absorption band place of 888-1007nm in can fine reflection green tea; Adopt wavelet transformation to come packed data to extract wavelet character information again, and optimize and choose db3 (Daubechies 3) wavelet basis function and 3 yardstick low frequency wavelet combinations of coefficients, thereby obtain and closely-related 19 the wavelet character coefficients of the water percentage of green tea; And then be independent variable with these 19 wavelet character coefficients, the green tea water percentage is that dependent variable is set up multiple linear regression model, realizes effective detection of water percentage in the green tea.
Compared with prior art, the present invention has following beneficial technical effects:
1. quick, the near infrared spectrum sweep velocity is fast, can in 1s, accomplish the scanning of whole infrared band scope.
2. simple, near infrared spectrum detection method step is few, simple to operate, has avoided traditional oven dry to claim the very long drying course of mass method and loaded down with trivial details repeatedly weighing process.
3. low-cost, the shortwave near infrared spectral range of employing is short, so corresponding instrument price is relatively cheap, the cost of maintenance is also low.
4. has good economic benefit; Traditional measurement means needs manpower, financial resources, the material resources of labor at aspects such as sampling, sample preparation, mensuration; This detection method is simple, easy to use because of step, and water percentage that can accurate detection green tea is so have good economic benefit.
Description of drawings
Fig. 1 is the absorbance spectrum figure of green tea sample.
Fig. 2 is 19 wavelet character coefficients of green tea sample.
Fig. 3 is the water percentage detected value and the diffusing point of the actual value distribution plan of green tea sample among the embodiment.
Embodiment
Specify the present invention below in conjunction with embodiment and accompanying drawing, but the present invention is not limited to this.
A kind of quick nondestructive based on wavelet transformation detects the method for green tea water percentage, may further comprise the steps:
(1) collect the green tea sample:
Collect totally 738 in representative multiple tealeaves sample, comprise the bright leaf sample of five kinds, as shown in table 1; Seven grade green tea samples, as shown in table 2; Raw material sample in eight types of green tea primary making process, as shown in table 3.
The water percentage of the bright leaf sample of five kinds of table 1. (w.b., %)
The water percentage of seven grade green tea of table 2. sample (w.b., %)
The water percentage of eight types of samples in the table 3. green tea primary making process (w.b., %)
(2) calculate the absorbance spectrum of acquisition sample in the 888-1007nm scope:
Adopt the Handheld Field Spec spectrometer of U.S. ASD company, its spectrum sample is 10nm at interval, measurement range 325-1075nm, and scanning times 30 times, resolution 3.5nm, the probe field angle is 20 degree.Light source is the 14.5V Halogen lamp LED supporting with spectrometer.The software ASD View Spec Pro that carries with this spectrometer gathers spectroscopic data.
Scan the diffuse reflection spectrum of the 888-1007nm scope of above-mentioned green tea sample, obtain the diffuse reflection spectrum reflectivity of each wavelength in the 888-1007nm scope, and become absorbance to the diffuse reflection spectrum reflectivity conversion, obtain the absorbance spectrum of above-mentioned green tea sample.Wherein, become absorbance to be based on that following formula carries out the diffuse reflection spectrum reflectivity conversion: A=log (1/R), wherein, R is the diffuse reflection spectrum reflectivity, A is an absorbance.The absorbance spectrum figure of above-mentioned green tea sample, as shown in Figure 1.
(3) extract the small echo low frequency coefficient:
Absorbance spectrum to the green tea sample that obtained adopts db3 (Daubechies 3) wavelet basis function to carry out wavelet transform, extracts 3 yardstick low frequency wavelet coefficients, obtains 19 wavelet character coefficients of green tea sample.Wherein, 3 yardstick low frequency wavelet coefficients are meant that absorbance spectrum is carried out 3 yardstick discrete wavelets decomposes the low frequency wavelet coefficient that obtains.
Above-mentioned processing can use following code to realize on the Matlab software platform:
[c，l]＝wavedec(s，3，′db3′)；
ca3＝appcoef(c，l，′db3′，3)；
Wherein, s represents the absorbance of green tea sample, and ca3 represents 19 wavelet character coefficients.
19 wavelet character coefficients of resulting green tea sample are as shown in Figure 2.
(4) the substitution formula calculates water percentage: 19 small echo low frequency coefficient substitution formula (I) of the green tea sample that obtains, can obtain the water percentage of green tea sample:
Y
Water percentage=0.206-10.718x
1-18.337x
2+ 29.155x
3+ 13.073x
4+ 5.081x
5+ 4.935x
6-12903x
7-10.960x
8-3.334x
9-12292x
10-2.915x
11+ 7.334x
12+ 5.165x
13+ 4.296x
14+ (I) 7.772x
15+ 5.366x
16-4.253x
17-5.163x
18-1.262x
19
Wherein, Y
Water percentageBe the water percentage of green tea sample, x
1... X
1919 wavelet character coefficients for the green tea sample.
The detected value of the green tea sample that is obtained by aforementioned calculation and the actual value point that looses distributes as shown in Figure 3.Can find out that by Fig. 3 the related coefficient of detected value and actual value is 0.9908, the coefficient of determination is 0.9816, and root-mean-square error is 0.0346, and this explanation detected value and the actual value goodness of fit are good, show that the green tea water percentage spectrum detection method based on wavelet transformation is feasible.
Claims (1)
1. the method based on the quick nondestructive detection green tea water percentage of wavelet transformation is characterized in that, may further comprise the steps:
(1) obtains the diffuse reflection spectrum of green tea sample in the 888-1007nm scope; Obtain the diffuse reflection spectrum reflectivity of each wavelength in the 888-1007nm scope; And calculate the absorbance of said green tea sample based on formula A=log (1/R), obtain the absorbance spectrum of said green tea sample; Wherein, R is the diffuse reflection spectrum reflectivity, and A is an absorbance;
(2) select for use the db3 wavelet basis function that the absorbance spectrum of said green tea sample is carried out wavelet transform, extract 3 yardstick low frequency wavelet coefficients, obtain 19 wavelet character coefficients of said green tea sample;
(3), calculate the water percentage of said green tea sample 19 wavelet character coefficient substitution formula (I) of said green tea sample:
Y
Water percentage=0.206-10.718x
1-18.337x
2+ 29.155x
3+ 13.073x
4+ 5.081x
5+ 4.935x
6-12.903x
7-10.960x
8-3.334x
9-12.292x
10-2.915x
11+ 7.334x
12+ 5.165x
13+ 4.296x
14+ (I) 7.772x
15+ 5.366x
16-4.253x
17-5.163x
18-1.262x
19
Wherein, Y
Water percentageBe the water percentage of green tea sample, x
1... X
1919 wavelet character coefficients for said green tea sample.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103743697A (en) * | 2013-12-20 | 2014-04-23 | 贵州省分析测试研究院 | Method for monitoring tea production in real time by adopting near infrared spectrum |
| CN104502305A (en) * | 2014-12-09 | 2015-04-08 | 西北师范大学 | Near infrared spectrum useful information distinguishing method based on wavelet transform |
| CN104931453A (en) * | 2015-06-12 | 2015-09-23 | 湖北省农业科学院果树茶叶研究所 | Method for predicting water content of spread green leaves of green tea based on near infrared spectrum technology |
| CN105424640A (en) * | 2015-11-27 | 2016-03-23 | 浙江大学 | Method for detecting lead chrome green addition content of tea leaves |
| CN105510269A (en) * | 2015-11-27 | 2016-04-20 | 浙江大学 | Detection method of add content of talcum powder in tea |
| CN106706559A (en) * | 2017-03-03 | 2017-05-24 | 上海事凡物联网科技有限公司 | Method, system and server for measuring moisture content of fallen leaves |
| CN110261345A (en) * | 2019-06-25 | 2019-09-20 | 大连海事大学 | A kind of near infrared spectrum flexible measurement method and system based on wavelet function |
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| CN101598714A (en) * | 2009-03-26 | 2009-12-09 | 安徽农业大学 | The evaluation method of quality of fresh tea leaf raw material |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103743697A (en) * | 2013-12-20 | 2014-04-23 | 贵州省分析测试研究院 | Method for monitoring tea production in real time by adopting near infrared spectrum |
| CN104502305A (en) * | 2014-12-09 | 2015-04-08 | 西北师范大学 | Near infrared spectrum useful information distinguishing method based on wavelet transform |
| CN104502305B (en) * | 2014-12-09 | 2017-02-22 | 西北师范大学 | Near infrared spectrum useful information distinguishing method based on wavelet transform |
| CN104931453A (en) * | 2015-06-12 | 2015-09-23 | 湖北省农业科学院果树茶叶研究所 | Method for predicting water content of spread green leaves of green tea based on near infrared spectrum technology |
| CN105424640A (en) * | 2015-11-27 | 2016-03-23 | 浙江大学 | Method for detecting lead chrome green addition content of tea leaves |
| CN105510269A (en) * | 2015-11-27 | 2016-04-20 | 浙江大学 | Detection method of add content of talcum powder in tea |
| CN106706559A (en) * | 2017-03-03 | 2017-05-24 | 上海事凡物联网科技有限公司 | Method, system and server for measuring moisture content of fallen leaves |
| CN106706559B (en) * | 2017-03-03 | 2019-06-18 | 上海事凡物联网科技有限公司 | Measurement method, system and the server of fallen leaves moisture content |
| CN110261345A (en) * | 2019-06-25 | 2019-09-20 | 大连海事大学 | A kind of near infrared spectrum flexible measurement method and system based on wavelet function |
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Inventor after: Li Xiaoli Inventor after: Luo Liubin Inventor after: He Yong Inventor after: Nie Pengcheng Inventor after: Bao Yidan Inventor after: Qiu Zhengjun Inventor before: Li Xiaoli Inventor before: Nie Pengcheng Inventor before: He Yong Inventor before: Bao Yidan Inventor before: Qiu Zhengjun |
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Free format text: CORRECT: INVENTOR; FROM: LI XIAOLI NIE PENGCHENG HE YONG BAO YIDAN QIU ZHENGJUN TO: LI XIAOLI LUO LIUBIN HE YONG NIE PENGCHENG BAO YIDAN QIU ZHENGJUN |
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