CN102507495B - 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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- CN102507495B CN102507495B CN 201110375608 CN201110375608A CN102507495B CN 102507495 B CN102507495 B CN 102507495B CN 201110375608 CN201110375608 CN 201110375608 CN 201110375608 A CN201110375608 A CN 201110375608A CN 102507495 B CN102507495 B CN 102507495B
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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 basisfunction 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 field, be specifically related to the method that a kind of quick nondestructive detects the green tea water percentage.
Background technology
Tea products is made through series of physical and chemical change by the new fresh and tender tip of tealeaves, the manufacturing procedure of green tea comprises and completes, kneads and the operation such as dry, water percentage has directly affected 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.Take the operation that completes as example, the gordian technique that completes is to determine fixation time and the temperature that completes for the water percentage of blade.And the Measurement accuracy of tealeaves water percentage all is to adopt the oven dry Weight at present, this method Measuring Time is long, at least need 1～2 hour, and the hyperthermia drying destroyed nutritional labeling of tealeaves, cause test sample book not eat again, can't satisfy the needs that the Tea Processing process detects in real time.
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 green tea sample at the diffuse reflection spectrum of 888-1007nm scope, obtain the diffuse reflection spectrum reflectivity at each wavelength place in the 888-1007nm scope, and calculate the absorbance of described green tea sample based on formula A=log (1/R), obtain the absorbance spectrum of described green tea sample; Wherein, R is the diffuse reflection spectrum reflectivity, and A is absorbance;
(2) select db3 (Daubechies 3) wavelet basis function that the absorbance spectrum of described green tea sample is carried out wavelet transform, extract 3 yardstick low frequency wavelet coefficients, obtain 19 wavelet character coefficients of described green tea sample;
(3) 19 wavelet character coefficient substitution formula (I) of described green tea sample, calculate the water percentage of described 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 described green tea sample.
In the step (1), described green tea sample can obtain by the spectrometer of shortwave near infrared range at the diffuse reflection spectrum of 888-1007nm scope.
Among the present invention, at first by gathering green tea at the diffuse reflection spectrum of 888-1007nm and calculating absorbance, because 888-1007nm is the characteristic absorption wave band of feature 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 again wavelet transformation to come packed data to extract wavelet character information, and optimize and choose db3 (Daubechies 3) wavelet basis function and the combination of 3 yardstick low frequency wavelet coefficients, thereby obtain and closely-related 19 the wavelet character coefficients of the water percentage of green tea; And then take these 19 wavelet character coefficients as independent variable, 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 useful technique effect:
1. quick, near infrared spectrum scanning speed is fast, can finish the scanning of whole infrared band scope in 1s.
2. simple, near infrared spectrum detection method step is few, simple to operate, has avoided the very long drying course of traditional oven dry Weight, 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 need to expend a large amount of manpowers, financial resources, material resources at aspects such as sampling, sample preparation, mensuration, this detection method is simple, easy to use because of step, can detect fast and accurately the water percentage of green tea, 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 water percentage detected value and the actual value scatter diagram of green tea sample among the embodiment.
Embodiment
Describe the present invention in detail 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; Eight class green tea primary making process Raw samples, as shown in table 3.
The water percentage (w.b., %) of the bright leaf sample of five kinds of table 1.
The water percentage (w.b., %) of seven grade green tea of table 2. sample
The water percentage (w.b., %) of eight class samples in the table 3. green tea primary making process
(2) calculate to obtain sample in the absorbance spectrum of 888-1007nm scope:
Adopt the Handheld Field Spec spectrometer of U.S. ASD company, its spectrum sample interval 10nm, measurement range 325-1075nm, 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 at each wavelength place in the 888-1007nm scope, and the diffuse reflection spectrum reflectivity conversion is become absorbance, obtain the absorbance spectrum of above-mentioned green tea sample.Wherein, become absorbance to be based on following formula the diffuse reflection spectrum reflectivity conversion and carry out: A=log (1/R), wherein, R is the diffuse reflection spectrum reflectivity, A is 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 obtains 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 refer to 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 at 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 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.
Detected value and the loose point of actual value by the above-mentioned green tea sample that calculates distribute as shown in Figure 3.The related coefficient of detected value and actual value is 0.9908 as seen from Figure 3, and 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 green tea sample at the diffuse reflection spectrum of 888-1007nm scope, obtain the diffuse reflection spectrum reflectivity at each wavelength place in the 888-1007nm scope, and calculate the absorbance of described green tea sample based on formula A=log (1/R), obtain the absorbance spectrum of described green tea sample; Wherein, R is the diffuse reflection spectrum reflectivity, and A is absorbance;
(2) select the db3 wavelet basis function that the absorbance spectrum of described green tea sample is carried out wavelet transform, extract 3 yardstick low frequency wavelet coefficients, obtain 19 wavelet character coefficients of described green tea sample;
(3) 19 wavelet character coefficient substitution formula (I) of described green tea sample, calculate the water percentage of described 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+ 7.772x
15+ 5.366x
16-4.253x
17-5.163x
18-1.262x
19(I)
Wherein, Y
Water percentageBe the water percentage of green tea sample, x
1... x
1919 wavelet character coefficients for described green tea sample.
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| 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 |
| 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 |
| CN105510269A (en) * | 2015-11-27 | 2016-04-20 | 浙江大学 | Detection method of add content of talcum powder in tea |
| CN105424640A (en) * | 2015-11-27 | 2016-03-23 | 浙江大学 | Method for detecting lead chrome green addition content of tea 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 |
| CN110261345B (en) * | 2019-06-25 | 2021-08-24 | 大连海事大学 | Near infrared spectrum soft measurement method and system based on wavelet function |
Citations (1)
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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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| 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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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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