CN105223240A - A kind of method utilizing detection by electronic nose crab freshness - Google Patents

Abstract

The invention discloses a kind of method utilizing detection by electronic nose crab freshness.The method comprises the following steps: crab sample to be measured is put into sampling receptacle by (1), sealing, left at room temperature 30 ~ 50min; (2) the gas probe head of Electronic Nose good for filtering is inserted sampling receptacle, setup times is 40 ~ 60s, allow collection of head space gas; (3) gas enters the detected analysis of gas sensor array; (4) collect also stored-gas related data, detailed process is as follows: the response characteristic value 1. extracting gas sensor array, comprises initial value, stationary value, rise time, climbing speed; 2. solidify non-linear stochastic resonance algorithm in the digital signal processor that Electronic Nose is built-in, the Electronic Nose response primitive character value gathered is inputted DSP to calculate output signal-to-noise ratio spectroscopic eigenvalue; 3. crab grade of freshness is calculated according to freshness forecast model and signal to noise spectrum eigenwert.The present invention is easy, quick, effective.

Description

A kind of method utilizing detection by electronic nose crab freshness

Technical field

The present invention relates to crab class freshness detection technique field, more particularly, is a kind of method utilizing detection by electronic nose crab freshness.

Background technology

Freshness is one of major criterion evaluating crab class quality.A series of index and method are now developed to evaluate crab freshness, as sensory evaluation method, micro-biological process, Physico-chemical tests method etc., but above detection method is more difficult meets the requirements such as accurate, quick, simple to operate, there is the shortcomings such as testing process is loaded down with trivial details, cost is high, length consuming time.

At present, be applied to the problem such as the baseline wander of gas sensor ubiquity, poor repeatability of Electronic Nose, affect the accuracy of testing result, become the obstacle of Electronic Nose Technology development.In addition, the recognition methods of traditional mode mainly comprises principal component analysis (PCA), factorial analysis, cluster analysis, partial least square method, artificial neural network etc., and these methods also also exist certain limitation.Original multi-dimensional Data Dimensionality Reduction to low-dimensional, is assigned to evaluate the contribute information influence power of raw data by principal component analysis (PCA) by calculating major component function call.But when the symbol of the factor loading of major component have just have negative time, evaluation function meaning is just indefinite.Factorial analysis restructuring original variable information is to seek the common factor of variation, but the method adopts least square method that result may be caused to lose efficacy when calculated factor score.Cluster analysis obtains cluster result when sample size is larger comparatively difficult.Partial least square method can overcome the problem of sample size lower than regression modeling during variable number effectively, but there is Influential cases regression result will be made to lose efficacy.Artificial neural network there will be the problem that training effectiveness reduces, forecast precision declines when input amendment is more, need repetition learning.Meanwhile, above mode identification method can distinguish sample qualitatively, but substantially cannot quantize sample differentiation information.

Summary of the invention

In order to the process of the method solving existing crab freshness is loaded down with trivial details, cost is high, length consuming time, sensor base line drift etc. problem, the object of the present invention is to provide a kind of easy, method of utilizing detection by electronic nose crab freshness fast and effectively.

The present invention is described below for the adopted concrete technical scheme that achieves the above object.

The invention provides a kind of method utilizing detection by electronic nose crab freshness, concrete steps are as follows:

(1) crab sample to be measured is put into sampling receptacle, sealing, left at room temperature 30 ~ 50min;

(2) the gas probe head of Electronic Nose good for filtering is inserted sampling receptacle, setup times is 40 ~ 60s, allow collection of head space gas;

(3) gas enters the detected analysis of gas sensor array;

(4) collect also stored-gas related data, utilize data handling system to carry out Treatment Analysis to the data of collecting; Detailed process is as follows:

1. extract the response characteristic value of gas sensor array, response characteristic value comprises initial value Vs, stationary value Ve, rise time Ti, climbing speed

2. solidify non-linear stochastic resonance algorithm in the digital signal processor that Electronic Nose is built-in, Electronic Nose is responded primitive character value input DSP to calculate output signal-to-noise ratio spectroscopic eigenvalue Eig _sNR; Computing method are as follows:

System input signal is $I\left(t\right)=\frac{Ve-Vs}{Ti}+Vs;$ System features is expressed as:

Wherein a and b is the parameter of potential function, and x is the position of Brownian movement particle, and ξ (l) is white Gaussian noise, and its autocorrelation function E [ξ (t) ξ (0)]-2D ζ (t), A are input signal strengths, f ₀be frequency modulating signal, D is noise intensity it is a real parameter;

Signal to noise ratio (S/N ratio) characterizes the conventional parameter of accidental resonance characteristic, by signal to noise spectrum eigenwert Eig _sNRbe defined as:

${\mathrm{Eig}}_{SNR}=2\[\underset{\mathrm{\Δ}\mathrm{\ω}\→0}{\lim }\underset{\mathrm{\Ω}-\mathrm{\Δ}\mathrm{\ω}}{\overset{\mathrm{\Ω}+\mathrm{\Δ}\mathrm{\ω}}{\∫}}S\left(\mathrm{\ω}\right)d\mathrm{\ω}\]/S_N\left(\mathrm{\Ω}\right)$

Wherein S (ω) representation signal power spectrum density, S _n(Ω) be the intensity of noise in signal frequency region, ω is the frequency that power spectrum spike is corresponding, and Ω is the frequency that accidental resonance noise is corresponding;

3. Electronic Nose experiment is used to detect the signal to noise spectrum eigenwert Eig of the crab sample of the different freshness of many groups _sNR, the signal to noise ratio (S/N ratio) eigenwert matching according to crab sample obtains crab freshness forecast model: Tq=f (Eig _sNR), wherein Tq is crab grade of freshness;

If 4. crab grade of freshness Tq≤Tl, Tl are shelf life terminal critical value, be then fresh; If crab grade of freshness Tq>Tl, then crab sample has reached shelf life terminal.

In the present invention, in step (3), described sensor array is classified as 8 kinds of sensitive gas sensor arrays, is made up of TGS-825, TGS-821, TGS-826, TGS-822, TGS-842, TGS-813, TGS-2610 and TGS-2201; Described sensitive gas sensor array is for realizing the identification to sulfide, hydrogen, ammonia, toluene, dimethylbenzene, hydrocarbon gas, methane, propane, propane, butane, oxynitrides.

In the present invention, in step (3), be 1000 ~ 1200m1/min by the gas flow of Electronic Nose air chamber.

In the present invention, in step (4), the measuring process of described shelf life terminal critical value Tl is as follows:

A. according to SC/T3032-2007, the total volatile basic nitrogen change of crab in continuous 8 days is detected;

B. according to GB2733-2005, the time diacritical point of crab corruption is determined, i.e. shelf life terminal S1;

C. verify the accuracy of the shelf life model set up according to the testing result of TVB-N method, and obtain shelf life terminal critical value Tl.

In the present invention, in step (4), described crab freshness forecast model is:

$Tq=\frac{{\mathrm{Eig}}_{SNR}+65.7548}{2.6142},$

Wherein: Tq is crab grade of freshness, Eig _sNRfor signal to noise spectrum eigenwert.

Cleaning Principle of the present invention is: Electronic Nose sensor array responds to the gas that tested crab sample volatilizes, and causes the conductivity of each sensor to change, and kind, the concentration of this change and each sensor specificity sensitive gas are relevant.This mutual relationship can as the foundation of demarcating sample information.Before a kind of gas is presented on a sensor cover specifically, sensor converts electric signal to gas input, multiple sensor just constitutes the response spectra of sensor array to this smell to a kind of response of gas, often kind of gas all can have its characteristic response, and the characteristic response intensity different according to multisensor just can distinguish kind, the concentration of gas.

Also different at its escaping gas composition of crab sample of different freshness, follow the tracks of the change of crab sample escaping gas by Electronic Nose, process detection by electronic nose signal with non-linear stochastic resonance and extract freshness eigenwert, realizing the target that crab freshness detects.

The present invention has following beneficial effect:

(1) detection method of the present invention adopts the Electronic Nose be made up of 8 class sensors to detect crab sample, testing result is objective, accurate, quick, reproducible, as long as and the response of the Electronic Nose of testing inspection crab sample, and the signal to noise ratio (S/N ratio) eigenwert calculating sample just can realize the object that crab sample freshness detects, analytic process is simple, has the advantages such as convenient, cheap, accurate;

(2) detection method gas of the present invention directly by detect sensor array, gas can fully with sensor contacts, detection time is short;

(3) cost of the present invention is low, is easy to penetration and promotion.

Accompanying drawing explanation

Fig. 1 is the process flow diagram utilizing the method for detection by electronic nose crab freshness of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

With reference to Fig. 1, a kind of method utilizing detection by electronic nose crab freshness, utilize the system of detection by electronic nose crab freshness mainly comprise data acquisition, sensor array, air chamber, air chamber scavenging pump, gas samping pump; Described data acquisition unit core devices adopts embedded microcontroller, realizes sensor array signal collection, transmission and pump valve thereof and opens controlling functions; When detection system is tested, the pure air that air cleaner produces by air chamber scavenging pump sends into air chamber, calibrating sensors; Afterwards under the drive of gas samping pump, enter air chamber with the gas that sample in sample introduction needle aspirate container volatilizes, produce response signal with after sensor contacts, discharge finally by gas outlet.Sensor response signal through data acquisition by portable computer record, preservation processing, the grade of freshness of final this sample of display.

Utilize a method for detection by electronic nose crab freshness, detect the crab sample of 0 DEG C of storage.

(1) 10 grams, crab sample to be detected is put into sampling receptacle and leave standstill 30 ~ 50min;

(2) before detection sample, first by scavenging pump, the pure air that filter cleaner produces is passed into sensor air chamber by under normal temperature, sensor response is calibrated.The gas that the sample that sample introduction needle aspirate at normal temperatures by Electronic Nose after calibration has left standstill 30 ~ 50min volatilizes, the absorption time is 40 ~ 60s, and volatilization gas information is detected by the gas sensor array in Electronic Nose device;

(3) first sensor and sulfide sensor TGS-825 in gas sensor array is collected, second sensor and hydrogen gas sensor TGS-821, 3rd sensor and ammonia gas sensor TGS-826, four-sensor and alcohol, toluene, the sensor TGS-822 such as dimethylbenzene, 5th sensor and hydrocarbon component gas sensor TGS-842, 6th sensor namely for methane, propane, butane sensor TGS-813, 7th sensor and propane, butane sensor TGS-2610, the data that 8th sensor and NOx sensor TGS-2210 gather.Sensor array output signal is as shown in table 1 with the relation table of acquisition time.

Table 1

The initial value (Vs) of Electronic Nose response data is extracted, stationary value (Ve), rise time (Ti), climbing speed from the data obtained 4 primitive character values, are input to the dsp chip of solidification in electric nasus system, linear random resonance program, calculate the signal to noise ratio (S/N ratio) eigenwert Eig exporting crab sample _sNR=-5.99909

The signal to noise ratio (S/N ratio) eigenwert of each freshness crab sample obtained according to step (3) obtains crab freshness forecast model through matching:

$Tq=\frac{{\mathrm{Eig}}_{SNR}+65.7548}{2.6142}$

By Eig _sNR=-5.99909 substitute into formula, and calculating crab freshness parameter value is Tq=1.05.

(5) T1=7; Because Tq<7, therefore tested crab sample freshness is fresh, not yet reaches shelf life terminal.

Detect the crab sample of reserve temperature 20 DEG C, repeat above-mentioned steps (1) ~ (5), obtain Tq=10.26, because Tq>7, therefore tested crab sample freshness is non-fresh, has reached shelf life terminal.

Claims (6)

1. utilize a method for detection by electronic nose crab freshness, it is characterized in that, concrete steps are as follows:

(1) crab sample to be measured is put into sampling receptacle, sealing, left at room temperature 30 ~ 50min;

(2) the gas probe head of Electronic Nose good for filtering is inserted sampling receptacle, setup times is 40 ~ 60s, allow collection of head space gas;

(3) gas enters the detected analysis of gas sensor array;

(4) collect also stored-gas related data, utilize data handling system to carry out Treatment Analysis to the data of collecting; Detailed process is as follows:

1. extract the response characteristic value of gas sensor array, response characteristic value comprises initial value Vs, stationary value Ve, rise time Ti, climbing speed

2. solidify non-linear stochastic resonance algorithm in the digital signal processor that Electronic Nose is built-in, Electronic Nose is responded primitive character value input DSP to calculate output signal-to-noise ratio spectroscopic eigenvalue Eig _sNR; Computing method are as follows:

System input signal is $I\left(t\right)=\frac{Ve-Vs}{Ti}+Vs;$ System features is expressed as:

Wherein a and b is the parameter of potential function, and x is the position of Brownian movement particle, and ξ (t) is white Gaussian noise, and its autocorrelation function E [ξ (t) ξ (0)]=2D ξ (t), A are input signal strengths, f ₀be frequency modulating signal, D is noise intensity it is a real parameter;

Signal to noise ratio (S/N ratio) characterizes the conventional parameter of accidental resonance characteristic, by signal to noise spectrum eigenwert Eig _sNRbe defined as:

${\mathrm{Eig}}_{SNR}=2\&lsqb;\underset{\mathrm{\&Delta;}\mathrm{\&omega;}\&RightArrow;0}{\lim }\underset{\mathrm{\&Omega;}-\mathrm{\&Delta;}\mathrm{\&omega;}}{\overset{\mathrm{\&Omega;}+\mathrm{\&Delta;}\mathrm{\&omega;}}{\&Integral;}}S\left(\mathrm{\&omega;}\right)d\mathrm{\&omega;}\&rsqb;/S_N\left(\mathrm{\&Omega;}\right)$

Wherein S (ω) representation signal power spectrum density, S _n(Ω) be the intensity of noise in signal frequency region, ω is the frequency that power spectrum spike is corresponding, and Ω is the frequency that accidental resonance noise is corresponding;

3. Electronic Nose experiment is used to detect the signal to noise spectrum eigenwert Eig of the crab sample of the different freshness of many groups _sNR, the signal to noise ratio (S/N ratio) eigenwert matching according to crab sample obtains crab freshness forecast model: Tq=f (Eig _sNR), wherein Tq is crab grade of freshness;

If 4. crab grade of freshness Tq≤Tl, Tl are shelf life terminal critical value, be then fresh; If crab grade of freshness Tq>Tl, then crab sample has reached shelf life terminal.

2. the method utilizing detection by electronic nose crab freshness according to claim 1, it is characterized in that: in step (3), described sensor array is classified as 8 kinds of sensitive gas sensor arrays, is made up of TGS-825, TGS-821, TGS-826, TGS-822, TGS-842, TGS-813, TGS-2610 and TGS-2201; Described sensitive gas sensor array is for realizing the identification to sulfide, hydrogen, ammonia, toluene, dimethylbenzene, hydrocarbon gas, methane, propane, propane, butane, oxynitrides.

3. the method utilizing detection by electronic nose crab freshness according to claim 1, is characterized in that: in step (3), is 1000 ~ 1200ml/min by the gas flow of Electronic Nose air chamber.

4. the method utilizing detection by electronic nose crab freshness according to claim 1, is characterized in that: in step (4), and the measuring process of described shelf life terminal critical value Tl is as follows:

A. according to SC/T3032-2007, the total volatile basic nitrogen change of crab in continuous 8 days is detected;

B. according to GB2733-2005, the time diacritical point of crab corruption is determined, i.e. shelf life terminal S1;

C. verify the accuracy of the shelf life model set up according to the testing result of TVB-N method, and obtain shelf life terminal critical value Tl.

5. the method utilizing detection by electronic nose crab freshness according to claim 1, is characterized in that: in step (4), and described crab freshness forecast model is:

$Tq=\frac{{\mathrm{Eig}}_{SNR}+65.7548}{2.6142},$

Wherein: Tq is crab grade of freshness, Eig _sNRfor signal to noise spectrum eigenwert.

6., according to the method utilizing detection by electronic nose crab freshness one of claim 1-5 Suo Shu, it is characterized in that, its method adopt detection system mainly comprise data acquisition, sensor array, air chamber, air chamber scavenging pump, gas samping pump; Described data acquisition unit core devices adopts embedded microcontroller, realizes sensor array signal collection, transmission and pump valve thereof and opens controlling functions; When detection system is tested, the pure air that air cleaner produces by air chamber scavenging pump sends into air chamber, calibrating sensors; Afterwards under the drive of gas samping pump, enter air chamber with the gas that sample in sample introduction needle aspirate container volatilizes, produce response signal with after sensor contacts, discharge finally by gas outlet.Sensor response signal through data acquisition by portable computer record, preservation processing, the grade of freshness of final this sample of display.