Study On Baijiu Discrimination System Based On Micro-nanomaterial Optics Response Of Cross-reaction Sensor Array

Baijiu,one of the oldest distillates in the world,has a history of more than 2 thousand years.It enjoys an enduring popularity in China,and possesses an irreplaceable position in Chinese culture.The main components of Chinese Baijiu are water and alcohol,totally about 98%.Other components are responsible for the special and attractive taste.Today more than 1874 compounds have been reported,such as alcohol,aldehydes,ketones,acids,esters,nitrogen-containing compounds,and sulfur-containing compounds.Sensory evaluation is the most common method to identify Baijiu.However,few inevitable blemishes greatly hinder their practicability.Sensory evaluation mainly depends on professional tasters,who may be subjective or even biased.The shortcomings of sophisticated instruments can be summarized as follows,time-consuming procedures,requirement for professional operation,complicated pretreatment and high cost.Furthermore,the physical and chemical analyses of sophisticated instruments only measure chemical components of Baijiu,but neglect the flavors which are an ensemble of multiple ingredients.With the inspiration of the non-specific interactions in olfactory systems and mammalian gustatory,sensor array was built.Unique fingerprints for characterization of complex analytes can be provided by such a cross-reactive colorimetric sensor array in either the liquid or the gas phase.In every colorimetric sensor array,the active center with chromophore must interact strongly with desired analytes via not only Van Der Waals and physical adsorption,but also involve stronger intermolecular interactions.Therefore,the sensitivity and specific of the array discrimination was comparatively high.So far,colorimetric arrays have been proven as a facile,efficient and rapid way for comprehensive identification of complex mixtures based on colorimetric changes quantified by digital imaging.And principal component analysis(PCA),linear discriminant analysis(LDA),hierarchical cluster analysis(HCA)and radial basis function neural network(RBFN)were employed for the deep analysis of complex mixtures.In our study,the method of sensor array was used to discriminate Baijiu,the main contents are as follow:(1)Based on the broad-spectrum properties of organic dyes and detection sensitivity of nanomaterial,a 3×3 colorimetric sensor assay consisted of 6 nanophase materials and3 organic dyes was built to discriminate commercial Baijiu.?RGB was captured from digital subtraction,pixel by pixel,of the image of the‘initial'and‘final'images.The results of PCA and LDA showed 8 types of samples were distinguished significantly.According to HCA,five parallel experimental samples clustered together without mis-classification,which shows the discrimination ability of this array.RBFN was employed to determine the fitting relationship between the predicted sample and the actual sample.The predicted results are basically in accord with the real ones,suggesting a promising potential for application in baijiu determination.Accidentally,baijiu samples are grouped along 2 different series,which are accord with actual alcoholic-5,in both PCA and LDA.RBFN gave the same guidance,indictating the sensor array can distinguish the liquor with different alcohol content.(2)The previous stuy has showed the sensitivity of array was improved by introducing nanomaterial as detection probe.Herein,the Au NPs as the sources of color signal synthesized by a simple,one-pot and green way.4 ions(Mg²⁺,Pb²⁺,Fe²⁺,Fe³⁺)with 2 concentrations are used to construct sensor array for the detection of 16 kinds Baijius.With the addition of Baijiu samples,the color of Au NPs changed on certain degree.Reasons for Au NPs aggregated with color change can be summarized into the following 3 categories.1)The colloidal system of Au NPs was destroyed by huge change in electric charge.2)The abundant sulfhydryl-containing substances in Baijiu shorten the distance between nanoparticles.3)As a catalyst,Au NPs changes the composition of Baijiu.The final different degrees aggregation of Au NPs reacted with Baijiu is described by RGB.Furthermore the pattern recognition and radial basis function neural network were conduected to evaluate the performance of array.In PCA,the first nine principal components accounted for 99%of total information,indictating that the array is effective for Baijiu discrimination.In HCA,the same samples were clusted into one group with classification accuracy of 97.5%.In order to increase analysis accuracy,we built the discrimination function by LDA to achive the idenfication of 16 kinds of Baijiu with accucy rate of 100%.Furthermore,the RBFN results showed the predicted results are basically in accord with the real ones,and the average relative error in our experiment is0.14.The results indicate that the the colormetric sensor array showed good performance in Baijiu determination.(3)The colormetric sensor array was constructed based on silver mirror action to detect different Baijiu.The Aldehydes widely existed in Baijiu,such as acetaldehyde,acetal and furfural.During the process of siliver mirror reaction,the Ag+in Tollens'reagent was reduced by aldehyde group and generate Ag absorpting on the Au NPs and Ag NPs surface,leading to the color chage of reaction system.Firstly,Four kinds of Au NPs(4 nm,13 nm)and Ag NPs(6 nm,13 nm)were synthesized by citrate reduction method,respectively.TEM,UV-Vis and Zeta potential were conducted to characterize the synthesized material.Under the optimized detection conditions,10 aldehydes were distinguished by Tollen's reagent based colorimetric sensor array,indicating that the array has potential to detect Baijiu.The Euclidean distance of the array?RGB have a good response relationship with the formaldehyde concentration in the range of 0.05-50000?m(R²=0.9864),and the lowest detection limit is 0.04?m,which shows that the sensor array has a quantitative detection ability for formaldehyde concentration.Based on previous experiment,the array was used to determine 16 kinds of Baijius.The results showed a great identification and classification ability of array toward Bajiu with classification accuracy of 100%.This method provides a good way for the detection of aldehydes and the identification of Baijiu types.(4)In this chapter,based on the theory of oxidant accelerated etching reaction,a sensor array was constructed for the detection of different brands of Baijiu.Hydrogen peroxide,molybdenum disulfide quantum dots and manganese dioxide nanoflakes as the axidant were used to accelerate the the etch of silver nano prism and gold nano shuttle.The trace component in Baijiu can react with oxidant and nanomaterial and influence the etching reaction.In the optimal reaction system,30 reducing substances were succeefully determined through PCA,HCA and LDA.This results show that this sensor array owns the potential for Baijiu discrimination.Moreover,the array has a good response relationship with the ethyl acetate concentration in the range of 100-1750?m(R²=0.9962).On the basis of single analyte detection,the array was used to distinguish 16different brands of Baijiu.The results show that the array can distinguish 16 kinds of liquor,with the classification accuracy of 100%.(5)On the basis of visible light detection,the quantum dots(QDs)array was constructed to identify Baijiu.QDs,as a novel detection material,possess the ability to cross-react with alcohol,aldehydes,ketones,acids,esters,nitrogen compounds and sulfur compounds abundant in Baijiu exhibiting a modulation,i.e.,either fluorescence quenching or fluorescence enhancement.Owing to this sensitive mechanism,only 3 array points could achieve clear classification of 22 Baijius which is impressive.Pattern recognition and neural network were used to analyse the the data obtained from the reaction between QDs and Baijiu.in pattern recognition,LDA was performed to built discrimination function to identify different Baijiu.The accuracy reached 100%.The RBFN results showed the predicted results are basically in accord with the real ones,indicating the colormetric sensor is able to distinguish different Baijius.(6)In the previous study,we successfully employed liquid array to achive the determination of Baijiu.But the storage time of liquid array is short and must be prepared immediately before Baijiu detection.Herein,we reported an amplifying fluorescence sensor array chip,which employed fluorescence enhancement property of photonic crystals(PCs)in distilled liquor identify for the first time.Firstly,transmission electron microscope were employed to characterize polystyrene microspheres and PCs,which exhibits characteristic of uniform and compact arrangement.Spotting machine and the fluorescence scanner were used for dye loading and data collection.The array performance was evaluated by pattern recognition and neural network simulation.All evidence proved our array chip,was successfully manufactured with outstanding discrimination ability for diffrent Baijius and the HCA classification accuracy was 100%.Furthermore,comparing with liquid sensor array,our array chip possesses above 90%“Leave One Out”(LOO)accuracy after 10 days of dry storage under N₂,showing potential for quality control and detection in practical production.