Study On Detection Method And Portable Device For Testing The Internal Quality Of Cherry Tomato By Near Infrared Spectroscopy

Cherry tomato is very popular among the customers due to its beautiful color,rounded shape,delicious taste and overwhelming nutritious value.Under the circumstances of expanding market demand,cherry tomato industry is developing rapidly.However,there is considerable room for improvement in monitoring and post-processing of fruit production.At the same time,with the improvement of people's living level,the higher requirements of the fruit's quality are in great demand.It is of greate significance to design a rapid and non-destructive method for testing the internal quality of cherry tomato and to develop a portable testing device for improving the commercialization level and promoting intelligent development of cherry tomato industry.In this study,near infrared spectroscopy(NIRS)coupled with chemometrics was used to build quantitative detection model for testing the internal quality of cherry tomato with high precision,good stability and strong temperature adaptability.Also,a portable device for testing the internal quality of cherry tomato based on Android system was developed.The main contents and conclusions of this study are as follows:1.A rapid non-destructive method for the determination of soluble solids content(SSC)and lycopene content of cherry tomato based on NIRS was carried out.The diffuse reflectance spectra of cherry tomato samples were collected by NIR spectrometer and the reference analysis of SSC and lycopene content were determined by physicochemical methods.The partial least squares(PLS)model for SSC and lycopene content were established by combining various spectral pretreatment methods and variable selection methods.The results showed that the model established by using Savitzky-Golay smoothing and SPA-PLS was noted best.The correlation coefficient of calibration set(Rc)of SPA-PLS model for SSC was 0.9348,and the root mean square error(RMSEC)was 0.250 °Brix;the correlation coefficient of prediction set(Rp)was 0.9266,and the root mean square error(RMSEP)was 0.265 °Brix.The Rc of SPA-PLS model for lycopene content was 0.8750,and the RMSEC was 6.17 mg/kg;the Rp was 0.8604,and the RMSEP was 6.57 mg/kg.The results showed that it was feasible to detect the internal quality of cherry tomato by NIRS.2.Considering the problem that the sample temperature has an effect on the accuracy of detection model,the temperature correction methods were studied.PLS models were established before and after temperature correction.Then the SSC and lycopene content of the samples at different temperatures were determined by the established model.The results indicated that PLS with external parameters orthogonalisation(EPO)had better prediction ability.The correlation coefficient(R)for SSC was 0.8988,and the root mean square error(RMSE)was 0.292 °Brix;the R for lycopene content was 0.8023,and the RMSE was 7.45 mg/kg,which showed better performance than single temperature PLS model and mixed temperature PLS model.It showed that EPO method had better temperature correction effect.3.A portable non-destructive detection device based on Android system was developed for testing internal quality of cherry tomato.The device included hardware system and software system.The hardware system mainly included miniaturized NIR spectrometer,Android mobile phone,power supply,boost regulator board,device housing etc.The software system included user registration and login,bluetooth communication,positioning,spectral data processing,detection data management,user main interface and other functional modules.Finally,the performance of the device was verified.The SSC and lycopene of 15 other cherry tomatoes under different temperature conditions were monitored by this portable device three times.The mean absolute error(MAE)between predicted values and standard values of SSC was 0.273 °Brix,and the mean relative error(MRE)was 4.04%.The maximum coefficient of variation(CV)of the parallel prediction of SSC was 1.01%.The MAE between predicted values and standard values of lycopene was 6.06 mg/kg,and the MRE was 7.84%.The maximum CV of the parallel prediction of lycopene was 1.83%.Also,the results of paired t-test showed that there was no significant difference between the predicted values and standard values.It showed that the portable detection device had good accuracy,stability and superior performance under different temperature conditions.