Study On The Processing Characteristics Of Lingkou Dried Radish Using A Handheld Near-Infrared Spectrometer

Dried radish is a traditional and well-known food in China,and is deeply loved by people.Recently,its processing characteristics mainly relie on the sensory perception of the workers.However,this quality detection method based on subjective perception is no longer suitable for the development of science and technology.The reason is that perception is easily influenced by human subjective factors and the results are not stable.Moreover,the rapid development of food automated processing and production technology requires the real time monitoring of processing characteristics parameters and regulation of production conditions in order to achieve efficient production.Therefore,dried radish production enterprises need objective detection methods based on equipment.In this paper,the dry processing characteristics of radish were studied by means of a hand-held near infrared spectrometer combined with chemometris.The main work and conclusions are as follows:（1）Study on the method of identifying the sundried grade of pickled radish using NIR spectroscopy.The diffuse reflectance spectra of dried radish during pickling and dehydration were collected using a handheld near-infrared spectrometer Micro NIR 1700.By comparison,the best spectral pretreatment method was obtained from 10 methods,including 1st derivative（1st der）,Standard normal variable（SNV）,and Multivariate scattering correction（MSC）.After Principal Component Analysis（PCA）was applied,Soft Independent Modeling of Class Analogy（SIMCA）and Linear Discriminant Analysis（LDA）were used to establish the identification modes.The results showed that the LDA model was the best,with a prediction accuracy of 96.25%at 5 principal components（PC）.（2）Identification of the deterioration time of dried radish by the handheld NIR spectroscopy technology.Collected the diffuse reflectance spectra of dried radishes,which were stored for different days,and then obtained the optimized spectral pretreatment method,first derivative.Then PCA and LDA models were applied.The results showed that PCA cannot accurately distinguish the deterioration days of dried radish.The 3D scatter plots of the first three PCs can show the differences before and after 3 days of deterioration.The LDA method can distinguish the deterioration days of the dried radish before and after 3 days,with a high accuracy of 100%,and an accuracy of over 98%before and after 6 days.Moreover,the model has been validated with the test set（unknown samples）and has high accuracy,which indicated that the LDA model had a good application ability.（3）A rapid detection method for the tenderness of dried radish was established by NIR spectroscopy.A handheld near-infrared spectrometer was used to collect the diffuse reflectance spectra of dried radish during dehydration,and the shear force was used as the quantitative indicator of tenderness.Obtained the best method combination"1st der+SNV"from multiple spectral pretreatment methods.A Partial Least Squares Regression（PLS）model was built,and the results were as follows:the root mean square errors of the calibration set,cross validation set,and validation set were 4.274N,4.931N,and 5.044N,respectively,and the corresponding determination coefficients R_C²,R_CV²,and R_P² were 0.881,0.845,and 0.823,respectively To further improve the prediction accuracy,two algorithms,Competitive Adaptive Weighted Sampling（CARS）and Continuous Projections Algorithm（SPA）,were used to extract feature wavelengths,which were used for PLS modeling.The results showed that the CARS algorithm had the best performance,the root mean square errors of the calibration set,cross validation set,and validation set were 4.043 N,4.679 N,and 4.73 N,respectively,and the corresponding determination coefficients R_C²,R_CV²,and R_P²were 0.894,0.865,and 0.850,respectively.In summary,it is feasible that the sundried grade,deterioration process,and tenderness of dried radish can be fast determined by the handheld NIR spectroscopy technology.The research results provide new ideas for the monitoring technology for the processing characteristics of dried radish,which is beneficial for the technology innovation and transformation and upgrading of traditional industries.