Evaluation For Fresh Juice Of Strawberries By Electronic Nose And Electronic Tongue

An electronic nose (e-nose) and an electronic tongue (e-tongue) were employed to detect the fresh juice of strawberries at different degrees of ripeness, fresh juice of strawberries stored for different time, fresh juice of strawberries with different pre-treatment, and fresh strawberries juice before and after sterilization stored for different time at room temperature. The qualitative and quantitative analysises of fresh strawberry juice were completed, which provide a theoretical basis for the quality evaluation and grading of fresh fruit juice.Test result of fresh juice of strawberries at different degrees of ripeness:the fresh juice of strawberries at different degrees of ripeness could be discriminated by PCA and LDA well, and e-nose was proved to be superior to e-nose to classify the samples and as well as the combination of e-nose and e-tongue. It was found that response signals of e-tongue coupled with PLS provided a good predication of soluble solids content, Vc content and pH value, but excluding total acid content. The combination of e-nose and e-tongue coupled with PLS had also been indicated to be an efficient method to predict soluble solids content, Vc content, total acid content and pH valueTest results of fresh juice of strawberries stored for different time:the different response feature value had a significant effect on the results of PCA and LDA, and the discrimination effect could be best with the mean value of first30s as feature value by electronic nose. BP neural network has a good recognition result. PLS was proved to be more capable of building models with good prediction than diverse line regression. Electronic nose signals show weak correlation with TSS, Vc and pH, but a certain correlation with TA. Electronic tongue signals and the combination of electronic nose and electronic tongue signals show the good predictive validity on TSS, TA, Vc and pH, and the combination of electronic nose and electronic tongue signals have better predictive validity than electronic tongue signals for TSS, TA and Vc, but weaker for pH.Test result of fresh juice of strawberries with different pre-treatment:the samples pretreated by microwave and steam blanching and and the samples pretreated by hot water blanching could have a good keep for aromatic characteristics and taste characteristics of original sample, respectively. It was found that the results of PCA changed slightly and that of LDA got optimized by rejecting the sensors with the worst response, electronic nose signals show weak correlation with Vc, TA and pH, but good with TSS; electronic tongue signals have good correlation with TSS, Vc and pH, but weak with TA; the combination of electronic nose and electronic tongue signals show good predictive validity on TA.Test result of fresh strawberries juice before and after sterilization stored for different times at room temperature:the results of PCA and LDA changed slightly by rejecting the sensors with the worst response. Quality of the samples began to change after9h stored before sterilization and6h stored after sterilization. TSS and pH of the samples couldn’t be predicted well by e-nose and e-tongue. However, TSS, TA and pH could be predicted well by the combination of e-nose and e-tongue, better than e-nose and e-tongue.