Based on differences in near infrared spectroscopy of lettuce leaf in different storage time, the non-destructive identification method of lettuce storage time was researched. Because there are various noises in lettuce leaf spectroscopy coming from external environmental factors, chemical composition and photoelectric detection circuit, several pretreatment methods, such as smoothing, MSC (Multiplication scatter correction ), SNV (Standard Normalized Variable), BC (Baseline Correction), VN (Vector Normalize), FD (First Derivative) and SD (Second Derivative) were studied and used to pre-treat lettuce leaf spectroscopy respectively. PCA (Principal Component Analysis) method was used to reduce dimension and extract feature of spectroscopy pretreated. Finally, the identification model was built based on SVM(Support Vector Machine).Test results showed that, the model based on lettuce leaf spectroscopy pretreated by SD is best because its lettuce storage time accuracy was 100%,which was better than those of other models. The result also showed that, the spectrum noise factors affected the modeling accuracy, so it is important to select an appropriate pretreatment method, and SD+PCA+SVM is an effective identification model of lettuce storage time based on Near Infrared Spectroscopy.
Near Infrared Spectrum, Lettuce, Storage Time
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