Ensemble Learning Combined with Laser-Induced Breakdown Spectroscopy for Detecting Pesticide Residues in Xinhui Dried Tangerine Peel

In recent years, pesticides have been widely applied in the commercial cultivation of traditional Chinese medicinal plants to increase the yield of medicinal materials. Xinhui dried tangerine peel (Citri Reticulatae Pericarpium), a common ingredient in traditional Chinese medicine, utilizes the citrus peel as its medicinal part. During cultivation, the peel is directly exposed to pesticides, making it susceptible to pesticide residue accumulation. To enable the rapid identification of pesticide types and their targeted removal, this study integrated laser-induced breakdown spectroscopy with ensemble learning algorithms. Three lightweight neural network models—1D-CNN, Res-CNN, and LIBS-UNet—were developed and trained using either a single loss function or a composite loss function. The 1D-CNN, Res-CNN, and LIBS-UNet models achieved accuracies of 97.50% and 98.69%, 95.00% and 95.73%, and 74.06% and 76.88% for the single loss and composite loss functions, respectively. During the model ensemble stage, individual models were weighted according to their classification accuracy and test similarity matrices. Through this approach, the pesticide identification accuracy reached 99.99%. This study demonstrates that ensemble learning can effectively integrate the strengths of multiple weak classifiers, thereby significantly enhancing classification performance and providing a novel approach for the rapid detection of pesticide residues in traditional Chinese medicine ingredients.