Classification of Pomelo Maturity Using Low-Cost Peel Feature Analysis and Machine Learning Algorithms
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Abstract
The lack of accurate pre-harvest maturity assessment tools is a critical challenge for pomelo production. Since pomelo is a non-climacteric fruit, its internal quality becomes fixed immediately upon harvest. Consequently, inaccuracies in harvest timing decisions directly result in economic losses. This study presents a cost-effective machine learning framework for maturity classification (early-mature vs. mature) of Khao Nampueng pomelos. A balanced dataset of 1,008 images from 70 pomelos was obtained using a Raspberry Pi camera at two critical times: 180 and 210 Days After Fruit Set (DAFS). To capture the non-linear relationships between peel appearance and maturity, color and texture features were analyzed using the Permutation Feature Importance method integrated with a Support Vector Machine (SVM) utilizing a Radial Basis Function (RBF) kernel. The proposed method yielded an optimized subset of biologically relevant features. The SVM-RBF model trained on this subset achieved robust classification performance, with a test accuracy of 95.6%. Interpretability analyses confirmed that the model’s decision boundary aligned with physiological and biological changes, identifying variation in the chromatic component (b* channel) and micro-texture (LBP) as the most significant predictors. This study demonstrates that cost-effective peel feature analysis driven by machine learning algorithms provides a high-precision tool for optimizing pomelo harvest timing.
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