Introduction
Detecting visible defects on peaches is crucial for maintaining fruit quality, reducing economic losses, and ensuring food safety. Various advanced imaging and sensing technologies have been explored to address the challenges posed by the high variability in peach skin color and the similarity between defects and other features like stems.
Key Insights
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Hyperspectral Imaging and Multispectral Analysis:
- Hyperspectral imaging combined with multivariate analysis and band math can effectively detect both artificial and non-artificial defects on peaches, achieving an overall classification accuracy of 93.3%.
- Multispectral detection using visible-near infrared (vis-NIR) hyperspectral imaging, coupled with principal component analysis (PCA) and a band ratio algorithm, can differentiate defects from normal surfaces with an accuracy of 96.6%.
- Short-wave near infrared (SW-NIR) hyperspectral imaging, combined with an improved watershed segmentation algorithm, is effective for detecting early bruises on peaches, with detection accuracies of 96.5% for bruised and 97.5% for sound peaches.
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Artificial Neural Networks (ANN) and Machine Learning:
- Hyperspectral reflectance imaging combined with an artificial neural network (ANN) model can detect cold injury in peaches with an accuracy of 95.8%.
- Structured-illumination reflectance imaging (SIRI) coupled with convolutional neural networks (CNN) can detect early fungal infections in peaches with a detection rate of 98.6%.
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Optical and Reflectance Techniques:
- Spatially-resolved diffuse reflectance techniques can assess the optical properties of peaches and correlate them with tissue structural and biochemical properties, aiding in early disease detection.
- Laser Doppler detection can remotely sense changes in fruit texture and detect internal disorders, offering a non-destructive method for evaluating fruit firmness and maturation.
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Electronic Nose (E-nose) Technology:
- E-nose technology, based on volatile organic compounds (VOCs), can non-destructively predict compression damage levels in yellow peaches, with a correct identification rate of 93.33%.
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Rotating Hyperspectral Imaging:
- A rotating hyperspectral imaging system can detect decay caused by Rhizopus stolonifera in peaches, achieving 100% classification accuracy for sound and rotten peaches.
Conclusion
The best methods for detecting visible defects on peaches involve advanced imaging technologies such as hyperspectral and multispectral imaging, combined with machine learning algorithms like ANN and CNN. These methods provide high accuracy in identifying various types of defects, including bruises, cold injuries, and fungal infections. Additionally, optical techniques and e-nose technology offer promising non-destructive alternatives for assessing fruit quality and detecting internal disorders.