A non-destructive detection method for crab roe within live Chinese mitten crabs (Eriocheir sinensis) via near-infrared transmittance spectroscopy

This study pioneers a rapid, non-destructive methodology for detecting crab roe in live Chinese mitten crabs using near-infrared transmittance spectroscopy (NIR-TS), motivated by the high edible and economic value of this component. A customized optical system was used to measure NIR transmission spectra from 62 live crabs, including intact specimens, dissected tissues (roe, shell, and roe-removed), and nine specific body regions, while simultaneously measuring crab central thickness and roe distribution. A classification model was developed based on regional spectra to distinguish roe-containing and roe-free regions, enabling prediction of crab roe distribution within live specimens. A dataset of 558 specta was split into training, validation, and test sets at a ratio of 6:2:2. The results indicated measurable non-zero transmittance in both intact crabs and isolated shells, suggesting the potential ability of short-wave NIR (SW-NIR, 780-1100nm) to penetrate multi-layered tissues. Regional spectral analysis revealed that crab roe was the primary transmission modulator, surpassing thickness effects, with roe-containing regions consistently exhibiting lower transmittance than roe-free. Modeling result showed that after multiplicative scatter correction (MSC) preprocessed for spetra, Backpropagation Neural Network (BPNN) model combining both LASSO-selected feature and 30 spectral statistic features (SFs30) achieved the best performance with 96.2% accuracy. Furthermore, roe distribution prediction showed 94.4% concordance with ground-truth validation. The model's classification capability was attributed to specific NIR wavelengths associated with key biochemical signatures, forming a distinctive fingerprint for crab roe detection. This methodology provides a novel solution for quality grading of crabs, addressing environmentally friendly, and cost-effective requirements for aquatic supply chain. • First application of NIR transmittance spectroscopy to live crab roe detection • The customized NIR system measured the non-zero transmittance of live crabs • Significant transmittance differences: crab roe-containing vs. roe-free regions • BPNN combined “LASSO-SPs30” feature achieves 97.4% roe detection accuracy • The model enables accurate distribution prediction of crab roe in live crabs