Detection of adulterated sugar with plastic packaging based on spatially offset Raman imaging

Authors: LIU, ZHENFANG - Jiangnan University; HUANG, MIN - Jiangnan University; ZHU, QIBING - Jiangnan University; Qin, Jianwei - Tony Qin; Kim, Moon

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2021
Publication Date: 5/8/2021
Citation: Liu, Z., Huang, M., Zhu, Q., Qin, J., Kim, M.S. 2021. Detection of adulterated sugar with plastic packaging based on spatially offset Raman imaging. Journal of the Science of Food and Agriculture. 101:6281-6288. https://doi.org/10.1002/jsfa.11297.
DOI: https://doi.org/10.1002/jsfa.11297

Interpretive Summary: Safety and quality inspection of packaged foods and ingredients is important and challenging for both food industry and regulatory agencies. Nondestructive detection of food adulterants through packaging using optical sensing techniques is difficult due to complex interactions between light and the packaging materials. This study presented a novel method using laser-based spatially offset Raman imaging technique for detection of adulterated sugar in plastic packaging. Raman image and spectral data were collected from adulterated sugar samples that were made by mixing soft sugar and cheap glucose as an adulterant in different ratios. A mathematic prediction model was developed and was successfully used to evaluate the adulteration ratios for the mixed sugar samples with the packaging. The results proved that the proposed method can be used for through-packaging inspection of the foods and ingredients for safety and quality applications. The technique would benefit food industry in ensuring the safety and quality of the packaged food products and also regulatory agencies, such as FDA, with an interest in enforcing standards of food safety and quality for the packaged foods and ingredients.

Technical Abstract: BACKGROUND: The application of optical sensing technology in food adulteration detection has been extensively studied. However, due to the impact of packaging materials on the penetration depth of photons in foods and the interference from the optical properties of the packaging materials themselves, the use of optical sensing technology to detect packaged foods adulteration is still a well-known problem. RESULTS: The line-scan Raman imaging systemwas used to collect Raman hyperspectral images of adulterated sugars,made bymixing soft sugar and cheap glucose in seven different ratios. With the 0 and 3 mm (optimal offset distance) between line-laser source and scanning line, the Raman hyperspectral images of adulterated sugars covered by packaging plastic were acquired respectively. Using adulterated samples un-covered by packaging plastic as training samples, the Random Forest prediction model was developed, and excellent prediction performancewas achieved for adulterated samples un-covered by packaging plastics. Comparedwith Ramandata acquiredwith0 mmoffsetdistance, the performance of the prediction model was significantly improved,with 0.957 for coefficient of determination (R2), 0.413 for rootmean square error of prediction (RMSEP), and 4.846 for residual predictive deviation (RPD), for adulterated samples with plastic packaging acquired with the 3 mm offset distance. CONCLUSIONS: The novel non-destructive method based on spatially offset Raman imaging technology, which can reduce the interference of packaging materials and enhance the signal of internal interesting materials, was proposed for detection of adulterated sugar with plastic packaging. The experiment results show that spatially offset imaging technology provides a candidate method for detecting adulteration of packaged foods. © 2021 Society of Chemical Industry