A packaged food internal Raman signal separation method based on spatially offset Raman spectroscopy combined with FastICA

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

Submitted to: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2022
Publication Date: 3/15/2022
Citation: Liu, Z., Huang, M., Zhu, Q., Qin, J., Kim, M.S. 2022. A packaged food internal Raman signal separation method based on spatially offset Raman spectroscopy combined with FastICA. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 275:121154. https://doi.org/10.1016/j.saa.2022.121154.
DOI: https://doi.org/10.1016/j.saa.2022.121154

Interpretive Summary: Evaluating safety and quality for packaged foods and ingredients is an important and difficult issue for both the food industry and regulatory agencies. Optical sensing based nondestructive inspection of packaged foods for adulterants is challenging due to the difficulties in obtaining the optical signals of the contents through the packaging materials. This study presented a novel method that can separate spectral signals from food and package using laser-based spatially offset Raman spectroscopy (SORS) coupled with fast independent component analysis (FastICA). Raman image and spectral data were acquired from lab prepared samples and packaged sugar, bagged rice flour, and boxed butter. The results indicated that useful Raman signals can be extracted under different package materials, such as food-grade plastic sheets. The SORS-FastICA method can be used for through-package inspection of the foods and ingredients for safety and quality applications. The technique would benefit the food industry and the regulatory agencies (e.g., FDA and USDA FSIS) in ensuring and enforcing standards of the safety and quality of the packaged food products.

Technical Abstract: Raman spectroscopy attempts to reflect food quality by characterizing molecular vibration and rotation. However, the blocking of optical signals by packaging materials and the interference of the optical signal generated by the packaging itself make the detection of internal food quality without destroying packaging highly difficult. In this regard, this paper proposes a novel packaged food internal signal separation based on spatially offset Raman spectroscopy (SORS) coupled with improved fast independent component analysis (FastICA). Firstly, the Raman scattering image of the packaged food with offset laser incident point was obtained. Then, the movable quadratic mean of information entropy was used to select the observation feature region of the image. Thirdly, the main independents decomposed by the optimized FastICA method were identified by spectral attenuation characteristics of the SORS peak signal. Finally, the non-negativity of the separated signal was ensured by baseline recognition and correction. The effectiveness of this method was verified by refactoring the similarity between the signal and the reference signal by testing three different packaging and four internal materials under standard experimental conditions. The applicability of the method was proved by the internal signal separation of three packaged foods on sale. The experimental results indicate that the proposed method can separate the Raman signal of packaged food and can be used as a pretreatment method and auxiliary analysis means for the detection of packaged food.