Detection of Melamine in Soybean Meal Using Near-Infrared Microscopy Imaging with Pure Component Spectra as the Evaluation Criteria

Abstract

Soybean meal was adulterated with melamine with the purpose of boosting the protein content for unlawful interests. In recent years, the near-infrared (NIR) spectroscopy technique has been widely used for guaranteeing food and feed security for its fast, nondestructive, and pollution-free characteristics. However, there are problems with using near-infrared (NIR) spectroscopy for detecting samples with low contaminant concentration because of instrument noise and sampling issues. In addition, methods based on NIR are indirect and depend on calibration models. NIR microscopy imaging offers the opportunity to investigate the chemical species present in food and feed at the microscale level (the minimum spot size is a few micrometers), thus avoiding the problem of the spectral features of contaminants being diluted by scanning. The aim of this work was to investigate the feasibility of using NIR microscopy imaging to identify melamine particles in soybean meal using only the pure component spectrum. The results presented indicate that using the classical least squares (CLS) algorithm with the nonnegative least squares (NNLS) algorithm, without needing first to develop a calibration model, could identify soybean meal that is both uncontaminated and contaminated with melamine particles at as low a level as 50 mg kg−1.

Fourier Transform Infrared and Raman and Hyperspectral Imaging Techniques for Quality Determinations of Powdery Foods: A Review

“…FT‐IR HSI can be used to investigate the additives present in food at the microscale level of a few micrometers. Based on FT‐IR HSI, the melamine concentrations of 50 and 25 mg/kg, respectively, were visually determined in soybean flour by CLS and PLSDA (Yang and others ; Li and others ). Although PLSDA needs a prior step to develop a calibration model, the higher detection precision (25 mg/kg) of melamine indicates that the performance of PLSDA is analogous to CLS (Amigo and others ).…”

Detection and Removal of Aristolochic Acid in Natural Plants, Pharmaceuticals, and Environmental and Biological Samples: A Review

“…Near-infrared spectroscopy is an efficient, nondestructive, and nonpolluting detection method. Based on the vibration absorption of molecular groups in the sample [ 75 ], an unknown sample is compared with an established calibration model for qualitative and quantitative analysis. This method requires a small amount of sample and produces no secondary pollutants.…”

La spectrométrie dans le proche infrarouge pour la caractérisation des ressources alimentaires

“…En alimentation animale l'imagerie (en microscopie) a par exemple été proposée pour prédire la composition en ingrédients d'aliments complets, et y détecter la présence de farines animales (Piraux et Dardenne, 2000 ;Fernández Pierna et al, 2006). Une application a été également proposée pour détecter par discrimination spectrale des particules de mélamine dans des échantillons de soja, permettant une quantification à de très faibles teneurs (Yang et al, 2016). L'imagerie hyperspectrale permet également de classifier des échantillons de végétaux (prairie) selon l'origine botanique des plantes qui la composent (Dale et al, 2013).…”