Feasibility of Surface-Enhanced Raman Spectroscopy for Rapid Detection of Aflatoxins in Maize

Abstract

Rapid and sensitive surface-enhanced Raman spectroscopy (SERS) for aflatoxin detection was employed for development of the models to classify and quantify aflatoxin levels in maize at concentrations of 0 to 1,206 μg/kg. Highly effective SERS substrate (Ag nanosphere) was prepared and mixed with a sample extract for SERS measurement. Strong Raman bands associated with aflatoxins and changes in maize kernels induced by aflatoxin contamination were observed in different SERS spectroscopic regions. The k-nearest neighbors (KNN) classification model yielded high classification accuracy and lower prediction error with no misclassification of contaminated samples as aflatoxin negative. The multiple linear regression (MLR) models showed a higher predictive accuracy with stronger correlation coefficients (r = 0.939-0.967) and a higher sensitivity with lower limits of detection (13-36 μg/kg) and quantitation (44-121 μg/kg) over other quantification models. Paired sample t test exhibited no statistically significant difference between the reference values and the predicted values of SERS in most chemometric models. The proposed SERS method would be a more effective and efficient analytical tool with a higher accuracy and lower constraints for aflatoxin analysis in maize compared to other existing spectroscopic methods and conventional Raman spectroscopy.

Recent developments in quantitative SERS: Moving towards absolute quantification

“…With respect to other food safety concerns, several potentially carcinogenic substances that may be present in food have also been targeted for quantitation with SERS and these include aflatoxins in maize [34], Sudan I spiked in chili powder [35] and Rhodamine B in chili oil [36]. Finally, although not hazardous to health the boar-taint compounds skatole and androstenone, which alter the flavor of meat, have also been recently detected and quantified in pork fat using SERS [37].…”

Trace analysis of organic compounds in foods with surface‐enhanced Raman spectroscopy: Methodology, progress, and challenges

“…SERS has been applied to analyze trace chemicals in various foods, mainly hazardous compounds that may pose health risks. These typically include residual pesticides, herbicides, or insecticides in plant source foods (Fan et al., , ; Kang, Wu, Chen, Li, & Du, ; Liou, Nayigiziki, Kong, Mustapha, & Lin, ; Sun, Yu, & Lin, ; Zhao, Huang, Fan, & Lai, ), banned and restricted drugs (such as growth hormones and antibiotics) in muscle foods such as fish and chicken (Li et al., ; Xu et al., ), naturally occurred toxicants such as aflatoxins in grains (Lee, Herrman, Bisrat, & Murray, ) and histamine in fish (Janči et al., ), as well as prohibited or restricted additives such as melamine in processed foods (Lin et al., ; Zhao et al., ), formaldehyde in shrimp and squid (Zhang, Zhao, Ma, & Li, ), Sudan dyes in chili flakes (Ou et al., ), Sunset Yellow and Allura Red in beverages (Ou et al., ), and tert‐butylhydroquinone (TBHQ) in vegetable oils (Pan et al., ).…”

Current methods for mycotoxins analysis and innovative strategies for their reduction in cereals: an overview

“…These techniques include near‐infrared reflectance (NIR), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, which can provide qualitative and quantitative information about the structure of mycotoxins . Some examples of Raman spectroscopy application have been reported for qualitative and quantitative analysis of aflatoxins in ground maize …”