Determination of aflatoxin level in peanut paste using Fourier transform mid-infrared spectroscopy with attenuated total reflection

摘要

A detection and quantification method for the aflatoxin content in peanuts by rapid and non-destructiveassessment of Fourier Transform Infrared Spectroscopy (FTIR) equipped with Attenuated Total Reflectance cell(ATR) was developed. Aflatoxins are fungal bio-agents that merit attention on account of being highly toxic andcarcinogenic to humans and great treat to vulnerable agricultural commodities such as peanuts. Thus, a deductionmethod to evaluate peanuts for aflatoxin contamination is necessary. FTIR-ATR spectral data of peanut pastesamples contaminated at varying levels of aflatoxin were preprocessed (mean-centering, smoothing the 1stderivative), and normalized with logarithmic method and used for the partial least square (PLS) regressionanalysis for training/prediction sample sets created by spiking known amount of aflatoxins with clean peanutpaste. After data manipulation, PLS approaches were tested for the full and reduced spectra by using “leave oneout” cross-validation method. Major peaks representing the structural vibrations of peanut were selected andresults were ranked to determine spectral features describing the minor contributions of aflatoxin molecules inbulk peanut paste medium. The highest correlation coefficient of determination (R_C~2) and the lowest root meansquarederror of calibration (RMSEC) and cross validation (RMSECV) were determined as 99.42%, 4.90 ppband 22.45 ppb, respectively. Analyzing the data in the spectral regions 1584-1484 and 1424-1127 cm~(-1) hasimproved the prediction error (RMSEP = 12.84 ppb), but on the cost of lower R_C~2 (97.01%). For moderateresults, selected spectral regions (3028-2752, 1800-1707, 1584-1424, and 1408-1127 cm~(-1)) were considered andcorresponding vibration modes and intensities were labeled.