Aflatoxin contamination can occur in a wide variety of agricultural products pre- and post-harvest, posing potential severe health hazards to human and livestock. However, current methods for detecting aflatoxins are generally based on wet chemical analyses, which are time-consuming, destructive to test samples and require skilled personnel to perform, making them impossible for large-scale non-destructive screening and on-site detection. In this study, we utilized the visible/near-infrared (Vis/NIR) spectroscopy over the spectral range of 400-2500 nm to detect contamination of shelled commercial peanut kernels with the predominant aflatoxin B1 (AFB1). Our results indicated the usefulness of Vis/NIR spectroscopy combined with the chemometric techniques of partial least squares discriminant analysis (PLS-DA) and least squares support vector machine (LS-SVM) in identifying the AFB1 contamination of peanut kernels. Both PLS-DA and LS-SVM methods provided satisfactory classification results using the full spectral information over the ranges of 410-1070 (I), 1120-2470 nm (II) and I+II. Based on the classification threshold of 20 ppb, the best PLS-DA prediction results using the full spectra yielded the average accuracy of 87.9% and overall accuracy of 88.6%. With 100 ppb as the classification threshold, the best PLS-DA model using the full spectra achieved the average accuracy of 94.0% and overall accuracy of 91.4%. Using the full spectra, the best average accuracies recorded by LS-SVM were 90.9% and 98.0%, with the classification thresholds of 20 and 100 ppb, respectively. Correspondingly, the best overall accuracies by LS-SVM were 90.0% and 97.1%. In addition, the simplified models of CARS-PLS-DA and CARS-LS-SVM also demonstrated good prediction capability in identifying the AFB1 contamination from peanut surface. Based on both classification thresholds of 20 and 100 ppb, the best CARS-PLS-DA and CARS-LS-SVM prediction results were ≥ 90.0% in both average accuracy and overall accuracy. Most importantly, the computation complexity and the employed data dimensionality were significantly reduced by using the simplified models.
Traditionally, XRD had been used to study the crystalline structure of cotton celluloses. Despite considerable efforts in
developing the curve-fitting protocol to evaluate the crystallinity index (CI), in its present state, XRD measurement can
only provide a qualitative or semi-quantitative assessment of the amounts of crystalline and amorphous cellulosic
components in a sample. The greatest barrier to establish quantitative XRD is the lack of appropriate cellulose standards
needed to calibrate the measurements. In practical, samples with known CIs are very difficult to be prepared or
determined. As an approach, we might assign the samples with reported CIs from FT-IR procedure, in which the threeband
ratios were first calculated and then were converted into CIs within a large and diversified pool of cotton fibers.
This study reports the development of simple XRD algorithm, over time-consuming and subjective curve-fitting process,
for direct determination of cotton cellulose CI by correlating XRD with the FT-IR CI references.
Fourier transform infrared (FT-IR) spectra of seed and lint cottons were collected to explore the potential for the
discrimination of immature cottons from mature ones and also for the determination of actual cotton maturity. Spectral
features of immature and mature cottons revealed large differences in the 1200-900 cm-1 region, and such spectral
distinctions formed the basis on which to develop simple three-band ratio algorithm for classification analysis. Next, an
additional formula was created to assess the degree of cotton fiber maturity by converting the three-band ratios into an
appropriate FT-IR maturity (MIR) index. Furthermore, the MIR index was compared with parameters derived from
traditional image analysis (IA) and advanced fiber information system (AFIS) measurements. Results indicated strong
correlations (R2 > 0.89) between MIR and MAFIS and between MIR and MIA among either International Cotton Calibration
(ICC) standards or selected cotton maturity references. On the other hand, low correlations between the pairs were
observed among regular cotton fibers, which likely resulted from the heterogeneous distribution of structural, physical,
and chemical characteristics in cotton fibers and subsequent different sampling specimens for individual and independent
measurement.
Lint cleaning at cotton processing facilities is performed in order to remove the non-lint materials with minimal fiber
damage. The resultant waste contains some degree of cotton fiber having good equal qualities, and hence is of great
concern for operating cost. Traditional methods for measuring non-lint trash are labor intensive and time consuming. UV
/ visible / NIR technique was examined for its feasibility in determining the portions of cotton fiber and trash. Overall
result indicated that NIR prediction was limited to screening purpose for probable reasons as heterogeneous trash distribution, relatively small sampling, and gravimetric reference method.
Techniques for routine and rapid screening of the presence of foodborne bacteria are needed, and this study reports the
feasibility of citrate-reduced silver colloidal SERS for identifying E. coli, Listeria, and Salmonella. Relative standard
deviation (RSD) of SERS spectra from silver colloidal suspensions and ratios of P-O SERS peaks from small molecule
(K3PO4) were used to assess the reproducibility, stability, and binding effectiveness of citrate-reduced silver colloids
over batch and storage process. The results suggested the reproducibility of silver colloids over batch process and also
stability and consistent binding effectiveness over 60-day storage period. Notably, although silver colloidal nanoparticles
were stable for at least 90 days, their binding effectiveness began to decrease slightly after 60-day storage, with a
binding reduction of about 12% at 90th day. Colloidal silver SERS, as demonstrated here, could be an important
alternative technique in the rapid and simultaneous screening of the presence of three most outbreak bacteria due to the
exclusive biomarkers, label-free and easy sampling attribute.
Rapid and routine identification of foodborne bacteria are considerably important, because of bio- / agro- terrorism threats, public health concerns, and economic loss. Conventional, PCR, and immunoassay methods for the detection of bacteria are generally time-consuming, chemical reagent necessary and multi-step procedures. Fast microbial detection requires minimal sample preparation, permits the routine analysis of large numbers of samples with negligible reagent costs, and is easy to operate. Therefore, we have developed silver colloidal nanoparticle based surface-enhanced Raman scattering (SERS) spectroscopy as a potential tool for the rapid and routine detection of E. coli and L. monocytogenes. This study presents the further results of our examination on S. typhimonium, one of the most commonly outbreak bacteria, for the characteristic bands and subsequent identification.
Several of visible and NIR bands were sought to explore the potential for the classification of fecal / ingesta ("F/I")
objectives from rubber belt and stainless steel ("RB/SS") backgrounds. Spectral features of "F/I" objectives and
"RB/SS" backgrounds showed large differences in both visible and NIR regions, due to the diversity of their chemical
compositions. Such spectral distinctions formed the basis on which to develop simple three-band ratio algorithms for the
classification analysis. Meanwhile, score-score plots from principal component analysis (PCA) indicated the obvious
cluster separation between "F/I" objectives and "RB/SS" backgrounds, but the corresponding loadings did not show any
specific wavelengths for developing effective algorithms. Furthermore, 2-class soft independent modeling of class
analogy (SIMCA) models were developed to compare the correct classifications with those from the ratio algorithms.
Results indicated that using ratio algorithms in the visible or NIR region could separate "F/I" objectives from "RB/SS"
backgrounds with a success rate of over 97%.
Hyperspectral images of cucumbers were acquired before and during cold storage treatments as well as during subsequent room temperature (RT) storage to explore the potential for the detection of chilling induced damage in whole cucumbers. Region of interest (ROI) spectral features of chilling injured areas, resulting from cold storage treatments at 0°C or 5°C, showed a reduction in reflectance intensity during multi-day post chilling periods of RT storage. Large spectral differences between good-smooth skins and chilling injured skins occurred in the 700-850 nm visible/NIR region. A number of data processing methods, including simple spectral band algorithms, second difference, and principal component analysis (PCA), were attempted to discriminate the ROI spectra of good cucumber skins from those of chilling injured skins. Results revealed that using either a dual-band ratio algorithm (Q811/756) or a PCA model from a narrow spectral region of 733-848 nm could detect chilling injured skins with a success rate of over 90%. Furthermore, the dual-band algorithm was applied to the analysis of images of cucumbers at different conditions, and the resultant images showed more correct identification of chilling injured spots than other processing methods.
Consumers have long considered regulated inspections of meat and poultry production and slaughter as a means to protect the general public from health-threatening or even deadly unwholesome meat and poultry supplies. Today, consumers rely on United States Department of Agriculture Food Safety and Inspection Service (USDA/FSIS) inspectors to ensure a healthy, risk-free supply of poultry products in retail establishments.
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