Synchronous fluorescence and multivariate classification analysis as a screening tool for determining Sudan I dye in culinary spices

Comprehensive Investigations About the Binding Interactions of Sudan Dyes with DNA by Spectroscopy and Docking Methods

Sudan dyes are recognized as carcinogens, which are strictly determined whether there are them in food for food safety. Hence, in order to understand the mechanism at the molecular level, this work investigated the binding interactions of Sudan I-IV with calfthy mus DNA. The synchronous fluorescence and UV-vis spectral results suggested the complex formation between Sudan I-IV and ct-DNA. EB and Hoechst 33258 displacement experimental results confirmed the binding sites of Sudan I-IV in ct-DNA and the minor groove-binding mode of Sudan I-IV with ct-DNA. The molecular modeling computational method also proved binding mode, which is consistent with the spectral experiments. In addition, the aromatic rings of Sudan I-IV play important roles in binding with DNA. Compared to Sudan I and II, the increase of molecular conjugation system enhances the binding abilities of Sudan III and Sudan IV with DNA. Vdm + Hbond + desolv energies of them are the main contribution of their combined energies.

Detection of Red Pepper Powder Adulteration with Allura Red and Red Pepper Seeds Using Hyperspectral Imaging

This study used shortwave infrared (SWIR) technology to determine whether red pepper powder was artificially adulterated with Allura Red and red pepper seeds. First, the ratio of red pepper pericarp to seed was adjusted to 100:0 (P100), 75:25 (P75), 50:50 (P50), 25:75 (P25), or 0:100 (P0), and Allura Red was added to the red pepper pericarp/seed mixture at 0.05% (A), 0.1% (B), and 0.15% (C). The results of principal component analysis (PCA) using the L, a, and b values; hue angle; and chroma showed that the pure pericarp powder (P100) was not easily distinguished from some adulterated samples (P50A-C, P75A-C, and P100B,C). Adulterated red pepper powder was detected by applying machine learning techniques, including linear discriminant analysis (LDA), linear support vector machine (LSVM), and k-nearest neighbor (KNN), based on spectra obtained from SWIR (1,000-1,700 nm). Linear discriminant analysis determined adulteration with 100% accuracy when the samples were divided into four categories (acceptable, adulterated by Allura Red, adulterated by seeds, and adulterated by seeds and Allura Red). The application of SWIR technology and machine learning detects adulteration with Allura Red and seeds in red pepper powder.

Front-face synchronous fluorescence spectroscopy for rapid and non-destructive determination of free capsanthin, the predominant carotenoid in chili (Capsicum annuum L.) powders based on aggregation-induced emission

Capsanthin is the major natural carotenoid pigment in red chili pepper possessing important bioactivity. Its conventional determination method is high performance liquid chromatography (HPLC) with complex and tedious sample pretreatment. In this study, synchronous front-face fluorescence spectroscopy (FFFS) was applied for the fast and non-invasive detection of free capsanthin in chili powders. Although capsanthin was only weak fluorescent in solution state, it showed strong fluorescence in two separated regions in front-face geometry which could also be clearly observed in chili powders. The mechanisms of these emissions are revealed to be aggregation-induced emission (AIE) and J-aggregate formation (JAF). The free capsanthin in 85 chili powder samples were determined by HPLC as in the range of 0.6-3.0 mg/g. The total synchronous FFFS spectra of these samples were scanned. Simple first-order models were built by partial least square regression (PLSR), and were validated by 5-fold cross-validation and external validation. The coefficients of determination (R²) were higher than 0.9, and the root mean square errors (RMSE) were less than 0.2 mg/g. The relative error of prediction (REP) was 9.9%, and the residual predictive deviation (RPD) was 3.7. The method was applied for the estimation of free capsanthin in several real-world samples with satisfactory analytical results. The average relative error to HPLC reference values was -11.8%.

The use of new metallophthalocyanines carrying peripherally 4-methyl-N-(3-morpholinopropyl)benzenesulfonamide moieties for the sensitive fluorimetric determination of banned food dye Sudan II in red chili peppers

The structural elucidation and syntheses methods of new peripherally tetra-substituted MPcs [CuII(6), CoII(7), MnCIIII(8), and NiII(9) phthalocyanines] carrying 4-methyl-N-(3-morpholinopropyl)benzenesulfonamide moieties were reported in the present study. The corroboration of the prepared compounds (3, 5, and 6 to 9) was made by LC-TOF/MS, UV-Vis, Fourier Infrared, 1H NMR, 13C NMR, and MALDI-TOF mass spectral data. Herein, we submit a new procedure that uses metallophthalocyanine complexes for the first time as spectrofluorimetric agents to detect and determine health-threatening food additive, Sudan II dye, with a new simpler, cheaper, and faster spectrofluorimetric method instead of time-consuming and expensive HPLC processes. Furthermore, the sensitivities of the proposed methods are good enough to determine the amount of dye at a concentration of 0.1 mg/L. The methods have LOD values between 0.035 and 0.050 mg/L. The linear ranges are found to be between 0 and 8.3 mg/L. The precision of the methods is determined to be between 1.1 and 2.4 as % RSD. Therefore, this study would make a good contribution to the food industry and phthalocyanine chemistry by detecting and determining the hazardous food colorant Sudan II with metal phthalocyanines.

The Detection of Substitution Adulteration of Paprika with Spent Paprika by the Application of Molecular Spectroscopy Tools

The spice paprika (Capsicum annuum and frutescens) is used in a wide variety of cooking methods as well as seasonings and sauces. The oil, paprika oleoresin, is a valuable product; however, once removed from paprika, the remaining spent product can be used to adulterate paprika. Near-infrared (NIR) and Fourier transform infrared (FTIR) were the platforms selected for the development of methods to detect paprika adulteration in conjunction with chemometrics. Orthogonal partial least squares discriminant analysis (OPLS-DA), a supervised technique, was used to develop the chemometric models, and the measurement of fit (R²) and measurement of prediction (Q²) values were 0.853 and 0.819, respectively, for the NIR method and 0.943 and 0.898 respectively for the FTIR method. An external validation set was tested against the model, and a receiver operating curve (ROC) was created. The area under the curve (AUC) for both methods was highly accurate at 0.951 (NIR) and 0.907 (FTIR). The levels of adulteration with 100% correct classification were 50–90% (NIR) and 40–90% (FTIR). Sudan I dye is a commonly used adulterant in paprika; however, in this study it was found that this dye had no effect on the outcome of the result for spent material adulteration.

Fluorescence Spectroscopy for the Monitoring of Food Processes

Different analytical techniques have been used to examine the complexity of food samples. Among them, fluorescence spectroscopy cannot be ignored in developing rapid and non-invasive analytical methodologies. It is one of the most sensitive spectroscopic approaches employed in identification, classification, authentication, quantification, and optimization of different parameters during food handling, processing, and storage and uses different chemometric tools. Chemometrics helps to retrieve useful information from spectral data utilized in the characterization of food samples. This contribution discusses in detail the potential of fluorescence spectroscopy of different foods, such as dairy, meat, fish, eggs, edible oil, cereals, fruit, vegetables, etc., for qualitative and quantitative analysis with different chemometric approaches.