Real or fake yellow in the vibrant colour craze: Rapid detection of lead chromate in turmeric

Synthesis of PbCrO4 nanorods-Ti3C2Tx MXene composites: A sensitive photoelectrochemical sensor for the detection of cysteine in human blood serum

BACKGROUND

l-cysteine plays an important role in protein synthesis, osmoregulation, detoxification, nervous system function, and antioxidant process. Low levels of cysteine are associated with various diseases like cardiovascular diseases, ischemic stroke, neurological disorders, diabetes, cancer like lung and colorectal cancer, renal dysfunction-linked conditions, and vitiligo. Therefore, it is of great significance to develop a rapid and accurate method for the determination of cysteine concentration.

RESULTS

A photoelectrochemical (PEC) biosensor based on PbCrO4-MXene composites is proposed MXene for the determination of l-cysteine. The original PbCrO4 nanorods are synthesized via a redox reaction that occurred between Pb2+ and K2Cr2O7 in a weakly acidic environment using a hydrothermal approach. The PbCrO4 nanorods show outstanding PEC performance in the catalytic oxidation of l-cysteine. The introduction of Ti3C2Tx MXene nanosheets on PbCrO4 nanorods enables the formation of the local Schottky junction to efficiently improve charge transport and charge separation of PbCrO4 nanorods, achieving excellent catalytic performance. The PbCrO4-MXene composites be used as a photoelectrocatalyst for rapid and sensitive detection of l-cysteine in the human body. Compared with the traditional PEC sensor, this sensor based on PbCrO4-MXene composites can significantly improve the catalytic performance of PEC, showing a better response to l-cysteine. This PEC sensor shows a low limit of detection (LOD) of 0.23 μM for l-cysteine, and a wide linear range of 0.01-18 mM, exceeding expectations compared to previously published papers.

SIGNIFICANCE

Our PEC sensor has been successfully used for the detection of l-cysteine in human blood serum. This work provides a new inspiration for the great practical application of PEC sensors in medicine and clinical diagnosis fields.

Smartphone-based imaging colorimetric assay for monitoring the quality of curcumin in turmeric powder

This research developed a colorimetric assay for semi-quantitative curcumin detection. The screening test was performed using a ferric chloride to form a brownish color which was further used to evaluate the amount of curcumin in the turmeric powder samples. The quantitative assay was performed based on the color intensity of the curcumin target using a smartphone digital image colorimetry with a developed lightbox constructed with a white light-emitting diodes (LED) light source as the measurement device. Images in red, green, and blue (RGB) color were processed to obtain relevant colors from the image and the color values were used to analyze curcumin concentrations. The intensity of the ΔB was correlated to the concentration of curcumin with high sensitivity. The method showed a linear range between 0.25 and 5 mg L-1 with the LOD and LOQ of 0.12 and 0.41 mg L-1, respectively. Sample analysis was carried out in turmeric powders. Curcumin in turmeric powder samples was simply extracted using acetonitrile followed by dilution 100 times for sample preparation. The accuracy was tested by spiking 0.25, 1.00, and 4.00 mg L-1 of standard curcumin into the turmeric sample solution. The average percentage recoveries were acceptable in all samples (90-104%). The method was validated by comparing the results obtained from the proposed method and high-performance liquid chromatography (HPLC). There was no statistically significant difference between the two methods (P = 0.05).

Addressing forensic science challenges with nuclear analytical techniques - A review

We review the application of Nuclear Analytical Techniques (NATs) to forensic problems for the first time. NATs include neutron activation analysis (NAA), carried out in nuclear reactors for elemental analysis; accelerator-based techniques, mainly Ion Beam Analysis (IBA) for elemental and molecular analysis; and Accelerator Mass Spectrometry (AMS) for dating of traces of forensic interest by "radiocarbon dating" and other related methods. Applications include analysis of drugs of abuse, food fraud, counterfeit medicine, gunshot residue, glass fragments, forgery of art objects and documents, and human material. In some applications only the NATs are able to provide relevant information for forensic purposes. This review not only includes a wide collection of forensic applications, but also illustrates the wide availability worldwide of NATs, opening up opportunities for an increased use of NATs in routine forensic casework.

Comparison of Multiple NIR Spectrometers for Detecting Low-Concentration Nitrogen-Based Adulteration in Protein Powders

Protein adulteration is a common fraud in the food industry due to the high price of protein sources and their limited availability. Total nitrogen determination is the standard analytical technique for quality control, which is incapable of distinguishing between protein nitrogen and nitrogen from non-protein sources. Three benchtops and one handheld near-infrared spectrometer (NIRS) with different signal processing techniques (grating, Fourier transform, and MEM-micro-electro-mechanical system) were compared with detect adulteration in protein powders at low concentration levels. Whey, beef, and pea protein powders were mixed with a different combination and concentration of high nitrogen content compounds-namely melamine, urea, taurine, and glycine-resulting in a total of 819 samples. NIRS, combined with chemometric tools and various spectral preprocessing techniques, was used to predict adulterant concentrations, while the limit of detection (LOD) and limit of quantification (LOQ) were also assessed to further evaluate instrument performance. Out of all devices and measurement methods compared, the most accurate predictive models were built based on the dataset acquired with a grating benchtop spectrophotometer, reaching R2P values of 0.96 and proximating the 0.1% LOD for melamine and urea. Results imply the possibility of using NIRS combined with chemometrics as a generalized quality control tool for protein powders.

Status of food colorants in India: conflicts and prospects

Food colorants are imperative ingredients for attracting consumers and in deciding their preferences. Here we discuss the current status of natural colorants and synthetic food colorants on the Indian market by appraising the growth of the food colorant market both globally and nationally, based on published case studies on synthetic food colorants (SFCs), rules, and regulations implemented by Food Safety and Standards Authority of India on natural food colorants and SFCs. The substantial lacunae in the research on the impacts of SFCs in the Indian population identified through our literature survey signify the scope and need for appraisal of the issues prevailing in the Indian food colorant market as well as the necessity of renewing the food colorant policies. The illegal use of banned food colorants, the adulteration of natural food colorants, mislabelling of SFCs as natural colorants, and the permitted use of internationally banned food colorants, as well as the unawareness among consumers are serious issues recognized. Appropriate labelling to denote natural food colorants' presence, renewed standards of policy to determine the permitted use of food colorants, comprehensive regulations for the production and use of natural food colorants, stringent rules to constrain the production of toxic SFCs are obligatory to breakdown the dilemma on the Indian food market. Most importantly, awareness and responsiveness should be generated among consumers regarding the illegal use and adulteration of colorants and the need to use natural colorants. We also recommend a logo to designate the presence of natural colorants which will aid the consumers to make the right choice.

Estimating the potential of spices for mineral provision in a refugee context in East Africa

Micronutrient deficiency remains an enormous problem in refugee settings. Transforming refugees’ food systems through the scaling up of kitchen gardening and fortifying relief food crops with minor food components including nutrient-dense spices can help improve the quality of staple foods. Globally, spices are indispensable in the daily diet and play an important role in the socio-cultural setting of different communities. Forty turmeric and curry powder samples were collected from different market establishments and geographic locations in East Africa. The samples were analyzed for selected elements using Portable X-Ray Fluorescence (PXRF). The contents of potassium (K), calcium (Ca), zinc (Zn) and strontium (Sr) in turmeric powder were statistically different among geographic origins (Ethiopia, Kenya and Uganda). We also aimed to determine if a small portion of spices (turmeric (5 g) and curry (4 g)) would contribute to an adequate intake (AI) or recommended dietary allowance (RDA) for selected minerals, for refugee men and women aged between 19 and 50 years as defined by the Food and Nutrition Board of the Institute of Medicine (IOM). For the reference groups, the contributions of turmeric and curry powder to AI/RDA for K, Ca and Zn varied between 0.48 to 4.13%. On the other hand, turmeric was identified to contribute > 20% AI/RDA for refugee men and women aged between 19 and 50 years for two micro minerals: manganese (Mn) and iron (Fe). Considering turmeric and curry powder of East African origins are good sources of minerals and present acceptable toxic metal(loid)s loads coupled with low cost, these spices particularly turmeric should be more widely popularized and recommended for food-to-spice fortification among the refugee population located in East Africa.

Assessing Analytical Methods for the Rapid Detection of Lead Adulteration in the Global Spice Market

Lead adulteration of spices, primarily via Pb chromate compounds, has been documented globally as a growing public health concern. Currently, Pb detection in spices relies primarily on expensive and time-consuming laboratory analyses. Advancing rapid Pb detection methods, inclusive of their accuracy and precision, would improve field assessments by food safety inspectors, stakeholders, and the public in the hope of reducing Pb exposure risks at its source. Here, we present two field procedures for Pb detection: portable X-ray fluorescence analysis (pXRF) and a simple colorimetric test. We assess their efficacy to detect Pb and its chemical form in seven spice types, including powders, spice-salt mixtures, and dried roots, compared to the proven laboratory technique, inductively coupled plasma mass spectrometry (ICP-MS). Lead concentrations measured using pXRF and ICP-MS were within 5% of each other for spice powders and 24% for dried roots. By pXRF, spice samples were analyzed within collection plastic bags without preparation, resulting in a detection limit of 2 mg Pb/kg for spice powders, which is comparable to national food standards. The colorimetric test utilized here targets hexavalent chromium, making the method selective to Pb chromate adulteration assuming that this is its dominant source in spices. Color development, and thus detection, was observed when Pb concentrations exceeded approximately 5-70 mg/kg in dried turmeric roots and 1000 mg/kg in spice powders; however, it was ineffective for the spice-salt mixture. We show that pXRF analysis and a colorimetric assay provide information that may improve field decisions about Pb adulteration in a range of spice types, helping to minimize Pb exposure.

The Use of Pb Isotope Ratios to Determine Environmental Sources of High Blood Pb Concentrations in Children: A Feasibility Study in Georgia

The incidence of lead (Pb) poisoning in children in Georgia has been identified as a major health concern, with a recent national survey identifying that 41% of children aged 2-7 years had blood lead concentrations (BLCs) greater than the blood lead reference value (BLRV) of ≥5 µg dL^-1. This study collected samples of blood, spices, paint, soil, dust, flour, tea, toys, milk, and water from 36 households in Georgia where a child had previously been identified as having a BLC > BLRV. The Pb concentrations of these samples were determined and compared to Georgian reference values. Samples from 3 households were analysed for their Pb isotope composition. The Pb isotope composition of the environmental and blood samples were compared to identify the most likely source(s) of Pb exposure. This approach identified that some spice and dust samples were the likely sources of Pb in the blood in these cases. Importantly, some soil, paint, and dust sources with high Pb concentrations could be discounted as contributing to blood Pb based on their distinct isotope composition. The data presented demonstrate the significant contribution that Pb surveillance and Pb isotope ratio analyses can make to managing Pb exposure in regions where high BLCs are identified.

Label compliance for ingredient verification: regulations, approaches, and trends for testing botanical products marketed for "immune health" in the United States

During the COVID-19 pandemic, the botanical product market saw a consumer interest increase in immune health supplements. While data are currently insufficient to support public health guidance for using foods and dietary supplements to prevent or treat COVID-19 and other immune disorders, consumer surveys indicate that immune support is the second-most cited reason for supplement use in the United States. Meanwhile, consumers showed increased attention to dietary supplement ingredient labels, especially concerning authenticity and ingredient claims. Top-selling botanical ingredients such as elderberry, turmeric, and functional mushrooms have been increasingly marketed toward consumers to promote immune health, but these popular products succumb to adulteration with inaccurate labeling due to the intentional or unintentional addition of lower grade ingredients, non-target plants, and synthetic compounds, partially due to pandemic-related supply chain issues. This review highlights the regulatory requirements and recommendations for analytical approaches, including chromatography, spectroscopy, and DNA approaches for ingredient claim verification. Demonstrating elderberry, turmeric, and functional mushrooms as examples, this review aims to provide industrial professionals and scientists an overview of current United States regulations, testing approaches, and trends for label compliance verification to ensure the safety of botanical products marketed for "immune health."

Fluorescence quenching by competitive absorption between solid foods: Rapid and non-destructive determination of maize flour adulterated in turmeric powder

Fluorescence quenching induced by competitive absorption between different components of solid foods was observed for the first time. By using front-face synchronous fluorescence spectroscopy (FFSFS) and fluorescence titration, competitive absorption between maize flour and turmeric powder was proven to occur between phenolic acids in maize flour and curcumin in turmeric powder. FFSFS was applied for the rapid and non-destructive determination of maize flour adulterated in turmeric powder. Prediction models were constructed by partial least square (PLS) regression based on unfolded total synchronous fluorescence spectra, and were validated by five-fold cross-validation and external validation, with the determination coefficient of prediction (R_p²) greater than 0.95, root mean square error of prediction (RMSEP) < 6%, relative error of prediction (REP) < 15% and residual predictive deviation (RPD) greater than 5. The limit of detection (LOD) of maize flour was approximately 9%. In addition, most relative errors for test samples were from -20% to 20%.

A novel method based on machine vision system and deep learning to detect fraud in turmeric powder

Assessing the quality of food and spices is particularly important in ensuring proper human nutrition. The use of computer vision method as a non-destructive technique in measuring the quality of food and spices has always been taken into consideration by researchers. Due to the high nutritional value of turmeric among the spices as well as the fraudulent motives to gain economic profit from the selling of this product, its quality assessment is very important. The lack of marketability of grade 3 chickpeas (small and broken chickpeas) and their very low price have made them a good choice to be mixed with turmeric in powder form and sold in the market. In this study, an improved convolutional neural network (CNN) was used to classify turmeric powder images to detect fraud. CNN was improved through the use of gated pooling functions. We also show with a combined approach based on the integration of average pooling and max pooling that the accuracy and performance of the proposed CNN has increased. In this study, 6240 image samples were prepared in 13 categories (pure turmeric powder, chickpea powder, chickpea powder mixed with food coloring, 10, 20, 30, 40 and 50% fraud in turmeric). In the preprocessing step, unwanted parts of the image were removed. The data augmentation (DA) was used to reduce the overfitting problem on CNN. Also in this research, MLP, Fuzzy, SVM, GBT and EDT algorithms were used to compare the proposed CNN results with other classifiers. The results showed that prevention of the overfitting problem using gated pooling, the proposed CNN was able to grade the images of turmeric powder with 99.36% accuracy compared to other classifiers. The results of this study also showed that computer vision, especially when used with deep learning (DL), can be a valuable method in evaluating the quality and detecting fraud in turmeric powder.

Sensing and bioimaging of lead ions in intracellular cancer cells and biomedical media using amine-functionalized silicon quantum dots fluorescent probe

A novel amine-functionalized silica quantum dots (SiQDs) fluorescent nanoprobe was developed for sensing of lead concentration in water, plasma and cell lysate. In addition, the developed probe was utilized for bioimaging of intracellular lead ions in HT 29 cancer cells. The amine-functionalized nanoprobe exhibited fluorescence emission at 445 nm under excitation at 355 nm. Upon addition of lead ions, the fluorescence of SiQDs linearly enhanced from 50 ng/mL to 5 µg/mL and 50 ng/mL to 25 µg/mL for plasma and standard media, respectively. The synthesis and fabrication of this probe are simple and serves high sensitivity with a limit of detection down to around 20 ng/mL. In the presence of various molecular and ion interfering, reliable results are obtained, confirming the specificity of the nanoprobe for lead ion detection. Meanwhile, amine-functionalized SiQD-based nanoprobe exhibits excellent cell membrane-permeability and biocompatibility. Thus, this probe is utilized for lead tracing in HT 29 cancer live cells. Fluorescent microscopy results confirmed the attachment of the produced nanomaterials to the HT 29 cancer cells.