Food Analytical Methods最新文献

Saxitoxins are potent neurotoxins originating the acute human neurological syndrome of paralytic shellfish poisoning (PSP) via bivalve vectors. The official testing method in the European Union, commonly known as the ‘Lawrence method’, involves pre-column oxidation steps. The Portuguese monitoring adopted the hydrogen peroxide oxidation screening approach for bivalves contaminated with Gymnodinium catenatum toxins, which can quantify chromatographically at once 6 out of 10 analogues commonly found in bivalves. Seasonal fluctuation in the fluorescence yield of calibration curves was observed across years in a consistent manner. It correlated with fluctuations in average monthly air temperature in Lisbon, highlighting the importance of recording the room temperature during the oxidation steps as a matter of routine practice. Incubation experiments also showed an increase in fluorescence yield with temperature, more pronounced for the 11-hydroxysulphate analogues (dcGTX2 + 3, C1 + 2, GTX2 + 3) than for the 11-H toxins (dcSTX, GTX5[B1], STX). Temperature can be exploited to increase fluorescence yield, assisting in spectral confirmation, but must not exceed 40–50 °C to avoid toxin decomposition or production of extra oxidation products.

Foods high in erucic acid (EA), a fatty acid considered a natural toxin, can pose various health risks. Studies have reported that people exposed to high levels of EA are more likely to experience cardiovascular disease, are susceptible to myocardial adiposity, and have increased rates of diabetes. Therefore, in 2019, the European Commission (EC) declared that the maximum EA content in vegetable oils should be no more than 2%. These regulations require EA analysis in import and export food samples. A methyl ester of EA (EAME) standard is required to analyze EA content. In many countries, this analytical standard is not available and is being imported. This study endeavored to economically produce the EAME standard, which is in high demand due to mandated analysis, using natural oils. Initially, the fatty acid amounts in the food samples were analyzed by the gas chromatography–mass spectrometry/flame ionization detection (GC-MS/FID) method. The analyses revealed that mustard seed oil had the lowest EA content, while yellow mustard seed oil had the maximum EA content. The esterification was conducted on the samples containing both high and low EA, resulting in an efficiency of approximately 80%. The crystallization process was subsequently repeated to increase the EA quantity until the highest EAME content was obtained. By this process, 14 different concentrations of EAME ranging from 2.33 to 55.66% were produced. These results demonstrate the first successful production of EAME standards from natural oils that can be used in validation and internal quality control studies for food control analysis.

Corncob biochar was produced by pyrolisis (400 °C, N₂ flow of 3 L/min, yield of 42%) and applied as an alternative adsorbent in solid-phase extraction (SPE) for pesticide control in water. Part of the biochar was activated with KOH (3 mol/L) and HCl (3 mol/L). The non-activated biochar (NB) and activated biochar (AB) were characterized by Fourier-transform infrared spectroscopy (FTIR) and point of zero charge (PZC) analyses, with PZC pH values of 7.37 and 6.07 obtained for NB and AB, respectivey. For AB, Boehm titration, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses indicated the presence of acidic groups, high silicon content, surface area of 99.59 m²/g, and pore volume of 0.265 cm³/g, respectively. The adsorption of pesticides in water (1 μg/mL) was performed by SPE using C18 and AB. The eluents that provided the best recoveries were acetonitrile and dichloromethane/methanol (50:50). Pesticide analysis was performed by LC/MS, with a C18 column and a mobile phase of water (5 mmol/L NH₄HCO₂) and methanol (5 mmol/L NH₄HCO₂). The effects of the variables adsorbent amount, sample volume, and eluent volume were evaluated using 2³ factorial design for SPE with AB. Among 13 pesticides, 10 presented recoveries between 75.9 and 117%. Statistical analysis (Pareto chart, response surface, and ANOVA) showed that the best condition was obtained with 100 mg of AB, 50 mL of sample, and 15 mL of eluent, while the use of 5 mL of eluent also provided satisfactory results. Under the optimal conditions, the SPE method exhibited good linear relation (r² ˃ 0.99) in the linear range of 1–1000 μg/L. Detection and quantification limits ranged from 0.01 to 0.04 μg/L and from 0.1 to 0.4 μg/L_, respectively.

The limited data on the systematic evaluation and composition of metabolic compounds in different sorghum varieties makes their distinction difficult. Here, we employed untargeted metabolomic and multivariate statistical analyses on 129 sorghum samples collected from various regions across China using ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). This approach enabled us to differentiate between two specific varieties of sorghum: Guizhou glutinous sorghum (GZGS), used in the production of soy sauce-flavoured baijiu in the Zunyi baijiu production area, and Guizhou Hongyingzi sorghum (GZ-HYZ), used in the production of Maotai-flavoured baijiu. The metabolic compounds in GZGS, mixed sorghum from other production areas, GZ-HYZ, and other glutinous sorghum varieties in Guizhou (GZ-others) were analysed, and key differential metabolites were identified. Differences were observed between the composition of GZ-HYZ and GZ-others. The phenylpropanoid biosynthesis pathway produced large amounts of flavonoids and lignins with antioxidant activity and phenols, which partially explained the formation of the Maotai liquor aroma. UPLC–MS/MS-based untargeted metabolomics can effectively reveal the differences in metabolites among sorghum varieties, thereby facilitating the authentication of GZGS and GZ-HYZ for brewing purposes.

Betel nut (Areca nut, AN) products are extensively consumed across East and South Asian countries, with Binglang being the predominant chewable AN product in China. Given the increased risk of carcinogenicity associated with alkaloid nitrogen oxides compared to the primary alkaloids in AN, this study aimed to establish a precise and sensitive method for quantitative analysis of the arecoline N-oxide (ACNO) and arecaidine N-oxide (ADNO) at three different processing stages of Binglang using liquid chromatography-tandem mass spectrometry (LC–MS/MS). The developed method underwent comprehensive validation, evaluating key analytical parameters including selectivity, linearity, sensitivity, accuracy, precision, and stability. Notably, the method demonstrated excellent sensitivity, with the limits of detection (LOD) ranging from 0.029 to 0.135 ng/mL, while the limits of quantification (LOQ) ranging from 0.095 to 0.450 ng/mL. Subsequently, the established analytical technique was applied to analyze 15 Binglang samples at three different processing stages, providing the first evidence of the content and variability of alkaloid nitrogen oxides throughout these stages. ACNO and ADNO were detected in all samples, and their total contents ranged from 4.31 to 32.82 μg/g. The changes observed across different processing stages indicated that the roasting process at 80 ℃ resulted in the promotion of alkaloid nitrogen oxides. This analytical approach constitutes a valuable tool for the quality control and risk assessment of Binglang and can be extended to other AN products, thereby assisting in addressing health concerns associated with these products.

To identify a fast and non-destructive way to determine nutritional traits in soybean, a study was conducted using near-infrared spectroscopy (NIRS) to quantify the oil, protein, and fatty acid contents in soybean seeds. Three hundred soybean accessions obtained from the International Institute of Tropical Agriculture and six varieties were evaluated at two locations in 2021. Fifty random samples of the soybean accessions were scanned over a wavelength of 400–2500 nm at every 0.5 nm interval at the instrumentation laboratory of the Centre for Dryland Agriculture. The spectral data was analyzed using multivariate data analysis software (Unscrambler v9.7). Partial least square analysis was performed on the spectral data and derivative data to determine the best calibration model based on standard error of calibration and R². Goodness of fit was evaluated based on standard error of prediction and the residual percent deviation. Calibration models developed using absorbance gave an R² ranging from 0.991 to 1.000 while that of reflectance ranges from 0.993 to 0.997. Standard error of calibration (SEC) values was between 0.160 and 2.093 for the absorbance groups and 0.166 and 1.376 for the reflectance group. Residual percent deviation (RPD) values greater than 5.0 were obtained using both absorbance and reflectance data for oil and protein, and this signifies that the models were good for quality control and analysis. The result showed an excellent correlation (> 97%) between the predicted and references for all the nutritional traits studied which makes the models good predictors. The developed model was used to predict the oil, protein, and fatty acids of the 306 soybean genotypes, and the observed values were within the reported range for soybean seeds. Thus, NIRS can be used to quantify the nutritional contents of seeds, and it is fast, accurate, and non-destructive.

Cultivated Carica papaya L. (Caricaceae) orchards are threatened by papaya sticky disease (PSD) caused by PMeV viral complex, leading to significant losses in fruit quality and production decline. Secondary metabolites with potential antiviral activity may serve as disease progression markers aiding in early diagnosis and chromatographic approach can assist in this detection. Here, the molecular profiles of crude extracts from C. papaya leaves in the initial stage of development and postflowering stages, with and without PSD symptoms, were evaluated using ultraviolet–visible spectroscopy, reverse-phase, and ion-exchange chromatography. Analytical parameters and chromatographic-based results indicate quantitatively higher chromatographic peaks in the initial stage leaf extract compared to postflowering leaf extracts, potentially reflecting the plant’s defense response against viral infection. This study aimed to identify biomarkers for PSD through the molecular profiling of C. papaya leaf extracts in different stages of the plant. Early disease detection using these biomarkers holds promise for reducing postharvest losses and ensuring fruit safety and quality for consumers allied to the existing diagnosis techniques.

Graphical Abstract

The study is aimed at developing a simple analytical method based on color reactions that is capable of detecting adulteration in teff injera (Ethiopian flatbread) and flour. The analytical method was developed using three distinct varieties of teff injera (white, red, and mixed), as well as teff injera containing gesso or cassava. These are commonly used as adulterants with a 2:1 ratio of teff and adulterants. The method uses visual observation by the naked eye. The powdered injera sample is suspended in deionized water, reagents are added, and a colored result appears. The colors generated by pure teff injera differ significantly from those produced by teff injera containing gesso or cassava. Samples collected from injera traders were tested to determine whether the method could be applied to real samples. The developed method was further confirmed by microwave plasma–atomic emission spectroscopy (MP-AES). The mean concentrations of iron (in mg/kg) in the pure teff injera and injera samples collected from the market can be ranked in the following order: mixed teff injera (360.53) > red teff injera (293.87) > white teff injera (263.8 g) >  >  > injera collected from the market (127.07 for red and 48.2 for white injera). In general, the newly developed method is simple to perform. Thus, the method can be used by researchers, food buyers, regulators, and law enforcement agencies to prevent and detect teff injera adulterations.

The objective of this work was the multi-element determination of Ca, Zn, Sr, Ba, Cu, Mn, Mg, and Cr in handmade chocolate samples after extraction induced by emulsion breakage (EIEB) using optical emission spectrometry with plasma induced by microwaves (MIP OES). After study of each parameter, the most efficient extraction conditions were obtained using 0.250 g of sample, 5.0 mL of extraction solution consisting of HNO₃ 1.5 mol L⁻¹ and Tween 80 1.5% m/v, submitted to an ultrasonic bath for 5 min, followed by breaking the emulsion by heating at 90 °C in a water bath for 4 min. The detection limits obtained, in mg kg⁻¹, were 0.35 (Cr), 0.013 (Zn), 0.064 (Sr), 0.083 (Ca), 0.46 (Fe), 0.010 (Ba), 0.099 (Cu), 0.016 (Mg), and 0.036 (Mn). Precision, based on the relative standard deviation (RSD%), was less than 9.8% (N = 7). The accuracy was confirmed by analyzing the SRM Baking Chocolate 2384 and comparing the proposed method with a calcination method. The method was applied to samples of chocolate bars made in the southern region of Bahia and containing cocoa contents at 50, 58, 60, 63, 70, 80, and 85%. The average results obtained were 328 to 1424 mg kg⁻¹ (Ca), 561 to 2152 mg kg⁻¹ (Mg), 7.8 to 251 mg kg⁻¹ (Cu), 8.5 to 304 mg kg⁻¹ (Mn), 6.22 to 98.32 mg kg⁻¹ (Fe), 8.38 to 80.2 mg kg⁻¹ (Zn), 3.4 to 175 mg kg⁻¹ (Ba), and 2.15 to 12.79 mg kg⁻¹ (Sr). It was observed that as the percentage increases cocoa, there is a tendency to increase the concentration of the studied elements. The developed method has satisfactory precision and accuracy, and is simple, fast and with low consumption of reagents, has good sensitivity, especially when compared to digestion methods.

A simple, rapid, and robust hydrophilic interaction liquid chromatography–tandem mass spectrometry method has been applied for the determination of acrylamide in bread, potato-based heat-processed products, and cereal-based infant food. The QuEChERS methodology was used for sample extraction and clean-up. Enzyme asparaginase was used to prepare an acrylamide-free bread-like matrix, thereby eliminating the lack of acrylamide-free food matrices as one of the limitations for method development and validation. The obtained linear range was 10–2500 µg/kg, and the limit of detection and the limit of quantification were 2.71 and 10.0 μg/kg (S/N = 3 and 10, respectively). The developed method demonstrated good recoveries (98.9–102.8%), intra-day (2.1–3.8%), and inter-day precision (2.9–4.0%). The acrylamide was found in all samples; the concentrations were lower than benchmark levels set by the European Union. In the baby food sample, the AA concentrations were below the limit of quantification (10 µg/kg), and the benchmark level set by the European Union is 40 µg/kg.