Journal of AOAC International最新文献

Background: Ligustri Lucidi Fructus (LLF), the dried fruit of Ligustrum lucidum Ait. (LLA), is a traditional Chinese medicine used for nourishing the liver and the kidney.

Objective: To chemically characterize and compare medicinal and non-medicinal plant parts of LLA to potentially improve biomass utilization.

Method: The metabolite profiles of three different plant parts were evaluated by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). PCA (principal components analysis) and PLS-DA (partial least-squares discriminant analysis) were used to compare the chemical composition of the leaf, stem, and fruit of LLA. Differential metabolites were analyzed via the Pathway Analysis module of MetaboAnalyst 5.0 for pathway enrichment.

Results: A total of 37 compounds were identified from three different plant parts by UPLC-QTOF-MS/MS combined with UNIFI v1.8.1 software. Significant metabolic differences were observed between the leaf, stem, and fruit of LLA using PCA and PLS-DA. Eleven compounds were identified as markers. The content of loganate, secologanoside, nuzhenal C, luteolin, iso-oleonuezhenide, and dammarenediol-II was very much higher in the fruit than in the leaf and stem. The content of oleanolic acid was higher in the fruit and stem than in the leaf. Metabolic pathway analysis revealed that triterpenoids (dammarenediol-II, oleanolic acid, and β-amyrin) exhibited significantly higher abundance in the fruit and stem than in the leaf.

Conclusion: The stem of LLA may be processed as a source of oleanolic acid in the future. This study laid the foundation for the rational utilization of non-medicinal LLA resources.

Background: Basic orange 2, as an industrial dye, exhibits severe effects on human health and has been forbidden for use as a food additive in many countries. The practical use of a common pretreatment process for basic orange 2 in food might be limited owing to time-consuming, high consumption of solvents and weak selectivity. Therefore, the aim of this study was to validate a pretreatment technology for basic orange 2 based on simplicity, being rapid, good selectivity, high sensitivity, and inexpensiveness to ensure safety for people.

Objectives: To develop a strategy for the extraction and enrichment of basic orange 2 in food matrixes by the specific magnetic molecularly imprinted polymers (MIPs) prior to the determination by high-performance liquid chromatography (HPLC).

Methods: The polymers with basic orange 2 as the template were deposited on the surface of ferroferric oxide nanoparticles (Fe3O4@PDA MIPs) through the self-assembly of dopamine in the weak alkaline solution. The Fe3O4@PDA MIPs as a dispersed solid phase extraction (SPE) sorbent were used for extracting and detecting basic orange 2 using HPLC. Parameters influencing extracting efficiencies were optimized, including the mass of MIPs, pH value, time for ultrasonication, elution solvent, and volume.

Results: Under optimal experimental conditions, the detection linearity of basic orange 2 was in the range of 0.04-1.0 μg/mL with a correlation coefficient of 0.9991 and limit of detection (LOD) of 5.8 ng/mL. The recoveries from spiked samples were 73.3-90% with a RSD of 3.1-8.1% in food samples. Notably, the magnetic MIPs showed excellent reusability during three extraction procedures.

Conclusion: The Fe3O4@PDA MIPs prepared have great potential for purification and enrichment of basic orange 2 prior to its determination by HPLC in dried beancurd stick, yellowfish, chili powder, drinks, and wine.

Highlights: The magnetic MIPs developed show good adsorption performance for basic orange 2 with a very low detection and excellent reusability. The assay was applied to detect basic orange 2 in food samples successfully.

Background: Produced naturally by lactic acid bacteria, L-lactic acid is found in many fermented milk products such as yogurt, and also in pickled vegetables, cured meats, and fish. It also serves as a quality parameter in wine, beer, whole egg, whole egg powder, and juices.

Objective: To validate the performance of the Enzytec™ Liquid D-/L-Lactic acid for the determination of the sum of D- and L-lactic acid in food and beverages such as milk and (fermented) milk products, fermented vegetable products, wines, beer, fruit and vegetable juices, and eggs and egg powder.

Methods: The kit contains two ready-to-use components, which makes handling easy and suitable for automation. Both lactic acids react in the presence of NAD and D- or L-Lactate dehydrogenase to pyruvate and NADH. The NADH formed is equivalent to the amount of D-/L-lactic acid converted.

Results: Ascorbic acid, 3-hydroxybutyric acid, and sulfite were found to have a low activity at concentrations higher than 0.5, 0.05, and 0.1 g/L, respectively. Oxaloacetic acid and D-fructose do not interfere at concentrations at or below 0.2 and 20 g/L, respectively. The calculated LOD when using a test solution volume of 100 µL is 3 mg/L, and the LOQ is 10 mg/L. The practical upper measurement range is 600 mg/L. Relative intermediate precision was between 3.8 and 5.3% for pineapple juice, sauerkraut juice, wine, and liquid egg. Cream cheese Certified Reference Materials showed a recovery between 98 and 103%. A reference wine was found with a recovery of 104%. For automation, three applications with different test solution volumes were validated. Linearity is given from 4 up to 3125 mg/L.

Conclusions: The method is robust and accurate and was approved as an AOAC Official Method of Analysis℠.

Highlights: The ready-to-use components of the test kit have a shelf life of at least 24 months.

Background: Peste des petits ruminants (PPR) was a highly contagious and economically devastating disease affecting sheep and goats. The performance and cost of serological diagnostic kit remained a major challenge for PPR eradication.

Objective: The nucleocapsid (N) protein of PPR virus and its monoclonal antibody (mAb) were engineered for development of a blocking ELISA.

Methods: The N protein was truncated and expressed by eukaryotic expression system. The mAb 65A8 was recovered, followed by sequencing and cloning of its variable regions into expression vector. The recombinant mAb was expressed in 293F cells. Key characteristics of the recombinant mAb were evaluated. A blocking ELISA was developed and validated. Comparison between the blocking ELISA and a commercial blocking ELISA kit was performed.

Results: The truncated N protein exhibited a higher yield compared to the full-length N protein. Recombinant mAb 65A8 demonstrated the same blocking efficacy as that of ascites-derived mAb. The yield of recombinant mAb reached 5.3 mg/100 mL. The affinity constant of recombinant mAb 65A8 was comparable to that of the ascites -derived 65A8 (3.48 × 109 L/mol vs 6.76 × 109 L/mol). Based on the truncated N and recombinant mAb, a blocking ELISA was established. The detection limit of blocking ELISA was 1:128 and 1:32 based on strong positive serum and weak positive serum, respectively. Inter- and intra-assay coefficients of variation were <10%, indicating robust reproducibility. The blocking ELISA kit showed high coincidence with the commercial ELISA kit recommended by World Organization for Animal Health reference lab.

Conclusion: This study had successfully developed a reliable and cost-effective blocking ELISA by protein engineering of the antigen and mAb.

Highlights: The mAb of PPR Virus was recombinantly expressed in 239F cells, which was employed in development of a reliable blocking ELISA. This work provided novel ideas and methods for the developing of the blocking ELISA kits.

Background: Chilli powder is a widely consumed spice, however during cultivation of chilli crops are often subjected to pesticide treatments to control pests and diseases. Thus, monitoring pesticide residues in such matrices is crucial for food safety and to comply with national as well as international regulations for export/import purposes. However, accurate analysis of pesticide residue in chilli powder is challenging due to its complex nature.

Objective: To develop and validate a high-throughput LC-MS/MS method for the quantification of multiclass pesticide residues in a complex chilli powder matrix.

Methods: The acetonitrile-based extraction method was optimized for chilli powder samples. The targeted analytes were separated using reverse-phase liquid chromatography and detected using tandem mass spectrometry. Validation was conducted following SANTE guideline to comply with regulatory requirements.

Results: The method with an optimised sample preparation workflow demonstrated a lower matrix effect of < 35% for the target pesticides. The LOQ was determined to be 0.005 mg/kg for 135 analytes, with recovery ranging from 70 to 110%, and intra-day and inter-day precision (%RSD) were below 15%. Analysis of market/incurred samples and measurement uncertainty further provided more confidence on the method performance.

Conclusions: The developed LC-MS/MS method provides a robust, sensitive, and high-throughput approach for the quantification of pesticide residues in complex chilli powder. Its intra- and inter-day validation confirms suitability for routine analysis in food safety laboratories.

Highlights: A high-throughput LC-MS/MS method is developed for pesticide analysis in complex chilli powder. The method was validated according to SANTE 11312/2021-v2 with excellent precision and accuracy. Suitable for routine food safety monitoring of wide range of pesticide residues in a testing laboratory.

Rationale: Qinghai-Tibet Plateau (QTP) rape honey, recognized as a Protected Geographical Indication (PGI) product in China, has faced significant challenges due to fraudulent mislabeling of its origins in the market. To ensure the authenticity of PGI honey products and uphold market integrity, it is crucial to develop a rapid, precise, and efficient geographical traceability technology.

Methods: A total of 208 honey samples were collected from QTP (n = 71) and 5 provinces in the southern region (SR, n = 137) of China. Stable isotope ratios (δ13C, δ15N, δ2H, and δ18O) of bulk honey, endogenous proteins, and saccharides (glucose, fructose, and sucrose) were measured. One-way analysis of variance (ANOVA) was employed to analyze regional differences among the variables. Partial least squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) models were constructed based on stable isotopic data to discriminate honey sample origins.

Results: ANOVA indicated the geospatial differences (P < 0.05) in δ2H and δ18O of bulk honey, as well as all four ratios of honey protein, are significant between QTP and SR. LDA exhibited superior discrimination performance, with leave-one-out cross-validation accuracies of 87.3% for QTP, 89.1% for SR.

Conclusion: An integrated strategy combining stable isotope ratios analysis with multivariate modeling provides an accurate and effective verification method for geographical origin traceability of high-value honey from QTP. This approach provides a reliable tool to address the issue of fraudulent mislabeling of PGI rape honey.

Highlights: Stable isotopic signatures of Qinghai-Tibet Plateau rape honey were discussed. Bulk and component-specific isotopic ratios were informative geospatial indicators. Machine learning algorithms significantly enhanced honey origin discrimination. LDA accuracy for Qinghai-Tibet Plateau honey samples reached up to 87.3%. This strategy was developed to combat origin mislabeling and ensure food integrity.

Background: 1,4-dioxane is a hazardous by-product commonly found in sanitary detergents due to certain manufacturing processes. Accurate detection and quantification of this compound are essential for consumer safety.

Objective: This study aims to develop and optimize a method for detecting and quantifying 1,4-dioxane in sanitary detergents. The approach involves electropolymerization of graphene oxide nanocomposites on stainless-steel mesh, followed by headspace microextraction (HS-ME) and analysis using gas chromatography with a flame ionization detector (GC-FID).

Methods: Graphene oxide nanocomposites were electropolymerized on stainless-steel mesh to create the absorbent material. This absorbent was used in HS-ME for extracting 1,4-dioxane from sanitary detergent samples. A Plackett-Burman design (PBD) screened seven factors, including extraction time, extraction temperature, salt addition effect, stirring speed, desorption time, type of extraction solvent, and volume of extraction solvent. Based on the screening results, a central composite design (CCD) optimized the four critical factors: extraction time, extraction temperature, stirring speed, and type of extraction solvent. Quantification of 1,4-dioxane was performed using GC-FID.

Results: The optimized method demonstrated a linear range of 0.5 to 200 μg/mL with a correlation coefficient (R2) of 0.9989. The limits of detection and quantification were determined as 0.15 and 0.5 μg/mL, respectively. Method accuracy, assessed through the relative recovery percentage of 1,4-dioxane, yielded values between 91.6% and 104%. Intra-laboratory reproducibility percentages ranged from 3.2 to 6.8%.

Conclusions: The developed method, using electropolymerized graphene oxide nanocomposites on stainless-steel mesh for HS-ME coupled with GC-FID, provides a sensitive and accurate approach for detecting and quantifying 1,4-dioxane in sanitary detergents.

Highlights: Electropolymerization of graphene oxide nanocomposites on stainless-steel mesh was successfully implemented to create an effective absorbent for HS-ME of dioxane. A systematic optimization approach, combining PBD and CCD, identified and fine-tuned critical factors influencing extraction efficiency.

Background: Prunus mume Sieb. et Zucc. (P. mume) is rich in various phenolic compounds; however, there is a lack of effective quality evaluation methods.

Objective: The aim of this study was to establish and validate a quality evaluation method that combines composition and activity to evaluate P. mume.

Methods: Phenolic compounds were quantified using an ultra-high performance liquid chromatography-diode array detector (UPLC-DAD) and identified using quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). A solid-phase extraction (SPE) method was used for enrichment and purification. An Eclipse Plus-C18 (2.1 × 50 mm, 5 μm) column was used for separation at a flow rate of 0.25 mL/min, column temperature of 30°C, and detection wavelength of 325 nm. 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and ferric ion-reducing antioxidant power (FRAP) assays were used to determine the antioxidant activity of P. mume. In addition, tyrosinase inhibitory activity (TIA) was verified for the first time.

Results: Twelve major phenolic compounds were identified, among which taxifolin and ferulic acid were first detected in P. mume. The established UPLC-DAD method exhibited a strong linear relationship (R2 = 0.9999). The limit of detection and limit of quantitation of the standard compounds were in the ranges of 0.001-0.014 ng/g and 0.009-0.048 ng/g, respectively. The method exhibited good linearity, precision, stability, and repeatability. The phenolic compound content was in the range of 0.38-75.88 mg/g. In addition, P. mume extract showed excellent ABTS•+ radical scavenging capacity (half maximal inhibitory concentration (IC50) = 108.93 ± 9.43 μg/mL), FRAP (10.23 ± 0.11 μM), and TIA (IC50 = 4.79 ± 0.08 mg/mL).

Conclusion: The established QC method based on composition and activity is dependable and can be used for QC of P. mume.

Highlights: The chromatographic analysis method is reliable and can provide a reference for QC methods for the determination of ingredients and activity in flower-based foods.

Background: Vibrio parahaemolyticus in seafood poses a major public health concern, particularly in tropical regions.

Objective: The present study aims to isolate, assess antibiotic susceptibility, and determine the biofilm-forming ability of V. parahaemolyticus strains isolated from seafood sold in Cochin, India.

Methods: One hundred seafood samples were collected from retail markets in Cochin and analyzed for V. parahaemolyticus. Phenotypic identification was confirmed through biochemical assays and molecular characterization using polymerase chain reaction (PCR) targeting toxR, tdh, and trh genes. Biofilm formation was assessed using the microtiter plate-crystal violet assay, and antibiotic resistance was determined using the disc diffusion method.

Results: V. parahaemolyticus was detected in 43.0% (43/100) of the total seafood analyzed. A total of 43 isolates were confirmed by the toxR gene, of which five carried the tdh gene, while none harbored the trh gene. Antimicrobial susceptibility testing revealed 100% resistance to ampicillin, whereas all isolates were fully susceptible to chloramphenicol. The multiple antibiotic resistance (MAR) index ranged from 0.13 to 0.50. Notably, some multidrug-resistant isolates exhibited strong biofilm formation at 37°C.

Conclusion: The high prevalence of antibiotic-resistant V. parahaemolyticus in seafood sold in Cochin and their ability to form biofilms underscores the need for rigorous monitoring and effective control strategies to safeguard public health.

Highlights: The overall prevalence of V. parahaemolyticus in seafood from the retail market was 43.0%. The tdh gene was detected in five isolates, and none had the trh gene. All isolates exhibited resistance to ampicillin and were fully susceptible to chloramphenicol. The MAR index ranged from 0.13 to 0.50.

Background: Lauric arginate ethyl ester (LAE) is a natural cationic surfactant exhibiting excellent antimicrobial activity and has been approved as a safe additive in certain food according to the Codex Alimentarius Commission (CAC) General Standard for Food Additives (GSFA).

Objective: This study aimed to develop an analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) for the analysis of LAE in food using isotope-labeled LAE as internal standard.

Method: LAE in food was extracted by a mixture of acetonitrile (ACN)-water (9:1) and analyzed by LC-MS/MS via an internal standard calibration method using LAE-d23 hydrochloride as the internal standard.

Results: The limit of detection values of LAE were 0.32 mg/kg in liquid samples and 1.0 mg/kg in solid samples. The limit of quantitation values were 4.4 mg/kg and 14 mg/kg in liquid and solid samples, respectively. Spike recoveries consistently fell within the range of 90 to 110% at three different fortification levels, accompanied by a RSD below 10% in each instance.

Conclusions: An analytical method with LC-MS/MS detection for the analysis of LAE in various food matrixes was successfully developed, validated, and demonstrated to be fast, robust, and reliable.

Highlights: The developed analytical method with LC-MS/MS detection offered a fast and efficient way to analyze LAE in various food samples during a routine food surveillance program.