Journal of AOAC International最新文献

Background: Selenoneine exhibits antioxidant properties and is thus expected to become a new functional ingredient. Accurately determining selenoneine levels in foods is therefore critical.

Objective: This study investigated and validated extraction methods for selenoneine in seafood and seafood-derived products.

Methods: Selenoneine was extracted from seafood and seafood-derived products by sonication for 1 h and incubation at 37 °C for 24 h in a solution of 50 mmol/L dithiothreitol (DTT). The concentration of selenoneine was then determined using liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) and size-exclusion column chromatography using a mobile phase of 0.1 mmol/L ammonium acetate with 0.1% IGEPAL®.

Results: The method was validated using a DTT solution that effectively extracts selenoneine. The LOD (0.020-0.030 mg/kg), LOQ (0.067-0.099 mg/kg), repeatability (3.4-8.9%), intermediate precision (4.1-8.9%), and trueness (recovery of 94-109% based on spiked samples) of the proposed method were satisfactory for determining selenoneine in seafood and seafood-derived products. Selenoneine was detected in migratory fish and processed migratory fish products obtained in Japan. Particularly large amounts of selenoneine were detected in the dark muscle of bluefin tuna.

Conclusion: Using a reagent reactive to thiol groups, selenoneine was effectively extracted from seafood and seafood-derived products. The results of method validation analyses were satisfactory. Selenoneine was detected in processed products prepared from migratory fish, indicating that selenoneine remains even after processing. Water-soluble selenoneine was found to be extracted in the liquid.

Highlights: Selenoneine could be effectively extracted using DTT, and determination of selenoneine in various seafood was possible using LC-ICP-MS.

Background: The Bacillus cereus group (B. cereus sensu lato) is a group of spore-forming strains. B. cereus group is a human pathogen associated with foodborne outbreaks with symptoms of diarrhea and emesis.

Objective: This study evaluates the performance of BACARA® 2 (BAC2) and RAPID'B. cereus® (RAPID) agars compared to mannitol-egg yolk-polymyxin (MYP) agars and the original BACARA® (BAC) media to detect and enumerate the B. cereus group in pure culture and foods.

Methods: We incorporated five food types to include liquid milk, whey powder, mashed potatoes, rice, and tea bags. For each food matrix, there were five test portions per level inoculum prepared (low, medium, and high), and a negative control. Individual test portions were diluted 1:10 in Butterfield's phosphate buffer (BPB) and 0.1 mL of the dilutions were inoculated on BAC2, RAPID, and MYP agars. In-house R script was applied to conduct statistical analysis to compare medium performance in food adulteration tests.

Results: Inclusivity testing determined that all six B. cytotoxicus strains grew on BAC2, RAPID, and MYP but only one strain grew on BAC after 24 h incubation. RAPID had similar results as BAC2 in single-colony tests. In food tests, relative level of detection (RLOD) values indicated MYP was more sensitive for detecting B. cereus strains than BAC2 and RAPID, which is a result of B. cytotoxicus strains in mashed potato and whey powder needing an additional 24-hour incubation to exhibit typical morphology on BAC2 and RAPID.

Conclusion: Our study demonstrated the use of BAC2 and/or RAPID agar will improve the performance of the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) B. cereus method, particularly for the detection of B. cytotoxicus. Importantly, the use of BAC2 and/or RAPID will decrease the time to detect viable B. cereus strains without additional confirmation steps compared to MYP.

Highlights: For improved isolation and identification of B. cereus group in foods, we propose the use of BAC2 or RAPID as optional agars, along with MYP.

Background: The Petricore™ Aerobic Count (AC) method is used for enumeration of mesophilic bacterial colony counts in a broad range of food and environmental samples. The plate is a ready-to-use dry rehydratable film media composed of modified standard-method nutrients, water-soluble gelling agents and a tetrazolium indicator on the adhesive sheets, and transparent cover film.

Objective: The purpose of this study is to validate the Petricore AC for AOAC Performance Tested MethodsSM (PTM) certification.

Methods: Matrix studies were conducted on a broad range of foods and select environmental samples: fresh raw ground beef, fresh raw ground pork, raw bacon, raw shrimp, raw salmon, frozen raw tuna, frozen sliced mushrooms, frozen avocado, frozen blueberries, bacon-lettuce-tomato sandwich, frozen pizza (margherita), cooked sausage (fish and chicken breast), Romaine lettuce, cabbage, fresh green juice, stainless steel surface, plastic surface, and lettuce wash water. Petricore AC results were compared to standard-method plating procedure results appropriate to each matrix type. Product consistency and stability testing was performed on three production lots of Petricore AC, and robustness experiments examined the allowable range of three parameters: culture temperature, incubation time, and inoculum amount.

Results: In the matrix study, equivalent results were observed between the Petricore AC method and reference methods for all matrixes evaluated. The mean log10 differences between candidate method and reference methods were within the ranged from -0.23 to 0.35 log10 within the acceptable range of -0.50 to 0.50 log10. The range of standard deviation values of the candidate method (0.01-0.88 log10) and the reference method (0.02-0.91 log10) were similar in all matrixes evaluated. The range of correlation factor R2 was between 0.9539 and 0.9981, indicating strong correlation between the two methods. In the product consistency/stability study, the Petricore AC plate was proven to be equivalent across production lots, and the shelf life was established at 1 year. Small differences in method parameters did not affect the Petricore AC results in robustness testing.

Conclusion: The Petricore AC plate is an accurate method for the enumeration of mesophilic aerobic bacteria in the matrixes evaluated.

Highlights: The data were reviewed by the AOAC PTM Program and approval was granted for certification of Petricore AC as PTM 032502.

Background: The increasing popularity of herbal medicines and dietary supplements has raised concern about potential adulteration with pharmaceutical drugs.

Objective: To detect and determine cyproheptadine (CYP) and dexamethasone (DEX) as adulterants in weight gain herbal supplements found in the Iraqi market.

Methods: Nine herbal supplements marketed as natural weight gainers were purchased from local pharmacies and were screened using high-performance liquid chromatography (HPLC) for qualitative and quantitative detection of CYP and DEX.

Results: CYP was detected in seven of the nine products at levels of 2.65-8.6 mg per dosage unit. DEX was detected in all test solutions at levels of 6.2-18.75 mg per dosage unit.

Conclusion: A large proportion of herbal weight gain supplements was found to contain undeclared pharmaceuticals with severe health implications. The findings call for the immediate institution of tighter regulatory control and regular quality control tests in the name of consumer safety.

Highlights: Herbals and supplements for weight gain are increasingly popular but may be adulterated with pharmaceutical drugs that impose serious health risks for consumers. There is an urgent need for regulatory enforcement and routine quality checks are recommended.

Background: It is a common practice to process crude turmeric (CT) using different approaches; however, limited research is available on the comparison of volatile organic compounds (VOCs) before and after processing.

Objective: This study investigated the impact of five different processing methods on the VOCs of CT before and after processing.

Method: The five types of processed turmeric included vinegar-treated turmeric (VT), mussel powder-treated turmeric (MT), water extract of rice-processed turmeric (RT), stir-fried turmeric (ST), and wine-processed turmeric (WT). The gas chromatography-mass spectrometry (GC-MS) technique was used to identify the volatile profiles. Volatilomics based on multivariate statistics was used to assess the key metabolic differences between these five types of processed turmeric and CT within the VOCs.

Results: A total of 79 VOCs were detected between processed turmeric and CT, with terpenoids accounting for most of them. In the ST and WT groups, compared to the CT group, the number of changes in VOCs was relatively small, whereas in the VT, RT, and MT groups, there were a greater number of changes, with most metabolites exhibiting a downward trend. Through the volatilomics analysis, 13 potential differential compounds were screened out, among which there were three common differential compounds.

Conclusions: This study reveals the primary causes for the variations in VOCs in processed turmeric and CT, establishing the groundwork for evaluating the overall quality of processed turmeric and its use in therapeutic settings.

Highlights: The study systematically compared the effects of five different turmeric processing methods on VOCs using GC-MS-based volatilomics, providing a data reference for research on the changes in its pharmacological activity.

Background: D- and L-lactic acid are produced naturally by lactic acid bacteria and are found in fermented milk products, pickled vegetables, and cured meats. D-lactic acid is formed by some microorganisms only, e.g., Lactobacillus lactis and Leuconostoc cremoris. D-Lactic acid is not formed or only in traces by "higher organisms," e.g., by animals. Therefore, the presence of D-lactate may serve as an indicator for microbial contamination or spoilage, assuming that fermentation techniques have not been used.

Objective: To validate the performance of the Enzytec™ Liquid D-Lactic acid for the determination of D-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. D-lactic acids react in the presence of NAD and D-lactate dehydrogenase to pyruvate and NADH. The NADH formed is equivalent to the amount of D-lactic acid converted.

Results: Ascorbic acid, 3-hydroxybutyric acid, and sulfite interfere at concentrations higher than 0.2, 0.2, and 0.05 g/L, respectively. Oxaloacetic acid, pyruvic acid, and D-fructose do not interfere at or below concentrations of 0.2, 1, and 10 g/L, respectively. The calculated LOD when using a test volume of 100 µL is 5.4 mg/L, and the LOQ is 15 mg/L. The practical upper measurement range is 600 mg/L. Relative intermediate precision was between 3.5 and 5.7% for pineapple juice, sauerkraut juice, wine, and liquid egg. A reference material (wine) showed recoveries of 108%. For automation, three applications with different test volumes were validated. Linearity is given from 0.75 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: 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: 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: 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.