Tạp chí Kiểm nghiệm và An toàn thực phẩm

Overview and justification of a toxicological experiment design for establishing risk assessment indicators

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 02:39:35 +0700

N-nitrosamines in food products are a serious health threat due to their carcinogenic and non-carcinogenic effects on the kidneys, spleen, GIT, and liver. Meat products are a major source of their exposure. Within a joint Russian-Vietnamese study, health risks for the Vietnam population were assessed using the methodology developed in the Eurasian Economic Union. As a result, unacceptable risk levels associated with Nnitrosodimethylamine (NDMA) in meat products were established for children under 6 years and adults 18-50 years old. However, the reference dose for NDMA established by the US EPA is based on limited data and requires experimental definition. The objective of this study is to overview the publications devoted to the study of the toxic effects of N-nitrosamines and to justify an experiment design for identifying and validating biomarkers of exposure and response upon N-nitrosamines’ exposure. In conformity with the international standards OECD and GLP principles, a design is going to be created for a 180-day experimental study of NDMA chronic toxicity using Wistar rats. The number of animal groups exposed to NDMA is four, and one group is control. Oral exposure to NDMA will take place using gavage 7 days a week. The experiment involves monthly monitoring of biochemical indicators (AST, ALT, and GGT) and NDMA levels in blood. The created design is expected to help establish points of departure (reference level, benchmark dose level) for chronic exposure as well as provide significant data for risk assessment. Taking into account three established approaches used in experimental studies to refine risk assessment’s parameters, the Benchmark dose (BMD) method was selected for this experiment’s design.

Prevalence and antibiotic resistance characteristics of extended-spectrum beta-lactamase (ESBL)-Producing Escherichia coli Isolated from pork sold at retail markets in Hanoi

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 02:45:48 +0700

Antibiotic-resistant bacteria, particularly Extended-Spectrum β-Lactamase (ESBL)-producing Escherichia coli, have emerged as a serious threat to public health. The widespread use of antibiotics in agriculture, especially pig farming, contributes to the transmission of these resistant bacteria through the food chain. Pork, a staple food in Vietnam, represents a critical vector for this transmission. This study aimed to determine the prevalence, phenotypic antibiotic resistance profiles, and genetic characteristics (ESBL-encoding genes, phylogenetic groups, and clonal relatedness) of ESBL-producing E. coli isolated from pork sold at retail markets in Hanoi, Vietnam. A cross-sectional study was conducted to collect 70 fresh pork samples from retail markets across Hanoi. The prevalence of cefotaxime-resistant E. coli in pork samples was 88.6% (62/70). Among the 167 resistant isolates recovered, 87.4% (146/167) were confirmed as ESBL producers. These isolates exhibited high rates of multidrug resistance (MDR), with 71.2% (104/146) resistant to three or more antibiotic classes. Critically, resistance to last-resort antibiotics was detected, including colistin (10.3%) and carbapenems (2 isolates). Genotypically, blaTEM was the most prevalent gene, detected in 60.3% (88/146) of isolates, followed by blaCTX-M-9 (24.7%) and blaCTX-M-1 (22.6%). Phylogenetic analysis showed a dominance of group D (54.8%). MLVA revealed high genetic diversity, with 71.9% of strains showing no close clonal relationship. This study reveals an alarmingly high prevalence of MDR ESBL-producing E. coli circulating in retail pork in Hanoi.

Research on the treatment method and production process of high-purity calcium chloride from hatching poultry eggshells waste

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 03:01:38 +0700

The rapid growth of the poultry industry generates a significant volume of eggshell by-products from hatcheries, which pose biological hazards and are often discarded, causing environmental concerns. Eggshells consist of over 93% calcium carbonate (CaCO₃), representing a valuable natural source for calcium-based products, particularly calcium chloride (CaCl₂). This study investigated pre-treated methods to reduce microbial contamination, improve membrane separation, and recover eggshells rich in CaCO₃ for CaCl₂ production. Sterilization at 121℃ for 60 min, followed by drying at 45℃ for 4 h, achieved the best microbial reduction and membrane separation efficiency (93%), the purity of CaCO₃ reaches 98%. Conversion from CaCO₃ to CaCl₂ achieved 89% recovery and 100% purity, meeting the QCVN 4-9:2010/BYT standards, with technological conditions: demembraned eggshell with (particle size >3 mm) was mixed with a 5% HCl solution at a 1:15 (mass/volume) ratio for 3.5 h. These findings demonstrate the potential for industrial-scale CaCl₂ production from eggshell waste.

Prevalence of microbial contamination and disinfectant-resistant P. aeruginosa in bottled drinking water samples tested at the National Institute for Food Control in 2024-2025

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 03:06:20 +0700

Bottled drinking water (BDW) is increasingly consumed in Vietnam; however, the risk of microbial contamination remains a significant public health concern. In particular, Pseudomonas aeruginosa (P. aeruginosa) is not only an opportunistic pathogen but also exhibits resistance to common disinfectants used in production processes. This study aimed to describe the current status of microbial contamination according to QCVN 6-1:2010/BYT and the presence of heterotrophic plate counts (HPC) in 70 BDW samples (19–21 L) tested at the National Institute for Food Control between October 2024 and April 2025. Results showed that 28.57% (20/70) of samples failed at least one microbiological parameter, with P. aeruginosa accounting for the highest contamination rate (25.71%, 18/70). Moreover, 52.86% (37/70) of samples exceeded the 500 CFU/mL limit for heterotrophic bacteria. Antimicrobial susceptibility testing revealed that 83% (15/18) of P. aeruginosa isolates were resistant to benzalkonium chloride (BKC) and 44% (7/18) were resistant to didecyldimethylammonium chloride (DDAC). The presence of qacE and qacEΔ1 genes was strongly associated with the resistance phenotype, particularly in strains harboring both genes. These findings indicate that large-volume BDW poses a high risk of microbial contamination, with P. aeruginosa being both a prevalent contaminant and notably resistant to commonly used disinfectants, suggesting the potential dissemination of resistance mechanisms within production and consumer environments.

Quality evaluation of Vietnam traditional soy sauce concerning nutritional composition and aflatoxin criteria

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 03:11:43 +0700

Soy sauce (Tương) is a traditional Vietnamese fermented dipping sauce, known for its high nutritional value and cultural significance. However, the production process poses potential risks of contamination by pathogenic microorganisms and mycotoxins (aflatoxins). This study aimed to evaluate the quality and safety of tương through three main indicators: reducing sugar content, soluble protein content, and total aflatoxin levels in 38 samples collected from Hung Yen, Hanoi, Ha Nam, and Nghe An. The results showed that 35 out of 38 samples had aflatoxin levels below the detection limit (LOD = 0.74 µg/kg), while 3 samples from smallscale producers had levels above the LOD but still within the permissible limits set by QCVN 8-1:2011/BYT. Soluble protein content in the completed products ranged from 5.05% to 6.61%, and reducing sugar varied widely between 2.26% and 10.04%. These findings provide a scientific evidence for assessing the current quality status of traditional tương products and suggest directions for improving the production process to enhance and stabilize nutritional value and food safety of the product.

Study on antibiotic resistance profiles of Escherichia coli isolated from the surface of pork-selling counters in wet markets in Gia Lam, Hanoi

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 03:20:30 +0700

The presence of Escherichia coli (E. coli) on food contact surfaces is considered a significant risk to food safety and can have a major impact on public health. This study aimed to examine the contamination rate, antimicrobial resistance profiles, and several genes encoding virulence factors of E. coli recovered from the surfaces of pork-selling counters in wet markets in Gia Lam, Hanoi City. The findings in our study show that 50% (20/50) of swab samples carried E. coli. Resistance was most prevalent against tetracycline (75%), while ampicillin, streptomycin, and sulfamethoxazole/trimethoprim all demonstrated a slightly lower but identical resistance rate of 70%. The PCR test indicates that only one isolate (5%) harbored the stx2 gene and one (5%) carried the eae gene, while none of the isolated strains possessed stx1 and ehxA.

Simultaneous determination of bromine and iodine species in dairy products by LC-ICP-MS

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 04:55:07 +0700

This study developed and optimized a liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC-ICP-MS) method for the simultaneous determination of iodine (iodide and iodate) and bromine species (bromide and bromate) in dairy products. Samples were extracted with a 10 mM ammonium carbonate solution containing 0.5 mM Mg-EDTA, then analyzed by LC–ICP–MS using an anion-exchange column (Shodex NI-424, 5 µm × 4.6 mm × 150 mm) and a mobile phase of 50 mM ammonium carbonate containing 1% methanol (pH = 10). The limits of quantification (LOQs) for iodate, iodide, bromate, and bromide in liquid milk matrices were established at 1.10, 1.77, 8.50, and 12.2 µg/100g, respectively. The corresponding values for solid samples were found to be 5.50, 8.90, 42.5, and 61.0 µg/100g. The method repeatability ranged from 1.90% to 6.01%, with recoveries between 86.3% and 109.8%, meeting AOAC performance criteria. Analysis of 26 commercial milk samples from Hanoi showed no detectable iodate or bromate. Iodide concentrations were highest in powdered milk (13.5 – 203 µg/100g) and lowest in liquid milk (1.29–34.4 µg/100g). Bromide was detected in most products, with the highest levels in powdered milk (996– 2229 µg/100g), followed by liquid milk (5.60 – 397 µg/100g) and yogurt (259 – 383 µg/100g). The results confirm that LC-ICP-MS is a robust and reliable technique for the simultaneous determination of iodine and bromine species in dairy products, providing essential data for nutritional evaluation and food safety assessment.

Determination of phosphodiesterase type 5 inhibitors in health supplements using liquid chromatography–tandem mass spectrometry (LC–MS/MS)

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 05:04:43 +0700

Phosphodiesterase type 5 inhibitors (PDE-5i) are the common oral medications prescribed for the treatment of erectile dysfunction (ED). In recent years, health supplements have gained popularity as alternative options to prescription PDE-5i. However, concerns have emerged regarding the adulteration of these products with undeclared synthetic PDE-5i or their analogues, posing significant health risks. In this study, a rapid, simple, and efficient analytical method for the determination of PDE-5i was developed and validated using a liquid chromatography–tandem mass spectrometry system (LC-MS/MS) for the rapid detection of these compounds in health supplement products collected in Hanoi. The method demonstrated excellent linearity (R² ≥ 0.999). The limits of detection (LOD) and quantification (LOQ) were 1.5 µg/kg and 5.0 µg/kg for sildenafil, tadalafil, and vardenafil, and 15 µg/kg and 50 µg/kg for the remaining PDE-5i. Recoveries ranged from 80.9% to 113% with relative standard deviations (%RSD) below 15%. The validated procedure was applied to 24 real-world samples, and 13 of them were found to contain PDE-5i. Further comprehensive investigations involving larger sample sizes and additional PDE-5i compounds are necessary to better assess adulteration practices and potential health risks.

Simultaneous determination of nine nitrosamines in fermented vegetables by GC-MS/MS

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 05:08:42 +0700

In this study, nine nitrosamines were identified in fermented vegetables by gas chromatography tandem mass spectrometry (GC–MS/MS), using NDMA-d6 as the internal standard and a DB–17MS capillary column (30 m × 0.25 mm × 0.25 µm). The QuEChERS sample preparation procedure was optimized to achieve improved extraction efficiency for the analytes. The extracted sample was injected in splitless mode with a volume of 2 µL, with helium as a carrier gas at 1 mL/min, an EI ionization source at 280℃, and a collision energy of 50 eV. The method was validated according to EC 2021/808, showing good selectivity; a calibration curve was generated over the range of 0.5–20 ng/mL with correlation coefficient R² ≥ 0.995; recoveries ranged from 83.0 to 119.6%; relative standard deviation (RSD) and relative standard deviation for repeatability (RSDr) ranged from 4.62–11.06% and 7.65–11.9%, respectively, meeting the acceptance criteria. The limits of detection and quantification were 0.15 µg/kg and 0.5 µg/kg, respectively. The method was applied to analyze 108 fermented vegetable samples from the market, of which 14 samples were found to contain nitrosamines. The nitrosamines detected were mainly NDMA, NDEA, and NDBA, consistent with published results related to nitrosamine contamination in fermented foods.

Assessment of phenolic and flavonoid contents, tannins, and antifungal potential of heat-assisted aqueous Piper betle leaf extract

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 05:11:57 +0700

Piper betle leaf (betel leaf) has been traditionally used in Southeast Asian medicine to treat ailments such as sore throat, skin abscesses, and digestive disorders. Modern research has demonstrated that the leaf contains a wide range of bioactive compounds, including phenolic acids and essential oils such as eugenol, chavicol, and chavibetol, which possess notable antibacterial, antifungal, anti-inflammatory, antioxidant, and potential anticancer properties. This study evaluated the total phenolic content, flavonoid content, the tannin presence of the aqueous extract obtained from fresh young P. betle leaf using a heat-assisted extraction method as well as the antifungal efficacy of that extract. The antifungal activity was evaluated against two opportunistic yeast strains: Candida albicans, a representative of spoilage yeasts in food and dairy products, and Candida auris, a multidrug-resistant species. Antifungal activity was assessed in-vitro using the agar well diffusion method, and the extract exhibited inhibition zones diameter ranging from 1.37 ± 0.06 cm to 2.23 ± 0.06 cm, indicating clear growth suppression. The minimum inhibitory concentration (MIC) of the extract was determined to be 32 mg dry weight equivalent per mL of extract for C. albicans and 64 mg/mL for C. auris. The total phenolics and flavonoid content were 131.06 ± 2.92 µg GAE/mg and 8.48 ± 0.19 µg QUE/mg dry weight basis, respectively. Tannin was also found in betle leaves extract, indicated by the presence of a brownish green color when reacted with FeCl₃ . These findings suggested that aqueous extracts of P. betle leaves offered promising antifungal properties against both foodborne and clinically relevant yeasts. The use of water as a solvent not only ensured safety and compatibility with food systems but also supported the development of sustainable, plant-based antifungal agents. Overall, this study contributes to the growing body of evidence supporting the application of traditional medicinal plants in modern food preservation, with P. betle offering a viable natural alternative to synthetic antifungal compounds.

Development of a real-time PCR method for detection and enumeration of Plutella xylostella granulovirus in plant protection product

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 05:15:31 +0700

Plutella xylostella granulovirus (PlxyGV) is a baculovirus that specifically infects diamondback moths (Plutella xylostella) and is widely used in commercial biopesticide formulations. To ensure the quality and efficacy of PlxyGV-based biopesticides, this study developed a quantitative real-time PCR (qPCR) method for viral DNA detection and quantification. A 222 bp fragment of the ORF30 gene encoding the envelope protein ODV-E66 was cloned into the pGEM-T Easy vector, transformed into E. coli DH5α, and verified by Sanger sequencing, showing ≥ 99% identity with the published ORF30 sequence of PlxyGV (GenBank accession No. MN099286.1). The real-time PCR method demonstrates high sensitivity, with both the limit of detection and limit of quantification reaching 10¹ copies/µL. The assay exhibits specificity and accuracy are 100%. A standard curve was established showing a strong linear correlation between cycle values and the log of viral DNA concentration (R2 = 0.9957), with an amplification efficiency of 90.1%. Repeatability (RSDr = 0.20%) and reproducibility (RSDR = 0.28%) were within acceptable ranges based on ISO 22118:2011, confirming the method's reliability and applicability for quantifying PlxyGV in plant protection products.

Eco-friendly intelligent packaging film from dragon fruit peel pigment extract for real-time seafood freshness monitoring

Tạp chí Kiểm nghiệm và An toàn thực phẩm — Tue, 30 Dec 2025 05:19:27 +0700

Environmental concerns over persistent plastic waste have driven the development of biodegradable alternatives for food packaging. In this study, a pH-responsive biodegradable indicator film was fabricated from sodium alginate and starch, incorporated with a pigment-rich extract (betalain/anthocyanin mixture) obtained from dragon fruit (Hylocereus spp.) peel. Films were prepared at various sodium-alginate-to-starch ratios and pigment loadings, and their physicochemical, mechanical, thermal, and biodegradation properties were evaluated. The optimized formulation (SA:S = 3:7) exhibited the highest tensile strength (~21 MPa), balanced water resistance, and favorable swelling behavior. Thermal analysis revealed that the composite films exhibited enhanced stability compared to pure sodium alginate films, while biodegradation assays demonstrated a mass loss of up to 59% within 30 days under natural conditions. The pigment-containing films displayed distinct pH-dependent color changes, enabling real-time visual monitoring of shrimp freshness. Under room-temperature storage, the film changed from red to bluish-yellow after four days, corresponding to a TVB-N value of 30.1 mg/100 g, indicating complete spoilage. These findings suggest that sodium alginate– starch–pigment films are promising, eco-friendly intelligent packaging materials for freshness indication.