Types Of Food Samples Research Articles

Development of an ultrasensitive electrochemical aptasensor based on aptamer/rGO/SPGE for the detection of Botulinum neurotoxin A (BoTN/A) in food samples

Consumption of Botulinum neurotoxin A (BoTN/A) contaminated foods has increased the public health issues which necessitates the development of rapid and simple diagnostic tools for their sensitive detection. Electrochemical aptasensors can replace existing biosensors and traditional methods of BoTN/A detection in foods. These aptasensors are simple, quick response, economic, precise, sensitive, accurate and reproducible. In the present study, an electrochemical aptasensor was constructed by immobilizing BoTN/A specific aptamer and reduced graphene oxide (rGO) onto screen printed gold electrode (SPGE) for the detection of BoTN/A in spiked food samples. The specificity of this aptasensor was achieved by conjugating BoTN/A specific aptamer on rGO/SPGE. Test sample containing BoTN/A form aptamer-BoTN/A complex onto SPGE which was directly proportional to BoTN/A concentration. Formation of aptamer-BoTN/A complex reduced the surface of working SPGE for redox reactions. Thus decreased the current peaks that was taken as measuring signal of BoTN/A in test food sample. BoTN/A aptasensor showed optimum response at pH 6.5 and 30 °C temperature. The responsetime of BoTN/A/aptamer/rGO/SPGE was 6 s. In optimum conditions aptamer/rGO/SPGE BoTN/A aptasensor exhibited wide linearity ranges from 1-100 pM and 1 pM limit of detection (LOD). The analytical recoveries of aptamer/rGO/SPGE BoTN/A aptasensor at 5 pM and 10 pM BoTN/A were 98.5 % and 99.8 % respectively. The proposed aptasensor showed unique sensitivity, reproducibility and accuracy. Moreover, aptamer/rGO/SPGE aptasensor was used for the detection of BoTN/A in five different types of food samples.

Easy and fast detection of S2− by a new benzothiazole-based fluorescent probe in environmental, biological and food systems

The detection of S2− is required because of its harmful effects on human health. This led us to strategically design a new benzothiazole-based fluorescent chemosensor BTP (2-(benzo[d]thiazol-2-yl)-4,6-dichlorophenol). This sensor undergoes a fluorescence color change from orange to green in the presence of S2− via the deprotonation of phenol in near-perfect water. The detection limit for S2− reached 0.78 μM and BTP could selectively probe S2− over other competing analytes. The process whereby BTP responds to S2− was suggested to be improved intramolecular charge transfer (ICT), as was demonstrated by extensive DFT calculations. Particularly, BTP was successfully applied to detect S2− in zebrafish, real water, and beverage samples. Further, test strips coated with BTP were used to monitor the S2− released in raw meat. BTP is the first benzothiazole-based chemosensor developed to detect the S2− released from various types of food samples. The proposed method offers a novel tool for measuring S2− in biological and environmental systems, as well as the food quality under on-site conditions.

Antibiotic-resistant Pattern of Isolated Bacteria from Selected Foods Sold at the Street Side Stalls and Restaurants of Tangail Municipality, Bangladesh

Objectives:: The goal of this investigation was to determine the microbial load with special emphasis on total viable count (TVC), total coliform count (TCC), total E. coli (TE.cC), and Staphylococcus spp. counts (TSC) in food samples collected from selected areas of Tangail municipality, Bangladesh. Methods:: An intensive study was carried out from December 2021 to March 2022 in the Tangail district of Bangladesh for investigation. A total of 5 types of food samples (15 from street side stalls and 15 from the selected restaurants; n= 30) were collected with a semi-structured-based questionnaire and tested by using different standard microbiological methods. Biochemical and antibiogram tests were performed to confirm the bacterial isolates and antibiotic-resistant patterns Results:: The results revealed that the values of TVC, TCC, TE.cC and TSC were found in the range of 2.5 ×106 - 8.9 ×108, 2.5×105 - 7.1×107, 1.9×103 - 5.6×105 and 5.0×105 - 4.6×106 CFU/ml in street vended foods and 5.5 ×105 - 9.5 ×106, 4.3×104 - 7.1×105, 0 to 3.9×104 and 3.1×104 - 6.6×105 CFU/ml in restaurant foods. The E. coli isolates displayed the highest resistance rates to amoxicillin (80%), whereas Staphylococcus spp. showed 90% resistance to ampicillin. Conclusion:: From the interview and observational assessment, it was found that the food service system was not well managed, and there was a lack of hygiene practices. Thus, the study identified the foods from selected areas as carriers of food-borne pathogens.

Bisphenol analogues in infant foods in south China and implications for infant exposure

Bisphenol analogues (BPs) are commonly used as modifiers, stabilizers and photo-initiators in polymer materials, including those used in food packaging. Compared to adults, infants are more sensitive to chemicals because their bodies are growing and not fully developed. Therefore, it is essential to determine the concentrations of BPs in common infant foods to assess infant exposure and prevent hazards. We collected 54 infant formula (IF) samples, 90 complementary food (CMF) samples and 62 breastmilk samples from breastfeeding women in south China. Tandem mass spectrometry coupled to liquid chromatography separation (HPLC-MS/MS) was used to detect the concentrations of 8 BPs in the three types of food samples. The estimated daily intake (EDI) of infants was also assessed. The results showed that the detection frequency of bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF) and bisphenol AP (BPAP) were relatively high among the different infant foods. BPF, BPP and BPS were predominant among the detected BPs. The lowest 95th EDI for BPA was 0.67 ng kg-bw−1 day−1, exceeding the tolerable daily intake (TDI) limit for BPA set by the European Food Safety Authority in 2023. Thus, BP exposure is a significant risk to infants. More attention should be paid to the presence of BPs in daily use products and food, and intake limits should be set for BPs other than BPA.

A wearable gloved sensor based on fluorescent Ag nanoparticles and europium complexes for visualized assessment of tetracycline in food samples.

The abuse of tetracycline antibiotics leads to accumulating residues in the human body, seriously affecting human health. Establishing a sensitive, efficient, and reliable method for qualitative and quantitative detection of tetracycline (TC) is necessary. This study integrated silver nanoclusters and europium-based materials into the same nano-detection system to construct a visual and rapid TC sensor with rich fluorescence color changes. The nanosensor has the advantages of a low detection limit (10.5nM), high detection sensitivity, fast response, and wide linear range (0-30μM), which can meet the analysis requirements of different types of food samples. In addition, portable devices based on paper and gloves were designed. Through the smartphone's chromaticity acquisition and calculation analysis application (APP), the real-time rapid visual intelligent analysis of TC in the sample can be realized, which guides the intelligent application of multicolor fluorescent nanosensors.

Bacteriological quality and safety of bottle food and associated factors among bottle-fed babies attending pediatric outpatient clinics of Government Health Institutions in Arba Minch, southern Ethiopia

BackgroundMicrobial contamination of baby bottle food has been identified as a significant public health concern, especially in developing countries, but it remains overlooked. Therefore, this study aimed to determine microbiological hazards, compliance with hygiene practices, and critical control points of contamination in baby bottle food in Arba Minch, southern Ethiopia.ObjectiveTo evaluate the bacteriological quality and prevalence of foodborne pathogens in baby bottle food and to identify associated factors among bottle-fed babies attending three government health institutions in Arba Minch, southern Ethiopia.MethodsA cross-sectional study was conducted between February 24 and March 30, 2022. A total of 220 food samples, comprising four types prepared with different sources of materials, were collected from systematically selected bottle-fed babies attending health facilities. The data on sociodemographic characteristics, food hygiene, and handling practices were solicited by face-to-face interview using a semi-structured questionnaire. Food samples (10 mL) were quantitatively analyzed for total viable counts (TVC) and total coliform count (TCC) and qualitatively for the presence of common foodborne bacterial pathogens. Data were analyzed using SPSS; ANOVA and multiple linear regression analyses were done to identify factors influencing microbial counts.ResultsResults revealed that the means and standard deviations of TVC and TCC were 5.3 ± 2.3 log10 colony forming units (CFU)/mL and 4.1 ± 2.6 log10 CFU/mL, respectively. Of the various food samples analyzed, 57.3 and 60.5% had a TVC and TCC above the maximum acceptable limits, respectively. The result of the ANOVA showed that there was a significant difference in the mean score of TCV and TCC among the four types of food samples (p < 0.001). Enterobacteriaceae were found in the majority of positive food samples (79.13%), followed by Gram-positive cocci (20.8%). Salmonella spp., diarrheagenic Escherichia coli, and Staphylococcus aureus were the common foodborne pathogens detected in 8.6% of tested foods. The regression result revealed that the type of baby food, hand washing practices of mothers or caregivers, and sterilizing and disinfecting procedures of feeding bottles are independent determinants of bacterial contamination (p < 0.001).ConclusionThe high microbial load and the presence of potential foodborne bacterial pathogens in the bottle food samples analyzed indicate unsanitary practices and the potential risk of exposure to foodborne pathogens in bottle-fed babies. Thus, interventions such as educating parents about proper hygiene practices, sterilizing feeding bottles and limiting bottle feeding practices are critical to reducing the risk of foodborne to bottle-fed infants.

Drying kinetics, thermal and morphological analysis of starchy food material: Experimental investigation through an induced type solar dryer

Solar drying is a green and clean energy-based technique for food preservation. In this study, drying kinetics and thermal, and morphological analyses of food material have been investigated. A mathematical model has also been studied and modified to validate experimental findings. An induced-type solar dryer setup has been fabricated and experiments have been conducted with potatoes as food samples. The weight loss and temperature variations were monitored in all three types of food samples. The average drying efficiency of the dryer has been found as 20.3 %. Scanning electron microscopy analysis has also been done to examine the surface morphology of the solar-dried food samples. The spherical-shaped sample has shown interesting results and they have the quality to attain maximum temperature due to the small surface area among all three shapes. The fabricated experimental setup has an initial cost and better payback period of $ 205.78 and 1.50 yr respectively.

Ribotyping and assessment of toxigenic genes of clostridium difficile strains isolated from raw meat

Background: Clostridium difficile is an anaerobic, spore forming, rod shaped bacterium that can produce toxins and may transmit through some types of food samples. The present survey was done to assess the prevalence, toxigenic gene profile and ribotyping of C. difficile strains isolated from raw bovine and ovine meat samples. Methods: Two hundred and fifty raw meat samples were collected from Isfahan, Iran and analyzed for presence of C. difficile using the microbial culture. Genomic DNA was extracted from C. difficile isolates. Extracted DNA samples were subjected to PCR for determination of tcdA, tcdB, and cdtA toxigenic genes. Ribotyping was done using the 16S and 23S rRNA genes amplification in a separated PCR assay. Results: Fifteen out of 250 (6%) raw meat samples were contaminated with C. difficile. Prevalence of C. difficile strains amongst the raw bovine and ovine meat samples were 8% and 4%, respectively. The most commonly detected toxigenic genes were tcdA (33.33%) and cdtA (20%). Distribution of tcdB was 13.33%. Amongst the combined toxigenic genes, tcdA+cdtA had the highest distribution (13.33%).

Development of an Analytical Method for Simultaneous Determinationof Quinolones and Tetracyclines in Livestock and Fishery Products

In this study, we developed an analytical method for simultaneous determination of 14 quinolones and 4 tetracyclines in livestock and fishery products using LC-MS/MS. The analytes were extracted from food samples with citrate buffer (containing EDTA)-methanol-acetonitrile (3 : 1 : 1, v/v/v) in the presence of n-hexane, and the extract was purified with an Oasis PRiME HLB cartridge column. It was suggested that this analytical method can also extract analytes from solid samples containing fat by using n-hexane. In addition, using methanol-acetonitrile (3 : 7, v/v) containing 0.1 vol% formic acid as an eluent from the cartridge column, the purification effect could be improved, while minimizing the impairment of the recovery rate. As a result of the validation using six types of food samples, trueness (accuracy) was 70.6%-113.8%, the RSD of repeatability was 9.0% or less, and the RSD of within-laboratory reproducibility was 15.5% or less. Using this approach, the standard values mentioned in the Japanese guideline were successfully met.

Direct Detection of Viable but Non-culturable (VBNC) Salmonella in Real Food System by a Rapid and Accurate PMA-CPA Technique.

Salmonella enterica is a typical foodborne pathogen with multiple toxic effects, including invasiveness, endotoxins, and enterotoxins. Viable but nonculturable (VBNC) is a type of dormant form preserving the vitality of microorganisms, but it cannot be cultured by traditional laboratory techniques. The aim of this study is to develop a propidium monoazide-crossing priming amplification (PMA-CPA) method that can successfully detect S. enterica rapidly with high sensitivity and can identify VBNC cells in food samples. Five primers (4s, 5a, 2a/1s, 2a, and 3a) were specially designed for recognizing the specific invA gene. The specificity of the CPA assay was tested by 20 different bacterial strains, including 2 standard S. enterica and 18 non-S. enterica bacteria strains covering Gram-negative and Gram-positive isolates. Except for the two standard S. enterica ATCC14028 and ATCC29629, all strains showed negative results. Moreover, PMA-CPA can detect the VBNC cells both in pure culture and three types of food samples with significant color change. In conclusion, the PMA-CPA assay was successfully applied on detecting S. enterica in VBNC state from food samples.

Identification of new serovar-specific detection targets against salmonella B serogroup using large-scale comparative genomics

Salmonella serotyping is a critical step for the identification of pathological isolates in humans and animals. Whole-genome analysis is a proven method for Salmonella serovars identification. In this study, we analysed 1668 genomic sequences of 23 serogroup B serovars and 129 genomic sequences of 80 non-target serovars to detect serovar-specific molecular targets for serogroup B (O:4 epitopes). Serogroup B is the most common serogroup found in China, whose presence is increasing in recent years. We identified five, eight, one, and seven new serovar-specific genes for Indiana, Derby, Typhimurium, and Agona serovars, respectively. We then designed specific PCR primer sets for these genes to validate our results. All target Salmonella serovars could be detected successfully by PCR in different types of food samples. The analytical sensitivity of PCR for 19 out of 21 pairs of primers was 101–103 CFU/mL and 102–105 CFU/g in pure cultures of the bacteria and artificially contaminated fresh pork samples, respectively. Furthermore, we performed a functional analysis of the newly-identified serovar-specific genes. We found that the function was unknown for most of the genes, although for some of them we were able to identify their generic functional categories (membrane protein genes and secreted proteins genes). Our findings revealed that whole-genome analysis is a valuable tool to identify new serovar-specific targets, which could be used to develop rapid and accurate molecular detection methods and provide additional information about different Salmonella serogroup B serovars.

Prevalence, virulence, antimicrobial resistance, and molecular characterization of fluoroquinolone resistance of Vibrio parahaemolyticus from different types of food samples in China

Vibrio parahaemolyticus is the leading cause of foodborne bacterial poisoning in China. The aim of this research is to conduct a study on the prevalence, virulence, and antimicrobial resistance of V. parahaemolyticus from different types of food samples in 12 different cities of China. Since fluoroquinolones are the major choice of treatment for V. parahaemolyticus infections, the genetic basis for fluoroquinolone resistance in V. parahaemolyticus were also investigated. V. parahaemolyticus was detected in 163 of the 784 food samples collected from 12 different cities in China, resulting in a prevalence of 20.79%. The prevalence of V. parahaemolyticus in ready-to-eat (RTE) food (4.96%) was much lower than those of shrimp (32.62%) and fish (22.00%). Virulence gene screening showed that 44 (27.00%) V. parahaemolyticus strains carried at least one virulence gene. Four isolates from shrimp and three isolates from fish contained both the virulence genes tdh and trh. In addition, the trh was firstly detected in one isolate collected from RTE food. All isolates exhibited relatively high resistance rates to ampicillin (82.21%), gentamicin (19.63%), and tetracycline (14.11%), while <10% of strains were resistant to ciprofloxacin (4.91%), levofloxacin (4.91%), and tetracycline (4.29%). Eight fluoroquinolone-resistant V. parahaemolyticus were selected to determine the molecular basis for fluoroquinolone resistance. These eight isolates belonged to three different types according to enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR). A Ser83Ile substitution in GyrA was deteted in seven fluoroquinolone-resistant strains, except V209 which harbored a Ser83Phe substitution in GyrA. Moreover, A Ser85Leu substitution in ParC was found in five isolates (V52, V53, V61, V163, and V209). Plasmid-mediated quinolone resistance (PMQR) genes were detected in all eight fluoroquinolone-resistant V. parahaemolyticus strains. This is the first report of Ser83Phe substitution in GyrA, qnrD and qnrS1 in V. parahaemolyticus. The information generated in this study will provide valuable information for risk assessment of V. parahaemolyticus infections and future control of antibiotic-resistant V. parahaemolyticus species in China.

Comparison of Organic and Conventional Food and Food Production Part V: Human Health – Pesticide Residues

The present report is based on data from the 2010 EFSA Report on pesticide residues in food, the Norwegian monitoring programmes 2007-2012 and data from peer reviewed literature and governmental agencies. It is a challenge to perform quantitative estimates and comparative studies of residue levels due to large variation in the measured levels, and the large number of different pesticides present in the samples. Thus, the focus is on the frequency of observed contaminations in relation to regulatory limits and to present examples to illustrate the variation in residue values and number of detected substances. &#x0D; Pesticide residues in conventional and organic products:&#x0D; Of the 12,168 samples (plant- and animal products) in the 2010 EU-coordinated programme, 1.6% exceeded the respective maximum residue level (MRL) values, and 47.7% had measurable residues above the limit of quantification (LOQ), but below or at the MRL. Of the 1168 samples analysed in Norway in 2012 (from both imported and domestic products), 1.9% exceeded MRL and 53% contained measurable pesticide residues. Direct comparison of these values is however not possible, since they contain different types of food samples, and are analysed for a different number of pesticides.&#x0D; When organic and conventional samples from fruit, vegetables and other plant products in the 2010 EU-coordinated programme were compared, 4.2% of the conventional and 1.0% of the organic samples exceeded the MRL values, while 43.2% of the conventional and 10.8% of the organic samples had measurable residues below or at the MRL value. Most of the pesticide residues detected in organic samples are not permitted for use in organic farming. &#x0D; Of the 624 organic samples analysed in Norway 2007 - 2012, 0.2% (one sample) had residues exceeding MRL, while measurable residues were detected in 1.8% of the samples (11 samples).&#x0D; Conventional products were often found to contain different pesticides while most organic samples were found to contain few or only one type of pesticide. &#x0D; Lack of data on pesticide residue levels of organic samples in the EU-coordinated programme, and few Norwegian samples do not allow for a quantitative comparison of pesticide residue levels in organic and conventional samples. Comparative estimation of pesticide residues faces a number of challenges and uncertainties. However, it seems unquestionable based on available data that organic plant products contain fewer and substantially lower amounts of pesticide residues than conventional products.&#x0D; Health risk associated with pesticide residues:&#x0D; The general level of pesticide residues in both conventional and organic food is low, and well below what is likely to result in adverse health effects. This conclusion is based on the comparison of estimated dietary exposure with toxicological reference values i.e. acceptable daily intake (ADI) for chronic effects, and acute reference dose (ARfD) for acute effects. The finding of pesticide residues that exceeds established regulatory limits in a minority of tested samples is not considered to represent a health risk.&#x0D; When dietary exposure that was estimated in six different food commodities in the 2010 EUcoordinated programme was compared with their relevant reference values, EFSA concluded that for 79 of 18243 conventionally grown fruit and vegetable samples, a short-term acute consumer health risk could not be excluded. The conclusion was based on the exceeding of ARfD. None of these 79 samples were organic. It is important to also consider that the exceeding of the acute reference value only occurred in 0.4% of the samples and that the scenario used for acute intake assessment is conservative, suggesting that the toxicological implications are limited. This is also reflected in the chronic exposure assessment, where none of the samples were found to exceed the toxicological reference value ADI. &#x0D; Dietary exposure assessments on the basis of Norwegian samples of apples, tomatoes, carrots, strawberries and lettuce did not show an exceeding of any toxicological reference value. &#x0D; Combined exposure and cumulative risk assessment of pesticide residues:&#x0D; No generally accepted methodology is at present established for cumulative risk assessment of combined exposure to pesticide residues. Available data suggest however that combined exposure is not likely to result in increased human health risk.

Differences in subjective taste between Japanese and Sri Lankan students depending on food composition, nationality, and serum zinc

Summary Background & aims Taste is a very important factor affecting nutritional intake and compliance. Subjective taste may differ among nationalities. In the present study we examined differences in subjective taste according to food composition and nationality. Methods Twelve Japanese and 4 Sri Lankan students took part in the study. Food samples of 3 different mixtures of chicken and rice were tasted: Food 1, 3 g chicken/10 g rice; Food 2, 6 g chicken/10 g rice; Food 3, 9 g chicken/10 g rice. The sweet, salty, sour, bitter, and astringent taste of each of the food samples, as well as their deliciousness, were scored subjectively on a scale of 0–5. Results were compared between the 3 types of food samples, as well as between nationalities. In addition, concentrations of blood micronutrients were measured. Results Across all 3 types of food, the change in subjective taste of salty, sweet, and sour differed significantly between Japanese and Sri Lankan students (P = 0.022, P = 0.008, and P = 0.025, respectively). However, bitter and astringent taste, as well as the perceived overall deliciousness of the foods, was comparable between the 2 groups. Serum zinc levels were significantly lower in Sri Lankan than Japanese students (P = 0.004). Conclusions Subjective assessment of taste differs according to food composition and nationality, and it is important to consider taste preferences according to nationality when promoting oral nutritional support.

Detection of Escherichia coli in ready-to-eat fresh vegetables using broad-host-range recombinant phages.

To construct a simple method to detect Escherichia coli in ready-to-eat fresh vegetables using broad-host-range recombinant phages. Firstly, a gene encoding cytochrome c peroxidase (CCP) chromogenic enzyme was inserted into genomes of wild-type phages IP008 and IP052 to produce recombinant phages IP008BK and IP052BK. They were then used in the production of the chromogenic enzyme (CCP) through infection into E.coli. The method was then examined in the colorimetric detection of E.coli K12 in broth, and its appearance was confirmed by a significant change in absorbance after a few minutes of the enzyme assay. Secondly, the protocol using the recombinant phages for the detection of E.coli in vegetables, that is, lettuce and mustard greens, was investigated. A low E.coli concentration at 4CFU per g vegetable was detected within 16·5h that is of a shorter duration than agar plate methods and in some commonly known phage-based methods. The existence of E.coli as a faecal contamination indicator in two types of ready-to-eat fresh vegetables, that is, lettuce and mustard greens, can be identified by the broad-host-range recombinant phages. The method is simple and convenient since it enables the detection of E.coli without expensive apparatus. It is applicable to other types of food samples.

Monitoring of genetically modified food on the Czech food market and a cross-country comparison

The presence of genetically modified organisms (GMOs) was analysed in food samples from the Czech food markets. Four different types of food samples (soya beans, soya bean products, maize flour, and rice) were collected at twelve places in four terms in the years 2008–2013. It represents a total 1152 food samples. Soya and maize were chosen, because these are the major transgenic crops grown worldwide. Increased cultivation of GM rice in China, India, Indonesia, and the Philippines has been observed. Polymerase chain reaction-based methods were applied to detect GMOs. GMOs were detected in 107 samples (9.3%). The results show that in food from the Czech food market GMOs mainly in maize flour and rice were found. GM maize was detected in 63 (21.9%) maize flour samples. Maize lines MON810, NK603, and Bt176 were detected in 14 (22%), 9 (14%), and 1 (1.6%) maize flour samples, respectively. Unauthorised GM rice was detected in 39 (13.5%) rice samples. Unauthorised rice Bt63 was detected in one sample of rice. Roundup Ready soya was detected in 4 (1.4%) soya bean samples and in 1 (0.35%) soya product sample. These results were compared with results of the world´s studies.

Development of an Aluminium Doped TiO2 Nanoparticles‐modified Screen Printed Carbon Electrode for Electrochemical Sensing of Vanillin in Food Samples

AbstractA new chemically modified electrode based on titanium dioxide nanoparticles (TiO2‐NPs) has been developed. Aluminium was incorporated into the TiO2‐NPs to prepare aluminium doped TiO2 nanoparticles (Al‐TiO2‐NPs). Aluminium doped TiO2 nanoparticles‐modified screen printed carbon electrode (Al‐TiO2‐NPs/SPCE) was employed as easy, efficient and rapid sensor for electrochemical detection of vanillin in various types of food samples. Al‐TiO2‐NPs were characterized by energy‐dispersive X‐ray (EDX), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) and analyses showing that the average particle sizes varied for the Al‐NPs (7.63 nm) and Al‐TiO2‐NPs (7.47 nm) with spherical crystal. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to optimize the analytical procedure. A detection limit of vanillin was 0.02 μM, and the relative standard deviation (RSD) was 3.50 %, obtained for a 5.0 μM concentration of vanillin. The electrochemical behaviour of several compounds, such as vanillic acid, vanillic alcohol, p‐hydroxybenzaldehyde and p‐hydroxybenzoic, etc., generally present in natural vanilla samples, were also studied to check the interferences with respect to vanillin voltammetric signal. The applicability was demonstrated by analysing food samples. The obtained results were compared with those provided by a previous method based on liquid chromatography for determination of vanillin.

Screening and Detecting Salmonella in Different Food Matrices in Southern Tunisia Using a Combined Enrichment/Real-Time PCR Method: Correlation with Conventional Culture Method.

A combined enrichment/ newly developed invA TaqMan® real-time PCR (qPCR) method as a screening assay to detect Salmonella spp. in 500 naturally food matrices is evaluated. DNA template for qPCR was extracted from an overnight pre-enriched sample in buffered peptone water using lysis–guanidine isothiocyanate method. Heterologous internal amplification control (IAC) was incorporated during qPCR assays and co-amplified with the invA gene of the target pathogen. InvA qPCR exhibited 100% specificity when testing 94 Salmonella strains (inclusivity) and 32 non-Salmonella strains (exclusivity). The qPCR showed a consistent detection of two copies of the invA gene/PCR reaction, a good intra- and inter-run reproducibility with a good PCR efficiency (89.6%). QPCR was sensitive and showed Salmonella detection at 8.5 × 100 CFU mL-1 of artificially spiked poultry meat -BWP solution in less than 40 cycles. When analyzing 500 different food matrices and comparing the results with the ISO 6579:2002 conventional culture method, the sensitivity and specificity were 100 and 76.6%, respectively. QPCR showed Salmonella spp. DNA in raw poultry meat 27/45 (60%), milk 31/93 (33.3%), raw red meat 5/13 (38.5%), and fish 11/46 (23.9%) samples. The prevalence of Salmonella spp. in cakes, dairy, cooked meals, charcuterie products using qPCR was 11/14 (26.8%), 5/22 (22.7%), 32/150 (21.3%), and 5/20 (25%), respectively, compared to 0% as demonstrated by culture. S. Anatum was the most common serovar found associated with red meat compared to S. kentucky isolated from fish and poultry meat. In conclusion, our study is the first to use a combined enrichment/invA qPCR method as a screening assay to detect Salmonella DNA in different types of commercialized food in Southern Tunisia. QPCR results indicate that Salmonella contamination is common in milk and in other types of food samples.

Multi-contaminant analysis of organophosphate and halogenated flame retardants in food matrices using ultrasonication and vacuum assisted extraction, multi-stage cleanup and gas chromatography–mass spectrometry

A multi-residue analytical method was developed for the determination of a range of flame retardants (FRs), including polybrominated diphenyl ethers (PBDEs), emerging halogenated FRs (EFRs) and organophosphate FRs (PFRs), in food matrices. An ultrasonication and vacuum assisted extraction (UVAE), followed by a multi-stage clean-up procedure, enabled the removal of up to 1g of lipid from 2.5g of freeze–dried food samples and significantly reduce matrix effects. UVAE achieves a waste factor (WF) of about 10%, while the WFs of classical QuEChERS methods range usually between 50 and 90%. The low WF of UVAE leads to a dramatic improvement in the sensitivity along with saving up to 90% of spiking (internal) standards. Moreover, a two-stage clean-up on Florisil and aminopropyl silica was introduced after UVAE, for an efficient removal of pigments and residual lipids, which led to cleaner extracts than normally achieved by dispersive solid phase extraction (d-SPE). In this way, the extracts could be concentrated to low volumes, e.g. <100μL and the equivalent matrix concentrations were up to 100g ww/mL. The final analysis of PFRs was performed on GC–EI-MS, while PBDEs and EFRs were measured by GC–ECNI-MS. Validation tests were performed with three food matrices (lean beef, whole chicken egg and salmon filet), obtaining acceptable recoveries (66–135%) with good repeatability (RSD 1–24%, mean 7%). Method LOQs ranged between 0.008 and 0.04ng/g dw for PBDEs, between 0.08 and 0.20ng/g dw for EFRs, and between 1.4 and 3.6ng/g dw for PFRs. The method was further applied to eight types of food samples (including meat, eggs, fish, and seafood) with lipid contents ranging from 0.1 to 22%. Various FRs were detected above MLOQ levels, demonstrating the wide-range applicability of our method. To the best of our knowledge, this is the first method reported for simultaneous analysis of brominated and organophosphate FRs in food matrices.

음식물의 악취 황화합물 발생특성 조사: 계란, 우유, 고기통조림, 딸기에 대한 사례 연구

In this study, the emission patterns of reduced sulfur compounds (RSC) were investigated using four different types of food samples (boiled egg, milk, canned meat and strawberry) between fresh and decaying stages. To this end, the concentrations of RSCs were measured at storage days of 0, 1, 3, 6, and 9 under room temperature. Four sulfur compounds (, , DMS and DMDS) were selected as target compounds along with two reference compounds ( and ). Their concentrations were quantified using GC-PFPD equipped with thermal desorption (TD) system. The boiled egg showed the highest concentration of (3,655 ppb) at D-1, while reached its maximum value of 64.4~78.5 ppb after 3 days. In milk samples, concentration of , DMS, and DMDS went up to 487, 16.3, and 578 ppb, respectively with the progress of decay (D-9). In case of canned meat, concentration of and peaked in the beginning (D-0) such as 345 and 66.6 ppb. In case of strawberry, and DMDS showed the maximum concentrations 135 and 50.5 ppb at D-1, respectively. The olfactometry dilution-to-threshold (D/T) ratio by air dilution sensory (ADS) test showed similar patterns when sum of odor intensity (SOI) was derived via conversion of odorant concentration data. The results of this study confirm that the time of strong RSC emissions is distinguished for each food type between fresh (e.g., strawberries) and decaying conditions (e.g., milk).