Migration of silver from nanosilver–polyethylene composite packaging into food simulants

An analytical method for the determination of silver in food simulants (3% (w/v) aqueous acetic acid or 95% (v/v) aqueous ethanol) was developed based on inductively coupled plasma mass spectrometry (ICP-MS). Recoveries ranged from 87% to 109% and RSDs ranged from 0.7% to 7.8%. The procedure was applied to determine the migration of silver from nanosilver–polyethylene food packaging film into food simulants at different temperatures and migration times. Results indicated that the maximum migration ratios were 1.70%, 3.00% and 5.60% for 3% (w/v) aqueous acetic acid at 20, 40 and 70°C, respectively, while for 95% (v/v) aqueous ethanol the maximum migration ratios were 0.24%, 0.23% and 0.22% at 20, 40 and 70°C.     

Copper release from nano‑copper/polypropylene composite films to food and the forms of copper in food simulants

The influences of temperature, exposure time, different types of polypropylene (PP), (3-Aminopropyl) triethoxysilane (KH550) used as coupling agent, sterilizing conditions on copper migration from nano‑copper/PP composite films into food/ food simulants were explored. Results showed that copper migrated more easily from polypropylene (PPH) films with a maximum rate of 34.51%, compared to those from copolymer polypropylene (PPR) and block copolymer polypropylene (PPB) to 3% acetic acid (w/v). Gamma (γ) irradiation could significantly increase the copper migration (P < 0.05). Different forms of copper were found in different simulants. Copper crystals were found in 10% ethyl alcohol and identified by scanning electron microscopy and energy dispersed analysis of X-rays (SEM-EDX). The hydroxylation (%) of nano‑copper/PP films was less than 100%. These films had certain antioxidant and antimicrobial properties which could extend the shelf life of packaged food. The migration amount of copper into rice vinegar was the largest, with a maximum of 0.65 mg/ kg.Industrial relevanceAlthough nanomaterials are potentially beneficial for food packaging, migration of nanoparticles to the packaged food can be harmful to the human body. Therefore, it is very important to determine the presence and characterize the morphology of nanoparticles in food. In this paper, we have developed a new and effective packaging material containing nanoparticles and have explored the migration form and morphology in food simulants. In conjunction with the results of current study, nano‑copper/PP packaging material can be suggested for maintaining the product quality and has commercial potential.     

Establishing a food list for a Total Diet Study: how does food consumption of specific subpopulations need to be considered?

A Total Diet Study (TDS) consists of selecting, collecting and analysing commonly consumed foods to obtain concentration data of different chemical compounds in foods as eaten. A TDS food list summarises the most consumed foods and represents the dietary habits of the general population of the country under study. The work reported here investigated whether TDS food lists that were initially designed for the whole population of the country under study also sufficiently cover the dietary pattern of specific subpopulations that are extra vulnerable for certain contaminants. The work was performed using data of three European countries: the Czech Republic, France and the UK. Each national food consumption database was combined with the corresponding national TDS food list (containing 336, 212 and 119 food items for the Czech Republic, France and the UK, respectively). The data were aggregated on the highest level of hierarchy of FoodEx-1, a pan-European food classification system, including 20 main FoodEx-1 groups. For the group ‘milk and dairy products’, the coverage of the consumption by the food list was investigated for more refined subgroups. For each food group or subgroup and country, the average percentage of coverage of the diet by the national TDS food list was calculated for different subpopulations, including children versus adults, women versus men, vegetarians versus non-vegetarians, and women of child-bearing age versus older women. The average diet of the different subpopulations was sufficiently covered by the food list of the Czech Republic and France. For the UK the average coverage was low due to a different food-coding approach and because food lists were not derived directly from national food consumption data. At the level of the 20 main food groups, differences between the subpopulations with respect to the average coverage of consumption by the TDS food list were minimal. The differences were more pronounced when looking in detail at the coverage of the dairy consumption. TDS food lists based on the mean consumption of the general population are also applicable to study the chemical exposure of different subpopulations, e.g. children, women of child-bearing age and vegetarians. This lowers the effort when performing a TDS.     

Levels of dioxins and dioxin-like PCBs in food of animal origin in the Netherlands during the period 2001–2011

ABSTRACT

The aim of this study was to assess levels of dioxins (polychlorinated dibenzo-p-dioxins and dibenzofurans, PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) (DL-PCBs) in food of animal origin produced in the Netherlands, including potential trends in time. Test results from about 2500 samples of animal derived food products (beef, veal, lamb, chicken, pork, deer, milk and eggs), sampled for the National Residue Monitoring Plan from 2001–2011, were evaluated. Most samples were screened with a bioassay and, if suspected, analysed by GC-HRMS. The fraction of samples which were non-compliant with European maximum levels was rather low, being below 1% for most food products, except for lamb. Exceedance of action levels was particularly observed for lamb and beef. To obtain an insight into background levels, a randomly taken part of the samples was directly analysed by GC-HRMS. In general, only minor decreases in mean PCDD/F and DL-PCB concentrations could be observed for the period 2001–2011. This may be due to a plateauing of current background levels but also to factors like the sensitivity of the analytical method.     

Sensitive voltammetric determination of Sudan I in food samples by using gemini surfactant–ionic liquid–multiwalled carbon nanotube composite film modified glassy carbon electrodes

A novel modified electrode was fabricated, which comprised of hydrophobic ionic liquid (i.e. trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, [P_6,6,6,14][NTf₂]), multiwalled carbon nanotubes (MWNTs) and cationic genimi surfactant (i.e. C₁₂H₂₅N(CH₃)₂–C₄H₈–N(CH₃)₂C₁₂H₂₅Br₂, C₁₂–C₄–C₁₂). Cyclic voltammetry and linear sweep voltammetry were used to investigate the electrochemical behaviour of Sudan ?. The components showed good synergic interaction in sensing Sudan ?, thus the modified electrode presented higher sensitivity. After optimising the experimental conditions, the anodic peak current of Sudan I was linear to its concentration in the range of 0.05–2 μmol l⁻¹, and the detection limit was 0.03 μmol l⁻¹ in pH 4.5 potassium biphthalate buffer with acetonitrile. The modified electrode had good stability and repeatability. It was applied to the detection of Sudan ? in hot chilli powder and ketchup samples, and the recovery was acceptable.     

Occurrence of ochratoxin A in Canadian wheat shipments, 2010–12

Randomly selected domestic and export shipments (n = 1907) of Canadian durum and other wheat that occurred between 1 January 2010 and 31 December 2012 were analysed for ochratoxin A (OTA). The majority of samples did not contain OTA above the LOQ of 1 μg kg^–1. Only 37% of samples analysed contained quantifiable OTA; the median OTA of the positive results was 2.10 μg kg^–1. Canada Western Amber Durum shipments contained OTA more frequently, and at slightly higher concentrations, than Canada Western Red Spring wheat. For both wheat classes the frequency of OTA occurrence and mean concentrations appeared to increase in the lower grades, but these increases were not statistically significant. A periodic trend of a late summer increase of mean monthly OTA concentrations in shipments appears tied to the cycle of producer deliveries of wheat to primary grain elevators.     

Spectrofluorimetric determination of buparvaquone in biological fluids,food samples and a pharmaceutical formulation by using terbium–deferasirox probe

A simple spectrofluorimetric method is described for the determination of buparvaquone (BPQ), based on its quenching effect on the fluorescence intensity of Tb³⁺–deferasirox (DFX) complex as a fluorescent probe. The excitation and emission wavelengths were 328 and 545 nm, respectively. The optimum conditions for determination of BPQ were investigated considering the effects of various affecting parameters. The variations in fluorescence intensity of the system showed a good linear relationship with the concentration of BPQ in the range of 10–1500 μg L⁻¹, its correlation coefficient was 0.999 with the detection and quantification limits of 1.1 and 3.4 μg L⁻¹, respectively. Linearity, reproducibility, recovery, limits of detection and quantification made the method suitable for BPQ assay in biological fluids, meat, dairy products and BPQ parenteral solutions (vials). The method was applied to real samples of serum and milk of three cows receiving BPQ.     

Dietary exposure and health risk assessment for 11 minerals and trace elements in Yaoundé: the Cameroonian Total Diet Study

Dietary exposure to 11 elements was assessed by the Total Diet Study (TDS) method. Sixty-four pooled samples representing 96.5% of the diet in Yaoundé, Cameroon, were prepared as consumed before analysis. Consumption data were sourced from a household budget survey. Dietary exposures were compared with nutritional or health-based guidance values (HBGV) and to worldwide TDS results. Elevated prevalence of inadequate intake was estimated for calcium (71.6%), iron (89.7%), magnesium (31.8%), zinc (46.9%) and selenium (87.3%). The percentage of the study population exceeding the tolerable upper intake levels was estimated as <3.2% for calcium, iron, magnesium, zinc and cobalt; 19.1% of the population exceeded the HBGV for sodium. No exceedance of the HBGV for inorganic mercury was predicted in the population. The margin of exposure ranged from 0.91 to 25.0 for inorganic arsenic depending on the reference point. The “Fish” food group was the highest contributor to intake for calcium (65%), cobalt (32%) and selenium (96%). This group was the highest contributor to the exposure to total arsenic (71%) and organic mercury (96%). The “Cereals and cereal products” highly contributed to iron (26%), zinc (26%) and chromium (25%) intakes. The “Tubers and starches” highly contributed to magnesium (39%) and potassium (52%) intakes. This study highlights the dietary deficiency of some essential elements and a low dietary exposure to toxic elements in Yaoundé.     

Comparability of mineral oil testing for dry food and cardboard samples – Perspectives from different PT rounds

Mineral oil hydrocarbons (MOH) can be found in detectable levels in a multitude of foodstuffs. Therefore, chemical analysis of food for MOH gains importance. Different proficiency testing (PT) rounds on mineral oil testing have been performed in different matrices: cereals and rice as well as cardboard samples were examined. The laboratories participating in the PT rounds had to follow specific requirements for examination. The sample materials used contained different concentrations of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). The PT results were statistically evaluated according to ISO 13528:2005 and additionally the HorRat(R) value was calculated to gain information on the comparability of the mineral oil testing. It could be shown that for the examined sample materials and under the chosen specifications for testing a comparable determination of the mineral oil content is possible within the required relative standard deviations. A useful analytical determination can be achieved with an acceptable relative standard deviation of <50% from a concentration of defined mineral oil fractions at ≥1 mg/kg in food. In the concentration range for MOH in food of between 1 mg/kg and 2 mg/kg, relative standard deviations of 20–40% were achieved. MOH concentrations of ≥ 2 mg/kg food were determined with good relative standard deviations of around 20%. Moreover, due to the results gained within this work a statement concerning the comparability for MOSH and MOAH contents below concentrations of 1 mg/kg food is possible: under the chosen conditions for examination as part of this work, mineral oil determination below 1 mg/kg food showed high variability. To gain reliable information with regard to consumer protection on the risk of mineral oil contents in this low concentration range further standardisation of the test method is indicated.     

Elimination of matrix effects in the determination of bisphenol A in milk by solid-phase microextraction–high-performance liquid chromatography

Solid-phase microextraction coupled to high-performance liquid chromatography (SPME–HPLC) with fluorescence detection was employed to determine bisphenol A (BPA) in milk samples. The potential influence of the milk matrix on the determination of BPA by SPME–HPLC were investigated. Optimal conditions to eliminate any matrix effects were as follows: milk samples were deproteinized with trichloroacetic acid, diluted 20-fold with BPA-free Ultrapure water, dissolved in methanol, the precipitated protein was filtered out, rinsed with methanol and evaporated to remove the methanol. Then, a 40.0-ml solution was used for SPME extraction and HPLC analysis. Satisfactory recoveries (milk: 93.1–101%; soybean milk: 93.9–102%) were achieved. The proposed method was successfully applied to real samples, BPA being detected within the range 1.6–2.6 ng ml^?1 in four brands of commercial milk but not in soybean milk.     

Response surface modelling of lead pre-concentration from food samples by miniaturised homogenous liquid–liquid solvent extraction: Box–Behnken design

In this study, a new method called miniaturised homogenous liquid–liquid extraction, followed by graphite furnace atomic absorption spectrometry, was developed for the extraction and determination of lead from food samples. The procedure was based on the fast extraction of lead from an acetic acid sample solution into 0.5 mL chloroform, as an extraction solvent. After adding water into the mixture, the extracting solvent phase immediately formed a distinct water-immiscible phase below the vial, which could easily be separated, evaporated and re-dissolved in 1.0 mL nitric acid 0.1 mol L⁻¹ for further analysis. The effects of various experimental parameters in extraction step were studied using two optimisation methods, one variable at a time and Box–Behnken design. The results showed that the amount of salt and extraction time did not have effect on the extraction efficiency. Therefore, a three-level Box–Behnken experimental design with three factors, which combined the response surface modelling, was used to optimise lead extraction. Three independent variables, including pH of solution (ranging from 6.5 to 10.5), concentration of dithizone as chelating agent (ranging from 0.05 to 0.5 μg L⁻¹) and extracting solvent volume (ranging from 300 to 900 μL) were respectively coded as pH, D and V at three different levels (−1, 0 and 1). In this study, the optimum condition was determined at pH 8.4, a volume of chloroform at 0.45 mL, and concentration of dithizone at 0.5 μg L⁻¹. Under the optimum condition, the limit of detection (LOD) was 0.05 μg L⁻¹. Furthermore, the relative standard deviation of the ten replicate was <5.0%. The developed procedure was applied to the extraction and determination of lead in the food samples.     

Survey of sulfites in wine and various Turkish food and food products intended for export, 2007–2010

Surveys were carried out between 2007 and 2010 to determine the total levels of sulfites in 1245 samples of wines, dried apricots, dried vegetables, nuts, juices and purees, frozen foods and cereals containing dried fruit supplied by food inspectors and by food producers for testing or for export certification. Sulfite analysis of wine was carried out using the Ripper method with an LOQ of 5?mg?l^?1 and for dried and other foods the Monier-Williams distillation procedure was employed with an LOQ of 10?mg?kg^?1. In the survey all wines contained measurable sulfites, but with the exception of one sample of white wine they were otherwise below Turkish Food Codex limits of 160?mg?kg^?1 for red wine, 210?mg?kg^?1 to white wine and 235?mg?kg^?1 for sparkling wine. None of the cereal products, frozen foods, juices or purees contained sulfites above 10?mg?kg^?1. However, all dried apricot samples contained significant levels of sulfite with around 40% having levels exceeding the Turkish limit of 2000?mg?kg^?1. Significant levels of sulfite were found in other samples of dried fruit with even a fruit and nut bar containing 1395?mg?kg^?1 of sulfite, suggesting the dried fruit ingredients contained levels above regulatory limits.     

Investigation of Levels and Fate of Pyridalyl in Fruit and Vegetable Samples by Fast Gas Chromatography–Mass Spectrometry

The search on pyridalyl residues, the novel insecticide, in strawberries and spring onions was evaluated. The QuEChERS technique was used for sample preparation. A fast gas chromatography–mass spectrometry (GC–MS) method was developed and validated for the analysis of pyridalyl in both matrices. Fast GC–MS was performed with a narrow-bore capillary column and a quadrupole mass detector with electron ionization and negative chemical ionization, both operating in selected ion monitoring mode. Fortification studies at 1, 5, 10, and 250 μg/kg for fruit and vegetable matrices were performed. Recoveries for all fortification levels, two ionization modes ranged from 72 to 114 %. Matrix effects were discussed. Limits of quantification were established at 1 μg/kg. Field experiments to investigate the pre-harvest interval were carried out. The proposed method was applied successfully to the determination of pyridalyl residues in samples available on Slovak market, and none of the samples contained detectable amounts of pesticides. The developed method is simple, efficient, and easy to adopt in laboratories engaged in pesticide residue analysis method.     

Determination of brominated flame retardants in food by LC–MS/MS: diastereoisomer-specific hexabromocyclododecane and tetrabromobisphenol A

The levels of the brominated flame retardants (BFRs) hexabromocyclododecane (α, β and γHBCD diastereoisomers) and tetrabromobisphenol A (TBBPA) have been determined in two studies using LC–MS/MS. The methodology developed was validated in-house and used to analyse UK 2004 Total Diet Study (TDS) samples and shellfish (oysters, mussels and scallops) collected from Scotland. HBCD was detected in most samples; in both studies the αHBCD diastereoisomer was generally the most abundant as opposed to the γ diastereoisomer that tends to dominate in environmental samples and manufactured products. It is reported that selective metabolism or biotransformation of the β and γ diastereoisomers may be taking place. TBBPA was not detected in any samples above the limit of detection, which was as low as 0.05 µg kg^–1. This may be because TBBPA, unlike HBCD, is chemically bound to the polymer matrix during manufacture and not readily leached. The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) concluded that the concentrations of HBCD and TBBPA detected in the TDS study did not raise toxicological concerns and, as levels in the shellfish samples were in a similar concentration range, it was concluded that exposure to the BFRs measured is not significant when compared to exposure from the rest of the diet.     

Proton NMR relaxation study of swelling and gelatinisation process in rice starch–water samples

Proton transverse magnetization decay curves of rice flour starch–water samples were measured and analysed for the presence of four components in the relaxation curve. T₂ values were interpreted on the basis of the diffusive and chemical exchange model that provided evidence for extra granular bulk water and three more water populations whose relaxation rate is governed by diffusive and chemical exchange with starch components. The analysis of relaxation data provided information on dynamics of water molecules as well as on the size and dispersion of diffusive domains. Furthermore, by measuring solid to liquid ratio, transverse and longitudinal relaxation curves of starch–water mixtures at increasing temperatures – from 20 to 77 °C – swelling and gelatinisation processes were monitored.     

Study of the retention and release of n-hexanal incorporated into soy protein isolate–lipid composite films

This work deals with the study of the kinetic of aroma release, which had been previously incorporated into soy protein isolate (SPI)–lipid composite films. The aim was to determine the influence of type and amount of lipidic material on aroma (n-hexanal) release and retention, as well as the apparent diffusion coefficients. To carry out this study it have been employed SPI-based films containing two SPI:LIPID ratios (1:0.25 and 1:0.5), and two types of lipids, oleic acid (OA) and beeswax (BW), in OA:BW ratios 100:0, 70:30, 50:50, 30:70 and 0:100. The measurements were performed by a gas chromatography technique. The films that showed more retention were SPI:LIPID 1:0.5 100% BW and control film. Concerning release rate, films containing BW as unique lipid material gave the lowest aroma release rate. Apparent diffusion coefficients (D_app) of all films are in the same order of magnitude (10⁻¹⁵ m² s⁻¹). D_app decreases when BW increases in the film matrix and when oleic acid amount decreases. In conclusion, for encapsulating n-hexanal, SPI-BW films demonstrated the best performances, followed by control film (without lipids).     

Pervaporation flow injection analysis for the determination of sulphite in food samples utilising potassium permanganate–rhodamine B chemiluminescence detection

A simple pervaporation flow injection chemiluminescence (PFI-CL) procedure was utilised as an on-line separation for the analysis of contaminated sulphite in food samples. The method involves the injection of standard and/or sulphite sample solutions into a 0.20 M sulphuric acid donor stream. Sulphite is converted to sulphur dioxide and transported to the donor chamber of a pervaporation module. The sulphur dioxide gas then evaporates into the headspace and diffuses across a semi-permeable PTFE membrane into an acceptor stream containing 0.75% (m/v) sodium hexametaphosphate and 1.0 mg L⁻¹ rhodamine B in 0.02 M H₃PO₄, which functions as a carrier solution for the chemiluminescence detection. The sulphur dioxide in the acceptor stream merges at a T-piece with a reagent stream consisting of potassium permanganate (8.0 × 10⁻⁵ M) prepared in the acidic sodium hexametaphosphate carrier solution. The elicited chemiluminescence intensity of the resulting reaction mixture was measured at a red sensitive photomultiplier tube operated at a voltage of 1.00 kV. Optimal experimental conditions for an on-line determination of sulphite were investigated. The second-order polynomial calibration curve was developed over the concentration range of 0.5–10.0 mg L⁻¹ sulphite with a resulting equation of I = −0.239C² + 4.846C − 1.64, r² = 0.9997. The detection limit was found to be 0.2 mg L⁻¹ with a sampling frequency of 30 h⁻¹. The effects of common anionic and cationic interferences were also investigated. The proposed PFI procedure was successfully applied to the determination of sulphite in different food samples. The PFI data was validated versus standard differential pulse polarography.     

Simultaneous determination of bisphenol A,octylphenol, and nonylphenol by pressurised liquid extraction and liquid chromatography–tandem mass spectrometry in powdered milk and infant formulas

A new analytical method, using pressurised liquid extraction (PLE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS), was developed for the simultaneous determination of bisphenol A (BPA), octylphenol (OP) and nonylphenol (NP) in powdered infant formulas (IF) and powdered skimmed milk (PM). The analytes were extracted by PLE, using this optimised conditions: ethyl acetate as solvent, 70 °C of temperature, reversed-phase silica C₁₈ as dispersing agent and three cycles of extraction. The extracts were then injected in LC–MS/MS using a Gemini C₁₈ column and a mixture of 5% water and 95% methanol/acetonitrile, both with 0.1% ammonia, as a mobile phase. Recoveries at different fortification levels (0.5 and 0.05 mg kg⁻¹), were between 89% and 92% for BPA, 84 and 98% for OP, and 93% and 101% for NP. The method was applied to the analysis of samples of PM and IF, bought in Italian and Spanish markets. In positive samples, phenols concentration ranged from 0.07 to 1.29 mg kg⁻¹ for BPA, from 0.028 to 1.55 mg kg⁻¹ for OP and from 0.026 to 1.47 mg kg⁻¹ for NP.     

Correlation between acoustic and physical–mechanical properties of insulating composite boards made from sunflower stalk and wood chips

Physical and mechanical properties of low-density insulating particleboards (0.45 g/cm³) made from wood chips and waste sunflower stalk (SFS) were studied, and correlations with the acoustic properties were determined. Two types of layered boards were manufactured, one with SFS in the central section, and the other with SFS on the surface layers; the layered boards were then compared with two kinds of homogeneous boards made from 100 % SFS and wood chips. Two types of resin were used, urea–formaldehyde (UF) and isocyanate; the press time was 5 and 7 min. Results showed that higher compression ratio in boards containing sunflower stalk resulted in significant improvement of physical–mechanical properties. Interaction between different layers of wood chips and sunflower stalk caused no clear trend in the acoustic properties of the layered boards with none of the resins; however, significant difference was found in the homogeneous boards produced with UF and isocyanate resins. High significant correlations were found between modulus of rupture and elasticity and thickness swelling (24 h) versus six acoustic properties. It can therefore be concluded that acoustic properties, as non-destructive tests, can be used to estimate some of the physical–mechanical properties of new insulating particleboards with different density and compositions.