Further insights into the mechanism of migration from the PVC gaskets of metal closures into oily foods in glass jars

Factors influencing migration from the gaskets of metal closures into oily foods were investigated. Tightening of the lid has an effect presumably through the deformation of the gasket, the amount of oil adhering to the latter, and the proportion of its surface being covered by oil. The substantial difference observed in the migration determined with the jar in an upright or a reversed position is partly related to this. The nature of the plasticizer determines the saturation in the partitioning process between the gasket and the small amount of oil in contact with the gasket as well as the adherence of oil (wettability). If saturation is rapidly reached, the frequency of exchanging the oil by shaking of the jar is an important factor. A complete exchange of the oil in contact with the gasket requires vigorous and persisting shaking, presumably because of the high viscosity and the hindered access to the angle between the gasket and the jar rim. The limited data available on long-term performance suggest that migration accelerates after roughly one year of storage. It is concluded that the extrapolation of long-term migration from short-term data presupposes a deeper investigation of the course of migration over years.     

Determination of nine preservatives in processed foods using a modified QuEChERS extraction and quantified by HPLC-PDA

ABSTRACT

In this study, a new method was developed for simultaneously determining nine preservatives, that is, benzoic acid (BA), sorbic acid (SOA), dehydroacetic acid (DHA) and PHBAs (methyl p-hydroxybenzoate [PHBA-me], ethyl p-hydroxybenzoate [PHBA-et], isopropyl p-hydroxybenzoate [PHBA-ipro], propyl p-hydroxybenzoate [PHBA-npro]), isobutyl p-hydroxybenzoate [PHBA-ibut] and butyl p-hydroxybenzoate [PHBA-nbut]), in processed foods, employing liquid chromatography (LC). This procedure accelerated sample preparation and improved efficiency by employing modified quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction without clean-up. Samples were prepared with 20 mL of acetonitrile/water (1:1) with the assistance of a ceramic stone. The extract solutions were diluted 10 times or according to the detection amount and then injected into an LC-PDA. This method showed good linearity, and the LOQs were 10 mg/kg for BA, SOA and DHA and 5?mg/kg for the PHBAs. When validating this method, the recoveries of the nine preservatives were in the range 77.0–99.6%, RSD_r values were in the range 0.7–5.3% and those of RSD_wr were in the range 2.3–8.4%. These results suggest that this new method is highly reproducible.     

Effect of some habitual cooking processes on the domoic acid concentration in the cockle (Cerastoderma edule) and Manila clam (Ruditapes philippinarum)

The effect of cooking on the concentration and burden of domoic acid in two bivalve molluscs was studied. The Manila clam (Ruditapes philippinarum) and cockle (Cerastoderma edule) were subjected to steaming and boiling, respectively. In both cases, factorial plans were used to evaluate the effects of common cooking methods and the variations likely to take place during the cooking procedure (cooking time and salt concentration in both species, in addition to ethanol percentage in Manila clam). The domoic acid concentration and toxin content were affected by cooking in very different ways in the two species studied. The cockle lost a significant part of its domoic acid content, while the clam did not. Since the weight of the soft tissues in cooked bivalves was lower than in the raw samples in both species, the toxin concentration decreased less than the toxin burden in the cockle, while it increased in the clam, where the toxin burden did not change significantly. Among the cooking variables tested, only cooking time had a noticeable effect on the domoic acid content in the clam and cockle, with the bivalves that were cooked for a longer time having smaller amounts of toxin. It is clear that cooking affects the toxin concentration in bivalves in a way that is species specific. This characteristic must be taken into account when evaluating epidemiological information, establishing allowable toxin levels and in cases where pre-processing treatments such as cooking or similar methods are used in monitoring systems.     

The chemistry and analysis of annatto food colouring: a review

Annatto food colouring (E160b) has a long history of use in the food industry for the colouring of a wide range of food commodities. The principal colouring component of annatto is the oil-soluble diapo carotenoid bixin, which is the methyl ester of the dicarboxylic acid norbixin and soluble in aqueous alkali. Bixin and norbixin, therefore, exhibit not only physicochemical properties normally associated with carotenoids, but also certain anomalous properties that have an impact on the stability, food colouring applications, and importantly the analysis of annatto. This review summarizes the key aspects of the structural determination of bixin (and norbixin) with special attention to cis-trans isomerization and how this links with its chemical structure, spectroscopic properties, and stability. The oxidative, thermal, and photo-stability of annatto and the subsequent implications for its use in the colouring of foods, food processing, and the analysis of foods and beverages are discussed along with important mechanistic, thermodynamic and kinetic aspects. The main analytical techniques used for the chemical characterization of annatto, i.e. spectrophotometry, nuclear magnetic resonance (NMR), chromatography (particularly high-performance liquid chromatography (HPLC)) and mass spectrometry are reviewed in detail and other methods are discussed. This links in with a review of the methods available for the detection and measurement of annatto in colour formulations and foods and beverages, which highlights the importance of the need for a good understanding and knowledge of the chemistry of bixin and norbixin in order to meet new analytical challenges.     

Corrosion behaviour of tinplate cans in contact with tomato purée and protective (inhibiting) substances

The dissolution of iron and tin from tinplate cans filled with tomato purée (pH 4.34) and dioctyl sebacate oil (DOS), essential onion oil (EOO) or potassium nitrate was studied using atomic absorption spectroscopy (AAS), while nitrate was determined using high-performance liquid chromatography (HPLC). The maximum values found in cans were up to 284 mg kg^?1 for tin and 513 mg kg^?1 for iron at elevated storage temperature. Results indicated that the addition of EOO to tomato purée prevents the corrosion process in the case of tin, where concentrations were lowered from 223 to 28 mg kg^?1 for cans with DOS oil and EOO at 20°C, respectively (inhibition rate of 87%). On the other hand, the presence of EOO enhanced the corrosion process for iron increasing the concentration from 15 to 46 mg kg^?1 during 7 months of storage, although this value did not exceed maximum permitted value (50 mg kg^?1). In cans with tomato purée and potassium nitrate, dissolution of tin started after 30 (36°C) and 60 (20°C) days of storage as a consequence of nitrate action, which act as a corrosion accelerator. Since the addition of EOO improves the taste of canned tomato purée, its potential use as a corrosion inhibitor would be of interest.     

Usage pattern and exposure assessment of food colours in different age groups of consumers in the State of Uttar Pradesh,India

The present study aims to investigate the nature and levels of colours in food items and to undertake risk assessment vis-à-vis intake among different age groups of consumers in the State of Uttar Pradesh, India. A total of 478 edible foodstuffs were analysed, and of six permitted colours, Sunset Yellow FCF (SSYFCF) and Tartrazine were most popular, and two non-permitted colours, namely Metanil Yellow and Rhodamine B, were encountered. The study showed a marked improvement in the trend of use of non-permitted colours over previous surveys, with 90% foods now resorting to approved food colours. However, 59% of foods employing permitted colours exceeded the maximum allowable limit, with average quantities crossing the threshold of 100 mg kg^?1 in most food commodities. The intake of SSYFCF exceeded the acceptable daily intake (ADI) for children and adolescents by 88% and 39%, respectively, and was statistically significant when analysed by error bars and distribution curves. In adults, SSYFCF saturated 59% of the ADI. For Carmoisine, Tartrazine and Ponceau 4R, saturation of ADI ranged from 27.4% to 90.3% in children and adolescents and from 10.8% to 47.6% in adult subjects. These results indicate that children and adolescents are more vulnerable to higher intakes of food colours compared with the adult population. Allowing a uniform level of all colours in foods under Indian rules, notwithstanding wide variations of 250-fold in their allocated ADIs, could be one reason for the higher intake and hence only technological need-based levels of individual colours are desired to be prescribed.     

Migration of polyolefin oligomeric saturated hydrocarbons (POSH) into food

POSH are polyolefin oligomeric saturated hydrocarbons, such as oligomers from polyethylene or polypropylene. POSH that have migrated into foods are easily mistaken for mineral oil-saturated hydrocarbons (MOSH). In fact, both POSH and MOSH largely consist of highly isomerised branched and possibly cyclic hydrocarbons, both forming humps of unresolved components in gas chromatography. Chromatograms are reported to show typical elution patterns of POSH and help analysts distinguishing POSH from MOSH as far as possible. Since the structures of the POSH are not fundamentally different from those of the MOSH, it would be prudent to apply the evaluation of the MOSH. However, the migration is frequently beyond that for which safety has been demonstrated. This is shown for a few examples, particularly for powdered formula for babies.     

Controlled release of α-tocopherol,quercetin, and their cyclodextrin inclusion complexes from linear low-density polyethylene (LLDPE) films into a coconut oil model food system

Polymer additive migration into a food product is dependent upon numerous factors including the original concentration of the additive in the polymer, its solubility in the food, its diffusion coefficient in the polymer, its partition coefficient between the polymer and food, temperature, and time. The limited solubility of quercetin in linear low-density polyethylene (LLDPE) did not allow release from the film due to phase segregation of the quercetin in the bulk polymer. Increasing the molecular weight of α-tocopherol by β-cyclodextrin inclusion complexation can greatly reduce its diffusion coefficient in LLDPE. Ziegler–Natta and metallocene LLDPE contain different crystalline structure morphologies and diffusion path networking arrangements that allow for differences in additive release rates. Effective controlled-release packaging should combine β-cyclodextrin complexation of additives and polymer morphology control to target delivery of an optimal antioxidant concentration to achieve prolonged activity, resulting in extended shelf life foods.     

Diffusion behaviour of additives in polypropylene in correlation with polymer properties

The migration behaviour of polymer additives in 17 polypropylene (PP) samples is described. These samples cover the major types of PP used in food packaging. The diffusion coefficients of additives with relatively small molecular masses, M _r = 136 (limonene), as well as the migration of typical antioxidants used in PP up to M _r = 1178 (IRGANOX 1010), were measured at different temperatures. In addition, the diffusion data and percentages of xylene-soluble fractions were correlated. This enables a prediction of the migration behaviour of a PP sample by testing its ‘isotactic index’ with xylene. The results clearly indicate that PP can be subdivided, from the migration point of view, into the monophasic homopolymer (h-PP), the monophasic random copolymer (r-PP), and the heterophasic copolymer (heco-PP). The diffusion coefficients for r-PP are at least one order of magnitude higher than those of h-PP and comparable with the values for heco-PP. Upper limits for the diffusion values can be calculated based on the safety margin required by consumer protection laws.     

Production of citreoviridin by Penicillium citreonigrum strains associated with rice consumption and beriberi cases in the Maranhão State,Brazil

The aim of this study was to determine the levels of Penicillium citreonigrum and citreoviridin present in rice samples from Maranhão State, Brazil, where an outbreak of beriberi was reported and 32 deaths occurred (7% of the notified cases died in 2006). The ability of P. citreonigrum to produce citreoviridin was assessed, and a total of 420 samples of 21 different kinds of rice were collected. Mycobiota isolation and identification, the ability of citreoviridin strains to produce toxin, and the natural occurrence of citreoviridin were established. Rice samples were found to have high fungal counts and showed increasing levels from 2004 to 2007 harvest years. The most frequent genus was Aspergillus followed by Penicillium and Cladosporium. Ten out of eleven strains of P. citreonigrum were able to produce citreoviridin. Three rice samples had levels of citreoviridin ranging from 12 to 96.7 ng g^?1, and two bran samples had levels of 128 and 254 ng g^?1. These samples contaminated with P. citreonigrum and citreoviridin were involved in the beriberi cases from Maranhão State. Monitoring rice for mycotoxins in areas where this substrate is the basic food is crucial to prevent outbreaks like the one reported in this study, to improve management practice, and to diminish exposure risk of humans to these harmful toxins.     

Agaritine content of 53 Agaricus species collected from nature

Fifty-three different species of the genus Agaricus were collected in the Czech Republic during the period 1998–2001 and identified by an experienced mycologist. The samples were analysed for agaritine (N ²-(γ-L-glutamyl)-4-hydroxymethylphenylhydrazine) content, a precursor to a suspected rodent carcinogen. There was a huge variation in agaritine content between species, but less variation between samples of a species. Whereas the cultivated mushroom Agaricus bisporus commonly contain 200–500 mg agaritine kg^?1 fresh weight, no less than 24 of the 53 species contained agaritine levels above 1000 mg kg^?1 fresh weight. The highest level was found in A. elvensis containing up to 10, 000 mg kg^?1 fresh weight. Twenty species contained intermediate levels (100–1000 mg kg^?1), and nine species were below 100 mg kg^?1. Some of the species producing low levels of agaritine might be candidates for future strain development of Agaricus mushrooms for cultivation. No correlation could be observed between agaritine content and size of the mushroom, week of the year when collected, year of collection, or site of collection. Besides occurring in the genus Agaricus, some species of the genera Leucoagaricus and Macrolepiota were also shown to contain agaritine.     

Formation of fumonisins and other secondary metabolites by Fusarium oxysporum and F. proliferatum: a comparative study

The principal aim of this study was to estimate the formation of fumonisins (FB₁ and FB₂), moniliformin (MON), and ergosterol (ERG) by Fusarium oxysporum and Fusarium proliferatum, while the formation of beauvericin (BEA) was estimated by the latter Fusarium species only. Moreover, the effect of temperature on the biosynthesis of mycotoxins was also evaluated. Fumonisins were formed by F. proliferatum, with the highest yield at 18°C (720.0–1976.6 µg g^?1 for FB₁, 74.2–670.8 µg g^?1 for FB₂) and only by three of four F. oxysporum strains at a very low level (0.02–4.77 µg g^?1 for FB₁, 0.02–2.15 µg g^?1 for FB₂). The amount of MON formed by F. proliferatum was the highest (p < 0.001) at 32°C (3056.87 µg g^?1), while MON biosynthesis by F. oxysporum was lower 227.54 µg g^?1 (p < 0.001). BEA was produced by F. proliferatum with the highest level at 25°C (p < 0.001). ERG–recognized as an indicator of fungal biomass development and as a consequence of mycotoxin formation–was found at the highest concentration at a biosynthesis temperature of 25°C for F. proliferatum and F. oxysporum (p < 0.001).     

Survey of aflatoxins in retail samples of whole and ground black and white peppercorns

A total of 126 local and imported samples of commercial white and black pepper in Malaysia were analysed for aflatoxins B₁, B₂, G₁ and G₂ (AFB1, AFB2, AFG1, AFG2) content using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). An acetonitrile–methanol–water (17 : 29 : 54; v/v) mixture was used as a mobile phase and clean-up was using an immunoaffinity column (IAC). Seventy out of 126 (55.5%) samples were contaminated with total aflatoxins, although only low levels of aflatoxins were found ranging from 0.1 to 4.9 ng g^?1. Aflatoxin B₁ showed the highest incidence of contamination and was found in all contaminated samples. There was a significant difference between type of samples and different brands (p < 0.05). The results showed black peppers were more contaminated than white peppers.     

高效液相色谱法测定牛奶中林可霉素的残留量

研究建立牛奶中林可霉素残留量的高效液相色谱测定方法。样品用水相提取,离心分离,经C18固相萃取柱净化,在210nm波长下用二极管矩阵检测器检测。色谱柱为Agilent ZORBOX SBC18柱(4.6×250mm,5μm),以0.05mol/L硼砂溶液(用磷酸调节pH6.0)-甲醇(55:45,V/V)为流动相,流速1.0ml/min。林可霉素浓度在1.0～10.0μg/g范围内与峰面积呈良好的线性关系,平均回收率为82.9%～93.1%,变异系数为1.45%～4.58%,最低检测限为0.5μg/ml。本方法简便、快速、准确。     

Comparison of extraction solvents and conditions for herbicide residues in milled rice with liquid chromatography-diode array detection analysis (LC-DAD)

Different extraction procedures and clean-up methods were compared in order to develop a sample preparation procedure for the multi-residue analysis of six post-emergence herbicides (metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium and cyhalofop butyl) in rice grains followed by liquid chromatography-diode array detection (LC-DAD). Optimum results were obtained dispersing milled rice grain in water, followed by the addition of 1% acetic acid in acetonitrile, MgSO₄ and sodium acetate as a modification of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method but no primary and secondary amine (PSA) sorbent was added due to the acidic nature of the herbicides. The method was further expanded to other post-emergence herbicides (quinclorac, clomazone and propanil). Except for quinclorac, which cannot be analysed with this method, the recoveries of the other eight herbicides were in the range 73–111%, with relative standard deviations lower than 12%. Limits of detection (LODs) ranged from 0.03 to 0.08 mg kg^?1. A single analyst can extract twelve samples in 4 h. The method presented here allows the simultaneous residue determination of the most common post-emergence herbicides employed in cultivating rice. It is simple, rapid, sensitive, and can be applied routinely to polished rice grain herbicide residue analysis.     

Residues of antibacterial drugs in honey from the Italian market

Antibacterial drugs are used worldwide for the control of American and, less often, European foulbrood. Their administration is mostly uncontrolled and applied without approved protocols and instructions for use as well as precautionary recommendations. Consequently, this practice is responsible for the contamination of beehive products and contributes to the problem of food safety. According to this situation, 4672 analyses were carried out on 5303 honeys collected from 2001 to 2007. These samples were investigated for antibacterial residues of tetracyclines, sulphonamides, streptomycin, chloramphenicol and tylosin. Honeys were classified according to their origin: imported honey and honey from the Italian market. In the last group (only for samples collected from 2001 to 2004), another type of honey was distinguished: that of local honey. A total of 6.3% of all samples were positive for the antibacterial drugs analysed; in particular, 6.8% of imported honeys and 6.1% of honeys on the Italian market. Only 1.7% of local honey had antibacterial residues. These results are indicative of a rather frequent presence of antibacterial drug residues in both Italian and imported honeys. Furthermore, the data showed that among the active substances analysed, sulphonamides are the most used antibacterial substance followed by tetracyclines, streptomycin, tylosin, and chloramphenicol. Finally, a continuous monitoring programme is needed, accompanied by an education programme to beekeepers on proper hive management.     

Five-year survey of ochratoxin A in processed sultanas from Turkey

The results of surveillance for ochratoxin A (OTA) in 1885 samples of sultanas taken during five crop years between 1999 and 2003 are reported. The analytical method was based on extraction with methanol + sodium bicarbonate and clean-up by immunoaffinity column chromatography followed by high-performance liquid chromatography with fluorescence detection. The limit of detection for OTA was 0.3 µg kg^-1. The results show that 9.3% of the samples contained no detectable levels of OTA, whereas 0.6% had concentrations exceeding 10 µg kg^-1; the remaining 90.3% had levels within the range 0.3-10 µg kg^-1. The overall mean OTA concentration in the total number of 1885 samples taken was 1.36 ± 2.91 µg kg^-1; the overall median was calculated as 0.90 µg kg^-1.     

芹菜提取物中芹菜素的HPLC与HPTLC定量分析研究

通过采用高效液相色谱(HPLC)、紫外光谱和黄酮颜色特征反应对芹菜提取物主要成分芹菜素进行定性鉴定,同时建立定量测量芹菜素的高效薄层色谱(HPTLC)方法.结果表明:芹菜提取物的主要成分是黄酮醇.芹菜素,与芹菜素标准品具有相同的光谱和色谱性质;采用G60高效硅胶板,以氯仿-甲醇-水(18:2.3:0.35)为展开剂,芹菜素标样与试样有相同的Rf值为0.65;用最小二乘法作线性回归,芹菜素含量与斑点峰面积的标准曲线回归方程:y=15138x 7594.8,R2=0.993,线性范围:0.332～0.996μg/斑点.精密度实验RSD(n=5)=1.33%,平均回收率97.82%.     

Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection. It is capable of separating and quantifying both C8-isomers of ergocornine, α-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61% ±?10% with limits of detection from 0.2 to 1.1 µg kg^?1. Twenty-four unknown rye flour samples from Danish mills contained on average 46 µg kg^?1 with a maximum content of 234 µg kg^?1. The most common ergot alkaloids were ergotamine and α-ergocryptine including their C8-isomers. A total of 54% of the ergot alkaloids were detected as C(8)-S isomers.     

高效液相色谱法测定食品中的黄曲霉毒素B1

用甲醇-水(55:45)、三氯甲烷、苯-乙腈(98:2)等有机溶剂作为提取剂,用三氟乙酸作衍生剂,通过带荧光检测器的高效液相色谱仪测定食品中黄曲霉毒素B1的含量。结果表明,该方法的线性回归关系良好,方程为y=3.10x-0.63,相关系数r=0.9999。不同样品中黄曲霉毒素B1回收率为84.2%-86.9%,平均变异系数RSD=6.09%。在总共150份检测的玉米、大米和花生样品中,黄曲霉毒素B1总的检出率为82.0%,总的超标率仅为6%,但不同样品中黄曲霉毒素B1含量的变幅较大(0-485.34μg/kg)。