Voltammetric analysis of DL‐α‐tocopherol with a paste electrode

BACKGROUND: A voltammetric study of vitamin E (DL‐ α‐tocopherol) detection using square wave stripping and cyclic voltammetry is discussed in this paper. The working sensor was made by mixing carbon nanotube powder with DNA (double‐stranded calf thymus DNA) and mineral oil. In this electrode, the anodic peak was obtained for ? 0.6 V in a 0.1 mol L^?1 phosphate electrolyte solution. RESULTS: Under optimized stripping conditions, analytical linear working ranges of 0.5–4.0 µg L^?1 and 40.0–160.0 µg L^?1 were obtained. The RSD precision was pegged at 0.105% with seven points using an 80 µg L^?1 spike. The detection limit (S/N) was found to be 0.056 µg L^?1 (1.30 × 10^?10 mol L^?1). CONCLUSION: The developed method was found to be applicable to quality control analysis in the food, pharmaceutical and other manufacturing sectors. Copyright © 2008 Society of Chemical Industry     

Cholesterol and lipid oxidation in raw and pan‐fried minced beef stored under aerobic packaging

BACKGROUND: The type of packaging atmosphere has been reported as a technological factor that consistently affects the quality of lipid fraction in meat. Oxidation of cholesterol and lipids was evaluated before and after pan frying in commercial refrigerated minced beef stored under aerobic atmosphere for 1 and 8 days. RESULTS: In raw beef, cholesterol and lipid oxidation developed at a slow rate. Cholesterol oxidation products (COPs) did not significantly vary (～8 µg COPs g^?1 of fat) over 8 days, while in the same period thiobarbituric acid reactive substances (TBARS) less than doubled (from 0.7 to 1.2 malondialdehyde equivalents kg^?1 of muscle). Pan frying did not influence the oxidative degree in the fresh product but consistently catalyzed cholesterol oxidation in stored beef. A significant increase was assessed in beef at the end of storage: from 8.6 to 30.0 µg COPs g^?1 of fat in raw and cooked beef, respectively. CONCLUSION: Aerobic packaging did not appear as a pro‐oxidant factor in fresh minced beef with a good oxidative quality during a short period of refrigerated storage. Copyright © 2010 Society of Chemical Industry     

Antioxidant activity of hydrolysates derived from porcine plasma

BACKGROUND: In China alone, more than 400 million pigs are slaughtered each year to provide meat. Porcine blood is rich in proteins but is usually discarded, which can cause environmental contamination. Recovering porcine blood and converting it to high‐value products is therefore economically and environmentally desirable. However, very little information on antioxidant peptides from porcine blood by‐products is currently available. In this study the antioxidant properties of porcine plasma hydrolysates PPE and PPA prepared with pepsin and papain respectively were investigated. RESULTS: Both PPE and PPA showed excellent antioxidant activity in a linoleic acid system (AL) compared with α‐tocopherol (VE) at the same concentration (P < 0.01). Their activities were respectively 3.33 and 1.83 times stronger than that of VE at a concentration of 10 µg mL^?1 and 5.4 and 5.6 times stronger at 100 µg mL^?1. The 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical‐scavenging activity (DRSA) reached 48.4 and 43.1% for PPE and PPA respectively at 500 µg mL^?1. The ferrous ion‐chelating power (FICP) of PPE at 100 µg mL^?1 was about 1.5 times stronger than that of 10 µmol L^?1 ethylene diamine tetraacetic acid (EDTA) in a 50 µmol L^?1 Fe²⁺ system, whereas the FICP of PPA at 100 µg mL^?1 was 61% that of 10 µmol L^?1 EDTA. Furthermore, PPE was separated on Resource 15RPC and Superdex peptide 10/300GL columns, and the antioxidant activity of the peptides and its relationship to their polarity and molecular weight (MW) were analysed. The hydrolysate was divided into four groups (R1–R4) with hydrophobicities ranging from weak to strong by Resource 15RPC, while it was divided into three groups (S1, MW 7–12 kDa; S2, MW 3–7 kDa; S3, MW 1–3 kDa) by Superdex peptide 10/300GL. CONCLUSION: The results showed that AL was significantly and positively correlated with the relative amounts of R1, S2 and S3 and that DRSA was dependent on R3 and S1. The fractions of PPE were not responsible for FICP. Copyright © 2009 Society of Chemical Industry     

Characterization and event‐specific quantitative detection of DAS‐59122‐7 maize insert with the application of plasmidic reference material

BACKGROUND: With the development of genetically modified organisms (GMOs), event‐specific qualitative and quantitative polymerase chain reaction (PCR) detection methods have become the internationally agreed standard. RESULTS: The flanking regions of DAS‐59122‐7 maize were characterized by inverse PCR (I‐PCR). In the qualitative PCR assay, a duplex PCR was established with the event‐specific and taxon‐specific primers, and the limit of detection (LOD) was 1 g kg^?1 (approximates to 38 haploid genome copies). In the quantitative TaqMan® real‐time PCR assay, a plasmidic reference material was constructed by recombinant PCR and standard curves were set up. By using the plasmidic reference material, we obtained standard curves with good linearity and relatively high efficiency. The results indicated the usability of the plasmid as standard material. CONCLUSION: From above results, we believe that the developed event‐specific qualitative and quantitative PCR systems for DAS‐59122‐7 maize in this study are acceptable and suitable for DAS‐59122‐7 maize detection. Copyright © 2008 Society of Chemical Industry     

Isolation of eriocitrin (eriodictyol 7‐O‐rutinoside) as an arachidonate lipoxygenase inhibitor from Lumie fruit (Citrus lumia) and its distribution in Citrus species

An inhibitory compound acting against rat platelet 12‐lipoxygenase was isolated from the peel of Lumie fruit (Citrus lumia) by activity‐guided separation. It was identified as eriocitrin (eriodictyol 7‐O‐rutinoside) by spectroscopic analyses. Eriocitrin inhibited 5‐lipoxygenase (IC₅₀29.1 µmol L^?1) from rat peritoneal polymorphonuclear leukocytes in addition to 12‐lipoxygenase (IC₅₀22.3 µmol L^?1). Its aglycone, eriodictyol (5,7,3′, 4′‐tetrahydroxyflavanone), was a much more potent inhibitor of both 12‐lipoxygenase (IC₅₀0.07 µmol L^?1) and 5‐lipoxygenase (IC₅₀0.20 µmol L^?1). It also inhibited the production of leukotriene B₄ in intact peritoneal polymorphonuclear leukocytes stimulated with calcium ionophore A23187 (IC₅₀12.7 µmol L^?1). The distribution of eriocitrin in 39 citrus fruits was investigated by high‐performance liquid chromatography analysis. Lumie, eureka lemon (Citrus limon), Sambokan (Citrus sulcata), Sudachi (Citrus sudachi) and Koji (Citrus leiocarpa) fruits were found to contain high levels of eriocitrin in both peel and juice vesicles. Copyright © 2006 Society of Chemical Industry     

Value‐added use of mushroom ergothioneine as a colour stabilizer in processed fish meats

BACKGROUND: Ergothioneine (ESH), a potent antioxidant, has been found in certain edible mushrooms. Our previous research showed that ESH extracted from the edible mushroom Flammulina velutipes has a positive effect on the colour stability of beef and tuna meat. The purpose of the present study was to compare the efficacy and applicability of ESH extracts prepared from different mushroom species as a colour stabilizer in fish meats. RESULTS: Levels of ESH higher than 2.8 mg mL^?1 were found in extracts prepared from the fruiting bodies of F. velutipes, Lentinula edodes, Pleurotus cornucopiae and Pleurotus eryngii and the processing waste of F. velutipes. When 1 mL of each of the extracts was added to 100 g of minced bigeye tuna and yellowtail meats, the bright‐red colour remained after 5 and 2 days, respectively, of ice storage. The anti‐discoloration efficacy of 1 mL of the extracts prepared from 10 g of the fresh waste portion of F. velutipes was similar to that of its fruiting body or 0.5 g kg^?1 of sodium ascorbate when added to 100 g of minced bigeye tuna meat under ice storage. CONCLUSION: The results of this study clearly showed that ESH prepared from different mushroom species stabilized the colour of fish meats, and the extract from the F. velutipes was the most effective. Copyright © 2010 Society of Chemical Industry     

Scirpusin A,a hydroxystilbene dimer from Xinjiang wine grape,acts as an effective singlet oxygen quencher and DNA damage protector

BACKGROUND: Grapes and red wines are rich sources of phenolic compounds such as anthocyanins, catechins, flavonols and stilbenes, most of which are potent antioxidants showing cardioprotective properties. We first isolated scirpusin A, a hydroxystilbene dimer, from a wine grape of Xinjiang, and studied its antioxidant activity. RESULTS: Reactive oxygen species scavenging effects and the protection against reactive singlet oxygen‐induced DNA damage of scirpusin A have been investigated in our experiments. The concentration of scirpusin A required to inhibit 50% of ¹O₂ generation was 17 µmol L^?1, while addition of scirpusin A at 140 µmol L^?1 caused complete inhibition. Further kinetic study revealed that the reaction of Scirpusin A with singlet oxygen has an extremely high rate constant (k_a = 4.68 × 10⁹ L mol^?1 s^?1). Scirpusin A (140 µmol L^?1) exhibited significant inhibition effects on pBR322 DNA breakage. However, scavenging effects of scirpusin A on superoxide anion O₂^?? and hydroxyl radical ·OH were not potent as the inhibitor rates at a concentration of 1400 µmol L^?1 were 28.83% and 19.5%, respectively. CONCLUSION: The present study shows that scirpusin A is a selective quencher of singlet oxygen and a protector against reactive singlet oxygen‐induced pBR322 DNA damage at very low concentrations. Copyright © 2010 Society of Chemical Industry     

In‐house validation of a high‐performance liquid chromatography analytical method for quantification of ochratoxin A in unfermented grape juice

A validated high‐performance liquid chromatography (HPLC) method with fluorescence detection for the quantitative analysis of ochratoxin A (OTA) in unfermented grape juice is described. Five millilitres of unfermented grape juice was mixed with 45 mL of PBS, and the pH was adjusted to 7.2. Then the mixture was filtered under vacuum through a glass microfibre filter and cleaned up with immunoaffinity columns prior to analysis by HPLC. Validation of the analytical method was based on the following criteria: selectivity, linearity, limit of detection and quantification, precision (within‐day and between‐day variability) and recovery and uncertainty estimation. Detection and quantification limits obtained were 0.02 µg L^?1 and 0.05 µg L^?1 respectively. The percentage recovery was 91.5% (RSD = 3.9). This method was applied to the measurement of 30 veraison stage unfermented grape juice samples. Copyright © 2007 Society of Chemical Industry     

Carotenoids in yellow‐ and red‐fleshed papaya (Carica papaya L)

Vitamin A deficiency is a disorder of public health importance in Sri Lanka. A recent national survey revealed that 36% of preschool children in Sri Lanka have vitamin A deficiency (serum retinol <0.2 µg ml^?1). In view of its well‐established association with child morbidity and mortality, this is a reason for concern. One of the main fruits which has been recommended for prevention of vitamin A deficiency in Sri Lanka is papaya (Carica papaya L). In this study the carotenoid profiles of yellow‐ and red‐fleshed papaya were analysed by medium‐pressure liquid chromatography (MPLC) and UV‐vis spectrophotometry. A section of yellow‐fleshed papaya showed small carotenoid globules dispersed all over the cell, whereas in red‐fleshed papaya the carotenoids were accumulated in one large globule. The major carotenoids of yellow‐fleshed papaya were the provitamin A carotenoids β‐carotene (1.4 ± 0.4 µg g^?1 dry weight (DW)) and β‐cryptoxanthin (15.4 ± 3.3 µg g^?1 DW) and the non‐provitamin A carotenoid ζ‐carotene (15.1 ± 3.4 µg g^?1 DW), corresponding theoretically to 1516 ± 342 µg kg^?1 DW mean retinol equivalent (RE). Red‐fleshed papaya contained the provitamin A carotenoids β‐carotene (7.0 ± 0.7 µg g^?1 DW), β‐cryptoxanthin (16.9 ± 2.9 µg g^?1 DW) and β‐carotene‐5,6‐epoxide (2.9 ± 0.6 µg g^?1 DW), and the non‐provitamin A carotenoids lycopene (11.5 ± 1.8 µg g^?1 DW) and ζ‐carotene (9.9 ± 1.1 µg g^?1 DW), corresponding theoretically to 2815 ± 305 µg kg^?1 DW mean RE. Thus the carotenoid profile and organisation of carotenoids in the cell differ in the two varieties of papaya. This study demonstrates that carotenoids can be successfully separated, identified and quantified using the novel technique of MPLC. Copyright © 2003 Society of Chemical Industry     

Effect of caffeic acid on haemoglobin‐mediated lipid and protein oxidation in washed cod mince during ice and frozen storage

BACKGROUND: Little is known about the relation between haemoglobin (Hb)‐mediated lipid and protein oxidation in muscle foods and how these two reactions can be inhibited by naturally occurring antioxidants. This study was aimed at evaluating (1) lipid oxidation and protein oxidation induced by 20 µmol L^?1 Hb during chilled and frozen storage of washed cod mince and (2) the efficiency of 10–1000 ppm (0.063–6.3 mmol L^?1) caffeic acid in preventing these reactions. RESULTS: Addition of 20 µmol L^?1 Hb increased peroxide value (PV), rancid odour, protein carbonylation, protein insolubilisation, redness loss and α‐tocopherol loss in ice‐stored washed cod mince. Since both lipid and protein oxidation developed at the same time, it was not possible to conclude which reaction initiated the other. All studied reactions were efficiently inhibited by ≥ 50 ppm caffeic acid, which could be a result of α‐tocopherol regeneration, general radical scavenging, reduced formation of oxidised Hb forms and/or conformational changes in Hb structure. During frozen storage the only clear effect of Hb was increased PV, and here caffeic acid was less efficient as an antioxidant. CONCLUSION: Hb‐induced lipid and protein oxidation occurred quickly in ice‐stored washed cod mince, and the two reactions could not be separated in time. During frozen storage, Hb caused only limited lipid oxidation. Caffeic acid (≥50 ppm) was an efficient antioxidant during ice storage. Copyright © 2010 Society of Chemical Industry     

Preparation of antibacterial chito‐oligosaccharide by altering the degree of deacetylation of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process

BACKGROUND: Chito‐oligosaccharide (COS) is generally known to possess many specific biological functions, especially antibacterial activity, depending on its size. To prepare a specific size range of COS, however, has proved difficult. The aim of this study was to establish a method for preparing a specific size range of antibacterially active COS by adjusting the degree of deacetylation (DD) of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process. RESULTS: The molecular weight spectrum, elucidated by viscosity‐average molecular weight, high‐performance liquid chromatography and thin layer chromatography, of COS in chitosan hydrolysate was significantly related to the DD of its original chitosan. Compared with the original form, COS produced at 90% DD showed superior activity against most Gram‐negative bacteria tested, with a minimum inhibition concentration (MIC) ranging from 55 ± 27 to 200 ± 122 µ g mL^?1. Conversely, most Gram‐positive strains tested were less sensitive to COS (MIC > 880 ± 438 µ g mL^?1) than to its original form. Among the Gram‐positive strains, Staphylococcus xylosus was the only exception in that it showed a high susceptibility to COS and had an MIC as low as 45 ± 11 µ g mL^?1. CONCLUSION: The results indicate that the production of a specific size range of COS product is possible by altering the DD of chitosan in the chitinase‐catalysed process. To produce various sizes of COS for versatile biological functions, as seen in this study to inhibit various types of bacteria, is made possible in this established process. Copyright © 2008 Society of Chemical Industry     

Application of polymerase chain reaction–restriction fragment length polymorphism analysis and lab‐on‐a‐chip capillary electrophoresis for the specific identification of game and domestic meats

BACKGROUND: The objective of this study was to adapt and improve previously published polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) methods aimed at the identification of game and domestic meats, by replacing the gel electrophoretic steps for DNA fragment analysis by a chip‐based capillary electrophoresis system. RESULTS: PCR amplification of a mitochondrial 12S rRNA gene fragment and subsequent digestion of the amplicons with either MseI or a combination of MboII, BslI, and ApoI endonucleases generated characteristic PCR‐RFLP profiles that allowed discrimination among ten relevant game and domestic meat species. The Agilent 2100 Bioanalyzer utilises capillary electrophoresis on a microchip device that is capable of rapidly sizing DNA fragments, offering a valuable recent development for the analysis of complex DNA banding patterns. CONCLUSION: Results obtained in this work indicated that banding resolution on the system was sensitive, with detection of some small DNA fragments that were not observed with the published conventional PCR‐RFLP gel‐based method. Therefore, the new faster and easy handling procedure provides an additional powerful tool that can be employed for meat speciation. Copyright © 2009 Society of Chemical Industry     

Development of novel species‐specific primers for species identification of the Lactobacillus casei group based on RAPD fingerprints

BACKGROUND: It is difficult to clearly distinguish and identify specific species of the Lactobacillus casei group using phenotypic and genotypic (16S ribosomal DNA sequence analysis) techniques alone. Some species of this group are probiotic and are widely used in the food and feed industries. The objective of this study was to develop species‐specific primers based on randomly amplified polymorphic DNA (RAPD) fingerprinting for species identification within the closely related L. casei group of bacteria. RESULTS: Three random primers termed OPT‐14, OPA‐11 and OPT‐16 were developed for analysis. The primer pairs each produced a species‐specific band found only in the tested Lactobacillus rhamnosus, Lactobacillus paracasei subsp. tolerans and Lactobacillus zeae isolates respectively. These specific fragments were then sequenced for further analysis. The species‐specific primers were designed according to cloned sequencing, which was employed for polymerase chain reaction (PCR) with the template DNA of Lactobacillus strains. Single 102, 179 and 451 bp species‐specific bands were found only in L. rhamnosus, L. paracasei subsp. tolerans and L. zeae respectively. CONCLUSION: Using PCR, the novel species‐specific primers have been shown to rapidly, accurately and effectively identify species of L. rhamnosus, L. paracasei subsp. tolerans and L. zeae from within the L. casei group of probiotic bacteria. Copyright © 2009 Society of Chemical Industry     

Measurement and prediction of the concentration of 1‐methylcyclopropene in treatment chambers containing different packaging materials

BACKGROUND: 1‐methylcyclopropene (1‐MCP) has been shown to suppress ethylene response and extend the post‐harvest shelf life and quality of several fruits and vegetables. In the US and Canada, the label treatment dosage for apples is 1.0 and 0.6 µL L^?1, respectively. It has been demonstrated that wood and corrugated fiberboard materials, commonly found in apple storage facilities, absorb 1‐MCP. Losses of 1‐MCP during the exposure period might compromise the effectiveness of the product. The effects of type of material (corrugated fiberboard and high density polyethylene), relative humidity (50%, 80%, and > 95%), ratios of mass of packaging material (kg) per unit volume (m³) of airspace in a treatment chamber, and initial concentration of 1‐MCP (10 and 20 µL L^?1) on the available concentration of gaseous 1‐methylcyclopropene (1‐MCP) in an enclosed chamber were studied. RESULTS: The concentration of 1‐MCP declined in the presence of the materials tested, but the rate at which 1‐MCP gas was removed from the chamber headspace differed markedly. The average percentage loss for HDPE was between 10 and 12% at all conditions tested, while for corrugated fiberboard it ranged from 12 to 94%. CONCLUSIONS: The concentration of 1‐MCP at any time, t, follows an exponential decay behavior. For corrugated boxes, the rate at which 1‐MCP is removed increased up to 10‐fold as the relative humidity increased from 50 to 80%. The 1‐MCP depletion rate doubled as the ratio of material was increased from 4 to 8 kg of corrugated fiberboard m^?3 air. An increase of initial concentration from 10 to 20 µL L^?1 reduced the rate by half. This trend was also observed for HDPE boxes. Copyright © 2009 Society of Chemical Industry     

Maintaining quality and bioactive compounds of broccoli by combined treatment with 1‐methylcyclopropene and 6‐benzylaminopurine

BACKGOUND: Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green colour and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of 1‐methylcyclopropene (1‐MCP) combined with 6‐benzylaminopurine (6‐BA) treatment on visual quality, antioxidant enzymes and bioactive compounds in broccoli florets were investigated. RESULTS: A combined treatment of 2.5 µL L^?1 1‐MCP and 200 mg L^?1 6‐BA significantly reduced the increase of lightness (L*) value, and retained a high level for the hue value (H) and chlorophyll content. Superoxide dismutase, ascobate peroxidase and catalase activities increased while the activity of peroxidase decreased during storage in treated samples in comparison with the controls. The combined treatment enhanced the biosynthesis of glucosinolate and the formation of the anticarcinogen sulforaphane, which improved the health benefit of broccoli. CONCLUSION: These results indicate that a combined treatment of 1‐MCP and 6‐BA could be a good candidate for maintaining the visual quality and enhancing the nutritional value in broccoli during storage at 15 °C. © 2012 Society of Chemical Industry     

Development and in‐house validation of the event‐specific qualitative and quantitative PCR detection methods for genetically modified cotton MON15985

BACKGROUND: To implement genetically modified organism (GMO) labeling regulations, an event‐specific analysis method based on the junction sequence between exogenous integration and host genomic DNA has become the preferential approach for GMO identification and quantification. RESULTS: In this study, specific primers and TaqMan probes based on the revealed 5′‐end junction sequence of GM cotton MON15985 were designed, and qualitative and quantitative polymerase chain reaction (PCR) assays were established employing the designed primers and probes. In the qualitative PCR assay, the limit of detection (LOD) was 0.5 g kg^?1 in 100 ng total cotton genomic DNA, corresponding to about 17 copies of haploid cotton genomic DNA, and the LOD and limit of quantification (LOQ) for quantitative PCR assay were 10 and 17 copies of haploid cotton genomic DNA, respectively. Furthermore, the developed quantitative PCR assays were validated in‐house by five different researchers. Also, five practical samples with known GM contents were quantified using the developed PCR assay in in‐house validation, and the bias between the true and quantification values ranged from 2.06% to 12.59%. CONCLUSION: This study shows that the developed qualitative and quantitative PCR methods are applicable for the identification and quantification of GM cotton MON15985 and its derivates. Copyright © 2009 Society of Chemical Industry     

Fate of aflatoxin B(1) in contaminated corn gluten during acid hydrolysis

BACKGROUND: Aflatoxins are a group of mycotoxins that cause serious chronic disease outbreaks and contaminate several food products such as corn and its by‐product, corn gluten. The aim of the current study was to evaluate the effect of hydrochloric acid (HCl) on aflatoxin B₁ (AFB₁) degradation in contaminated corn gluten under different HCl concentrations, hydrolysis temperatures and hydrolysis times. RESULTS: During the wet milling process the highest AFB₁ level (45.68 µg kg^?1) (37.86%) was found in corn gluten fraction. Treatment with 1 mol L^?1 HCL at 110 °C resulted in degradation of AFB₁ by 27.6% (33.07 µg kg^?1) after 4 h and reached 42.5% (26.26 µg kg^?1) after 8 h. Increasing HCl concentration from 1 to 3 mol L^?1 HCl resulted in increased degradation of AFB₁, while complete degradation occurred in the presence of 5 mol L^?1 HCl after 4 h at 110 °C. Meanwhile, half‐life time of AFB₁ was recorded after 2 h at 100 °C and was < 2 h at 110 °C in the presence of 3 mol L^?1 HCl. CONCLUSION: It could be demonstrated that the manufacture of hydrolyzed vegetable protein is a suitable method for decontamination of aflatoxin in highly contaminated grains, especially gluten fractions. The hydrolysis reaction could be considered in terms of first‐order reaction kinetics of AFB₁ degradation. Copyright © 2010 Society of Chemical Industry     

Application of host‐specific source‐tracking tools for rapid identification of fecal contamination in fresh produce by humans and livestock

BACKGROUND: Fecal contamination in fresh produce is a public health concern because it may contain human pathogens. We introduced host‐specific quantitative real‐time polymerase chain reaction (qPCR) assays for the rapid detection and identification of fecal contamination sources from humans and farm animals (cow, pig, chicken) in fresh produce. Each composite fecal sample was spiked on lettuce at two contamination levels (0.2 mg or 2 mg feces g^?1), followed by qPCR assays for detecting each host‐specific genetic marker: BoBac (cow); PF163 (pig); CP3‐49 (chicken); and HF183 and gyrB (human). Two commercial DNA extraction kits were compared to evaluate DNA recovery yields and removal of PCR inhibition. Sketa2 assay was conducted to assess the presence of PCR inhibition in the contaminated lettuce. RESULTS: All the qPCR assays yielded reliable detection from contaminated lettuce (2 mg feces g^?1), where their target gene numbers were 1.5–5.0 × 10³ (HF183), 0.8–2.2 × 10³ (gyrB), 0.6–1.6 × 10³ (BoBac), 1.6–3.0 × 10³ (CP3‐49) and 1.1–2.2 × 10³ (PF163) copies g^?1 of lettuce. Among the two extraction kits, QIAamp DNA Stool Kit resulted in 2–3 times higher sensitivity and 20% less PCR inhibition than the PowerFood^? kit. CONCLUSION: This study provides information on the optimized host‐specific qPCR assay in identifying sources of fecal contamination in fresh produce and is useful for tracking the contamination source and improving agricultural practice. © 2012 Society of Chemical Industry     

Occurrence of pyrrolizidine alkaloids in animal- and plant-derived food: results of a survey across Europe

Pyrrolizidine alkaloids (PAs) are secondary metabolites of plant families such as Asteraceae or Boraginaceae and are suspected to be genotoxic carcinogens. Recent investigations revealed their frequent occurrence in honey and particularly in tea. To obtain a comprehensive overview of the PA content in animal- and plant-derived food from the European market, and to provide a basis for future risk analysis, a total of 1105 samples were collected in 2014 and 2015. These comprised milk and milk products, eggs, meat and meat products, (herbal) teas, and (herbal) food supplements collected in supermarkets, retail shops, and via the internet. PAs were detected in a large proportion of plant-derived foods: 91% of the (herbal) teas and 60% of the food supplements contained at least one individual PA. All types of (herbal) teas investigated were found to contain PAs, with a mean concentration of 460 µg kg^?1 dry tea (corresponding to 6.13 µg L^?1 in [herbal] tea infusion). The highest mean concentrations were found in rooibos tea (599 µg kg^?1 dry tea, 7.99 µg L^?1 tea infusion) and the lowest in camomile tea (274 µg kg^?1 dry tea, 3.65 µg L^?1 tea infusion). Occurrence of PAs in food supplements was found to be highly variable, but in comparable ranges as for (herbal) tea. The highest concentrations were present in supplements containing plant material from known PA-producing plants. In contrast, only 2% of the animal-derived products, in particular 6% of milk samples and 1% of egg samples, contained PAs. Determined levels in milk were relatively low, ranged between 0.05 and 0.17 µg L^?1 and only trace amounts of 0.10–0.12 µg kg^?1 were found in eggs. No PAs were detected in the other animal-derived products.