Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products

A simple method for the verification of supplemental (6R,S)-5-methyl-5,6,7,8-tetrahydrofolic acid, “5-MTHF,” in nutritional products is described. Nutritional product samples are prepared for the liquid chromatographic/fluorescence detection (LC/FLD) determination of 5-MTHF by buffer dilution, 10-min centrifugation, and syringe filtration. Method performance has been defined by assessments of 5-MTHF linearity (r ² averaged 0.9999 ± 0.0001, and all relative calibration errors averaged ≤0.6%, for ten consecutive six-point standard curves), intermediate precision (rsd = 1.1%, n = 9, for three products fortified at ～1.73 μmol/kg = ～795 μg/kg, tested on each of 3 days), accuracy (spike recovery average = 92.8 ± 1.0%, n = 9, for nutritional products spiked with 5-MTHF at ～1.73 μmol/kg, or ～795 μg/kg), and selectivity (absence of interference from reagent blanks, and from four compounds structurally related to 5-MTHF). The 5-MTHF recovery, as % of unheated controls, from a simulated heat treatment (20 min at 120 °C) averaged 99.1 ± 0.6%, n = 4. The limits of 5-MTHF detection (S/N = 3) and quantification (S/N = 10) were experimentally determined to be 10 μg/kg (～0.020 μmol/kg) and 30 μg/kg (～0.060 μmol/kg), respectively (<10× the expected fortification rate). The method provides a simple and inexpensive means for verifying proper fortification, and for assessing the stability to processing and storage conditions, of free 5-MTHF in nutritional products. A finding of interest is the indication that liquid nutritional products may comprise a stable matrix for 5-MTHF fortification.     

Ochratoxin A in dried vine fruits from Chinese markets

A total of 56 dried vine fruits, including 31 sultanas and 25 currants, were selected from Chinese markets in 2012. All samples were analysed for Ochratoxin A (OTA) using solid-phase extraction and high-performance liquid chromatography (HPLC) with fluorescence detection. It turned out that 58.9% of the samples were positive and the OTA amount ranged from <0.07 to 12.83 μg/kg, with a mean level of 0.99 μg/kg. Only one sample exceeded the European Union (EU) maximum level of 10 μg/kg. Meanwhile, it was shown that OTA contamination increased among north-western, northern and southern China, which showed OTA means of 0.08, 0.99 and 2.01 μg/kg, respectively. Moreover, in samples of products sold in sealed plastic bags, i.e. consumer-size packages (n = 19, mean = 0.30 μg/kg) less OTA was detected when compared with sampled bulk packages (n = 37, mean = 1.67 μg/kg). In addition, sultanas (mean = 0.92 μg/kg) had less OTA contamination than currants (mean = 1.22 μg/kg).     

Citrinin in cereals and feedstuffs coming from Croatia and Bosnia & Herzegovina

The aim of this study was to investigate the occurrence of citrinin in different cereals (n = 341) and feedstuffs (n = 67) coming from farms and feed factories established in Croatia and Bosnia & Herzegovina. The highest mean citrinin concentration (103 ± 102 µg/kg) was observed in cereals sampled in Bosnia & Herzegovina during 2014, although significantly different levels between the two countries were not observed. Across the cereal samples, the maximal citrinin concentration was determined in wheat (429 µg/kg), while across the feedstuffs, the highest concentration was found in pig feed (63 µg/kg). Despite of the increased citrinin levels found in some samples, especially wheat, the obtained values cannot be compared against the maximum limits, since no such levels are stipulated under the applicable legislation. But, given that data on citrinin are very scarce, they can serve as an indicator of cereal and feed contamination in this part of Europe.     

Quality of Banana Puree During Storage: a Comparison of High Pressure Processing and Thermal Pasteurization Methods

The quality features of banana puree after high pressure processing (HPP) at 500 MPa for 10 min and thermal pasteurization (TP) at 90 °C for 2 min during 30 days of refrigerated storage were compared in this study. Initial counts in banana puree of greater than 3.80 log colony-forming units (CFU)/g of total aerobic bacteria (TAB) and 3.10 log CFU/g of molds and yeasts (M&Y) were reduced by HPP and TP. TAB were approximately 1.0 CFU/g, and M&Y were less than 0.3 log CFU/g in HPP- and TP-processed puree during storage. HPP and TP did not change pH, titratable acidity (TA), total soluble solids (TSS), lightness (L), and yellowness (b), total phenolic content (TPC), and antioxidant capacity (AC), but HPP raised redness (a) and TP reduced a and ascorbic acid (AA). During storage, L, a, and b in HPP- and TP-processed purees did not change but HPP-processed puree increased pH and decreased TA. After storage, the percentage of TPC and AA was 75.85 and 55.09 % in the HPP group and 96.30 and 68.09 % in the TP group, indicating a significant loss of TPC and a greater loss of AA in HPP-processed puree. The loss of AC agreed with the loss of AA and TPC. HPP preserved particle size distribution and viscosity of purees, whereas TP increased the number of smaller particles and viscosity after processing and in storage. Twenty-six volatiles (18 esters) and 22 volatiles (15 esters) were detected in HPP- and TP-processed purees, and the ester fraction was 69.79 and 52.36 %, respectively. HPP was found to be an effective alternative pasteurization method for preserving the quality of fresh banana puree.     

Isotope Internal Standard Method for Determination of Four Acrylamide Compounds in Food Contact Paper Products and Food Simulants by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry

A new method was developed for the determination of four acrylamide compounds (acrylamide, methacrylamide, N-methylol acrylamide, N-(Methoxymethyl)methacrylamide) in food contact paper products, three kinds of water-based food simulants, and dry food simulant (modified polyphenylene oxide, MPPO) by using ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Acetonitrile was used as the extraction solvent for different kinds of samples. The extraction solution of paper products was purified with QuEChERS technology. Four analytes were separated by gradient elution in a UPLC HSS T3 column (100 mm?×?2.1 mm, 1.8 μm) with methanol and 0.1 % formic acid water as mobile phases, and then detected in electrospray ionization mode of MS/MS with multiple reaction monitoring (MRM). Under the optimal conditions, the calibration curves for four analytes were linear within the range of 1.0–200 μg/L and the correlation coefficients were higher than 0.998. The quantitation limits of the method (S/N?=?10) of four analytes were in the range of 0.3–20 μg/kg. The mean recoveries for five sample matrixes at three spiked concentration levels of 0.3–200 μg/kg were in the range of 81–108 % with the relative standard deviations (RSDs, n?=?6) values ranging from 2.5 to 7.1 %. The developed method is accurate, simple and rapid, which can be applied to the determination of acrylamide compounds in food contact paper products and food simulants.     

Thermophysical Properties of SweetPotato Puree at Freezing and Refrigeration Temperatures

The thermophysical properties (initial freezing point, unfreezable water, enthalpy of freezing, and specific heat) of alginate-restructured sweet potato (SP) puree at freezing and refrigeration temperatures were determined using differential scanning calorimetry. Restructuring of SP puree increased the amount of unfreezable (bound) water in the puree from 0.44 g H₂O/g solids to about 0.56 g H₂O/g solids and reduced the freezing point from ?2.5 to ?3.2°C. During freezing (or melting), the specific heat increased from about 1.9 to 90 kJ/kg. After freezing, the specific heats of restructured and nonrestructured SP puree were respectively 3.695 and 3.404 kJ/kg. Between 358 and 403 kJ/kg of heat have to be removed when SP puree (at 20°C) is to be frozen to ?40°C.     

Pyrrolizidine and tropane alkaloids in teas and the herbal teas peppermint,rooibos and chamomile in the Israeli market

Dehydro pyrrolizidine alkaloids (dehydro PAs) are carcinogenic phytotoxins prevalent in the Boraginaceae, Asteraceae and Fabaceae families. Dehydro PAs enter the food and feed chain by co-harvesting of crops intended for human and animal consumption as well as by carry-over into animal-based products such as milk, eggs and honey. Recently the occurrence of dehydro PAs in teas and herbal teas has gained increasing attention from the EU, due to the high levels of dehydro PAs found in commercially available teas and herbal teas in Germany and Switzerland. Furthermore, several tropane alkaloids (TAs, e.g. scopolamine and hyoscyamine) intoxications due to the consumption of contaminated herbal teas were reported in the literature. The aim of the present study was to determine the dehydro PAs and TAs levels in 70 pre-packed teabags of herbal and non-herbal tea types sold in supermarkets in Israel. Chamomile, peppermint and rooibos teas contained high dehydro PAs levels in almost all samples analysed. Lower amounts were detected in black and green teas, while no dehydro PAs were found in fennel and melissa herbal teas. Total dehydro PAs concentrations in chamomile, peppermint and rooibos teas ranged from 20 to 1729 μg/kg. Except for black tea containing only mono-ester retrorsine-type dehydro PAs, all other teas and herbal teas showed mixed patterns of dehydro PA ester types, indicating a contamination by various weed species during harvesting and/or production. The TA levels per teabag were below the recommended acute reference dose; however, the positive findings of TAs in all peppermint tea samples warrant a more extensive survey. The partially high levels of dehydro PAs found in teas and herbal teas present an urgent warning letter to the regulatory authorities to perform routine quality control analysis and implement maximum residual levels for dehydro PAs.     

Occurrence of aflatoxins in selected spices in Poland

The aim of this study was to determine the contamination of aflatoxins B₁, B₂, G₁, G₂ in some selected spices (n = 84) in the Kuyavian-Pomeranian province of Poland. Aflatoxins were found in 63.1 % of the analysed samples. The presence of these compounds was confirmed in all the samples of pepper, nutmeg and turmeric. The maximum content for the sum of aflatoxins B₁, B₂, G₁, G₁ exceeding the acceptable level (10 μg/kg) was 16.91 μg/kg in one sample of nutmeg and 12.1 μg/kg in one sample of pepper, whereas in one sample of nutmeg the maximum content was equal to the regulatory limit. The lowest degree of contamination was found in black pepper.     

Co-occurrence of ochratoxin A and citrinin in unprocessed cereals established during a three-year investigation period

The aim of this study was to investigate ochratoxin A (OTA) and citrinin (CIT) co-occurrence in different unprocessed cereals (n = 189) originating from Croatia during a three-year investigation period (2014–2016) using validated enzyme immunoassay (ELISA) methods. CIT and OTA were determined in 49% and 7% of samples, respectively. Significantly higher (p < 0.05) overall mean concentrations were determined for CIT (66.8 ± 76.0 µg/kg) in comparison to OTA (5.2 ± 1.1 µg/kg). Based on the analysis of all investigated cereals, CIT was found about 15 times more frequently than OTA and in similarly (15-fold) higher concentrations, irrespective of the cultivation year. The results revealed a moderately positive correlation between OTA and CIT concentrations in maize (r_s = 0.44) and wheat (r_s = 0.59), whereas in barley and oat this correlation (p > 0.01) was not significant.     

Estimation of weekly intake of cadmium and lead by consumption of commercial ready-to-feed infant foods

The purpose of this survey was to estimate the safety of ready-to-eat infant foods in terms of Pb and Cd content. The studied samples were ready-to-eat infant products: dinners (n = 74), soups (n = 27) and desserts (n = 82) containing components of animal origin: meat and/or milk. Cd and Pb content was determined using a GF-AAS method. The analysed products contained 1.82–3.54 µg Pb and 1.32–1.50 µg Cd per kg. The content of Pb per kg of the product can be represented as dinners > soups > desserts, whereas the content of Cd was dinners > desserts > soups. The analysed ready-to-eat products could be regarded as safe, because they supply 12-month-old infants with Pb in an amount accounting for nearly 22% BMDL01 and Cd accounting for ca. 8.6% of the total weekly intake.     

Phytosterol Determination and Method Validation for Selected Nuts and Seeds

A method involving alkali and/or acid hydrolysis of phytosterols followed by trimethylsilyl ether derivatization coupled with GC-FID analysis was validated and applied in the analysis of major phytosterols (campesterol, stigmasterol, β-sitosterol, and Δ⁵-avenasterol) in nuts (n = 7), seeds (n = 9), legumes (n = 2), and grain (n = 1). The acid-labile Δ⁵-avenasterol was extracted with alkaline hydrolysis only before derivatization. Quantification of all phytosterols was done using the computed relative response factor of 5α-cholestane (internal standard). Analyses of internal and external phytosterol standards showed good linearity for all phytosterols (R ² of 0.999); LOD and LOQ of phytosterols were determined to be 0.01–0.12 and 0.04–0.40 mg/100 g, respectively. Repeatability and reproducibility precision analyses showed acceptable coefficient of variation of less than 3 and 4%, respectively, and satisfactory Horwitz ratio values of <1.0. Excellent accuracy was proved by the high recovery values of 91.4–106.0% for campesterol, β-sitosterol, and stigmasterol. Δ⁵-Avenasterol, the most oxidation-susceptible sterol, showed a recovery of about 60%. The total phytosterol (sum of major phytosterols quantified) contents in the 19 samples varied from 38.8 mg/100 g (white quinoa seed) to 246.2 mg/100 g (sunflower seed). β-Sitosterol was the predominant phytosterol (54–86.0% of total) among all samples except fennel seed in which stigmasterol was predominant. Analytical quality control chart maintained during the study period showed that assays were performed under control. Method validation indicated that the analytical method can be applied for accurate determination of campesterol, β-sitosterol, and stigmasterol in selected food samples.     

Optimization and Validation of a Fluorescence Polarization Immunoassay for Rapid Detection of T-2 and HT-2 Toxins in Cereals and Cereal-Based Products

A fluorescence polarization (FP) immunoassay has been optimized and validated for rapid quantification of T-2 and HT-2 toxins in both unprocessed cereals, including oats, barley and rye, and cereal-based products for direct human consumption, such as oat flakes, oats crispbread and pasta. Samples were extracted with 90 % methanol, and the extract was filtered and diluted with water or sodium chloride solution prior to the FP immunoassay. Overall mean recoveries from spiked oats, rye, barley, oat flakes, oats crispbread and pasta ranged from 101 to 107 %, with relative standard deviations lower than 7 %. Limits of detection (LODs) of the FP immunoassay were 70 μg/kg for oats, 40 μg/kg for oat flakes and barley, 25 μg/kg for pasta and 20 μg/kg for rye and oats crispbread. The trueness of the immunoassay was assessed by using two oat and oat flake reference materials for T-2 and HT-2 toxins, showing good accuracy and precision. Good correlations (r?>?0.953) were observed between T-2 and HT-2 toxin contents in naturally and artificially contaminated samples determined by both FP immunoassay and ultra-high-performance liquid chromatography (UHPLC) with immunoaffinity column cleanup used as reference method. These results, combined with rapidity and simplicity of the assay, show that the optimized assay is suitable for high-throughput screening, as well as for reliable quantitative determination of T-2 and HT-2 toxins in cereals and cereal-based products.     

Occurrence of aflatoxins (B1, B2, G1, G2) in herbal tea consumed in Turkey

Aflatoxin contents in 12 types of herbal teas were determined by high performance liquid chromatography (HPLC) with fluorescence detector using immunoaffinity column clean-up. Forty eight samples were collected from four local herbal shops in Manisa, Turkey. Of the 48 samples analyzed, 43 were aflatoxin positive. The highest concentration of aflatoxin (34.18 µg/kg) was determined in a sample of camomile tea. The occurrence of AFB1, B2, G1 and G2 was found in samples at levels of 54, 29, 71 and 46 %, respectively. Aflatoxin B1, B2, G1 and G2 contamination levels varied from 0 to 14.2, 0 to 12.4, 0 to 13.5 and 0 to 28.7 µg/kg, respectively. Aflatoxin was not detected in five samples consisting of linseed, lime and fennel tea.     

Acrylamide in thermal-processed carbohydrate-rich foods from Chinese market

ABSTRACT

Acrylamide content in food market in China was determined with the goal to evaluate related health concern. In this survey, products of rice, potato corn, wheat as well as dried fruit slices and instant foods were analysed. All these types of thermal-processed carbohydrate-rich foods were frequently consumed in China. They were purchased from markets in Zhejiang province and analysed using a liquid chromatography tandem/mass spectrometry method. Acrylamide was detected in 94.3% of 105 investigated samples, ranging from 10 to 3649 μg/kg with an average value of 231 μg/kg and a median of 114 μg/kg. In this study, high levels were found in potato products (564 ± 285 μg/kg), corn products (524 ± 187 μg/kg) and instant foods (180 ± 35 μg/kg) while low levels were measured in rice products (82 ± 17 μg/kg), wheat products (96 ± 29 μg/kg) and dried fruit slices (83 ± 13 μg/kg).     

Furan in commercial baby foods from the Spanish market: estimation of daily intake and risk assessment

ABSTRACT

The occurrence of furan in commercial baby food samples from the Spanish market was evaluated using an automated headspace solid-phase microextraction method coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 76 baby food samples including infant formula, baby cereals, fruit in cans and/or jars, vegetables, meat, and fish, were surveyed for furan content. The lowest concentration of this compound was found in infant formula (<0.02–0.33 ng ml^?1), and cereal-based food (0.15–2.1 ng g^?1) while baby food containing fish showed the highest concentrations (19–84 ng g^?1). Following recommendation of the European Food Safety Authority (EFSA), the effect on furan content was evaluated of consumer home preparation of foods, heating and handling. Furan concentrations were reduced by up to 35% when samples were heated in a dish using microwave oven and by up to 53% when a hot water bath was used. Finally, we estimated the furan intake from baby food consumption (0.002–1.18 µg kg^?1 body weight day^?1) and we calculated the margin of exposure (MOE) from samples as purchased and also after home preparation of the food. For infant formula and cereal baby foods, the MOEs (26,278–412,776) indicated no infant health concern or priority, while for meat and fish-based baby foods the values pointed to a potential public health risk, even considering the furan losses during preparation at home.     

Validation of a LC–MS Method for the Determination of Urea Contamination in Market Teas

Tea is one of the most widely consumed beverages in the world preceded only by water. In some culture style of tea plant, urea fertilizer is sprayed on tea leaf in order to increase crop output; besides, in some processing method of green tea, urea is illegally added to maintain tea’s vivid color. The above-mentioned process may unavoidably cause urea residue, and prolonged or repeated exposure of body to urea may cause adverse effects. In this work, an easy and reliable hydrophilic interaction liquid chromatography/mass spectrometry analytical method for determination of urea in tea was firstly validated; the method exhibited a linear response from 4 to 60 μg mL^?1 (R ²?>?0.9996), the limit of quantitation for urea is 4 μg mL^?1, the mean recoveries of urea spiked at levels of 10 and 20 μg mL^?1 were 95–110 %, and the relative standard deviations of intra- and inter-day measurements were less than 7.8 %. The method was later successfully applied to the analysis of urea residue in some market tea samples. The result showed that there is obvious urea contamination in some market teas, and the contamination percentage is especially high in green tea samples. Among the samples investigated, urea was detected at concentration ranges of 24.02–46.02 mg/kg. Some attention should be paid on the health effect resulting from such urea contamination in tea.     

Simultaneous Determination of 23 Azo Dyes in Paprika by Gas Chromatography-Mass Spectrometry

The present work describes the development and validation of a simple, quick and precise gas chromatography-mass spectrometry (GC-MS) method for the analysis of 23 azo dye breakdown products in paprika samples. After the extraction procedure, dyes were identified on an Agilent J&W DB-5ms Ultra Inert capillary column using dichloroethane as a sample dissolvent. Limits of detection (LODs) were comprised between 10.6 and 84.4 ng/mL. Accuracy values in the range of 90–104 % for the 23 azo dye breakdown products were obtained, and RSD% for the analysis of 2.4 μg/mL of each compound was below 4.6 % (n = 9). The recovery for the azo dyes in paprika samples was comprised between 71.2 ± 3.5 % (benzidine) and 118.9 ± 2.5 % (para-cresidine). Results of this study suggest that the developed method is suitable for detection and quantification of azo dye breakdown products in the range of 60–240 μg/kg paprika. In addition, this GC-MS method allowed the simultaneous determination of disperse orange 3 (azo dye) with high accuracy and precision. The method has numerous advantages such as simplicity, low cost, easy operation and short analysis time and constitutes an efficient method for the monitoring of a large number of azo dyes in food matrices.     

Polycyclic aromatic hydrocarbons in teas using QuEChERS and HPLC-FLD

Polycyclic aromatic hydrocarbons (PAHs) are food-processing contaminants considered to be carcinogenic and genotoxic. Due to its drying process stage, teas may be contaminated with PAHs. The aim of the study was to validate an analytical method involving QuEChERS and HPLC-FLD for the determination of PAH4 in teas and evaluate the contamination levels in 10 different types of teas from Brazil. Recoveries varied from 54% to 99% and relative standard deviations from 1% to 21%. Limits of detection and quantification were from 0.03 to 0.3 µg/kg and 0.1 to 0.5 µg/kg, respectively. Mate tea presented the highest PAH levels, with PAH4 varying from 194 to 1795 µg/kg; followed by black (1.8–186 µg/kg), white (24–119 µg/kg), and green teas (3.1–92 µg/kg). Teas with lowest PAH4 were strawberry, lemongrass, peppermint, and boldo. Only trace levels of PAHs were detected in tea infusions, so apparently it would not affect PAH intake by Brazilian population.     

Survey of dioxins, dioxin-like PCBs and marker PCBs in German feeds of plant origin

Within a representative survey the levels of dioxins (PCDD/PCDF), dioxin-like PCBs and marker PCBs in 206 German feed samples were analysed in the years 2004/2005. The sampling plan included compound feed (N = 115) and roughage and succulent feed (N = 91) and reflected the representative feeding situation in Germany. The median content of WHO-PCB-TEQ in analysed feed samples was 0.017 ng/kg [88% dry matter (d.m.)] and consequently more than a factor of 10 below the action level of 0.35 ng/kg (88% d.m.). A differentiation between compound feed and roughage and succulent feed showed that compound feed [median 0.007 ng/kg (88% d.m.)] were significantly lower contaminated with dioxin-like PCBs than roughage and succulent feed [median 0.058 ng/kg (88% d.m.)]. The median sum contents of the six marker PCBs were 0.16 μg/kg (88% d.m.) for compound feed and 0.56 μg/kg (88% d.m.) for roughage and succulent feed. The median of the WHO-PCDD/F-TEQ was 0.03 ng/kg (88% d.m.), the maximum level of 0.75 ng/kg (88% d.m.) was not exceeded. The median of the WHO-PCDD/F-PCB-TEQ was 0.05 ng/kg (88% d.m.) and consequently a factor of 25 below the maximum level of 1.25 ng/kg. Additionally the samples of roughage and succulent feed were analysed according to their contents of ash insoluble in HCl, representing a degree of the proportion of earthy components in feed. A slight correlation was found between ash insoluble in HCl and WHO-PCDD/F-TEQ (R ² = 0.59) whereas no correlation was found between ash insoluble in HCl and WHO-PCB-TEQ (R ² = 0.06).     

Application of Portable and Handheld Infrared Spectrometers for Determination of Sucrose Levels in Infant Cereals

Sucrose coating of breakfast cereals is used to enhance the flavor and attractiveness of the final product but there is a need for monitoring its levels to meet consumer health concerns associated with sugar consumption. Our objective was to evaluate the use of portable (mid-infrared, MIR) and handheld (near-infrared, NIR) systems for rapid, simple and reliable determination of sucrose content in breakfast cereal products. Cereal-based and sucrose-coated samples were provided by an Ohio snack food company. Samples were ground and spectra were collected using portable ATR-MIR (Cary 630) and handheld NIR (microPHAZIR) spectrometers. Reference sucrose levels were determined by high-performance liquid chromatography (HPLC). Partial least squares regression (PLSR) was used to develop calibration regression models for prediction of sucrose levels in breakfast cereals based on spectral data. Sucrose levels in uncoated (n?=?28) and coated (n?=?62) cereal samples were on average of 1.2?±?0.7 and 11.8?±?3.5 g/100 g, respectively. Similar calibration (n?=?85) model performances were obtained for determination of sucrose content by using the portable MIR and handheld NIR instruments with standard error of cross-validation (SECV) of 1.45 %. However, superior predictive ability was obtained with the portable MIR unit using a validation set (n?=?20, SEP?=?1.27 % and RPD?=?4.41). Regression models using NIR spectrum of the cereal through a polyethylene bag resulted in reduction of the model goodness of fit and RPD values. Results support the application of handheld NIR and portable MIR spectrometers for close-to-real-time analysis of sucrose levels in breakfast cereals providing simple, rapid and reliable prediction for quality assurance.