Production of a certified reference material for the acrylamidecontent in toasted bread

The need for a certified matrix reference material (CRM) of acrylamide in a food type matrix was emphasized by the competent authorities as a tool to improve comparability, ensuring accuracy and traceability of analytical results. The institute for reference materials and measurements (IRMM) responded to the international request by producing a certified reference material, ERM-BD273, containing endogenous acrylamide in a toasted bread matrix. This work describes the production of the CRM, according to 2 and 3 [ISO Guide 34 (2000). General requirements for the competence of reference materials producers; ISO Guide 35 (2006). Reference materials – General and statistical principles for certification], which comprises the material processing, homogeneity and stability assessment, material characterisation and the acrylamide mass fraction value assignment in toasted bread. Heterogeneity of the material between the vials processed was determined by an in-house validated gas chromatographic methodology involving acrylamide derivatisation and mass spectrometric detection and found to be below 2%. Potential degradation during storage was also investigated and a shelf-life based on this value was established. A collaborative study for material characterisation involved sixteen laboratories applying different analytical methodologies including gas chromatography or high resolution liquid chromatography and isotopic dilution mass spectrometry. The certified value for acrylamide in ERM-BD273, traceable to the international system of units (SI), is (425 ± 29) ng g⁻¹.     

Impact of frozen storage on polyacetylene content, texture and colour in carrots disks

This study investigated the effect of freezing method (slow or blast freezing) with or without blanching during storage at −20 °C on the levels of three polyacetylenes, falcarinol (FaOH), falcarindiol (FaDOH), falcarindiol-3-acetate (FaDOAc) in carrot disks. The quality of the carrot disks was also assessed using instrumental texture and colour measurements. Blast frozen carrot disks retained higher amounts of polyacetylenes compared to their slow frozen counterparts. Whilst the levels of retention of total polyacetylenes was higher in unblanched than blanched disks prior to freezing there was a sharp decrease in the levels of polyacetylenes in unblanched frozen carrots during the storage period for 60 days at −20 °C. FaDOH was observed to be the most susceptible to degradation during frozen storage of unblanched carrot disks, followed by FaOH and FaDOAc. The changes in the level of polyacetylenes during storage were adequately described by using Weibull model. The texture and colour were also found to decrease during frozen storage compared to fresh carrots.     

High pressure–temperature degradation kinetics of polyacetylenes in carrots

The present study assessed the effect of high pressure–temperature (HPT) processing on the levels of three polyacetylenes in carrot disks immediately after processing in comparison to sous-vide processing. The degradation kinetics of these compounds following processing at HPT was also investigated. The highest pressure–temperature combination which gave maximum retention during the time 10–30 min, for falcarinol it was 400 MPa, at 50 and 60 °C for 10 min; for falcarindiol it was 400 MPa, at 50 °C for 10 min and for falcarindiol-3-acetate was 400 MPa, at 50 °C for 10 min, respectively. Falcarindiol-3-acetate was found to be most barosensitive and falcarindiol was found to be most thermosensitive of the three polyacetylenes studied. When compared with sous-vide (SV) processed carrot disks, HPT processed samples showed higher retention of polyacetylenes. The changes in the levels of polyacetylenes during HPT treatment were adequately described by Weibull model function.     

Fluidized-bed drying as a feasible method for dehydration of Enterococcus faecium M74

The suitability of fluidized-bed technology for the dehydration of probiotic Enterococcus faecium M74 was evaluated. Fluidized-bed drying was processed by layering the microorganisms on spherical pellets. The impact on cell viability of atomizing air pressure, processing temperature and time was investigated. Using 1.5 bar atomizing air pressure, 37 °C processing temperature, and 15 min processing time provided optimal dehydration condition. Changing these values resulted in excessive stress on the cells and affected the cell viability. Next, we compared the impact on cell viability of fluidized-bed drying with that of freeze-drying. Fluidized-bed drying caused more substantial losses of cell viability. However, viability of cells pre-treated with membrane protective agents such as sucrose or skim milk was less affected by fluidized-bed drying than by freeze-drying, resulted in a minor degree of membrane damage after 2 months storage. Comparison of the flow characteristics of freeze-dried cells and fluidized-bed dried cells layered on spherical pellets showed the superior flowability of the latter.     

Behaviour of some organophosphorus pesticide residues in peppermint tea during the infusion process

In order to investigate dissipation behaviour of malathion, fenitrothion, dimethoate, chlorpyrifos and pirimiphos-ethyl during the infusion process, pesticide-free dried peppermint leaves were spiked with the pesticides. Infusions were prepared according to the usual process of infusion preparation. The effect of the infusion process on the transfer of the pesticides from the spiked peppermint leaves into brew was examined at intervals of 5, 10, 15 and 20 min. Residues were determined using a gas chromatograph equipped with a flame ionisation detector (FID). The decrease in pesticide levels during infusion was found to be statistically significant (p < 0.05). Transfer of residues decreased significantly with infusion time. The carryover of the residues of dimethoate, which has the highest water solubility, into the infusion was the highest. Satisfactory relationships were found between water-solubility (Ws), partition coefficient (K_ow) and Henry’s law constant (H) of the pesticides with the transfer of pesticides to brewed tea. It was observed that not only water solubility or K_ow but also H controls the dissipation of the pesticides from water or their air–water partitioning.     

Analysis of pesticide residues in sugarcane juice using QuEChERS sample preparation and gas chromatography with electron capture detection

QuEChERS sample preparation was used for the determination of 7 pesticides residues in 80 samples of sugarcane juice collected from two Brazilian cities, in two different periods. The method involved extraction with acetonitrile, liquid–liquid partition with addition of MgSO₄ and NaCl followed by dispersive SPE cleanup with PSA sorbent and the analyses were carried out with a GC–ECD equipment. The method was validated using sugarcane juice spiked at 0.025, 0.10 and 0.20 mg/L and the average recovery by the method varied from 62.9% to 107.5% with RSDs < 18%. The method showed good linearity and the LODs for the pesticides studied ranged from 0.003 to 0.04 mg/L. No pesticide residue was detected (>LOD) amongst the 80 samples analysed.     

A preliminary assessment of consumer’s exposure to organochlorine pesticides in fruits and vegetables and the potential health risk in Accra Metropolis,Ghana

Accra Metropolis is the major recipient of agricultural produce in Ghana, with almost the entire population depending on rural agricultural activities for subsistence. To increase agricultural produce, various forms of pesticides are normally used in fruits and vegetable farming. The consequence is that several cases of pesticide poisoning have been observed. In this preliminary study, a field survey was carried out to assess the knowledge, attitudes, and peoples’ perception concerning the use of pesticides by farmers in fruit production. The residual concentrations of selected pesticides in pawpaw, imported apples and tomato samples and the potential health risks associated with the exposure to these pesticides were also assessed. The field survey data indicated that more than 70% of the participants reported one or more poisoning upon fruits consumption resulting in pesticide-related illnesses. Pesticide residues in the various environmental samples were determined by gas chromatography with electron capture detector (GC-ECD). The results showed that, the levels of pesticide residues varied from <0.01 μg/g to as high as 0.11 μg/g depending on the pesticide monitored. The analysis of health risk estimates revealed heptachlor, heptachlor epoxide, endrin aldehyde, and endrin ketone levels exceeded the reference dose, suggesting a great potential for systemic toxicity in children considered the most vulnerable population subgroup. Lastly, the public is in the know of pesticide residues in fruits and calls for the curtailing of pesticide use on fruits and vegetable production via educational programmes for farmers on control and safer use of pesticides.     

Simplified pesticide multiresidues analysis in fish by low-temperature cleanup and solid-phase extraction coupled with gas chromatography/mass spectrometry

A simple and fast method for the simultaneous analysis of thiobencarb, deltamethrin and 19 organochlorine pesticide residues in fish by gas chromatography–mass spectrometry was investigated in this study. Samples are extracted with acetonitrile. Most of lipids in the extract are eliminated by low-temperature cleanup, prior to solid-phase extraction cleanup. The lipids extracted from the fish samples were easily removed without any significant losses of the pesticides. Aminopropyl (NH₂) cartridge was effective to eliminate the remaining interference. Spiked experiments were carried out to determine the recovery, precision and limits of detection (LODs) of the method. The method detection limits ranged from 0.5 μg kg⁻¹ to 20 μg kg⁻¹, whilst recoveries of the pesticides were in the range of 81.3–113.7% with relative standard deviations ?13.5% at a spiked concentration of 0.05 mg kg⁻¹, 0.02 mg kg⁻¹ and 0.1 mg kg⁻¹. The newly developed method is demonstrated to give efficient recoveries and LODs for detecting pesticide multiresidues in fish.     

Processing blackcurrants dramatically reduces the content and does not enhance the urinary yield of anthocyanins in human subjects

Blackcurrant (BC) fruits are a rich source of biologically active anthocyanins but little is known of the anthocyanin content of commonly consumed BC products or how processing affects the absorption. We report that whereas fresh and frozen whole BC were a rich source of anthocyanins, containing 897 and 642 mg (100 g FW)⁻¹ of total anthocyanins the levels in all other products were substantially lower (0.05–10.3% of the levels in fresh fruit). Further, when the absorption and excretion of BC was assessed in volunteers consuming a portion (100 g) of frozen whole BC (642 mg total anthocyanins) and, 300 g of a BC drink made by diluting concentrated syrup (33.6 mg total anthocyanins), only small quantities of BC anthocyanins were excreted in urine (fruit, 0.053 ± 0.022%; drink, 0.036 ± 0.043%; mean percent urinary yield ± SD) and they were not detected in plasma. These data indicate that fresh and frozen BC, but not processed products, are rich sources of anthocyanins but, regardless of the food source, these anthocyanins are poorly bioavailable.     

Freezing of potato tissue pre-treated by pulsed electric fields

The effects of pulsed electric fields (PEF) pre-treatment on the freezing, freeze-drying and rehydration behavior of potato were studied. Potato samples (26 mm diameter, 10 mm high) were treated by PEF (400 V/cm) for various durations between 10⁻⁴ and 0.3 s. The degree of tissue damage was quantified by the change in electrical conductivity. PEF treated and untreated samples were either frozen in an air-blast freezer with air at −35 °C and 2 m/s velocity or freeze-dried at 0 °C and 0.04 mbar pressure and then rehydrated in water at 25 °C. The freezing times for PEF pre-treated samples reduced as the PEF-induced tissue damage increased. Scanning electron microscope images of the air-blast frozen and then freeze-dried samples showed increased deformation of cells and larger intercellular spaces (frozen samples only) for the PEF pre-treated samples. However, PEF pre-treatment improved the rate of freeze-drying and improved the quality and rehydration of the samples.     

Monitoring multi-class pesticide residues in fresh grape by hollow fibre sorptive extraction combined with gas chromatography–mass spectrometry

A fast and sensitive multi-residue analysis method is reported for simultaneous determination of 25 pesticides of chemical classes which are spiked into fresh grape. The sample pretreatment method involves extraction and clean-up in one step with SiO₂ hollow fibre from 1.0 mL fresh grape slurry to minimise the matrix effects, and determination by gas chromatography–mass spectrometry with selective ion monitoring mode. The validation of the optimised method in terms of linearity, precision, recovery and repeatability showed that the proposed procedure is sensitive (the limits of detection were in the range of 0.0009–0.0084 μg mL⁻¹ for 25 pesticides), precise and repeatable (average recoveries were between 61% and 108% with relative standard deviations from 4.0% to 12.4 %). The proposed method was also applied to the analysis of these groups of pesticides in fresh grape sample purchased from the local markets of Lanzhou (China), while no residues of the selected pesticides were detected in the sample.     

Analysis of quinolone antibiotics in eggs: Preparation and characterization of a raw material for method validation and quality control

A quality control material for the analysis of quinolone residues in egg samples has been prepared. Homogenized fresh whole egg spiked with nine quinolones (marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid and flumequine), at the concentration level of 500 μg kg⁻¹ was lyophilized and homogenized to obtain the reference material. The homogeneity of both the bulk and the packed material was verified. Two different strategies, classical and isochronous, were used for the stability study. Conclusions obtained with the classical and isochronous approaches were similar, but the variability of the isochronous results was lower and this led to lower material uncertainty. The reference material was found to be stable for at least 1 year when stored at either room temperature, 4 °C or −20 °C; −80 °C was taken as reference temperature in all cases.     

Effect of high pressure/high temperature processing on cell wall pectic substances in relation to firmness of carrot tissue

Thermal processing for food preservation results in undesired softening of fruits and vegetables. To explore the potential of high pressure sterilization in food processing, the effects of combined high pressure/high temperature (HP/HT) treatments on carrot pectic polysaccharides and the related textural properties were investigated and compared with that of samples thermally processed at atmospheric pressure. Disks of fresh carrot (Daucus carota var. Yukon) tissue were subjected to three different treatments (80 °C–0.1 MPa, 100 °C–0.1 MPa and 80 °C–600 MPa) for varying time intervals. Subsequently, the residual texture and microstructural changes of the carrots were evaluated. Alcohol-insoluble residues were prepared from the samples and sequentially fractionated with water, cyclohexane-trans-1,2-diamine tetra-acetic acid (CDTA) and Na₂CO₃ solutions. Thermal treatments at 0.1 MPa caused extensive tissue softening. This was marked by increased cell separation, an increase in water soluble pectin (WSP) paralleled by a decrease in chelator (CSP) and sodium carbonate (NSP) soluble pectin. HP/HT treated carrots showed minimal softening and negligible changes in intercellular adhesion. This was accompanied by a significant reduction in the degree of methyl esterification of pectin, low WSP in contrast to the high CSP and NSP fractions, minor changes in the different pectin fractions during treatment, and a substantial amount of pectin in the fractionation residue. There was a clear difference between HP/HT and thermally processed carrot pectin; HP/HT showing pronounced texture preservation.     

Degradation behaviour of methamidophos and chlorpyrifos in apple juice treated with pulsed electric fields

Apple juice (13 °Brix) spiked with methamidophos and chlorpyrifos (2–3 mg/l of each compound) was treated by pulsed electric fields (PEF), and pesticide residues were quantified by gas chromatography with flame photometric detection (GC-FPD). Results showed that electric field strength (8–20 kV/cm) and pulse number (6–26 pulses) have significant effects on the degradation of methamidophos and chlorpyrifos. PEF treatment is effective for the degradation of methamidophos and chlorpyrifos residues in apple juice, and chlorpyrifos is much more labile to PEF than methamidophos. An increase in either pulse number or electric field strength could speed the degradation of methamidophos and chlorpyrifos, and the kinetics equations and related parameters quantitatively characterized the degradation behavior of the pesticides. The exponential model better fits the experimental data for all treatments than the linear model.     

Simultaneous determination of pesticide residues in fruits and vegetables by GC/MS (SCAN mode) and HPLC

A method was developed for simultaneous determination of pesticide residues in fruits and vegetables. Residues were extracted from samples with acetonitrile, followed by a salting-out step and a partitioning step with n-hexane at the same time. Co-extractives were removed with ENVI-Carb/LC-NH2 mini-column cleanup. Analysis was performed by GC/MS (SCAN mode) and HPLC. Of the 139 pesticides spiked at 0.1 or 0.5 microgram/g into 6 fruits and vegetables (spinach, tomato, apple, radish, cabbage and carrot), recoveries of 117 pesticides were between 70 and 120%. This method is appropriate for determining these pesticides and for screening several other pesticides for which the recoveries were < or = 70% or > or = 120% (imazalil, etc.). The limits of detection for most pesticides in this method were equal to or lower than those of the bulletin method in Japan.     

A convective multi-flash drying process for producing dehydrated crispy fruits

The aim of this work was to evaluate the application of a convective multi-flash drying process (CMFD) to producing dehydrated and crisp fruits. To accomplish this process, samples of banana (Musa sapientum L.) or mango (Mangifera indica L.) were heated to 60 °C by hot air, and a vacuum pulse was applied, which resulted in dehydration by a combination of convective drying and flash evaporation. Banana processed by CMFD had a moisture content of 0.293 g/g (dry basis) and a_w = 0.272 after 3 h of processing. Mango had a moisture content of 0.09 g/g and a_w = 0.359 after 4 h of processing. Puncture tests on fruits dehydrated by CMFD and on commercial freeze-dried fruits showed strain-force curves with many peaks (jagged curves). For CMFD much smaller global shrinkage was observed. These results indicate that the CMFD process can be applied for producing crispy fruits and is an alternative to the freeze-drying process.     

Assessing the suitability of polylactic acid flexible films for high pressure pasteurization and sterilization of packaged foodstuff

Effects of high pressure (HP) pasteurization and sterilization processes on the properties of commercial biodegradable polylactic acid (PLA), used as packaging material, have been investigated. HP treatments have been performed at pressures of 200, 500 and 700 MPa on PLA pouches, containing different types of food, i.e. tap water, solid carrots, carrot juice and carrot puree. Process temperature was in the ranges 25–40 and 90–110 °C, respectively for HP pasteurization and HP sterilization.     

Evaluation of QuEChERS method for the determination of organochlorine pesticide residues in selected groups of fruits

This paper reports a method for organochlorine pesticide determination in selected fruit species where pesticide residues were extracted and cleaned using a buffered QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method, followed by GC–MS analysis. The method results showed the matrix-matched calibration curve linearity was >0.99 for all target analytes. With pesticide recovery rates (spiked at 0.008 mg kg⁻¹) ranging from 70% to 120%, and RSD values <17% for most compounds, the limit of quantification ranged from 0.001–0.013 mg kg⁻¹. Finally, the method ruggedness was further demonstrated by analysis of actual commercial fruits and baby food samples.     

Determination of matrix effects occurred during the analysis of organochlorine pesticides in agricultural products using GC-ECD

Matrix effects observed during the multiresidue analysis of seven organochlorine pesticides in six different agricultural products with GC-ECD were assessed. The presence of matrix coextractives, a major cause of observed matrix effects, directly and/or indirectly influenced the chromatographic responses of some pesticides. Two types of external calibrations, solvent calibration (SC) and matrixmatched calibration (MC), were used to assess matrix effects. Greater matrix effects were observed at the lower concentrations of each pesticide. The extent of matrix effects varied unpredictably with matrix type. Among the analyzed pesticides, iprodione, cyhalothrin, and cypermethrin exhibited greater matrix effects (>150%) for almost all matrices. The pesticide recovery rates obtained with MC were not statistically different from a 100% recovery rate in most samples, which indicates that MC may diminish the overestimates occurred due to matrix effects in GC analysis.     

Limonene encapsulation in freeze-drying of gum Arabic-sucrose-gelatin systems

Encapsulation of limonene in freeze-drying of various matrices consisting of gum Arabic, sucrose and gelatin was studied. Retention of limonene in freeze-drying was observed by measuring absorbance at 252 nm using a spectrophotometer. Two different levels of limonene, in the weight ratios (w/w) of 9:1 and 8.5:1.5 (total solids (TS):limonene) were studied. Highest amount of limonene (75.3±0.3% of initially added amount) in the emulsions homogenised at 25 MPa (4 MPa in second stage) followed by freeze-drying, was retained in a matrix consisting of gum Arabic, in the ratio of 9:1 (w/w). A mixture consisting of gelatin-sucrose-gum Arabic in the w/w ratio of 0.66:0.17:0.17 retained highest amount (71.8±0.1% of initially added amount) of limonene in the ratio (w/w) of 8.5:1.5 (TS:limonene). A matrix consisting of gum Arabic-sucrose-gelatin (1:1:1 w/w/w) with added limonene at a ratio (w/w) of 9:1 (TS:limonene), was used to study the effects of ultra high-pressure homogenisation (50-250 MPa) on limonene encapsulation in freeze-drying. Highest amount (84% of initially added amount) of limonene was retained in the emulsions homogenised at a pressure of 100 MPa. Electron micrograph of freeze-dried matrix of gum Arabic-sucrose-gelatin in the weight ratio of 1:1:1 suggested that it possessed a flake like structure, which was free of dents and shrinkage. A mixture consisting of gum Arabic-sucrose-gelatin is an efficient encapsulant for limonene encapsulation by freeze-drying.