Characteristics of Bacillus cereus isolates from legume-based Indian fermented foods

An antibiogram of 48 strains of Bacillus cereus isolated from 6 different kinds of legume-based Indian fermented foods (amriti, dhokla, dosa, idli, papad and wadi) was generated against 18 different antibiotics that are commonly used against foodborne diseases, mainly gastroenteritis. Each of the isolates was found to be resistant against at least nine different antibiotics. Production of extracellular enzymes, namely protease, lipase and amylase by 33%, 27% and 46%, respectively, of the isolates indicates their potentiality for food spoilage. In brain–heart infusion broth supplemented with glucose, the D_100 °C-values for the tested 12 strains ranged from 3.0 to 9.2 min. In nutrient broth, the minimum and maximum pHs permitting growth of B. cereus were 5.3 and 11.6, respectively. The minimum inhibitory concentrations of sodium chloride, benzoic acid and sorbic acid for the growth of the isolates were 65–85 mg ml⁻¹, 400–700 μg ml⁻¹ (pH 5.0–4.2) and 500–600 μg ml⁻¹ (pH 5.0–4.8), respectively. Of the tested 10 strains, eight were resistant to 300 μg nisin ml⁻¹ (pH 5.0). While studying the combined effect of selected hurdles on the growth of an isolate, the judicious combination considered was 20 mg sodium chloride, 300 μg benzoic acid and 25 μg nisin ml⁻¹ at pH 5.6. The whole-cell protein fingerprinting (WCPF) analysis using SDS–PAGE revealed a high level of diversity among the isolates. At 60% similarity level, the WCPF profiles could be grouped into four major clusters which were divided into 34 subclusters. Most of the subclusters were source-wise homogeneous.     

Assessment of estimated daily intake of nitrite by average consumption of processed foods in Korea

This study has been performed to estimate the average daily intake of nitrite used in Korea as a color fixative. The crude estimation of daily intake was calculated based on maximum permitted levels (MPL) and national food disappearance data in 1998. In order to refine estimated daily intake (EDI), daily food consumption nationwide National Health and Nutrition Survey in 1998 and the concentration of nitrite in their permitted foods were applied. The crude EDI of nitrite was 17.85 μg/kg bw/day, representing 25.5% of acceptable daily intake (ADI) assigned by JECFA. The refined average EDI for nitrite was 0.87 μg/kg bw/day, representing 1.25% of ADI. For average consumers of age–sex groups ranged from 0.2 to 4.8 μg/kg bw/day, representing 0.3%–6.9% of the ADI.     

Occurrence of contaminants in foods commonly consumed in Bahrain

The occurrence of mycotoxins (aflatoxins, zearalenone, deoxynivalenol), heavy metals and pesticide residues in 198 susceptible food commodities available in Bahrain was determined. Aflatoxins were found in many of the foods tested and three samples of red chili powder (35.9, 52.6 and 69.2 ng/g), one sample of black pepper powder (27.7 ng/g) and one sample of unshelled pistachio nuts (81.6 ng/g) exceeded the maximum allowable limit of aflatoxins. Zearalenone was present in some samples including cornflakes (3.1 ng/g) and crushed wheat (0.3 ng/g). Although many samples contained heavy metals, one sample of cinnamon powder (13.0 μg/g) and one sample of black pepper powder (11.2 μg/g) exceeded the maximum allowable limit for lead. The average levels of cadmium were highest in cinnamon powder (0.3 μg/g) and ginger powder (0.3 μg/g). Some amount of pesticides was found in cumin powder (0.06 μg/g of lindane), turmeric power (0.04 μg/g heptachlor) and coriander powder (0.4 μg/g permethrin). Almonds, peanuts, cashew nuts infant formulas were free of contaminants. Although the contamination of most foods in Bahrain was within the limit, strengthening of the food control systems is important.     

The in vitro antimicrobial and antioxidant activities of the essential oils and methanol extracts of endemic Thymus spathulifolius

The present study was conducted to evaluate the in vitro antimicrobial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Thymus spathulifolius (Hausskn. and Velen.). The antimicrobial test results showed that the essential oil of T. spathulifolius strongly inhibited the growth of test microorganisms studied, except for 4 fungi species while polar and non-polar subfractions of the methanol extract had moderate antibacterial, but not antifungal and anticandidal activity. The antioxidative potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid systems. The polar subfraction of the methanol extract was able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 16.15 ± 0.5 μg/ml, which was lower than that of synthetic antioxidant, BHT, (19.8 ± 0.5 μg/ml). Inhibition values of linoleic acid oxidation were calculated as 92% and 89% for the oil and the polar subfraction, respectively. Gallic acid equivalent total phenolic constituent of the polar subfraction was 141.00 ± 0.90 μg/mg (14.1%, w/w). The chemical composition of a hydrodistilled essential oil of T. spathulifolius was analyzed by a GC and GC/MS system. A total of 28 constituents representing 99.2% of the oil were identified; thymol (36.5%), carvacrol (29.8%), p-cymene (10.0%) and γ-terpinene (6.3%) were the main components comprising 82.6% of the oil. Results presented here may suggest that the essential oil and extracts of T. spathulifolius possess antimicrobial and antioxidant properties, and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry.     

Aflatoxins levels in dried fruits and nuts from Rabat-Salé area, Morocco

The occurrence of aflatoxins (AFs) in dried fruits and nuts available in Rabat-Salé area (Morocco) was surveyed in this study. One hundred samples of dried fruits and nuts, purchased from retail shops and local markets from January to October 2006, were analyzed for AFs content by immunoaffinity (IAC) clean-up with liquid chromatography and fluorescence detection. Results showed that the incidences of total aflatoxins (AFT) and aflatoxin B1 (AFB1) in peanut, dried raisins, dried figs, walnut, and pistachio were 5%, 20%, 30%, 30% and 45% and 5%, 20%, 5%, 30% and 45%, respectively. The highest contamination levels of AFB1 were found in one walnut sample (2500 μg/kg) and one pistachio sample (1430 μg/kg). 5%, 20% and 20% of samples of pistachio, walnut and dried raisins exceeded the maximum tolerable limit (2 μg/kg) set for AFB1 by EU regulations. While 15% of dried figs samples were above the maximum limit (4 μg/kg) set by EU regulations for AFT. The present paper is the first report on the natural occurrence of AFs in dried fruits and nuts available in Rabat-Salé area in Morocco.     

Pesticide residues in Brassica vegetables and exposure assessment of consumers

The presence of pesticide residues in Brassica vegetables (365 samples) produced in north-eastern Poland (2006-2009) was determined and their health risks assessed. The analytical procedure was developed to examine of 130 pesticides of different chemical classes (chloroorganic, phosphoroorganic, carbamates, strobilurines, neonicotinoids, amides, pyrimidines, benzimidazoles, imidazoles and triazoles) in broccoli, Brussels sprouts, cauliflower, head and Chinese cabbage. Pesticides were extracted using matrix solid phase dispersion (MSPD) and analyzed by gas chromatography (GC) with dual detection system: electron capture (ECD) and nitrogen-phosphorus (NPD). Linearity (R² ≥ 0.997) was good over the concentration range from 2.5 to 0.001 mg/kg for all the pesticides, and instrumental detection limits ranged from 0.001 to 0.01 mg/kg. Mean recoveries for vegetables spiked at three fortification levels (0.001-2.5 mg/kg) ranged from 70.07 to 118.90%. Relative standard deviations ranged from 0.15 to 8.58%, except: dicofol, pyridaben (acaricides), dichloran (fungicide), isofenphos, triasophos (insecticides) where mean recoveries were above 120% (122.2-127%) and also dichlofluanid, tecnazene (fungicides), dichlobenil (herbicide), endosulfan-sulfate, phorate, phosmet (insecticides) with mean recoveries below 70% (42.83-69.1%). The method used to monitor pesticide residues in vegetables. Fifteen different pesticides (insecticides mainly) were detected in 118 samples (32%), while multiple pesticides (more than one pesticide residue) in about 4% samples. Chlorpyrifos and cypermethrin were the most commonly detected pesticides. Chlorpyrifos was present in 27.4% items and ranged from 0.005 to 1.51 mg/kg, while cypermethrin were detected in 3.3% samples and ranged from 0.02 to 0.19 mg/kg. Thirty-three (9%) samples exceeded the maximum residue levels (MRLs). The dietary intake of residues of some pesticides can pose acute hazards. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The estimated daily intakes (EDIs) ranged from 0.005% of the ADI (acceptable daily intake) for fenhexamid to 4.454% of the ADI for diazinon. Combine cumulative exposure for chlorpyrifos detected on Brassica were 0.777% of ADI. The results show that occurrence of pesticide residues in Brassica vegetables from this region could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring and tighter regulation of pesticide residues in vegetables is recommended.     

Determination of biogenic amines in sucuk

The biogenic amines content of sucuk (Turkish dry fermented sausage) were determined on 30 samples obtained from retail markets and butchers in Turkey. Also, pH and a_w values, microbiological properties, and NPN levels of these samples were analyzed. The most important biogenic amines were tyramine (range 2.4–676 mg/kg), followed by putrescine varied from not detected to 364 mg/kg. Histamine content was under 50 mg/kg in 80% of the samples while it was over 100 mg/kg in only one sample. Tryptamine was detected in 16 of 30 samples in the range of 1.2–82.3 mg/kg.

Lactic acid bacteria, Micrococcus/Staphylococcus and Enterobacteriaceae counts of samples varied from 2.84 to 8.85 log cfu/g, <2.00 to 6.74 log cfu/g, and <2.00 to 5.04 log cfu/g, respectively. pH values were varied between 4.53 and 6.29 while water activity (a_w) were measured to be between 0.761 and 0.960. NPN values were determined to be between 1.47% and 4.10%. Generally, total amine content was high in samples that had high NPN levels.     

Surveillance of pesticide residues in fruits from Valencia during twenty months (2004/05)

The aim of this study was to investigate the pesticide residues in market fruits (oranges, tangerines, nectarines, peaches and khakis) from one Valencian Cooperative (Spain) and to conduct a monitoring of 32 organophosphorous, organonitrogen and organohalogenated pesticides and nine dithiocarbamate fungicides (DTCFs) usually applied on cultures of this area.Extracts were obtained by an official procedure for routine analysis based on ethyl acetate extraction. Residues of pesticides were determined by gas chromatography with nitrogen phosphorous detector (NPD), electron-capture detector (ECD) and mass spectrometry (MS) detectors. Mean recoveries obtained at fortification levels between 0.05 and 5 mg kg⁻¹ were in range of 56–97% with relative standard deviations (RSDs) from 5% to 18%. The limits of quantification (LOQs) were in range of 0.1–140 μg kg⁻¹ and lower than maximum residue limits (MRL) established by the Spanish legislation. 73% of the samples had no detectable residues. Of the contaminated samples, 13.8% exceeded the maximum residue limits (MRLs). Peaches and oranges showed the lowest contamination rates (13.9% and 21.3%, respectively). The contamination and violation rates were similar than the percentages recorded in previous monitoring studies in the same Community. Estimated daily intakes (EDIs) were calculated for these compounds in basis of European maximum residue limits (MRL) and residues found in the analysed samples and were compared with the acceptable daily intakes (ADIs).     

Aflatoxin occurrence in nuts and commercial nutty products in Malaysia

A total of 196 nuts and their products marketed in Penang, Malaysia were assessed for aflatoxins using a monitoring scheme consisting of enzyme-linked immunosorbent assay (ELISA) for rapid screening and reversed phase high performance liquid chromatography (HPLC) for quantification and confirmation. Thirty two out of 196 samples (16.3%): six raw groundnuts shelled, two roasted groundnut in shell, three roasted groundnut shelled, one walnut, four coated nut products, two peanut cakes (gung tang), 3 pounded groundnuts, one peanut slice, seven peanut butters, one bakery product and two confectionery were contaminated with aflatoxins, ranging in levels from 16.6 μg/kg up to 711 μg/kg (mean 17.2–350 μg/kg) for total aflatoxins.     

Method for analysis of 68 organic contaminants in food contact paper using gas and liquid chromatography coupled with tandem mass spectrometry

Food contact materials (FCMs) have been reported as a source of various xenobiotics. This study investigates the possibility of simultaneous analysis of 68 potential contaminants in paper FCMs, specifically phthalates, polycyclic aromatic hydrocarbons, photoinitiators, bisphenols, and polyfluorinated compounds. Target compounds were co-isolated using a technique based on ultrasonic extraction by mixture of acetonitrile and water followed by QuEChERS-like liquid–liquid partition in the presence of inorganic salts. Resulting extracts were analyzed using gas and high performance liquid chromatography coupled with tandem mass spectrometry (GC–MS/MS, HPLC–MS/MS). Acceptable recoveries (70–120%) and RSDs (<20%) were achieved for most of the analytes at spiking levels of 0.05, 0.2 and 1 mg/kg. LOQs ranged from 0.0013 to 0.22 mg/kg. The proposed method was successfully applied to analysis of 15 real samples. Complex mixtures of contaminants reaching levels up to 48 mg/kg were identified in the samples.     

Biogenic amines: quality index of freshness in red and white meat

Biogenic amine (BA) content in meat can be considered as a freshness marker or as a bad conservation marker. In particular the study of BA quantities in meat as a function of conservation time, could be a useful tool to control meat spoilage. In fact, the formation of some amines and concentration increase of those already existing in meat, are due to degrading processes in food, which are promoted by enzymatic reactions caused by external microbial activity or by endogenous tissue activities. The amines considered are: tryptamine, putrescine, cadaverine, serotonin, tyramine, spermidine, spermine. Their quantitative determination was carried out by means of HPLC, with spectrophotometric-UV detection, on pre-treated meat samples, both “red” (adult bovine) and “white” (chicken). The amines were extracted in acid aqueous solution (HClO₄) and then derivatised by dansylchloride. The trend of BA concentrations as a function of time was also investigated, in a period of 36 days, at the conservation temperature of 4±1 °C. The proposed method is linear in the range of concentrations between 0.01 and 5.0 μg/ml. For all the amines considered recoveries were 93%. The CV values for all the measures ranged between 1.47% and 2.94%. The results show that in red meat the BA levels are still low until 9 days of storage (30 mg/kg) and that over 36 days only cadaverine and tyramine concentrations become very high (120 mg/kg). In white meat all the BA levels remain quite low (40 mg/kg) all over the 36 days, instead of the cadaverine content which gains 50 mg/kg at the seventh day of storage.     

Rapid GC-FPD determination of organophosphorus pesticide residues in Sicilian and Apulian olive oil

A simple and quick method for the determination of dimethoate, parathion-methyl, fenthion, parathion-ethyl, and methidathion in olive oil is described. Analysis was carried out using GC (capillary column 5 m × 0.32 mm × 0.45 μm) with aspecific detector (FPD), after sample extraction with acetonitrile. No cleanup was necessary because there were no interferences in the chromatogram. Recoveries of five pesticides at three fortification levels (1.0, 0.2 and 0.05 mg/kg) were in the range 78–97%.Seventy-nine samples were collected from Sicilian and Apulian individual growers during 2002–2003. Only 16% of the samples contained fenthion in concentrations ranging from 0.09 to 0.73 mg/kg; no other pesticides were detected in the 79 samples.     

Microbiological quality of tomatoes and peppers produced under the good agricultural practices protocol AGRO 2-1 & 2-2 in Crete, Greece

The efficiency of the good agricultural practices (GAP) protocol AGRO 2-1 & 2-2, in advancing microbiological-quality of tomatoes and peppers, was studied in greenhouses at Ierapetra, Crete, Greece. The 240 tested vegetables-samples, produced under AGRO 2-1 & 2-2, showed satisfactory quality: Listeria monocytogenes absent per 25 g; Escherichia coli < 20 Colony Forming Units per gram (CFU/g); total coliforms 4.37–4.68 log CFU/g; aerobic plate counts 5.78–5.92 log CFU/g. Based on actual results and practices evaluation, we conclude that AGRO 2-1 & 2-2 can reduce microbial hazards for consumers and furthermore can establish practices in compliance to basic Euro-Retailer-Produce GAP (EUREPGAP) requirements.     

天然气制合成气工艺冷凝液中微量有机物分析

针对天然气制合成气工艺冷凝液中微量有机物难以定量的问题,采用总有机碳(TOC)测试仪测定冷凝液中总有机碳含量,采用气相色谱(GC)、离子色谱(IC)和高效液相色谱(HPLC)测定冷凝液中微量有机物组成,考察其定量的准确性。结果表明,冷凝液中总有机碳质量浓度为927 mg/L。采用GC测定冷凝液中甲醇质量浓度小于01 mg/L。采用HPLC测定冷凝液中甲酸质量浓度为325 mg/L,加标回收率为1026%。采用IC测定冷凝液中甲酸、乙酸质量浓度分别为3923、015 mg/L,加标回收率分别为1180%、1159%;用加标回收率校正后的甲酸质量浓度为3322 mg/L,与HPLC测定值接近。冷凝液中9146%的有机碳源于甲酸。采用TOC测试仪测定冷凝液中总有机碳含量可预测其有机物含量;IC可用于测定冷凝液中微量乙酸含量,但结果偏高;采用HPLC测定冷凝液中甲酸含量较为准确。     

Aflatoxins and ochratoxin A in Brazilian paprika

Seventy paprika samples collected in the city of São Paulo, Brazil, from January to April 2006 were analysed for aflatoxins and ochratoxin A (OTA) using an immunoaffinity column clean-up and HPLC-FLD. For aflatoxins, the limit of quantification (LOQ) were 0.23, 0.23, 0.45 and 0.45 μg/kg for AFB₁, AFB₂, AFG₁ and AFG₂, respectively. For OTA the LOQ was 0.80 μg/kg. Aflatoxins were found in 82.9% of samples and AFB₁ was detected in 61.4% at levels ranging from 0.5 to 7.3 μg/kg with mean concentration of 3.4 μg/kg. OTA was found in 85.7% at levels ranging from 0.24 to 97.2 μg/kg with mean concentration of 7.0 μg/kg.     

Survival and growth of Listeria monocytogenes on sausage formulated with inoculated and stored rework product

To assess the effect of including contaminated rework on survival and growth of Listeria monocytogenes, two sausage formulations (one American, Bologna sausage; and one Bulgarian, Stranja sausage) were inoculated with the pathogen and stored for 4 days at 10 °C plus 15 h at 30 °C. After storage, both rework types were included (at 20% and 40%) in corresponding fresh sausage emulsions and heated to 68, 70 and 71.7 °C; fresh Bologna and Stranja emulsions served as controls and were inoculated with 24 h broth cultures of the same 10-strain mixture of L. monocytogenes and thermally treated to the same temperatures. The results showed that heating to 68 and 70 °C inactivated 3–4 log CFU/g of the initial concentration of L. monocytogenes cells (>7 log CFU/g), while heat treatment to 71.7 °C in the center of experimental samples reduced counts by 6 log CFU/g. Survival of L. monocytogenes in samples heated to 68 and 70 °C was higher in controls. Control samples of Stranja emulsion heated to 71.7 °C allowed higher growth (P < 0.05) during storage (5 days at 10 °C) as compared to other control and experimental rework samples. The Stranja emulsion had a higher fat content (20.2%) compared to the Bologna emulsion (11%). This study provides evidence about the possible danger when potentially contaminated rework is stored and then introduced into fresh product formulations.     

Multi-residue determination method of pesticides in leek by gel permeation chromatography and solid phase extraction followed by gas chromatography with mass spectrometric detector

The paper describes a multi-residue determination method for 102 pesticides in leek. The preparation of samples included extraction by acetone and dichloromethane and cleaned up by gel permeation chromatography and solid phase extraction (SPE) tube. The target analytes were determined by gas chromatography–mass spectrometric detector with selected ions mode (GC–MS/SIM). The method was validated by fortified at the level 0.02–0.20 mg/kg in leek. The average recoveries of all analytes were between 70% and 113%, and standard deviations were below 13%. The limit of quantitation (LOQ) for most analytes was below 0.01 mg/kg. The method was used for other vegetables like spinach, cereal, capsicum, cucumber, tomato, eggplants, etc. For those matrixes, the same concentrations were fortified and got accepted recoveries and LOQ.     

Oxidative Dehydrogenation of Methanol on Chromium Oxide/Montmorillonite K10 Catalysts

Methanol conversion was carried out on a mesoporous material—chromia/montmorillonite K10 (MK10)—in a pulse microcatalytic system. Methanol was converted to formaldehyde and ethylene by two different mechanisms. Methanol dehydrogenation increases by increasing reaction temperature (300-400°C) and as chromia loading decrease. On the other hand, the dehydration of methanol occurs at a higher temperature (400-500°C) and as chromia loading increase, 3-18% Cr. Redox and exposed nonredox Cr³⁺ are responsible for formaldehyde formation. There is a relationship between increased C₂H₄ production and the increase of Cr⁶⁺ phase according to the acidity of chromia catalysts 34 and 76 μL tert-Butylamine/g catalyst for 3% Cr and 18% Cr, respectively. Formaldehyde formation is diffusionally controlled at high temperatures (400-500°C) and kinetically controlled at a lower reaction temperature (300-400°C), while methanol dehydration to ethylene is surface reaction controlled at 400-500°C.     

The fate of ochratoxin A during the Pekmez production from mouldy grapes

The grape juices produced from mouldy grapes that are contaminated naturally with OA between 2.1 and 9.8 μg/l were used in pekmez production. In the processing steps of pekmez, changes in OA amount were examined. The amounts of OA in pekmez samples were found to be 5–6 times higher than OA amount of grape juice.

The dry matter (%), total sugar (%) and pH values were 18.93, 17.82 and 3.36 at the beginning of the experiment while they were 71.42, 67.35 and 3.91 at the end of the experiment, respectively.     

A limited survey of zearalenone in Indonesian maize-based food and feed by ELISA and high performance liquid chromatography

A survey of zearalenone (ZON) in Indonesian maize-based food and feed was performed in 89 samples using an enzyme-linked immunosorbent assay (ELISA). Results indicated that 32 samples (36.0%) were contaminated in a range from 5.5 to 526 μg/kg. Only one highly contaminated sample was observed in a category of home-made food samples (>500 μg/kg) and the highest percentage of contaminated samples (>85.7%) was noted in a category of poultry feed. The positive samples based on the ELISA analyses were then confirmed using a high performance liquid chromatography (HPLC) method in combination with an immuno-affinity column for clean-up. Prior to sample measurement, the HPLC method was validated using a blank maize matrix. The overall average recovery of blank maize spiked with ZON at levels of 200–750 μg/kg were 100.2%. Detection limit based on a signal-to-noise ratio 3:1 was 3.0 μg/kg for ZON in maize samples and the linear range applicable for analyses was 5–900 μg/kg of ZON. Of 32 samples confirmed by HPLC, 25 samples were observed to be contaminated in a comparable range from 6.9 to 589 μg/kg. Comparative analysis of 25 positive samples using the ELISA and HPLC methods showed a reasonable correlation (R²=0.9258).