Dry Food Samples Research Articles

Taming Janus-Faced Quinoline-Derived Fluorescent Probes for Dual-Channel Distinguishable Visualization of HSO3- and HClO in Dried Foods and Living Cells.

With the booming development of food manufacturing, developing ideal analytical tools to precisely quantify food additives is highly sought after in the food science field. Herein, a new series of quinoline-derived multifunctional fluorescent probes has been synthesized. Bearing double reactive sites, these compounds display fluorescence response toward both bisulfite (HSO3-) and hypochlorous acid (HClO). Among these compact structures, compound ethyl-2-cyano-3-(6-(methylthio)quinolin-2-yl)acrylate (QTE) was screened out. Probe QTE not only shows ratiometric variation toward HSO3- with little cross talk but also performs turn-off signal toward HClO. In addition, probe QTE has been utilized for bioimaging of HClO in living cells. Furthermore, the HSO3- content in dried food samples has been appraised by QTE with satisfactory results. Meanwhile, relying on the apparent chromaticity change, a flexible dark-box device has been elaborated for chromatic analysis, promoting visualization of HSO3- in the field.

Drying characteristics of thin layer of potato (Solanum tuberosum): experimental and computational studies.

Solar drying is a renewable energy-based technique which is widely used for food preservation purpose. In this study, various drying characteristics of the solar-dried Solanum tuberosum samples of different thicknesses have been investigated at variable climate condition of Lucknow. A mathematical model has also been developed to validate experimental results to predict the drying rate, free moisture content, and other parameters. Pre-treatment of the food samples was also done before the experimental runs on the fabricated solar dryer. Global radiation has also been monitored during the study to correlate the heat transfer rate in inner and outer sides of the solar drying chamber. SEM analysis has also been done to analyze the surface morphology of solar-dried samples. All solar dried food samples have uniformly heated. There was no hot-spot condition present on the surface of the samples. The drying efficiency and payback period of the fabricated solar dryer have also been calculated as 22.9% and 1.42years, respectively. Model data have been found in good agreement with the experimental data within a 5% error. This modified model can be used for different agro-based food materials such as carrot, kiwifruit, and yam.

Total aflatoxin, aflatoxin B1, ochratoxin A and fumonisin in dry dog food: A risk assessment for dog health

The aim of this study was to measure total aflatoxin (AFT), aflatoxin B1 (AFB1), ochratoxin A (OCA) and fumonisin (FUM) concentrations in dry dog feed and to evaluate the risk to animal health posed by their increased levels. A total of 90 dry food samples, which were commercially available to the owner, were collected from different shops in Turkey. Some of the food samples were collected from open packages, from which the dry food was sold in smaller amounts. Using commercial Enzyme-Linked Immunosorbent Assay test kits, all samples were examined for AFT, AFB1, OCA, and FUM concentrations. High-performance liquid chromatography was used for confirmation of measured parameters in 30 samples. The ELISA tests found AFT, AFB1, OCA, and FM concentrations (ng g −1) as 1.66, 0.64, 2.14, and 87.06, respectively. In terms of risk assessment, consumption of the dry foods, which are contaminated by AFT, AFB1 and OCA due possibly to the fact that the dry foods are produced from inappropriate raw material or sold in open packages in smaller amounts, poses a significant health risk for dogs. As a result, it is necessary to monitor the mycotoxin load in dry dog food as the use of raw materials of poor quality and selling the feed in smaller amounts from open packages over an uncertain time period predispose the dry feed to the growth of mycotoxin, especially when the storage conditions are favorable.

Nutritional and Safety Surveillance Study of Some Puppies' Commercial Dry Foods

A surveillance study was conducted to evaluate the nutritional value and safety of some puppies' commercial dry foods available in Egypt. A total of (100) extruded puppies' dry food samples (18 imported and 2 locally produced) were collected from different batches and subjected to proximate analysis for determinations of Moisture, Crude protein, Ether extract, Crude fiber and total ash%. Moreover, all samples were examined for their water activity values as well as Mycotoxins levels (Aflatoxins and Ochratoxins). Results of proximate analysis in comparison with the values stated on the bag label revealed that, moisture ranged from 4.95 to 11.36 %, CP ranged from 23.37 to 40.96 %, EE ranged from 5.35 to 19.21, CF ranged from 1.30 to 4.19 % and total ash ranged from 3.48 to 12.49 %. Water activity values (a w ) ranged from 0.43 to 0.71 in comparison to the standard acceptable level of 0.6 for dry food, a condition that may be explained on the basis that the examined puppies' dry foods might be subjected to excessive dryness during the manufacture as a tool for protection against microbial growth. Results of Aflatoxins levels revealed that all samples were proved to be positive for the presence of Aflatoxins, 30% of them were over the permissible limits, which ranged from 1.2 to 17.6 ppb. Furthermore, all examined samples were proved to be positive for Ochratoxins with minimum and maximum levels 0f 3.9 and 42.3 ppb respectively.

Contamination of Pet Food with Mycobiota and Fusarium Mycotoxins-Focus on Dogs and Cats.

A wide range of pet food types are available on the market; the dominant type is dry food formulated in croquets. One of the most common ingredients of dry food are cereals—vectors of harmful mycotoxins posing the risk to pet health. In this study, 38 cat and dog dry food samples available on the Polish market were investigated. Morphological and molecular methods were applied to identify fungal genera present in pet food. Quantification of ergosterol and Fusarium mycotoxins: Fumonisin B1, deoxynivalenol, nivalenol, and zearalenone were performed using high performance liquid chromatography. Obtained results indicated five genera of mycotoxigenic fungi: Alternaria sp., Aspergillus sp., Cladosporium sp., Penicillium sp., and Fusarium sp., including Fusarium verticillioides and Fusarium proliferatum. Ergosterol and mycotoxins of interest were detected in both cat and dog food samples in the amounts ranging from 0.31 to 4.05 µg/g for ergosterol and 0.3–30.3, 1.2–618.4, 29.6–299.0, and 12.3–53.0 ng/g for zearalenone, deoxynivalenol, nivalenol, and fumonisin B1, respectively. The conclusion is the presence of mycotoxins in levels much lower than recommended by EU regulations does not eliminate the risk and caution is advised concerning that long-term daily intake of even small doses of mycotoxins can slowly damage pet’s health.

Comparative analysis of the Polycyclic Aromatic Hydrocarbon (PAH) content and proximate composition of unripe Musa paradisiaca (plantain) fruit exposed to varying methods of roasting.

This comparative study was carried out to ascertain the relative effect of smoking and non-smoking methods of food preparation on the concentration of PAHs in unripe plantain sample. The fruit samples were subjected to different smoking methods such as roasting with firewood, charcoal and charcoal augmented with polythene materials as well as non-smoking method such as frying and oven drying process, and compared with the fresh fruits. Gas chromatography-mass spectroscopy (GC-MS) method was used to determine the concentrations of sixteen priority PAHs content of each sample and the results were subjected to statistical analysis. The percentage compositions of crude fibre in the raw, smoked roasted (charcoal, firewood and augmented charcoal) and non-smoked (oven dried and fried) samples were; 4.4% 3.2%, 3.1%, 3.0%, 3.5% and 4.1% respectively. Percentage composition of protein and carbohydrate of the raw food samples were found to be 3.62% and 34.5% respectively which were higher than the dried food samples. The total PAHs concentration of the fresh plantain sample (control) was (8.0 ± 0.1mg/L). The Charcoal, firewood and augmented roasted sample had total PAHs concentration of (19.3 ± 0.2mg/L), (19.6 ± 0.1mg/L) and (20.1 ± 0.1mg/L) respectively, whereas the total PAHs concentration in the fried and oven dried samples were (9.8 ± 0.1mg/L) and (15.3 ± 0.2mg/L) respectively. From the result, it was observed that the total PAHs concentration of the smoke roasted sample were significantly higher (p < 0.05) than the non-smoke roasted sample which indicates that roasting and grilling over open fire or smoke do increase the level of Polycyclic aromatic hydrocarbons (PAHs) in food. Although the concentration of PAHs in the fried sample was significantly (p < 0.05) lower than the oven dried sample, however, it predisposes one to increased risk of atherosclerosis and related lipidemia due to its increased fat concentration. Hence smoking method of food preparation should be substituted with other non-smoking methods such as oven drying.

Occurrence and species diversity of human-pathogenic Mucorales in commercial food-stuffs purchased in Paris area.

Mucormycoses are life-threatening fungal diseases that affect a variety of patients including those with diabetes mellitus or hematological malignancies. The responsible agents, the Mucorales, are opportunistic pathogens originating from the environment such as soil or decaying organic matter. The aim of the present study was to assess the prevalence and diversity of human-pathogenic species of Mucorales in commercially available foodstuffs in France. All food samples were purchased from January 2014 to May 2015 in France. A total of 159 dried food samples including spices and herbs (n = 68), herbal tea (n = 19), cereals (n = 19), vegetables (n = 14), and other foodstuffs (n = 39) were analyzed. Each strain of Mucorales was identified phenotypically, and molecular identification was performed by ITS sequencing. From the 28 (17.6%) samples that were culture-positive for Mucorales, 30 isolates were recovered. Among the isolates, 13 were identified as Rhizopus arrhizus var. arrhizus, 10 R. arrhizus var. delemar, two Rhizopus microsporus, one Lichtheimia corymbifera, three Lichtheimia ramosa, and one Syncephalastrum racemosum. Culture-positive samples originated from different countries (Europe, Asia) and brands. The samples most frequently contaminated by Mucorales were spices and herbs (19/68, 27.9%), followed by herbal tea (2/19, 10.5%), cereals (2/19, 10.5%), other food products (5/39, 12.8%). The present study showed that human-pathogenic Mucorales were frequently recovered from commercially available foodstuffs in France with a large diversity of species. The potential danger represented by Mucorales present in food for immunocompromised patients should be further analyzed.

Measuring the Level of Radiation in some Dry Food Imported in the Markets of AL-Kifil - City and Estimating Excess of Cancer Risk Factor in this Town

The radioactive contamination is one of the main causes of cancers. Since the Dry food imported with the different global products is uncensored and is increasing, it is necessary to carry out periodic radiological surveys of all types in our local markets ,the aim of this project is to highlight of radiation level of same food with a statistical procedure for patients with cancer in the AL-Kifil region, there for the activity concentrations of 40K, 226Ra and 232Th radionuclide's calculated in 20 types of Dry food samples were taking from markets in (AL-Kifil City) by using γ-ray spectrometry with NaI(Tl) detector. The mean activity concentrations of 226Ra is (25.3+9.3) Bq/kg, 232Th(28.4+7.6)Bq/kg, and 40K (501.2+158.4) Bq/kg the activity concentration of 40K higher than the international recommended values (412) Bq/kg the reason is due to the nature of the terrain enjoyed by the industrialized countries for this type of food, which reflected negatively on the number of cancer patients in the digestive system of the population of the city of Kifil, the highest compared to other areas of the province of Babylon, an average of 33 cases.

Risk assessment of 22 chemical elements in dry and canned pet foods

There is little information on the levels of chemical elements in pet food considering the dietary requirements as well as risk assessment of toxicity. This study aimed to determine the essential and toxic elements in dry and canned foods for dogs and cats and estimate their daily intake. We compared the levels of the chemical elements between the dry and wet (canned) food to the levels recommended by the Association of American Feed Control Officials (AAFCO) and the European Pet Food Industry Federation (FEDIAF) and the maximum tolerable level proposed by European Commission (EC). In addition, the estimated daily intake (EDI) for each one of the elements through food was calculated. Seventy-six dry food samples (dogs n = 62 and cats n = 14) from 43 brands and 12 canned foods (dogs n = 6 and cats n = 6) from 5 brands, were purchased from Brazilian supermarkets. Mean levels of all essential elements reached the minimum level recommended by AACFO. Selenium levels were very close to the maximum limit proposed by AAFCO. Besides, the iron concentrations in canned (moist) food were statistically higher than in dry food and its EDI for cats (54 mg/day × kg body weight) exceeded the maximum limit recommended by FEDIAF. Regarding the toxic metals, the concentrations of mercury and cadmium, in dry and canned food, were considerably higher than the maximum tolerable level proposed by EC. Overall, the results show that levels of essential elements are in agreement with the nutrient requirement. On the other hand, mercury and cadmium in pet food are an issue of concern.

Evaluation of the Use of TRIzol-Based Protein Extraction Approach for Gel-Based Proteomic Analysis of Dried Seafood Products and Chinese Tonic Foods.

Although the emergence of gel-free approaches has greatly enhanced proteomic studies, two-dimensional gel electrophoresis (2-DE) remains one of the most widely used proteomic techniques for its high resolving power, relatively low cost, robustness, and high resolution. Preparation of high-quality protein samples remains the key in high-quality 2-DE for proteomic analysis. Samples with high endogenous levels of interfering molecules, such as salts, nucleic acids, lipids, and polysaccharides, would yield a low-quality 2-DE gel and hinder the analysis. Recently, a TRIzol-based protein extraction method has gained prominence and has attracted attention due to its promising performance in high-quality 2-DE. The authors evaluate the use of this approach for four valuable dried food products, namely two dried seafood products (abalone slices and whelk slices) and two traditional Chinese tonic foods (ganoderma and caterpillar fungus). The results indicate that 2-DE gels obtained through the TRIzol-based method are of high-quality and are comparable to those obtained through the trichloroacetic acid–acetone method in terms of spot number, spot intensity, and resolution. The TRIzol-based method is generally applicable to dried food samples and is simple and fast, which greatly streamlines the protein extraction procedure. Additionally, it enables the concurrent extraction and analysis of RNA, DNA, and protein from the same sample.

Presence of Mutagens and Carcinogens, Called Aflatoxins, and their Hydroxylated Metabolites in Industrialized Food for Dogs

Introduction: The Aflatoxin contamination in dog food poses a serious health threat for dogs and it affects pet food industry, veterinarians and owners. Pets that are long-lived and healthy consumers contribute to sales, so any reduction in product quality has an effect on profits or even a company’s survival. Pet food safety is the responsibility of the pet food industry. Aims: To determine the type and amount of aflatoxins in 29 samples of dry food and 24 brands of canned food for dogs. Methodology: The chemical extraction method used immunoaffinity columns with antibodies for total aflatoxins, and the quantification was performed with liquid chromatography and fluorescence detection. The method was validated, so the results were considered to be reliable once the recovery percentage was applied. Results and Discussion: With respect to dry food, the average Aflatoxins (μg kg-1) contamination was AFB1 (1.6), B2 (0.1), AFG1 (28.2), AFG2 (1.3), AFM1 (1.8), AFM2 (0.2), P1 (1.7), Aflatoxicol (28.6), and Total aflatoxins (59.1), and the average of dry food samples was 7.9 μg kg-1 total aflatoxins. Canned food contained AFB1 (14.2), AFB2 (2.3), AFG1 (60.4), AFG2 (4.5), AFM1 (2.1), AFM2 (4.6), AFP1 (18.4), AFL (13.1), and AFt (119.5), and the average of all of the samples was 15.3 μg kg-1. According to statistical analysis, significant differences (p-value) between dry food and canned food were observed for AFB1 (p<0.001) and AFL (p<0.001). Canned food was more contaminated than dry food.Conclusion: Aflatoxins are common carcinogens of food for dog. The dry food croquettes for dogs had 51.6% less aflatoxins, with an average of 7.9 μg kg-1 total aflatoxins, under the tolerable legal limit, and the canned food, more contaminated (15.3 μg kg-1), and surpassed the tolerable limit for Codex Alimentarius. The addition of hydroxylated metabolites gaves the true ingestion measure of Aflatoxins.

Trace element measurement for assessment of dog food safety.

The quality of dog diets depends on adequate ingredients capable of providing optimal nutrition and free of contaminants, for promoting long-term health. Trace elements in 95 samples of dry food for dog puppies (n=32) and adults (n=63) of various brands were measured using instrumental neutron activation analysis (INAA). The mass fractions of most elements were within the permissible limits for dogs. Aluminum, antimony, and uranium presented fairly high levels in some samples, which may imply health risks. Aluminum mass fractions ranged from <21 to 11,900mg/kg, in same brand, super-premium dog food. Antimony mass fractions ranged up to 5.14mg/kg, with the highest values measured in six samples of dog food from the same producer. The mass fractions of uranium was found up to 4mg/kg in commercial brands from five different producers.

Multi-contaminant analysis of organophosphate and halogenated flame retardants in food matrices using ultrasonication and vacuum assisted extraction, multi-stage cleanup and gas chromatography–mass spectrometry

A multi-residue analytical method was developed for the determination of a range of flame retardants (FRs), including polybrominated diphenyl ethers (PBDEs), emerging halogenated FRs (EFRs) and organophosphate FRs (PFRs), in food matrices. An ultrasonication and vacuum assisted extraction (UVAE), followed by a multi-stage clean-up procedure, enabled the removal of up to 1g of lipid from 2.5g of freeze–dried food samples and significantly reduce matrix effects. UVAE achieves a waste factor (WF) of about 10%, while the WFs of classical QuEChERS methods range usually between 50 and 90%. The low WF of UVAE leads to a dramatic improvement in the sensitivity along with saving up to 90% of spiking (internal) standards. Moreover, a two-stage clean-up on Florisil and aminopropyl silica was introduced after UVAE, for an efficient removal of pigments and residual lipids, which led to cleaner extracts than normally achieved by dispersive solid phase extraction (d-SPE). In this way, the extracts could be concentrated to low volumes, e.g. <100μL and the equivalent matrix concentrations were up to 100g ww/mL. The final analysis of PFRs was performed on GC–EI-MS, while PBDEs and EFRs were measured by GC–ECNI-MS. Validation tests were performed with three food matrices (lean beef, whole chicken egg and salmon filet), obtaining acceptable recoveries (66–135%) with good repeatability (RSD 1–24%, mean 7%). Method LOQs ranged between 0.008 and 0.04ng/g dw for PBDEs, between 0.08 and 0.20ng/g dw for EFRs, and between 1.4 and 3.6ng/g dw for PFRs. The method was further applied to eight types of food samples (including meat, eggs, fish, and seafood) with lipid contents ranging from 0.1 to 22%. Various FRs were detected above MLOQ levels, demonstrating the wide-range applicability of our method. To the best of our knowledge, this is the first method reported for simultaneous analysis of brominated and organophosphate FRs in food matrices.

A new approach for the determination of sulphur in food samples by high-resolution continuum source flame atomic absorption spectrometer

The new approach for the determination of sulphur in foods was developed, and the sulphur concentrations of various fresh and dried food samples determined using a high-resolution continuum source flame atomic absorption spectrometer with an air/acetylene flame. The proposed method was optimised and the validated using standard reference materials, and certified values were found to be within the 95% confidence interval. The sulphur content of foods ranged from less than the LOD to 1.5mgg−1. The method is accurate, fast, simple and sensitive.

Migration of mineral oil from printed paperboard into dry foods: survey of the German market

From the German market, 119 samples of dry food were analyzed for the migration of mineral oil. The products selected were packed in paperboard boxes and intended for storage for extended periods of time at ambient temperature. The 0.6 mg/kg limit for mineral oil saturated hydrocarbons (MOSH) derived from the WHO/JECFA evaluation was frequently exceeded by a factor of 10–100. Typically, 10–20% of the migrating mineral oil consisted of aromatic hydrocarbons (MOAH). Most samples were merely 2–3 months old and far from the end of their shelf life (usually 1–3 years). From the assumption that about 70% of the MOSH and MOAH which are eluted from GC up to the C24 n-alkane (<C24) end up in the food (potential of migration), it was estimated that migration might almost triple before the products reach the end of their shelf life, reaching 31 mg/kg on average, with several samples exceeding 100 mg/kg. At the time of the analysis, products without an internal bag and with a bag of paper or polyethylene reached up to about 80% of the potential of migration (average, 30–50%). Bags of polypropylene, acrylate-coated polypropylene, PET or with an aluminum layer seemed to block migration (with one possible exception), but it was premature to reach conclusions on long-term functional barrier properties. From the comparison with <C24 MOSH concentrations in unprinted recycled paperboards, it was estimated than on average about a quarter of the migrating mineral oil was from printing ink used for decorating the box.

Determination of polycyclic aromatic hydrocarbons in food samples by automated on-line in-tube solid-phase microextraction coupled with high-performance liquid chromatography-fluorescence detection

A simple and sensitive automated method, consisting of in-tube solid-phase microextraction (SPME) coupled with high-performance liquid chromatography-fluorescence detection (HPLC-FLD), was developed for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) in food samples. PAHs were separated within 15 min by HPLC using a Zorbax Eclipse PAH column with a water/acetonitrile gradient elution program as the mobile phase. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL of sample using a CP-Sil 19CB capillary column as an extraction device. Low- and high-molecular weight PAHs were extracted effectively onto the capillary coating from 5% and 30% methanol solutions, respectively. The extracted PAHs were readily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Using the in-tube SPME HPLC-FLD method, good linearity of the calibration curve ( r > 0.9972) was obtained in the concentration range of 0.05–2.0 ng/mL, and the detection limits ( S/ N = 3) of PAHs were 0.32–4.63 pg/mL. The in-tube SPME method showed 18–47 fold higher sensitivity than the direct injection method. The intra-day and inter-day precision (relative standard deviations) for a 1 ng/mL PAH mixture were below 5.1% and 7.6% ( n = 5), respectively. This method was applied successfully to the analysis of tea products and dried food samples without interference peaks, and the recoveries of PAHs spiked into the tea samples were >70%. Low-molecular weight PAHs such as naphthalene and pyrene were detected in many foods, and carcinogenic benzo[ a]pyrene, at relatively high concentrations, was also detected in some black tea samples. This method was also utilized to assess the release of PAHs from tea leaves into the liquor.

Analysis of major band of Enterobacter sakazakii by ERIC-PCR and development of a species-specific PCR for detection of Ent. sakazakii in dry food samples

ERIC (Enterobacterial Repetitive Intergenic Consensus)-PCR was employed to generate stable and reproductive ERIC-PCR fingerprints of Ent. sakazakii ATCC51329. Moreover, this study also cloned and sequenced a major band of Ent. sakazakii (ATCC51329) ERIC-PCR fingerprints. The major band was amplified with primer ERIC2 and sequences extending primer ERIC 2 showed poor similarity with ERIC elements. A comparison of the nucleotide acid with other sequences available in the GenBank revealed 90% of identity with Ent. sakazakii ATCC BAA-894, and 73%–74% of identity with oligopeptiase gene or proteaseⅡgene of some species from the Enterobacteriaceae family. Two primers were synthesized to develop and optimize an Enterobacter sakazakii-specific PCR based on regions of major band unique to Ent. sakazakii. The expected fragment was amplified from all of Ent. sakazkaii but not from the negative controls. As few as 10 2 CFU/ml of Ent. sakazakii of PCR were directly detected in the infant formulas. This was the case even in the presence of other bacteria. A comparison of traditional methods and new developed PCR in commercial foods suggested that without using API20-E test, the DFI chromogenic medium and FDA method showed 46.15% and 50% false positive respectively. Moreover, one false negative was observed with FDA method. In contrast, PCR was highly sensitive and specific to Ent. sakazakii. A high heterogeneity between Ent. sakazakii and the other microorganisms was found on expected fragment sequence. In addition, Ent. sakazakii ATCC51329 formed a separate branch with > 5% divergence from the type strain ATCC BAA-894 and major strains.

Development of a non-thermal accelerated pulsed UV photolysis assisted digestion method for fresh and dried food samples

A simple, fast digestion procedure for fresh and dried foods, using high-power pulsed UV photolysis in the presence of hydrogen peroxide, is being developed. The homogenized food samples were mixed with H 2O 2 or with a mixture of H 2O 2 and HNO 3, and irradiated for short times with a 248-nm UV excimer laser. After centrifugation, a clear, colorless solution was obtained and aliquots were deposited on Teflon filters for XRF and/or PIXE analyses. Standard reference materials (NIST Peach Leaves; Typical Diet) were also analyzed to compare recoveries and detection limits. Improvements in detection limits were observed, but a few trace elements (<1 ppm) were not reproducibly detected (Fe, Sr). This method proved to be practical for the accelerated digestion of food samples and preparing analytes in short-time intervals. In combination with PIXE and XRF, it allows high-sensitivity multi-elemental analyses for screening the nutritional elements and for food safety purposes regarding the potential presence of toxic elements. Further development to optimize and validate this procedure for a broader range of analytes is in progress.

Distributed magnetic coupling synchronizes a stacked 25-kV MOSFET switch

This paper reports the development of a stacked MOSFET switch with a uniformly distributed magnetic structure to coherently deliver 45-ns rise-time pulses from a 25-kV power supply. Gate jitter problems were avoided. This circuit is currently in use delivering variable-width 50-kV pulses for an electric field generator. These fields are applied to dry food samples at up to a 300-Hz repetition rate using oppositely biased floating MOSFET stacks for simultaneous switching of two 25-kV power supplies.

Liquid Chromatographic Determination of Seven Antioxidants in Dry Foods

The liquid chromatographic determinative step of the official method for propyl gallate, trihydroxybutyrophenone, tert-butylhydroquinone, nordihydroguaiaretic acid, butylated hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxymethylphenol, and butylated hydroxytoluene (BHT) in fats and oils has been applied to their determination in a number of dry foods. A representative sample (10 g) is homogenized first with hexane (25 mL), then with 5 mL added water, and finally with 75 mL added acetonitrile. The hexane and acetonitrile are decanted, filtered, and separated; the hexane and rehydrated food are reextracted with 2 additional portions of acetonitrile, and the combined acetonitrile extracts are concentrated and diluted to 10 mL. An aliquot is analyzed as described in the official method, using a 150 x 4.6 mm 5 microns C-18 column. The need for rehydration to maximize the recovery of BHA and other antioxidants from marketplace dry food samples such as potato flakes, dry coffee whiteners, and dessert topping mixes was demonstrated. Rehydration was not required for cheese snacks, breakfast cereals, cake mixes, and some other foods. The need for rehydration should be determined by analyzing other foods with and without the addition of water. Potato and corn chips, popcorn and cheese snacks, breakfast cereals, dry beverage mixes, rice, potato flakes, french fried potatoes, and cake mixes were spiked with the above antioxidants at 10-50 ppm. Overall recoveries ranged from 64.3 to 105.6% and repeatabilities ranged from 0.7 to 10.8%. A total of 109 samples of the above foods were analyzed, and 64% contained detectable (greater than 1-2 ppm) antioxidants, mainly BHA and BHT.