Determination of Some Endocrine-Disrupting Metals and Organochlorinated Pesticide Residues in Baby Food and Infant Formula in Turkish Markets

There is a paucity of data in respect of the nutritional quality of complementary foods for infants and young children aged between 6 and 12 months. In this study, we developed and validated an analytical method for determination of the endocrine-disrupting organochlorine pesticides (OCPs) and elements (As, Cd, and Pb) in infant formula and baby foods. Therefore, it found out the contamination level of the both OCPs and some trace metals (As, Cd, and Pb) in widely consumed infant formula and baby food in Turkey. Metal concentrations in baby foods and infant formula were determined by inductively coupled plasma mass spectrometry. Samples were digested with nitric acid and hydrogen peroxide in a microwave oven. Determination of 24 organochlorine pesticide residues in baby foods and infant formula was completed by using gas chromatography double mass spectrometry. QuEChERS extraction method was carried out in the sample preparation part. The analytical performance of the entire procedure, such as linearity, the detection of limit, limit of quantification, specificity/selectivity, recovery (%), and precision, were assessed. The recoveries ranged from 93% (As) to 100% (Pb) for elements 78–98% for organochlorine pesticide residues (OCPs) at 100 ng mL^?1. According to the results, lead, cadmium, and pesticides were not detected in any of the samples, while arsenic was detected in 16 samples.     

Ohmic Tempering of Frozen Potato Puree

Frozen potato puree samples were tempered using an ohmic heating technique. Three salt concentrations (0.50, 0.75, and 1.00 %) and three frequency levels (10, 20, and 30 kHz) were used as experimental variables, and the effects of salt concentration and frequency on ohmic tempering were investigated. Temperature, electrical current, and voltage were measured during the ohmic tempering. Electrical conductivities were evaluated based on the sample geometry and the ohmic heating principle. Increasing the salt concentration and/or frequency increased the electrical conductivity and heating rate, and hence contributed to decreasing the tempering time for the frozen potato puree samples. The tempering time was lowest with the highest salt concentration employed, and longest for the lowest salt concentration and frequency. Temperature differences within the sample during ohmic heating were found to be lowest when employing 0.50 % salt concentration and 10 kHz frequency.     

The effect of magnetic field on the impurity binding energy of shallow donor impurities in a Ga1?xInxNyAs1?y/GaAs quantum well

Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga_1−xIn_xN_yAs_1−y/GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations.     

Fermentation of cheese whey powder solution to ethanol in a packed‐column bioreactor: effects of feed sugar concentration

BACKGROUND: Cheese whey powder (CWP) is a concentrated source of lactose and other essential nutrients for ethanol fermentation. CWP solution containing different concentrations of total sugar was fermented to ethanol in an up‐flow packed‐column bioreactor (PCBR) at a constant hydraulic residence time (HRT) of 50 h. Total sugar concentration in the feed was varied between 50 and 200 g L^?1 and a pure culture of Kluyveromyces marxianus was used for ethanol fermentation of lactose. Variations of ethanol and sugar concentrations with the height of the column and with the feed sugar concentration were determined. RESULTS: Ethanol concentration increased and total sugar decreased with the column height for all feed sugar contents. The highest effluent ethanol concentration (22.5 g L^?1) and ethanol formation rate were obtained with feed sugar content of 100 g L^?1. Percentage sugar utilization decreased with increasing feed sugar content above 100 g L^?1 yielding lower ethanol contents in the effluent. The highest ethanol yield coefficient (0.52 gE g^?1S) was obtained with a feed sugar content of 50 g L^?1. Biomass concentration also decreased with column height, yielding low ethanol formation in the upper section of the column. CONCLUSION: The packed column bioreactor was found to be effective for ethanol fermentation from CWP solution. The optimum feed sugar content maximizing the effluent ethanol and the specific rate of ethanol formation was found to be 100 g L^?1. High sugar content above 100 g L^?1 resulted in low ethanol productivities due to high maintenance requirements. Copyright © 2008 Society of Chemical Industry     

Halogen lamp–microwave combination baking of cookies

The effects of halogen lamp–microwave combination baking on the quality of cookies in terms of texture, color and spread ratio were studied. In addition, gelatinization and pasting properties of cookies baked in different ovens were assessed by using a Rapid Visco Analyzer. The hardness values of the cookies increased with increasing baking time and/or halogen power. The microwave power also contributed to cookie hardness. The lightness values of the cookies decreased, while the a* and E values increased linearly during baking at different halogen lamp and microwave powers. The spread ratio of conventionally baked cookies was significantly lower than that of the other cookies. Halogen lamp power, microwave power and baking time were found to have a significant effect on the spread ratio of the cookies. The moisture contents of the cookies decreased during baking as the halogen lamp and/or the microwave power level increased. The best baking condition in a halogen lamp–microwave combination oven to produce cookies having similar quality parameters as conventionally baked ones was baking at 70% halogen lamp and 20% microwave power levels for 5.5 min. The baking time of these cookies is half of that required in conventional baking.     

Effect of osmotic pretreatment and microwave frying on acrylamide formation in potato strips

BACKGROUND: The presence of acrylamide, a probable carcinogen, is currently a major concern relating to the consumption of fried products. Therefore, recent frying studies have focused on ways of reducing the acrylamide content. The main objective of the present study was to determine the effects of microwave frying and osmotic treatment prior to frying on acrylamide formation in potato strips. RESULTS: Potatoes fried using 400 W microwave power for 1.0 min had an 87.85% lower acrylamide content than potatoes fried conventionally for 4.5 min (i.e. an 81.82% reduction in frying time) but a comparable moisture content. The acrylamide content of fried potatoes treated osmotically prior to both microwave and conventional frying was found to be lower than that of fried potatoes not pretreated osmotically. However, the reduction in acrylamide content was lower when osmotic treatment was applied before microwave frying. CONCLUSION: As a result of this study, it was concluded that microwave frying can be an alternative to conventional frying. Copyright © 2007 Society of Chemical Industry     

Pore Development,Oil and Moisture Distribution in Crust and Core Regions of Potatoes During Frying

The mechanism of moisture loss, oil uptake, and pore formation during frying is required to be clarified. The main objective of this study was to evaluate moisture content, oil uptake, and pore development of the crust and core regions of potatoes during frying. Potatoes were fried for 4, 8, 12, 16, and 20 min and separated into two parts as crust and core for the analysis of moisture and oil contents, porosity, and pore size distribution. Moisture contents of crust and core parts of fried potatoes were significantly different (p?≤?0.05). It was about 53.7 % for the crust and 82 % for the core region. On the other hand, oil content of the crust was found to be higher than that of the core region. Porosity and pore size distribution of crust and core regions were significantly different. Crust region of potatoes was less porous as compared to core region through the whole frying time. Larger pores were observed at the core region, especially at longer frying times. The size of the pores increased in both core and crust regions with increasing frying time.     

Estimation of uncertainties of the method to determine the concentrations of Cd, Cu, Fe, Pb, Sn and Zn in tomato paste samples analysed by high resolution ICP-MS

Cadmium, copper, iron, lead, tin and zinc were determined in tomato paste samples by using high resolution inductively coupled plasma mass spectrometry. This study was a part of Proficiency Testing scheme conducted by National Metrology Institute (UME) of Turkey. The method was validated. The percentage relative errors obtained for each element ranged between 1.4% and 9.0% for NIST SRM 1573a, tomato leaves. Measurement uncertainties of all elements were calculated by applying bottom-up approach. The calculated percentage relative uncertainties for the elements were between 8.2% and 16.4%. The major contributions to the uncertainty budget came from the calibration curves, repeatability and recovery. Tomato paste samples gathered from the supermarkets in Turkey were analysed by using the validated method. Their levels were compared both with the literature values and European Commission Regulations.     

Palladium-Catalyzed Suzuki–Miyaura Reaction Using Saturated N-Heterocarbene Ligands

Recent studies have pointed to the heptamethylbenzenium cation as a prominent intermediate in the methanol to hydrocarbons (MTH) reaction. The reactions of the heptamethylbenzenium cation in a H-beta zeolite was studied at 300 °C by feeding its corresponding base (WHSV = 0.4 h^?1). The reactant was converted completely into aliphatic products, polymethylbenzenes and coke under the employed conditions. The results testify that the proposed reaction intermediate yields the same product spectrum as methanol. The composition of the material retained in the catalyst micropores after 15 min of reaction was determined by dissolving the catalyst in 15% HF. Polymethylated benzenes (predominantly pentamethylbenzene), dihydro-trimethylnaphthalenes, and hexamethylnaphthalene were the major components. The results also support the idea that the lowest naphthalene derivative is formed from the heptamethylbenzenium cation by a molecular rearrangement. Hence, the heptamethylbenzenium cation is inherently linked to both product formation and catalyst deactivation in the MTH reaction.