Lower Oven Temperatures Research Articles

Effects of Oven Temperature and Addition of Ethanol on Measurement of Water Content and Specific Gravity of Cement-Stabilized Soft Clay

Abstract Water content and specific gravity are two fundamental soil properties. The water content is usually measured by the oven-drying method, and the dried soil is used for specific gravity determination of the soil. However, for cement-stabilized soils, high oven temperature accelerates the cement hydration rate and causes dehydration of some clay minerals, which may affect the measurement accuracy of water content and soil specific gravity. Hence, researchers have proposed the use of ethanol to terminate cement hydration reactions and a low oven temperature to reduce the dehydration of hydration products. To verify the effectiveness, this experimental study investigated the effects of oven temperature (60°C and 110°C) and the addition of ethanol on the measurements of both water content and specific gravity of cement-stabilized soft clay. These measurements are compared with those measured with the freeze-drying method, which is termed as a control measurement. The test results indicated that the effect of ethanol on water content measurement was insignificant. For 7-day stabilized clay, oven drying at 110°C achieved lower errors (3.06–3.63 %) than the oven-drying method at 60°C (7.36–9.44 %). For 180-day cement-stabilized clay, all the oven-drying methods had similar measurement errors (4.02–5.58 %). The effect of drying method on the specific gravity measurement was insignificant, with the percentage of measurement error ranging from 0.19 to 2.17 %.

Understanding the Impact of Oven Temperature and Relative Humidity on the Beef Cooking Process

The objective of this study was to evaluate the roles that cooking rate and relative humidity has on the sensory development of beef strip steaks. Thirty USDA Choice beef strip loins were collected from a commercial packing facility. Each strip loin was cut into steaks and randomly assigned to 1 of 6 cooking methods utilizing 2 oven temperatures (80°C and 204°C) and 3 levels of relative humidity [zero (ZH), mid (MH), and high (HH)]. Cooked steaks were used to evaluate internal and external color, Warner-Bratzler and slice shear force, total collagen content, protein denaturation, and trained sensory ratings. Relative humidity greatly reduced cooking rate, especially at 80°C. Steaks cooked at 80°C-ZH had the greatest (P < 0.01) cook loss of all treatments, and cook loss was not affected (P > 0.05). Steaks cooked at 80°C-ZH appeared the most (P < 0.01) well-done and had the darkest (P > 0.01) surface color. Total collagen was greatest (P < 0.01) in steaks cooked with ZH, regardless of oven temperature. Myosin denaturation was not affected (P > 0.05) by treatment. Increased (P = 0.02) sarcoplasmic protein denaturation was observed with ZH and MH, while increased (P = 0.02) actin denaturation was observed only with ZH. Oven temperature did not influence (P > 0.05) protein denaturation. Trained panelists rated steaks the most tender (P < 0.01) when cooked at 80°C and with ZH and MH. Humidity did not affect (P > 0.05) juiciness at 204°C; however, MH and HH produced a juicier (P < 0.01) steak when cooked at 80°C. Humidity hindered (P < 0.01) the development of beefy/brothy and brown/grilled flavors but increased (P = 0.01) metallic/bloody intensity. Lower oven temperatures and moderate levels of humidity could be utilized to maximize tenderness, while minimally affecting flavor development.

Baking of Flat Bread in an Impingement Oven: An Experimental Study of Heat Transfer and Quality Aspects

A new impingement oven was designed and tested for its thermal and quality performance for baking of thin flat bread. The test facility was instrumented to monitor and record during the baking process. Bread temperature and weight loss were recorded on-line during baking at oven temperatures of 150, 175, 200, 225, and 250°C and 1, 2.5, 5, 7.5, and 10 m/s jet velocities, respectively. Image processing was used for monitoring the bread volume and surface color changes during baking. Better baking conditions were obtained with the impingement oven in comparison with the conventional direct fired ovens. Experiments showed that a higher jet velocity can be used for flat bread baking at lower oven temperatures and yield shorter baking times for the same quality product. For very thin breads (such as the Iranian breads), results show that conduction heat transfer from the bottom surface of the tray must also be considered along with the convective heat transfer from the jets in selection of optimal operating parameters. It is noted that desirable baking conditions, e.g., good browning, uniform color, high volume increase, etc., can be achieved in a well-designed and operated impingement oven in shorter baking times compared to the conventional ovens.

Collision induced fragmentation of free sulfur clusters

Fragmentation of multiply charged sulfur clusters is investigated by ion–ion-coincidence spectroscopy. The experiments were performed at the electron cyclotron resonance (ECR) ion source at the KVI Groningen, where beams of Xeq+ (q=5, 10, 15, 20) were produced. The Xeq+ ions were accelerated to kinetic energies of 8–10·qkeV and collided with a beam of free sulfur clusters. Variable size sulfur clusters are prepared in a two-stage oven source, where the temperature of the oven was used to adjust the cluster size. Most experiments were performed using S8, the dominant cluster at low oven temperature. Ion–ion-coincidence as well as mass spectra were recorded. Coincidences between singly charged atomic and molecular fragments were studied, where changes of product channels were observed as a function of charge state of the Xeq+ projectile. The mechanisms of cluster fragmentation are discussed. The results are compared to earlier experiments on core-excited sulfur clusters using soft X-rays.

Ultra-short open capillary columns in gas–liquid chromatography

New area in capillary gas chromatography (GC) was investigated. Many important analytical tasks can be solved only use very short capillary columns. Variation of chromatographic characteristics of ultra-short capillary columns with column length was originally studied at the conditions of gas–liquid chromatography. The column length varied from 500 to 10 cm. Dependencies of height equivalent to one theoretical plate (HETP) and separation number (SN) on carrier gas velocity were considered for columns of various length. Field of ultra-short open capillary columns in gas–liquid chromatography has the following peculiarities: (1) more shorter retention times of sorbates, (2) more low temperatures of short column, that has as final result (a) high selectivities of used column and (b) the possibilities to separation more thermal lability compounds. It was shown that short capillary columns can be successfully used at both isothermal and temperature programming conditions for express-analysis at lower oven temperatures. Examples of express-analysis (high speed), analysis of high boiling and thermolabile compounds are listed, which demonstrate some radically new applications of capillary gas chromatography.

Time-resolved diagnostics of single wall carbon nanotube synthesis by laser vaporization

Three questions important to nanosecond laser ablation synthesis of single wall carbon nanotubes (SWNTs) have been addressed using in situ spectroscopic diagnostics: determining the temperature of the nanoparticles within the propagating plume at different times after ablation, monitoring the aggregation of the nanoparticles in the plume, and measuring the growth rates of the SWNTs. Short SWNTs were synthesized using nanosecond Nd:YAG-laser ablation of a C–Ni–Co target inside a high-temperature laser vaporization reactor by controlling and restricting the growth times. The time spent by the plume inside the oven was varied by positioning the target at various locations and imaging the plume using Rayleigh scattered light induced by a 308 nm XeCl laser. Statistical analysis of the short SWNT length distribution was performed using TEM images. The upper and lower limits of the growth rates of SWNTs were estimated as 0.6 and 5.1 μm/s. The particle temperature within the propagating plume was measured at different times after ablation through time-resolved measurements of the plume’s blackbody emission. The onset of SWNT growth was estimated based on the time when the particle temperature drops below the eutectic temperature for C/Co, C/Ni. For the first time, absorption spectroscopy was employed to study the aggregation of carbon nanoparticles in the propagating plume. It was shown that the aggregation rate increases rapidly at lower oven temperatures. A general picture of SWNT growth by laser ablation based on imaging, spectroscopy, and pyrometry of ejected material at different times after ablation is discussed.

Production and measurements of individual single-wall nanotubes and small ropes of carbon

This work focuses on the size and spatial dependence of single-wall carbon nanotubes produced by the pulsed-laser vaporization technique. The study indicates that very long (tens of microns) individual nanotubes form in the vicinity of the target, and subsequently coalesce into bundles. The role of the inner flow tube is confirmed to restrict plume expansion and improve interactions between carbon atoms resulting in nanotube and rope formation. The effect of the flowing buffer gas seems to influence the dispersion of particulate contaminant material in the nanotube product. More particulate matter is produced at lower oven temperatures.

Determination of solvent thinner components in human body fluids by capillary gas chromatography with trapping at low oven temperature for headspace samples.

A simple and sensitive method is presented for determination of solvent thinner components in human body fluids by capillary gas chromatography (GC) with a low oven temperature for trapping headspace vapor components. After heating a blood or urine sample containing ethyl acetate, benzene, butan-1-ol, toluene, butyl acetate, isoamyl acetate and ethylbenzene (internal standard) in a 7.5 ml vial at 90 degrees C for 30 min, 5 ml of headspace vapor were drawn into a glass syringe. All vapor was introduced through an injection port in the splitless mode into a DB-624 medium-bore capillary column at a 5 degrees C oven temperature for trapping the volatile compounds, and the oven temperature was programmed up to 110 degrees C for their detection by GC. These conditions gave sharp peaks, a good separation of each peak and low background noise for both whole blood and urine samples. As much as 3.58-55.1 and 3.52-57.9% of the six compounds, which had been added to vials, could be introduced to the GC instrument for whole blood and urine, respectively. The intra-day RSD values in terms of the introduction rate (net recovery) of the six compounds in whole blood and urine samples were < or = 8.1%. The calibration curves showed linearity in the range 0.78-400 ng per 0.5 ml whole blood or urine. The detection limits were 0.5-5 ng per 0.5 ml. The data on toluene in post mortem blood in an actual case are also presented.

Supercritical Fluid Chromatography of Garlic (Allium sativum) Extracts with Mass Spectrometric Identification of Allicin

Supercritical fluid chromatography-mass spectrometry has been used successfully to identify allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester), the predominant thiosulfinate in freshly cut garlic (Allium sativum). A low oven temperature (50 degrees C) and low restrictor tip temperature (115 degrees C) were needed in order to obtain a chemical ionization (CI) mass spectrum of allicin with the protonated molecular ion, m/z 163, as the major ion. The effects of tip temperature on the CI mass spectrum of allicin are presented.

ENERGY USE, TIME AND PRODUCT YIELD OF TURKEY ROLLS AT THREE OVEN LOADS AND COOKING TEMPERATURES IN A CONVECTION OVEN1

The energy consumption, cooking time and product yield of turkey rolls under three oven loads (2, 4, or 6 turkey rolls) and three oven temperatures (105, 135, and 165C) were investigated. The energy impact of three different holding loads (4, 8, or 12 pans) in the hot-holding cabinet after one and two hours of hot-holding was studied as well. The energy consumption and cooking time were significantly different among three oven loads and among three oven temperatures. However, further statistical analysis indicated that there was a significant cooking time difference between loads 2 and 4, but there was no significant difference between loads 4 and 6. The product yield was significantly different among three oven loads. Lower oven temperatures with longer cooking times resulted in greater product yields. Results also showed that the size of the loads does not affect the energy consumption during hot holding. Some considerations were identified for managers when making decisions in the foodservice operation.

Plasma quantification of quazepam and its 2-oxo and N-desmethyl metabolites by capillary gas chromatography

The authors have developed a gas chromatographic method for the simultaneous quantification of quazepam in plasma and its two main metabolites, 2-oxoquazepam and N-des-methylquazepam. This method involves an extraction from plasma using butyl acetate, and an analysis by electron-capture detection on a CP-Sil 5 WSCOT capillary column. Intra- and inter-day precision and accuracy were better than 10% for each of these three compounds, even near their detection limit estimated at 0.2 ng/ml. Linearity proved satisfactory between 0.2 and 60–70 ng/ml. For endogenous plasma components, adequate specificity was achieved. Despite some inconveniences, a long analysis time, a progressive saturation of the column owing to a low oven temperature, and a relatively short life-span of the CP-Sil 5 columns, this method was the only one available in the literature for the quantification of quazepam and its metabolites from the same plasma sample. It was successfully applied to phase I studies in healthy volunteers.

FOIL‐COVERED VERSUS OPEN‐PAN PROCEDURES FOR ROASTING TURKEY

SUMMARY Three procedures for roasting turkeys were investigated as follows: (1) open pan, low‐temperature oven (163°C); (2) loose foil wrap, low‐temperature oven; and (3) tight foil wrap, high‐temperature oven (233°C). Twenty‐four hens and 24 tom turkeys, held for zero and six months of frozen storage, were used in a comparison of open‐pan versus loose‐foil‐wrap roasting in a low‐temperature oven. Six toms were used in a similar comparison of open‐pan, low‐oven temperature roasting versus a tight‐foil‐wrap, high‐oven‐temperature procedure. Roasting was done as halves, with all halves cooked to an internal thigh temperature of 85°C. A taste panel evaluated portions of breast and thigh meat for flavor, tenderness, juiciness and over‐all preference. The L.E.E.‐Kramer shear press was also used to evaluate tenderness and the Carver press for juiciness tests. Meat prepared by open‐pan roasting in a low‐temperature oven was preferred by the taste panel. The adverse effect of foil wrapping as shown by the taste panel evaluation of less juiciness was highly significant. Drippings percentage was greater with foil wrapping. Total time for the meat to reach the same internal temperature in the thigh muscle was slightly less when the foil wrap with a high oven temperature was used, and greatly increased when a foil wrap was used with a low oven temperature.

Forced, Convection Roasting at 200° and 300° F.1

Forced convection heating shortens cooking time, due to faster heat penetration. However, slow heat penetration has been reported to have a tenderizing effect on meat. Are lower oven temperatures with forced convection desirable for institutional roasting of meat? These authors compared results of convection roasting at 200° and 300 °F., as to cooking losses and time, costs per serving, and acceptability.

A contribution to the study of the thermal properties of NaCl∶Ca crystals irradiated with X-rays

In order to investigate the influence of x-ray irradiation the process of annealings, the temperature difference, DELTA T, of the irradiated and nonirradiated sodium chloride crystals was registered. Crystals with molecular contents of 0.2, 0.05, and 0.002% calcium were investigated. The x-ray imradiation was carried out at 50 kev and 30 ma through a beryllium window for 2 hr. In each of the experiments a maximum was observed on the curve showing the dependence of DELTA T on the oven temperature. With increasing calcium concentration, the position of the maximum shifted toward the lower oven temperatures.