OPTICAL ASSESSMENT OF CORN OIL DETERIORATION DURING FRYING

The ultraviolet (UV), visible and near-infrared (NIR) absorption changes in corn oil were measured during processes simulating deep fat frying. Corn oil, maintained at 185C, was exposed to various treatments with nitrogen, air, water injection, air with water injection, and steam. Autoxidation due to a combination of air and high temperature in the simulated frying trials caused visible absorption changes between 400 and 580 nm as the oil deteriorated similar to those observed in potato frying experiments. These absorption changes were found to be associated with changes in an ultraviolet absorption band with a maximum near 270 nm. Second-derivative calibration equations developed at various visible and NIR absorption wavelengths successfully predicted the percentage of total polar materials (%TPM) which accumulated in the corn oil during simulated trials of autoxidation (R values from 0.93 to 0.98). Using spectral data from repetitive potato frying experiments, the predicted %TPM calculated with these equations correlated well with kinematic viscosity measurements (R values from 086 to 0.97).     

MECHANICAL PROPERTIES OF AN IMMERSION FRIED POTATO STARCH-GLUTEN GEL DURING POSTFRYING PERIOD

Moisture profiles in fried samples of potato starch with different gluten contents were determined during postfrying storage. Over time, moisture migrated from the core to the crust of the sample, and the moisture content of the crust region increased. The addition of gluten caused a significant increase in oil uptake in the crust. The initial hardness of the crust significantly decreased as the gluten content increased to 10 and 30%, during the first 30 min of storage. With longer storage time (> 240 min), the crust hardness tended to increase, due to an increase in firmness of the starch sample. This behavior was less pronounced for samples with 10 and 30% gluten. The range of linear viscoelastic behavior (up to 14% strain) was determined from the initial linear zone of the stress-strain curves. Stress relaxation tests were performed in the linear and nonlinear viscoelastic regions, with a strain level of 5% and 40%, respectively. According to stress relaxation curves, samples became less elastic with the addition of gluten and more elastic with the time of storage.     

CORRELATION OF TIME-TEMPERATURE INDICATOR RESPONSE WITH MICROBIAL GROWTH IN PASTEURIZED MILK

Commercially obtained pasteurized whole milk was stored at three constant temperatures (0°C, 5°C, and 10°C), and one variable temperature condition (cyclic exposure of 0°C for 14 days and 10°C for 2 days). Daily analyses were conducted to enumerate the growth of total bacteria, coliforms, psychrotrophs, and spore forming organisms in samples from each storage treatment. Microbial growth was correlated with the response of the I-POINT and LifeLine full-history time-temperature indicators. Response of the I-POINT model 2140 was strongly related to germination of the psychrotrophic bacteria, and significant correlations (r > 0.95) were found between total count enumeration and the LifeLine model 57 indicator.     

Influence of substrate temperature on the texture and superconducting properties of thin films of YBa2Cu3O7-x on (1 0 0) YSZ substrates prepared by glow discharge sputtering

Films of c-axis textured YBa2Cu3O7-x (YBCO) were grown on (1 0 0) oriented yttria stabilized zirconia substrates by high pressure glow discharge sputtering. The influence of substrate temperature on the texture and superconducting properties of the films is reported. X-ray pole figure analysis has shown that a c-axis orientation of the film normal to the substrate surface occurs at an optimized substrate temperature of 953 K. HREM investigation revealed that the deposited material nucleates and grows as YBCO with a large amount of stacking faults and with a few Y2BaCuO5 particles. A dominant cube-to-cube orientation relationship is found between the YBCO film and the substrate. This revised version was published online in August 2006 with corrections to the Cover Date.     

Grain Extract-Milk Beverage: Processing and Physicochemical Characteristics

Extracts from germinated barley, wheat, triticale, and corn showed compatibility when blended with milk in proportions of 30%, 40%, and 50%, respectively. The pH of grain extract-milk blends initially adjusted to 7.2 decreased to pH 6.2-6.4 when processed in bottles at 121°C for 15 min. The wheat and barley extract beverages scored highest preference followed by triticale and corn beverages. The beverage has excellent malty taste and smooth mouth feel.     

Studies on the skin uptake and efflux kinetics of N-phenyl-p-phenylenediamine: an aromatic amine intermediate

N-phenyl-p-phenylenediamine (N-PPDA), an industrial intermediate and hair dye ingredient, has been implicated in a variety of toxic symptoms including cutaneous manifestations. However, the role of physiological factors that may determine and modify its absorption and transport within and through the skin is not fully understood. The present study reveals that N-PPDA binds readily to skin showing saturation kinetics with K m and V_max of 2.54 × 10⁻⁴ M and 4.76 μmol g⁻¹ skin, respectively. The uptake was dependent upon the area of skin, concentration of the amine, exposure time, temperature and pH of the vehicle. Heat treatment facilitated the binding but temperatures abouv 50° caused significant lowering of the uptake, indicating the possible involvement of collagen matrix. Skin lipids also contributed in the binding of N-PPDA. Bioinhibitors such as KCN, sodium arsenate, NaF, N-ethylmaleimide, cycloheximide, iodoacetic acid and 2,4-dinitrophenol had no effect on the uptake potential, suggesting it to be a non-energy dependent process. Most of the skin-bound N-PPDA was effluxed through serum proteins reaching the target organs via systemic circulation.     

Surface Characteristics of Sodium (β-Alumina Electrolytes

Surfaces of sodium β/β"-alumina ceramics were characterized via techniques such as scanning electron microscopy, secondary ion mass spectroscopy, and electron spectroscopy for chemical analysis to determine the nature of the resistive surface film that leads to the phenomenon of asymmetric polarization in a sodium-sulfur cell. The results indicated that the resistive surface film is soda rich, has submicrometer thickness, and is removable by a surface treatment. A mechanism consistent with these observations is proposed for the formation of the resistive surface film on sodium β/β"-alumina during the sintering process.     

NATURAL AND APPLIED WAX COATINGS ON ORANGES

Scanning electron microscopy was used to examine the wax coating on oranges. The natural wax platelets are irregular in shape and size, have a rough surface and increase in numbers as the orange matures. Most natural platelets can be removed by dipping the orange in a chloroform-methanol solution and rubbing the surface. Store-bought oranges have natural wax platelets 1–2 microns thick covered with a 2–5 micron layer of commercial wax. Wax applied over platelets may be ineffective if the platelets break off in handling and expose the orange's surface. Removal of natural wax platelets prior to commercial waxing allows uniform wax application and consequently better storage life. Drying with air at 2.5 m/s produced uneven wax thickness while 14 m/s air produced a complete, uniform wax layer.     

Nutritional Quality of Vegetable Pigeonpeas [Cajanus cajan (L.) Mill sp.]: Mineral and Trace Elements

Mineral and trace elements of green and mature seed of pigeonpea genotypes were determined. Among the genotypes tested a considerable variation was observed in phosphorus, potassium and calcium of both green and mature seeds whereas the variation was small for magnesium. When consumed, green seeds are a richer source of iron, copper and zinc on a dry matter basis than the mature seed whereas there was a reverse trend for manganese. The calcium content of mature seed was significantly higher than green seed and this was attributed to the seed coat content of the mature seed.     

In vitro Digestibility of Whey Protein/K-Casein Complexes Isolated from Heated Concentrated Milk

The disulfide-linked complex of _K-casein and whey proteins that forms when concentrated milk is heated was isolated by centrifugation and column chromatography on Sephacryl S-1000. The rate of hydrolysis of β-lactoglobulin and _K-casein in the complex and the reduced and carboxymethylated components of the complex were measured by polyacrylamide gel electrophoresis. The rates of hydrolysis at pH 2.0 (pepsin) and pH 8.0 (trypsin and chymotrypsin) were similar for _k-casein in the complex and its reduced form. β-Lactoglobulin hydrolysis was faster for the reduced complex than for the complex which was much faster than for the native protein for all three enzymes. The results suggest that heating milk increases the digestibility of whey proteins, despite the formation of large protein complexes between the whey proteins and _K-casein.