Ochratoxin A in Korean food commodities: occurrence and safety evaluation

To evaluate the exposure of Koreans to ochratoxin A, we conducted a survey in 2003 for ochratoxin A in various domestic food commodities: 60 polished rices, 22 barleys, 35 wheat flours, 46 beers, and 14 unstrained rice wine (makkolli) samples. They were analyzed for ochratoxin A using immunoaffinity column and high-performance liquid chromatography (HPLC)-fluorescence detection, and the positive samples were confirmed using HPLC-tandem mass spectrometry. By combining results from different surveys on the levels of ochratoxin A in selected foods and the consumption patterns, we obtained the Korean probable daily intakes (PDI) of ochratoxin A. The polished rice commodity had the highest mean levels of ochratoxin A, which ranged from 0.2 (not detected, i.e., ND = 0) to 1.0 ng/g (ND = limit of detection, i.e., LOD). The estimated PDI for all Koreans fell into the range of 0.8-4.1 ng/kg bw/day, while for heavy consumers the estimates ranged from 1.7 to 9.1 ng/kg bw/day, which did not exceed the PTDI value (14 ng/kg bw/day). Staple rice is the major contributor (>90%) to the Korean dietary intake of ochratoxin A. On the basis of these estimates, it may be concluded that there is at present no considerable risk of ochratoxin A exposure for the average Korean consumer.     

Determination of the conjugated linoleic acids in cow's milk fat by Fourier transform Raman spectroscopy

The collective term "conjugated linoleic acid" or "CLA" generally refers to a mixture of conjugated positional and geometric isomers of linoleic (cis-9,cis-12-octodecadienoic) acid. In nature, these isomers are mainly formed in the rumen by biohydrogenation of polyunsaturated fatty acids. This study concerns a first trial of CLA determination in cow's milk fat by Raman spectroscopy. The spectra of pure cis-9-oleic, cis-9,cis-12-linoleic, cis-9,trans-11-linoleic, and trans-10,cis-12-linoleic acids have been examined in comparison with the spectra of selected milk-fat samples containing between 0 and 3% of CLA. The trial of CLA determination by Raman spectroscopy on cow milk fat has reached its objective with the two following results. First, the examination of the Raman spectra allows to identify three specific Raman signals of the chemical bonds associated to the cis,trans conjugated C=C in the rumenic and trans-10,cis-12-octodecadienoic acids at 1652, 1438, and 3006 cm(-1). Second, the calibration of Raman spectrometer for the CLA determination has indicated that these three specific signals suit very well for the accurate and reliable measurement of CLA concentration in milk fat. To our knowledge, the present study is the first successful attempt to determine the CLA content of milk fat by a spectrophotometric method.     

Synthesis of diethylamine-functionalized soybean oil

Specialty chemicals based on renewable resources are desirable commodities due to their eco-friendly nature and "green" product characteristics. These chemicals can demonstrate physical and chemical properties comparable to those of conventional petroleum-based products. Suitably functionalized amines in the triacylglycerol structure can function as an antioxidant, as well as an antiwear/antifriction agent. In addition, the amphiphilic nature of seed oils makes them an excellent candidate as base fluid. The reaction of amine and epoxidized seed oils in the presence of a catalyst almost always leads to different intra/intermolecular cross-linked products. In most cases, the triacylglycerol structure is lost due to disruption of the ester linkage. Currently, there is no reported literature describing the aminolysis of vegetable oil without cross-linking. Here the epoxy group of the epoxidized soybean oil has been selectively reacted with amines to give amine-functionalized soybean oil. The optimization procedure involved various amines and catalysts for maximum aminolysis, without cross-linking and disruption of the ester linkage. Diethylamine and ZnCl2 were found to be the best. NMR, IR, and nitrogen analysis were used to characterize the products.     

Antifungal mechanism of polygodial

The primary antifungal action of polygodial comes in part from its ability to function as a nonionic surfactant, disrupting the lipid-protein interface of integral proteins and denaturing their conformation. As a result, the antifungal mechanism of this sesquiterpene dialdehyde is associated with the membrane functions or derangement of the membrane. For example, the glucose-induced medium acidification process of Saccharomyces cerevisiae was inhibited by polygodial, presumably caused by inhibition of the plasma membrane H(+)-ATPase. However, the potent antifungal activity of polygodial results from its multiple functions.     

Investigation and optimization of the factors influencing sorghum protein extraction

To optimize the extraction of sorghum proteins, several variables were examined: sample-to-solvent ratio, detergent type and concentration, reducing agent type and concentration, extraction time, and buffer pH and concentration. Samples were quantified and characterized by RP-HPLC, FZCE, and nitrogen analysis. These studies revealed that pH, detergent type, reducing agent type, and sample-to-solvent ratio all had significant effects on the levels of protein extracted. Increasing SDS concentration (2%) and solvent-to-flour ratio (20:1) with multiple 5 min extracts reduced extraction time by 35-80% while still extracting the same levels of total protein relative to the control methodology. Reproducibility using the multiple extractions was found to be excellent with relative standard deviations of <2% for consecutive extractions.     

No-tillage agriculture

The no-tillage cropping system, a combination of ancient and modern agricultural practices, has been rapidly increasing in use. By the year 2000, as much as 65 percent of the acreage of crops grown in the United States may be grown by the no-tillage practice. Soil erosion, the major source of pollutants in rural streams, is virtually eliminated when no-tillage agriculture is practiced. The no-tillage system reduces the energy input into corn and soybean production by 7 and 18 percent, respectively, when compared to the conventional tillage system of moldboard plowing followed by disking. In addition, crop yields are as high as or higher than those obtained with traditional tillage practices on large areas of agricultural land.     

The elemental composition of asteroid 433 eros: results of the NEAR-shoemaker X-ray spectrometer

We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions during the period of May to July 2000. Low aluminum abundances for all regions argue against global differentiation of Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, and iron/silicon ratios are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur and possible aluminum and calcium depletions, relative to ordinary chondrites, may represent signatures of limited partial melting or impact volatilization.     

The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants

We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The Physcomitrella genome provides a resource for phylogenetic inferences about gene function and for experimental analysis of plant processes through this plant's unique facility for reverse genetics.     

Diamond genesis,seismic structure,and evolution of the Kaapvaal-Zimbabwe craton

The lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of southern Africa shows variations in seismic P-wave velocity at depths within the diamond stability field that correlate with differences in the composition of diamonds and their syngenetic inclusions. Middle Archean mantle depletion events initiated craton keel formation and early harzburgitic diamond formation. Late Archean accretionary events involving an oceanic lithosphere component stabilized the craton and contributed a younger Archean generation of eclogitic diamonds. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new lherzolitic and eclogitic diamonds to the Archean diamond suite.