Distribution pattern of total lipids and lipid fractions in forest humus

Mull, moder, and mor humus profiles were investigated for their total lipid contents and the behaviour of lipid-phosphorus and of five neutral lipid classes identified by HPTLC. The quantitative distribution of total and neutral lipids among the humus types is, besides by natural differences between the various parent litter materials, mainly controlled by soil physicochemical properties. In particular strongly acidic conditions, i.e. conditions corresponding to a reduced biological activity, inhibit significantly the decomposition of lipid compounds in (moder and) mor humus. A feature of the lipid depth functions is the input of microbial and root litter-derived lipid material in the fermentation layers and a considerable lipid accumulation in the A horizons, probably at least partly due to mechanical transport processes. Phospholipids show no distinct variation dependent on the humus type, as far as the organic layers are concerned. But obviously, lipid-P in the mineral, soil is closely correlated with, and therefore is a valuable measure for, the overall biological activity increasing from mor to moder and mull humus.     

Phytochemicals and antioxidant activity of milled fractions of different wheat varieties

The health-promoting effects of whole-grain consumption have been attributed in part to their unique phytochemical contents and profiles that complement those found in fruits and vegetables. Wheat is an important component of the human diet; however, little is known about the phytochemical profiles and total antioxidant activities of milled fractions of different wheat varieties. The objectives of this study were to investigate the distribution of phytochemicals (total phenolics, flavonoids, ferulic acid, and carotenoids) and to determine hydrophilic and lipophilic antioxidant activity in milled fractions (endosperm and bran/germ) of three different wheat varieties, two of which were grown in two environments. Grain samples of each of the wheat varieties were milled into endosperm and bran/germ fractions. Each fraction was extracted and analyzed for total phenolics, ferulic acid, flavonoids, carotenoid contents, and hydrophilic and lipophilic antioxidant activities. Total phenolic content of bran/germ fractions (2867-3120 micromol of gallic acid equiv/100 g) was 15-18-fold higher (p < 0.01) than that of respective endosperm fractions. Ferulic acid content ranged from 1005 to 1130 micromol/100 g in bran/germ fractions and from 15 to 21 micromol/100 g in the endosperm fractions. The bran/germ fraction flavonoid content was 740-940 micromol of catechin equiv/100 g. On average, bran/germ fractions of wheat had 4-fold more lutein, 12-fold more zeaxanthin, and 2-fold more beta-cryptoxanthin than the endosperm fractions. Hydrophilic antioxidant activity of bran/germ samples (7.1-16.4 micromol of vitamin C equiv/g) was 13-27-fold higher than that of the respective endosperm samples. Similarly, lipophilic antioxidant activity was 28-89-fold higher in the bran/germ fractions (1785-4669 nmol of vitamin E equiv/g). Hydrophilic antioxidant activity contribution to the total antioxidant activity (hydrophilic + lipophilic) was >80%. In whole-wheat flour, the bran/germ fraction contributed 83% of the total phenolic content, 79% of the total flavonoid content, 51% of the total lutein, 78% of the total zeaxanthin, 42% of the total beta-cryptoxanthin, 85% of the total hydrophilic antioxidant activity, and 94% of the total lipophilic antioxidant activity. Our results showed that different milled fractions of wheat have different profiles of both hydrophilic and lipophilic phytochemicals. These findings provide information necessary for evaluating contributions to good health and disease prevention from whole-wheat consumption.     

Use of microscopy to assess bran removal patterns in milled rice

During rice milling, the bran and germ are successively removed from the caryopsis (kernel). Because bran and germ contain large quantities of lipid, the amount of lipid remaining on the kernel surface may be used as a method for the assessment of milling quality. Bulk samples of rice pureline varieties and an experimental hybrid were milled for 0, 10, 20, 30, and 40 s. Scanning electron microscopy (SEM) revealed that brown rice kernels had large contours of linear protuberances and depressions running lengthwise along the kernel surface. The protuberances were abraded successively during milling, but varying amounts of material remained in the depressions. Light microscopy combined with the lipid-specific probes Nile Blue A or Sudan Black B demonstrated that the material in the depressions observed with SEM was lipid. Sections of whole, milled rice kernels, prepared using a modified sectioning technique and stained with Nile Blue A, showed that portions of the embryo remain after milling and that lipid is located on or near the surface of the kernel. Differences in quantity and distribution of residual lipid as milling duration increased were documented photographically to indicate the extent to which the bran and embryo components were removed during milling. This paper provides proof of concept that residual lipid is a robust measure of the degree of milling.     

HMW-glutenin and gliadin variations in Tibetan weedrace, Xinjiang rice wheat and Yunnan hulled wheat

Nine Tibetan weedrace, 9 Xingjiang rice wheat and 14 Yunnan hulled wheat accessions were evaluated for the variability of HMW-glutenins and gliadins. Higher variability was observed for both HMW-glutenins and gliadins in Tibetan weedrace and Xingjiang rice wheat, while lower variability was observed in Yunan hulled wheat. There were 4 HMW-glutenin and 9 gliadin patterns in 9 Tibetan weedrace accessions, 5 HMW-glutenin and 8 gliadin patterns in 9 Xingjiang rice wheat accessions, and 3 HMW-glutenin and 8 gliadin patterns in 14 Yunnan hulled wheat accessions. In Xinjiang rice wheat, one accession (i.e. Daomai 2) carried subunits 2.1 + 10.1 encoded by Glu-D1, which is very rare in common wheat.     

Effect of industrial processing on the distribution of aflatoxins and zearalenone in corn-milling fractions

The aim of this study was to investigate the distribution of aflatoxins and zearalenone levels in various corn-milling fractions. Corn kernels and six derived milling fractions (germ, bran, large and small grits, flour, and animal feed flour) were sampled in an industrial plant; both conventional and organic corns were sampled. To evaluate the effect of cooking, samples of polenta were prepared starting from naturally contaminated flour. Conventional and organic lots showed mycotoxin contamination. For both lots, germ, bran, and animal feed flour showed a marked concentration factor from 239 to 911% accounting for both the low yields of the derived products and the distribution of aflatoxins and zearalenone contamination in the outer parts of the kernels. Conversely, a reduction factor of at least four times from raw material to finished products was observed. Polenta samples were unaffected by the cooking process, with levels of contamination similar to those of starting flour.     

不同模拟储藏条件下粳米胚乳显微结构变化

为了弄清大米在储藏过程中胚乳结构的变化,从而探索其品质变化的机理。在模拟我国典型储粮环境条件下,利用Hitachi S3000N扫描电镜对储藏的粳米胚乳横断面、胚乳细胞表面以及胚乳淀粉颗粒形态进行观察。结果显示：随着储藏时间的延长和储藏温度的升高其胚乳横断面的放射状排列趋于模糊,胚乳细胞的破裂程度增加,尤其是在中心部位;胚乳细胞表面光滑度下降,小孔数量增多加大,其表面蛋白质膜有不同程度的翘起,膜的厚度有所下降;裸露的单粒淀粉增加,淀粉颗粒间的裂缝增多,部分复合淀粉颗粒表面的蛋白质膜变得模糊和粗糙。通过对储藏过程中胚乳微观结构及形态的变化与大米蒸煮和食味品质劣变的机理分析,解析出胚乳微观结构及形态的变化是导致大米主要品质变化的重要原因,为大米储存品质的控制提供了理论依据。     

Distribution of cyclolinopeptides in flaxseed fractions and products

Hydrophobic cyclic peptides, termed cyclolinopeptides, found in flaxseed are known for their immunosuppressive activity. This study is the first report of the occurrence of cyclolinopeptides in flaxseed fractions and products produced by aqueous processing and cold pressing. The distribution of cyclolinopeptides in flaxseed was determined after processing of flaxseed by various industrial and laboratory processes. Extracts of the water-soluble mucilage did not contain cyclolinopeptides. The cotyledon had the highest concentration of cyclolinopeptides, whereas seed coat had lower levels. An oil body fraction separated from seed after homogenization in water, followed by centrifugation, had the highest concentration of cyclolinopeptides of the fractions produced by this method. Further washing of the oil body fraction led to a loss of cyclolinopeptides. When oilseed was extruded using an expeller press, cyclolinopeptides were found in greater concentrations in crude oil and the solid sediment present in the oil fraction than in meal or the unprocessed seed. The concentration of cyclolinopeptides in crude flaxseed oil immediately after pressing was much higher than that observed in flaxseed oils purchased from a retail outlet. The effect of oil refining treatments on the removal of cyclolinopeptides was also tested. Acid degumming using aqueous H(3)PO(4) removed cyclolinopeptides from crude flaxseed oil. Alkali refining was less effective as this treatment failed to remove all peptides equally. This work illustrates ways that cyclolinopeptides may be extracted from flaxseed oil that could be developed for large-scale industrial extraction. The ability to extract cyclolinopeptides on a larger scale would allow faster exploitation of commercial applications of these molecules and provide the flaxseed industry with value-added coproducts.     

Kinetics and mechanism of free fatty acid formation on the surface of milled rice

The presence of free fatty acid (FFA) is an important factor in determining rice quality for brewing. FFA formation in milled rice during storage was monitored, and a two-parameter semiempirical kinetic model giving product concentration as a function of time is proposed to describe FFA formation on milled rice during storage. The model was tested using sets of data obtained from partially milled rice samples stored at 24, 37, and 50 degrees C and fully milled rice stored at 37 degrees C and 70% relative humidity. The predicted values provide very good fits (R(2) >or= 97%) of the experimental data at all storage temperatures. A two-substrate reaction mechanism representing a two-phase process is also presented. Milled rice FFA at a given storage time varied with storage temperatures. The kinetic model and mechanisms proposed could be useful in describing and predicting FFA contents of milled rice during storage and transportation.     

Continuous sorbent preconcentration for the electrothermal atomic absorption spectrometric determination of ultratrace amounts of cobalt in milled wheat fractions

A method for the rapid determination of cobalt at ultratrace levels was applied in flour and flour byproducts (shorts and bran) obtained from various types of wheat that includes on-line preconcentration and electrothermal atomic absorption spectrometry is proposed. Solutions in 0.1 mol/L HNO(3) of milled wheat fractions subjected to wet ashing are preconcentrated in a straightforward flow-injection system by sorption on a RP-C(18) column following chelation. The eluent, ethanol, is carried by an air stream, and the chelate is eluted and collected in a 500 microL PTFE autosampler cup. The determination of cobalt features a precision (RSD) of 6% for a concentration of 0.2 ng/mL and a sensitivity (slope of the calibration graph) of 0.38 +/- 0.03 A s x ng/mL. The cobalt content in each type of wheat was found to be influenced by its geographical origin and texture. Also, it was found to depend on the amount of bran present in the milled wheat fraction. On the other hand, it is not significantly affected by the technological processes involved in wheat milling at a flour-producing factory.     

Distribution of aflatoxins B1 and M1 in contaminated calf and pig livers

The determination of aflatoxins B1 and M1 in multiple sections of livers from 4 calves and 1 pig exposed to high levels of aflatoxins showed a uniform distribution of the aflatoxins in each liver, within the precision of the analytical method used. The thin layer chromatographic method has an expected within-laboratory coefficient of variation of 15%.     

Correlation analysis of mineral element contents and quality traits in milled rice (Oryza stavia L.)

The relationships among potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) contents in milled rice (Oryza stavia L.) of 274 genotypes and the relationships between these mineral element contents and other rice quality traits including 3 cooking quality traits, 17 amino acid contents, and protein content were investigated. The results showed that there were significant correlations among most of mineral element contents. Mg, Fe, and Mn contents were significantly correlated with most of the other mineral element contents, while Cu content had significantly negative associations with the K and Mg contents of rice. The relationships between mineral element contents and cooking quality traits showed that gel consistency (GC) was significantly correlated with K, Cu, and Mn contents of rice. Amylose content (AC) was significantly associated with K, Na, Mg, Cu, and Mn contents. The alkali spreading value (ASV) had closely positive relationships with Ca, Mg, and Mn contents. In addition, 8 mineral element contents had obvious correlations with different amino acid contents. Mg, Ca, and Zn contents were significantly correlated with most of the 17 amino acid contents, but Na content did not correlate with amino acid contents except aspartic acid of rice. Furthermore, significant associations were found between protein content and Na, Mg, Zn, Cu, or Mn content. Six principal components were extracted to explain 84.50% of the total variances and contained the information provided by the original 29 variables according to the principal component analysis.     

Developmental patterns of lamellae and stroma fractions of chloroplasts in rice plants

On examining the changes in lamellae and stroma nitrogen during leaf development, it is demonstrated that the lamellae and stroma fractions ofrice chloroplasts develop in quite different ways. In the case of stroma, the stroma materials existing in the leaf section which has just emerged from a leaf sheath are quite limited and the major part of this fraction is derived from the successive protein synthesis, i.e., the synthesis of this fraction was markedly increased during leaf expansion. This developmental pattern of the stroma coincided with the changes in the high-molecular-weight water soluble leaf protein, which seemed to be mainly composed of Fraction I protein. A rapid increase in stroma nitrogen was found to be a major cause for an increase in the leaf nitrogen content during leaf development.

On the other hand, the developmental pattern of the lamellae fraction was characterized by the fact that a considerable amount of this fraction had already been prepared when a leaf emerged from a leaf sheath and thereafter, no outstanding increase was seen compared to that of the stroma. This developmental pattern of the lamellae fraction resulted in a lowering of the proportion of lamellae nitrogen to the total leaf nitrogen during leaf development.

A great change in the lamellae-stroma composition of chloroplasts was observed. The proportion of stroma nitrogen to the total chloroplast nitrogen tended to increase as a leaf develops. Since the developmental stage varied according to the regions of a leaf, variation of the lamellaestroma composition was seen even within a leaf, i.e., the proportion of stroma nitrogen increased from base to tip.

In order to compare the synthetic rate of chlorophyll with those of the stroma and lamellae fractions, the changes in the ratios of stroma nitrogen/chlorophyll and lamellae nitrogen/chlorophyll were examined. The lamellae nitrogen/chlorophyll ratio decreased as a leaf developed, whereas the stroma nitrogen/chlorophyll ratio increased. Then the synthetic rates of these fractions during leaf development turned out to be of the same order as the stroma fraction, chlorophyll, lamellae fraction.     

New descriptions of hulled wheats on the infraspecific level

New morphological variation was detected in the hulled wheats Triticum monococcum L. (cultivated), T. urartu Thum. ex Gandil. (wild) and T. baeoticum Boiss. em. Schiemann (wild) and four, five and six new botanical varieties were described, respectively. This formal approach complements the classical infraspecific classifications.     

外源新碳在不同类型土壤团聚体中的分配规律

通过室内模拟实验,利用δ13C方法研究外源新碳(13C标记的水稻秸秆)在不同类型土壤(红壤、黄红壤和草甸土)团聚体中的分配规律。培养温度为25°C,培养时间为360 d。结果表明:在三种类型土壤中,外源新碳进入到土壤团聚体中的数量由大到小顺序依次为250～2 000μm、50～250μm和<50μm。而进入到土壤中的外源新碳,56.8%～59.6%残留在250～2 000μm团聚体中,25.9%～28.7%残留在50～250μm团聚体中,11.7%～17.3%残留在<50μm团聚体中,表明新进入的外源碳主要分配在大团聚体中。     

Distribution of total and extractable forms of iron,manganese, and aluminum in development of rice soils of saga polder lands

The distribution of pedogenic oxides of Fe, Mn, and Al was described for rice soils of Saga polder lands and its relationship to soil development with time was investigated. The distribution of Mn largely parallelled that of Fe and in response to the soil development their accumulation occurred in the B horizons of the profiles. Manganese was the clement most susceptible to downward movement, which lad to a pronounced lowering of extractable Mn content in the surface horizons in well-developed soil morphology. By contrast, this is not the case for Al which, in general, had little change in extractable Al and a slight increase in total Al with depth as the time increased. Apparently the distribution of Mn was largely governed by the extent of reduction processes, whereas in the Al distribution clay migration may be a principal controlling factor. The distribution of Fe may be due chiefly to the reduction processes, with some contribution from the clay migration.     

Determination of aflatoxins in vegetable oils

A simple method is proposed for determination of aflatoxins in vegetable oils. The method was successfully applied to both crude and degummed oils. The oil sample, dissolved in hexane, was applied to a silica column and washed with ether, toluene, and chloroform; aflatoxins were eluted from the column with chloroform-methanol (97 + 3). As quantitated by thin layer chromatography and liquid chromatography, the oils analyzed contained aflatoxin B1 at levels of 5-200 micrograms/kg. Recoveries of aflatoxin B1 standards added to aflatoxin-free oils were between 89.5 and 93.5%, with coefficients of variation of 6.3-8.0%.     

Distribution of applied cadmium in different size fractions of soils after incubation

The size fraction of soils is one of the important factors that influence the retention of heavy metals. The sorptive properties of soils for heavy metals are principally associated with clay and silt-size fractions. Phosphate fertilizers that are applied to highly weathered tropical soils contain a wide concentration range of cadmium (Cd) as an impurity. Tropical soils contain kaolinite and oxides of Al, Fe, and Mn, which have the ability to sorb Cd. However, the distribution of Cd in different size fractions and the chemical speciation of particulate-bound Cd in the clay size fractions when introduced to soil and allowed to incubate at field moisture capacity merits attention. Cadmium was, therefore, applied to selected surface Kenyan soils varying widely in physicochemical properties to investigate its distribution in different soil particle size fractions and the speciation of particulate-bound species in clay size fractions after incubation. The Cd content in different particle fractions was analyzed by graphite furnace atomic absorption technique after HF-HClO₄ digestion. The particulate-bound Cd species were investigated using chemical sequential extraction method. The study showed that clay size fraction of the natural and the Idaho monoammonium phosphate (MAP)-fertilizer or the Cd perchlorate-added MAP chemical reagent-treated soils contained the highest amount of the total Cd. However, silt and sand fractions of the treated soils also retained appreciable amounts of Cd. Speciation studies revealed that metal-organic complex-bound Cd was the most predominant compared to other particulate-bound Cd species in the clay size fractions of the soils treated with Idaho MAP fertilizer or the Cd perchlorate-added MAP chemical reagent. The distribution of total Cd in the different soil particle size fractions and the speciation of particulate-bound Cd in the clay size fractions varied with the soil type. The results indicate that clay size fractions can retain Cd making it less available; however, the influence of farming practices, which affect Cd mobility, should not be overlooked.     

Distribution of the particle-size fractions in soddy-podzolic soils subjected to sheet erosion

Tendencies in the formation of organomineral profiles of arable agrosoddy-podzolic soils on slopes in different denudation and accumulation zones were characterized on the basis of an integrated study of the humus status of the soils (using the granulodensimetric fractionation method), the content of clay, and the composition of clay minerals. It was shown that the organomineral and mineralogical parameters of the surface-horizon transformation could be used for improving the diagnostic accuracy of soils on the slopes basing on their conventional characteristics.