Detection of Argan Oil Adulteration Using Quantitative Campesterol GC-Analysis

Detection of edible oil adulteration is of utmost important to ensure product quality and customer protection. Campesterol, a sterol found in seed oils, represents less than 0.4% of argan oil total sterol content. Quantitative analysis of campesterol by gas chromatography of argan oil and of a mixture of argan oil and readily commercially available vegetable oils, consecutively with sterol separation, was carried out. Our study clearly demonstrated that determination of the campesterol level in argan oil (or oil presented as argan oil) can be proposed as the major analysis method to assess unambiguously argan oil purity up to 98%.     

Positional analysis and determination of triacylglycerol structure ofArgania spinosa seed oil

The distribution of fatty acids between the sn-1, sn-2 and sn-3 positions of triacylglycerols fromArgania spinosa seed oil of Morocco has been determined. Saturated fatty acids showed a preference for external positions. The sn-1 position contained slightly more palmitic acid than the sn-3 position, whereas stearic acid was preferentially esterified at the sn-3 position. Linoleic acid occurred predominantly in the sn-2 position with lesser amount evenly distributed between the sn-1 and the sn-3 positions, as generally found in vegetable oils. Oleic acid was distributed with a slight preference shown for the internal position, whereas the distribution between the external positions revealed a slight preference for the sn-1 position. The distribution of the triacylglycerols determined from high-performance liquid chromatography (HPLC) is at variance with that calculated from the 1-random 2-random 3-random distribution theory. This is particularly true for trioleoyl and trilinoleoylglycerols. In contrast, the agreement between theory and experiment is good for triacylglycerols containing two oleoyl and one linoleoyl chains, one oleoyl, one linoleoyl and one palmitoyl chains or one oleoyl, one palmitoyl, and one stearoyl chains.     

Inhibition of seedling growth of crop species by recirculating root exudates ofBidens pilosa L.

The allelopathic effects of root exudates ofBidens pilosa L. on seedling growth ofLactuca sativa L.,Phaseolus vulgaris L.,Zea mays L., andSorghum bicolor (L.) Moench were studied using a root exudate recirculating system that allows continuous exposure of crop plants to allelopathic chemicals. This system maintains an undisturbed rhizosphere and eliminates competition and physical contact between the donor and acceptor plants. Comparison of responses to hydrophobic and hydrophilic root exudates is made possible by removal of hydrophobic compounds using XAD-4. Treatments consisted ofB. pilosa, B. pilosa with an Amberlite XAD-4 resin column attached to the donor pot to remove hydrophobic allelochemicals, and a donor pot without weeds.B. pilosa significantly inhibited seedling growth of all crop species tested. The crop species varied in response to the root exudates, withL. sativa being most sensitive. Larger and olderB. pilosa plants caused greater inhibition of seedling growth ofL. sativa andP. vulgaris than did smaller (younger)B. pilosa plants.B. pilosa with XAD-4 caused significantly less inhibition to all crop species, exceptZ. mays, thanB. pilosa without XAD-4, indicating that the hydrophobic exudates played an important role in the allelopathic growth inhibition. Variability in species response toB. pilosa with and without XAD-4 was probably due to differences in sensitivity to hydophobic and hydrophilic allelochemicals.Supported by a grant under USDA Agreement No. 83-CRSR-2-2293. Journal Series No. 2887 of the Hawaii Institute of Tropical Agriculture and Human Resources.     

Characteristics of safflower seed oils of turkish origin

Technological characteristics of oils extracted from seventeen varieties of safflower seeds (Carthamus tinctorius L.) of Turkish origin were investigated for their utilization prospects in the food industry and in other industrial sectors. Standard procedures were applied to determine the technological characteristics of seventeen varieties of safflower seeds and the safflower seed oils; fatty acid compositions were determined by gas-liquid chromatography. Results show that safflower seed oils are suitable both for food and industrial purposes.     

C10-polyacetylenes as allelopathic substances in dominants in early stages of secondary succession

cis-Dehydromatricaria ester (cis-DME) inSolidago altissima, andcis-matricaria ester (cis-ME),trans-matricaria ester (trans-ME), andcis-lachnophyllum ester (cis-LE) inErigeron spp. show strong growth inhibitory effects on other plants. Thecis- andtrans-DMEs were found in soil at the border ofS. altissima communities in concentrations that were inhibitory to test plants. Among four species ofErigeron, the most dominant plant,E floribundus, showed the highest concentrations of the esters. From the results of our experiments, we conclude that these polyacetylenes are probably allelopathic substances with ecological importance.     

Response of lowland rice and common bean grown in rotation to soil fertility levels on a Varzea soil

Brazil has approximately 30 million hectares of lowland areas, known locally as Varzea, but very little is known about their fertility and crop production potential. A field experiment was conducted for three consecutive years to evaluate response of lowland rice (Oryza sativa L.) grown in rotation with common bean (Phaseolus vulgaris L.) on a Varzea (low, Humic Gley) soil. Rice was grown at low (no fertilizer), medium (100 kg N ha^–1, 44 kg P ha^–1, 50 kg K ha^–1, 40 kg FTE-BR 12 ha^–1), and high (200 kg N ha^–1, 88 kg P ha^–1, 100 kg K ha^–1, 80 kg FTE-BR 12 ha^–1 fritted trace element-Brazil 12 as a source of micronutrients) soil fertility levels. Green manure with medium fertility was also included as an additional treatment. Average dry matter and grain yields of rice and common bean were significantly (P < 0.01) increased with increasing fertilization. Across the three years, rice yield was 4327 kg ha^–1 at low fertility, 5523 kg ha^–1 at medium fertility, 5465 kg ha^–1 at high fertility, and 6332 kg ha^–1 at medium fertility with green manure treatment. Similarly, average common bean yield was 294 kg ha^–1 at low soil fertility, 663 kg ha^–1 at medium soil fertility, 851 kg ha^–1 at high fertility, and 823 kg ha^–1 at medium fertility with green manure treatment. Significant differences in nutrient uptake in bean were observed for fertility, year, and their interactions; however, these factors were invariably nonsignificant in rice.     

Fatty acid variation among U.S. Runner-type peanut cultivars

Fatty acid composition was determined among seven U.S. runner-type peanut (Arachis hypogaea L.) cultivars: Florunner, Sunrunner, GK-7, Southern Runner, Sunbelt Runner, Okrun, and Langley. Significant year and cultivar differences were found within these fatty acid profiles. Southern Runner had the best oleic to linoleic ratio and iodine values; whereas Florunner, Sunrunner, and Langley were the highest in unsaturated and lowest in saturated and long-chain fatty acids. For the future, breeding programs need to continue developing peanut cultivars with improved oil quality.     

Allelopathic properties of α-terthienyl and phenylheptatriyne,naturally occurring compounds from species of asteraceae

Alpha-terthienyl (-T), a naturally occurring polyacetylene derivative from roots ofTagetes erecta L., and phenylheptatriyne (PHT), from leaves ofBidens pilosa L., were tested as possible allelopathic agents against four seedling species (Asclepias syriaca L.,Chenopodium album L.,Phleum pratense L.,Trifolium pratense L.).Asclepias was the most sensitive of the species. Allelopathic activity was enhanced in the presence of sunlight or sources of near-UV, with LC_50s forA. syriaca of 0.15 ppm and 0.66 ppm with -T and PHT, respectively; 0.27 and 0.85 forC. album; 0.79 and 1.43 forP. pratense, and 1.93 and 1.82 forT. pratense. Near-UV exposure was saturating but never more than found in summer sunlight at Ottawa, Canada. Growth inhibition was observed with seedlings treated with -T and PHT but without near-UV irradiation. Germination of seedlings was also sensitive to -T and PHT with or without near-UV treatment. -T was extracted from soil surrounding the roots ofTagetes. Concentrations calculated for the soil (0.4 ppm) indicate that seedling growth could be significantly hindered. The activity and specificity of -T was sufficiently high to warrant future field trials to assess its potential as a natural weed-control agent.     

Chemical composition ofRumex crispus L. seed

Rumex crispus L. seeds harvested in Olavarría (Province of Buenos Aires, Argentina) were extracted with 60–80°C petroleum ether to render 6.0% (dry basis) of a lipid fraction with a 152.4 saponification value and 15.4% unsaponifiable matter. Fatty acid composition obtained by gas-liquid chromatography was: 14:0, 2.7; 16:0, 13.5; 16:1, 1.2; 18:0, 1.2; 18:1, 38.6; 18:2, 36.3; 18:3, 0.5; 20:0, 2.4; 20:2, 0.3; 22:0, 0.9; 22:1, 1.2; and 24:0, 1.2; with traces of 14:1, 15:1, 17:0, and 17:1. Residual meal contained 10.62% crude protein, with a low value of available lysine (3.31 g/16 g N). Ash, crude fiber, sugars, hydrolyzable carbohydrates, total and phytic acid phosphorus, calcium and residual lipids contents are reported here.     

Leaf surface chemicals fromNicotiana affecting germination ofPeronospora tabacina (adam) sporangia

A bioassay was used to evaluate the effects of cuticular leaf components, isolated fromN. tabacum, N. glutinosa (accessions 24 and 24a), and 23other Nicotiana species, on germinationof P. tabacina (blue mold). The leaf surface compounds included- and-4,8,13,-duvatriene-l,3-diols (DVT-diols), (13-E)-labda-13-ene-8-,15-diol (labdenediol), (12-Z)-labda-12,14-diene-8-ol (cis-abienol), (13-R)-labda-8,14-diene-13-ol (manool), 2-hydroxymanool, a mixture of (13-R)-labda-14-ene-8,13-diol (sclareol), and (13-S)-labda-14-ene-8,13-diol (episclareol), and various glucose and/or sucrose ester isolates. The above in acetone were applied onto leaf disks of the blue moldsusceptibleN. tabacum cv. TI 1406, which was then inoculated with blue mold sporangia. Estimated IC₅₀ values (inhibitory concentration) were 3.0g/cm² for-DVT-diol, 2.9/cm² for-DVT-diol, 0.4g/cm² for labdenediol and 4.7g/cm² for the sclareol mixture. Manool, 2-hydroxymanool, andcis-abienol at application rates up to 30g/cm² had little or no effect on sporangium germination. Glucose and/or sucrose ester isolates from the cuticular leaf extracts of 23Nicotiana species and three different fractions fromN. bigelovii were also evaluated for antimicrobial activity at a concentration of 30g/cm². Germination was inhibited by >20% when exposed to sugar esters isolated fromN. acuminata, N. benthamiana, N. attenuata, N. clevelandii, andN. miersii, and accessions 10 and 12 ofN. bigelovii. These results imply that a number of compounds may influence resistance to blue mold in tobacco.     

Allelopathic potentials of alfalfa (Medicago sativa) saponins: Their relation to antifungal and hemolytic activities

A wheat seedling bioassay was used to indicate the relationship between the chemical structure of alfalfa saponins and their allelopathic activity. None of the tested saponins significantly influenced wheat germination. Seedling growth bioassays indicated significant differences among the activities of individual glycosides. The most active were medicagenic acid, its glycosides substituted at the C-3 position with glucose, and hederagenin monoglycoside. Medicagenic acid glycosides, substituted at the C-3 position with glucuronic acid, and zahnic acid tridesmoside were less active. No significant correlation was found among the allelopathic, hemolytic, and antifungal activities of the individual glycosides.     

Allelopathic Potential and Chemical Constituents of Volatile Oil from Ageratum conyzoides

Fresh leaves and volatile oil of the important weed Ageratum conyzoides in south China were highly inhibitory to seedling growth of various cultivated crops, especially in an adverse habitat. The constituents of the volatile oil were analyzed by GC-MS. Eleven components were identified and six main components, precocene I, precocene II, 3,3-dimethyl-5-tert-butylindone, -caryophyllene, -bisabolene, and fenchyl acetate, were isolated by means of column chromatography. Precocene I, precocene II, -caryophyllene, and 3,3-dimethyl-5-tert-butylindone inhibited seedling growth of acceptor plants. Inhibitory activity of the volatile oil was more intense than that of the pure components. Fenchyl acetate and -bisabolene have no inhibitory activity, but when mixed with precocene II, they increased the inhibitory activity to growth of acceptor seedling plants. Experiments show that allelopathic synergism exists among allelochemicals of Ageratum conyzoides.     

Difference in hydroxamic acid content in roots and root exudates of wheat (Triticum aestivum L.) and rye (Secale cereale L.): Possible role in allelopathy

Hydroxamic acids (Hx) produced by some cereal crops have been associated with allelopathy. However, the release of Hx to the soil by the producing plant-an essential condition for a compound to be involved in allelopathy-has not been shown. GC and HPLC analysis of roots and root exudates of wheat (Triticum aestivum L.) and rye (Secale cereale L.) cultivars, with high Hx levels in their leaves, demonstrated the presence of these compounds in the roots of all cultivars analyzed and in root exudates of rye. Moreover, bioassays employing root exudates collected from wheat and rye seedlings demonstrated that only rye exudates inhibited root growth of wild oats,Avena fatua L., a weed whose root growth is inhibited by Hx. These results suggest that rye could potentially interfere with the growth ofAvena fatua in nature and that this interference could be due to the release of Hx to the soil by way of roots.     

Biorationals fromNicotiana protect cucumbers againstColletotrichum lagenarium (Pass.) ell. & halst disease development

Trichome exudate compounds isolated from leaves ofNicotiana tabacum, N. glutinosa (accessions 24 and 24a), and 21 otherNicotiana species were evaluated for biorational activity againstC. lagenarium, the anthracnose pathogen of cucumber. Exudate compounds tested were the cembrane diterpenes - and -4,8,13-duvatriene-1,3-diols (DVT diols); the labdane diterpenes (13-E)-labda-13-ene-8,15-diol (labdenediol) and (13-R)-labda-14-ene-8, 13-diol (sclareol); extracts fromN. gossei; and various sugar ester isolates. In dose-response experiments test compounds were applied to a water agar surface that was then inoculated with a conidial suspension. Low levels of most test compounds reduced or completely inhibited germination ofC. lagenarium conidia. IC₅₀ values, concentrations (micrograms per square centimeter) at which conidium germination was reduced 50%, were 6.3 for DVT diols, 19.3 for sclareol, 1.0 for labdenediol, 2.8 for a mixture of sclareol and labdenediol, 1.2 for anN. gossei sucrose ester and 4.1 for theN. gossei crude extract. Higher levels of DVT diols and the sclareol-labdenediol mixture were required to reduce lesion size and number on inoculated cucumber leaves. At the highest concentration tested, 100 µg/cm², the DVT diols and sclareol-labdenediol mixtures protected cucumbers against lesion development by 93 and 98%, respectively. Sugar ester mixtures from 20Nicotiana species and three different sugar ester fractions fromN. bideglovii had in vitro antifungal activity at a concentration of 48 µg/cm². Sugar esters from nine of the species includingN. acuminata, N. attenuata, N. clevelandii, N. maritima, N. miersii, N. noctiflora, N. occidentalis, N. rustica, and fractions 10, 12, and 13 fromN. bideglovii completely inhibitedC. lagenarium conidium from germinating. Sugar ester mixtures from only four species,N. plumbaginifolia, N. bonariensis, N. simulans, andN. palmerii, had no significant effect onC. lagenarium conidium germination. These results suggest the potential ofNicotiana exudates as biorationals in reducing disease development.     

Biodegradation ofVernonia galamensis seed Oil byAcinetobacter andPseudomonas sp.

The biodegradability ofVernonia galamensis seed oil (VO) has been demonstrated with two environmental bacterial strains,Acinetobacter Iwoffi (HU 3955), andPseudomonas sp. (HU 4020). A time-dependent increase in the degradative activities of both bacteria species was apparent. There wasca. 60% decrease in the amount of VO over an eightday incubation period. Additionally, lipolytic activity was evident from the amount of free fatty acid (FFA) that was generated. The percent FFA of the residual oil were 82% for thePseudomonas strain, and 62% for theAcinetobacter strain. The weight per epoxy value of the VO in the fermentation medium remained relatively constant over the incubation period, suggesting the lack of preference for either the epoxidized or nonepoxidized acids present in VO.     

Characterization and supercritical carbon dioxide extraction of walnut oil

Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO₂) in the temperature range of 308 to 321 K and in the pressure range of 18 to 23.4 MPa. The influence of particle size was also studied at a superficial velocity of 0.068 cm/s, within a tubular extractor of 0.2 L capacity (cross-sectional area of 16.4 cm²). FFA, sterol, TAG, and tocopherol compositions were not different from those of oil obtained with n-hexane. The main FA was linoleic acid (56.5%), followed by oleic acid (21.2%) and linolenic acid (13.2%). The main TAG was LLL (linoleic, linoleic, linoleic) (24.4%), followed by OLL (oleic, linoleic, linoleic) (19.6%) and LLLn (linoleic, linoleic, linolenic) (18.4%). The main component of sterols was β-sitosterol (85.16%), followed by campesterol (5.06%). The amount of cholesterol was low (0.31 and 0.16% for oils extracted by n-hexane and supercritical fluid extraction, respectively. The CO₂-extracted oil presented a larger amount of tocopherols (405.7 μg/g oil) when compared with 303.2 μg/g oil obtained with n-hexane. Oxidative stability determined by PV and the Rancimat method revealed that walnut oil was readily oxidized. Oil extracted by supercritical CO₂ was clearer than that extracted by n-hexane, showing some refining. A central composite, nonfactorial design was used to optimize the extraction conditions using the software Statistica, Version 5. The best results were found at 22 MPa, 308 K, and particle diameter (Dp) −0.1 mm.     

Nitrogen fixation associated with grasses and cereals: Recent progress and perspectives for the future

Over the last 20 years many new species of N₂-fixing bacteria have been discovered in association with grasses, cereals and other non-nodulating crops. Virtually all of these bacteria are microaerophylic, fixing N₂ only in the presence of low partial pressures of oxygen. Until a few years ago much attention was focussed on members the genusAzospirillum and it was assumed that N₂ fixation was restricted to the rhizosphere or rhizoplane of the host plants. Through the use of N balance and¹⁵N techniques it has been shown that in the case of lowland rice, several tropical pasture grasses and especially sugar cane, the contributions of biological N₂ fixation (BNF) are of agronomic significance.More detailed study of the N₂-fixing bacteria associated with sugar cane (Acetobacter diazotrophicus andHerbaspirillum spp.) has shown that they occur in high numbers not only in roots of this crop but also in the stems, leaves and trash but are rarely found in the soil. Some of these endophytic diazotrophs have now also been found in forage grasses, cereals, sweet potato and cassava, although evidence of significant BNF contributions is still lacking.The identification of these endophytic diazotrophs as the organisms probably responsible for the high contributions of N₂ fixation observed in sugar cane suggests that it may be possible to attain significant BNF contributions in some other gramineae and perhaps root crops.     

Nitrogen-15 balance as affected by rice straw management in a rice-wheat rotation in northwest India

The sustainability of the productive rice-wheat systems of Northwest India is being questioned due to the complete removal of straw for animal consumption and fuel, or the burning of straw which has reduced the soil organic matter contents. However, straw incorporation at planting can temporarily reduce the availability of fertilizer-N and reduce crop yields. In a field study on a loamy sand soil, the effect of 6 mg ha⁻¹ rice straw incorporated into the soil 20 or 40 days before sowing (DBS) the wheat was compared with removal or burning of rice straw on the fate and balance of 120 kg ha⁻¹ of 5 atom% ¹⁵N-urea applied to wheat and to a following crop of rice. Wheat grain yield and agronomic efficiency (AE) of applied N (kg grain/kg N applied) were not influenced by rice straw management. However, N uptake (NU), and recovery efficiency (RE) of N by the difference method were lower with rice straw incorporation than with burning. Nitrogen-15 recovery by wheat was highest (41%) when the rice straw was removed or burned and lowest (30.4%) when 30 of the 120 kg N ha⁻¹ was applied at the time of straw incorporation at 20 DBS of wheat. However, this strategy of adding 25% of the urea-N dose at the time of straw incorporation resulted in the highest ¹⁵N losses (45.2%). Inorganic N remaining at harvest in the 0 to 60 cm soil profile, mostly NO₃ ⁻, was 5.5% after wheat and 4.2% after rice. Rice grain yields, NU, and RE were not influenced by rice straw management. Nitrogen-15 losses were similar in rice and wheat (31% with straw removed) despite total irrigation and rainfall inputs of 340 and 32 cm to rice and wheat, respectively. These results suggest to the farmers of northwest India that straw incorporation does not necessarily hurt grain yields, and indicates to researchers that work is still needed to improve N use efficiency in rice and wheat. This revised version was published online in June 2006 with corrections to the Cover Date.     

A model of S,P and N uptake by a perennial pasture

An approach is presented for simulating the uptake of S, P and N by a perennial pasture, based upon diffusion theory and plant uptake kinetics. Plant uptake was limited by either (i) diffusion to the root, (ii) root uptake capacity, or (iii) plant demand. For S and P, uptake as limited by diffusion was calculated from the nutrient depletion pattern around the root, which is dependent upon soil diffusivity for the anion, and the length of time since the root grew into the new soil. To avoid time-consuming calculations at various uptake times and distances from the root, the nutrient depletion pattern was simplified into an effective rooting radius, whereby all plant-available nutrient within the radius was made available to the plant over a 30 day period, and none from outside the radius. Mycorrhizal enhancement of P uptake was simulated by increasing the radius by a factor of between 1 and 3 when P was the primary limiting nutrient. Limitations (ii) and (iii) were included for S and P for the rare occasions when nutrient concentrations were high either in a single layer, or in the profile overall. For N, uptake was limited by uptake capacity, adjusted for soil N concentration, root length density and soil moisture content.Because of a lack of data on diffusion coefficients close to the plant root, a calibration factor was applied to the effective rooting radius, which is described in the second paper in the series.     

Production and Application of Novel Sterol Esterases from <Emphasis Type="Italic">Aspergillus</Emphasis> Strains by Solid State Fermentation

Among numerous mesophilic fungi screened for sterol esterase activity followed by the esterification reaction between plant β-sitosterol and lauric acid in organic solvent, six Aspergillus strains were selected as the most active producers. These fungi had not been studied previously for sterol esterase production. The fungi were cultivated under solid state fermentation (SSF) conditions. The gently dried SSF cultures as such were tested in the esterification reactions, without any special enzyme isolation and purification (downstream) processes. All the six Aspergillus SSF preparations were able to synthesize sterol esters. Sterol esterase activity of these GRAS cleared Aspergillus strains was inducible by sterol ester supplementation to the SSF medium and showed remarkably different moisture optimum during growth as compared to the production of lipase (determined by pNP-palmitate). Genome analysis revealed that sterol esterase production might be a common feature of many Aspergillus species. The synthetic usefulness of the best SSF preparations of A. oryzae NRRL 6270 and A. sojae NRRL 6271 was demonstrated by synthesis of esters of plant sterols with lauric acid resulting in 45–63% conversions (GC) and 27–38% isolated yields of steryl laurates. The isomer preference of A. oryzae NRRL 6270 towards the 10E,12Z isomer of conjugated linoleic acid (CLA) in the esterification reaction with plant sterols was also determined.