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11.
Petrakis PV Agiomyrgianaki A Christophoridou S Spyros A Dais P 《Journal of agricultural and food chemistry》2008,56(9):3200-3207
This work deals with the prediction of the geographical origin of monovarietal virgin olive oil (cv. Koroneiki) samples from three regions of southern Greece, namely, Peloponnesus, Crete, and Zakynthos, and collected in five harvesting years (2001-2006). All samples were chemically analyzed by means of 1H and 31P NMR spectroscopy and characterized according to their content in fatty acids, phenolics, diacylglycerols, total free sterols, free acidity, and iodine number. Biostatistical analysis showed that the fruiting pattern of the olive tree complicates the geographical separation of oil samples and the selection of significant chemical compounds. In this way the inclusion of the harvesting year improved the classification of samples, but increased the dimensionality of the data. Discriminant analysis showed that the geographical prediction at the level of three regions is very high (87%) and becomes (74%) when we pass to the thinner level of six sites (Chania, Sitia, and Heraklion in Crete; Lakonia and Messinia in Peloponnesus; Zakynthos). The use of classification and binary trees made possible the construction of a geographical prediction algorithm for unknown samples in a self-improvement fashion, which can be readily extended to other varieties and areas. 相似文献
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This paper introduces a facile method to determine the amount of mono- and diglycerides in virgin olive oils. This method is based on the phosphorylation of the free hydroxyls of the mono- and diglycerides with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the integration of the appropriate peaks in the (31)P NMR spectrum. Quantitative (31)P NMR spectroscopy can be extended to the quantification of other constituents of olive oils bearing functional groups with labile protons. 相似文献
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Vigli G Philippidis A Spyros A Dais P 《Journal of agricultural and food chemistry》2003,51(19):5715-5722
A combination of (1)H NMR and (31)P NMR spectroscopy and multivariate statistical analysis was used to classify 192 samples from 13 types of vegetable oils, namely, hazelnut, sunflower, corn, soybean, sesame, walnut, rapeseed, almond, palm, groundnut, safflower, coconut, and virgin olive oils from various regions of Greece. 1,2-Diglycerides, 1,3-diglycerides, the ratio of 1,2-diglycerides to total diglycerides, acidity, iodine value, and fatty acid composition determined upon analysis of the respective (1)H NMR and (31)P NMR spectra were selected as variables to establish a classification/prediction model by employing discriminant analysis. This model, obtained from the training set of 128 samples, resulted in a significant discrimination among the different classes of oils, whereas 100% of correct validated assignments for 64 samples were obtained. Different artificial mixtures of olive-hazelnut, olive-corn, olive-sunflower, and olive-soybean oils were prepared and analyzed by (1)H NMR and (31)P NMR spectroscopy. Subsequent discriminant analysis of the data allowed detection of adulteration as low as 5% w/w, provided that fresh virgin olive oil samples were used, as reflected by their high 1,2-diglycerides to total diglycerides ratio (D > or = 0.90). 相似文献
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Robinson AL Donahue NM Shrivastava MK Weitkamp EA Sage AM Grieshop AP Lane TE Pierce JR Pandis SN 《Science (New York, N.Y.)》2007,315(5816):1259-1262
Most primary organic-particulate emissions are semivolatile; thus, they partially evaporate with atmospheric dilution, creating substantial amounts of low-volatility gas-phase material. Laboratory experiments show that photo-oxidation of diesel emissions rapidly generates organic aerosol, greatly exceeding the contribution from known secondary organic-aerosol precursors. We attribute this unexplained secondary organic-aerosol production to the oxidation of low-volatility gas-phase species. Accounting for partitioning and photochemical processing of primary emissions creates a more regionally distributed aerosol and brings model predictions into better agreement with observations. Controlling organic particulate-matter concentrations will require substantial changes in the approaches that are currently used to measure and regulate emissions. 相似文献
16.
Nathanailides Cosmas Klaoudatos Dimitris Perdikaris Costas Klaoudatos Spyros Kolygas Markos Athanassopoulou Fotini 《International Aquatic Research》2019,11(2):199-206
International Aquatic Research - The effects of triploidy were studied on indices of growth and metabolism in juvenile European sea bass. Ploidy affected flesh quality of Dicentrachus labrax, as... 相似文献
17.
Fragaki G Spyros A Siragakis G Salivaras E Dais P 《Journal of agricultural and food chemistry》2005,53(8):2810-2816
High-field 31P NMR (202.2 MHz) spectroscopy was applied to the analysis of 59 samples from three grades of olive oils, 34 extra virgin olive oils from various regions of Greece, and from different olive varieties, namely, 13 samples of refined olive oils and 12 samples of lampante olive oils. Classification of the three grades of olive oils was achieved by two multivariate statistical methods applied to five variables, the latter being determined upon analysis of the respective 31P NMR spectra and selected on the basis of one-way ANOVA. The hierarchical clustering statistical procedure was able to classify in a satisfactory manner the three olive oil groups. Subsequent application of discriminant analysis to the five selected variables of oils allowed the grouping of 59 samples according to their quality with no error. Different artificial mixtures of extra virgin olive oil-refined olive oil and extra virgin olive oil-lampante olive oil were prepared and analyzed by 31P NMR spectroscopy. Subsequent discriminant analysis of the data allowed detection of extra virgin olive oil adulteration as low as 5% w/w for refined and lampante olive oils. Further application of the classification/prediction model allowed the estimation of the percent concentration of refined olive oil in six commercial blended olive oils composed of refined and virgin olive oils purchased from supermarkets. 相似文献
18.
Diacylglycerol isomers and free acidity were determined for five extra virgin olive oils of different initial acidities by employing a facile (31)P NMR methodology as a function of storage time and storage conditions. The kinetic treatment of the hydrolysis of triacylglycerols (TGs) and the isomerization of 1,2-diacylglycerols (1,2-DGs) to 1,3-diacylglycerols (1,3-DGs) during storage of 18 months at ambient temperature in the dark and light and at 5 degrees C in the dark showed that the isomerization is strongly dependent on the rate of the TGs hydrolysis, the initial free acidity (H(0)) of the virgin olive oil samples, and storage conditions. Although the time-evolution of the diacylglycerols (DGs) depends on the TGs hydrolysis, the ratio D of the concentration of 1,2-DGs to the total amount of DGs was found to be independent of this factor. From the kinetic expression of the ratio D, a quantitative measure was formulated that allows the estimation of the storage time or age of virgin olive oils. Application of this quantitative measure to several olive oil samples of known and unknown storage history resulted in a very good agreement with respect to the actual storage time for up to 10-12 months of storage. For a longer storage period, where the isomerization of DGs is close to its equilibrium state, the calculated age index is only indicative. 相似文献
19.
Dimitrios Gotsis Mike Spiliotis Spyros Giakoumakis 《Irrigation and Drainage Systems》2011,25(4):385-394
Water management for irrigation in areas with high water scarcity includes not only domestic wastewater treatment but also practices for the reuse of drainage water during the irrigation period. The main problem that concerns the reuse of drainage water for irrigation is the accumulation of salts due to the effluents existing in the soil. In this paper an optimization technique is proposed for the management of drainage water that uses, in combination, a soil-water-plant model (SWAP) and a mixed 0-1 linear programming method. The optimization routine was applied to the irrigation network of Alfeios River in Western Greece, an area that is characterized by high precipitation imbalances between winter and summer months. 相似文献
20.
Despoina Konstantinou Rafael V. Popin David P. Fewer Kaarina Sivonen Spyros Gkelis 《Marine drugs》2021,19(6)
Sponges form symbiotic relationships with diverse and abundant microbial communities. Cyanobacteria are among the most important members of the microbial communities that are associated with sponges. Here, we performed a genus-wide comparative genomic analysis of the newly described marine benthic cyanobacterial genus Leptothoe (Synechococcales). We obtained draft genomes from Le. kymatousa TAU-MAC 1615 and Le. spongobia TAU-MAC 1115, isolated from marine sponges. We identified five additional Leptothoe genomes, host-associated or free-living, using a phylogenomic approach, and the comparison of all genomes showed that the sponge-associated strains display features of a symbiotic lifestyle. Le. kymatousa and Le. spongobia have undergone genome reduction; they harbored considerably fewer genes encoding for (i) cofactors, vitamins, prosthetic groups, pigments, proteins, and amino acid biosynthesis; (ii) DNA repair; (iii) antioxidant enzymes; and (iv) biosynthesis of capsular and extracellular polysaccharides. They have also lost several genes related to chemotaxis and motility. Eukaryotic-like proteins, such as ankyrin repeats, playing important roles in sponge-symbiont interactions, were identified in sponge-associated Leptothoe genomes. The sponge-associated Leptothoe stains harbored biosynthetic gene clusters encoding novel natural products despite genome reduction. Comparisons of the biosynthetic capacities of Leptothoe with chemically rich cyanobacteria revealed that Leptothoe is another promising marine cyanobacterium for the biosynthesis of novel natural products. 相似文献